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Sample records for diametral tensile strength

  1. Comparison of polymer-based temporary crown and fixed partial denture materials by diametral tensile strength

    PubMed Central

    Ha, Seung-Ryong; Yang, Jae-Ho; Lee, Jai-Bong; Han, Jung-Suk

    2010-01-01

    PURPOSE The purpose of this study was to investigate the diametral tensile strength of polymer-based temporary crown and fixed partial denture (FPD) materials, and the change of the diametral tensile strength with time. MATERIAL AND METHODS One monomethacrylate-based temporary crown and FPD material (Trim) and three dimethacrylate-based ones (Protemp 3 Garant, Temphase, Luxtemp) were investigated. 20 specimens ( 4 mm 6 mm) were fabricated and randomly divided into two groups (Group I: Immediately, Group II: 1 hour) according to the measurement time after completion of mixing. Universal Testing Machine was used to load the specimens at a cross-head speed of 0.5 mm/min. The data were analyzed using one-way ANOVA, the multiple comparison Scheffe test and independent sample t test (? = 0.05). RESULTS Trim showed severe permanent deformation without an obvious fracture during loading at both times. There were statistically significant differences among the dimethacrylate-based materials. The dimethacrylate-based materials presented an increase in strength from 5 minutes to 1 hour and were as follows: Protemp 3 Garant (23.16 - 37.6 MPa), Temphase (22.27 - 28.08 MPa), Luxatemp (14.46 - 20.59 MPa). Protemp 3 Garant showed the highest value. CONCLUSION The dimethacrylate-based temporary materials tested were stronger in diametral tensile strength than the monomethacrylate-based one. The diametral tensile strength of the materials investigated increased with time. PMID:21165182

  2. Diametral tensile strength and bonding to dentin of type I glass ionomer cements.

    PubMed

    Galun, E A; Saleh, N; Lewinstein, I

    1994-10-01

    This study evaluated the diametral tensile strength of type I glass ionomer cements and measured their tensile and shear bond strengths to dentin with and without conditioning. Four brands of glass ionomer cement and one brand of zinc phosphate cement were tested. Disks of each cement type were prepared and the 7-day diametral compression test for tension was conducted. The shear and tensile tests, with and without 10% polyacrylic acid dentin conditioning, were performed with an Instron testing machine. Two additional groups, one for each bond test, were prepared and conditioned with 90% trichloracetic acid. No significant differences of the diametral strength were found among the various glass ionomer cements. The comparison of means suggests that, except for trichloracetic acid dentin pretreatment, the conditioning is an effective promoter of shear strength and has no significant effect (p < 0.01) on the tensile bond strength. However, trichloracetic acid was found to be a most effective dentin conditioner for both shear and tensile bond strengths (p < 0.01). PMID:7990049

  3. Diametral tensile strength and film thickness of an experimental dental luting agent derived from castor oil

    PubMed Central

    CARMELLO, Juliana Cabrini; FAIS, Laiza Maria Grassi; RIBEIRO, Lgia Nunes de Moraes; CLARO NETO, Salvador; GUAGLIANONI, Dalton Geraldo; PINELLI, Lgia Antunes Pereira

    2012-01-01

    The need to develop new dental luting agents in order to improve the success of treatments has greatly motivated research. Objective The aim of this study was to evaluate the diametral tensile strength (DTS) and film thickness (FT) of an experimental dental luting agent derived from castor oil (COP) with or without addition of different quantities of filler (calcium carbonate - CaCO3). Material and Methods Eighty specimens were manufactured (DTS N=40; FT N=40) and divided into 4 groups: Pure COP; COP 10%; COP 50% and zinc phosphate (control). The cements were mixed according to the manufacturers' recommendations and submitted to the tests. The DTS test was performed in the MTS 810 testing machine (10 KN, 0.5 mm/min). For FT test, the cements were sandwiched between two glass plates (2 cm2) and a load of 15 kg was applied vertically on the top of the specimen for 10 min. The data were analyzed by means of one-way ANOVA and Tukey's test (?=0.05). Results The values of DTS (MPa) were: Pure COP- 10.941.30; COP 10%- 30.060.64; COP 50%- 29.870.27; zinc phosphate- 4.880.96. The values of FT (m) were: Pure COP- 31.093.16; COP 10%- 17.054.83; COP 50%- 13.034.83; Zinc Phosphate- 20.000.12. One-way ANOVA showed statistically significant differences among the groups (DTS - p=1.01E-40; FT - p=2.4E-10). Conclusion The experimental dental luting agent with 50% of filler showed the best diametral tensile strength and film thickness. PMID:22437672

  4. Diametral tensile strength and Vickers hardness of a composite after storage in different solutions.

    PubMed

    Medeiros, Igor S; Gomes, Maurcio N; Loguercio, Alessandro D; Filho, Leonardo E R

    2007-03-01

    This study evaluated the Vickers hardness (VHN) and diametral tensile strength (DTS) of the composite Z100 (3M ESPE) cured with: Quartz-Tungsten-Halogen light curing unit (QTH) (700mW/cm2- 40 s) and Argon laser (1,000mW/cm2- 10 s). Specimens of 2 mm depth and 8 mm diameter were immersed for 30 days at 37 degrees C in different storage means: water, alcohol, acetic acid, propionic acid and dry (control). The DTS (n = 8) was determined with a crosshead speed of 0.5 mm/min. The VHN (n = 8) test was carried out using a 50 g load for 60 s. Statistical analysis was performed by two-way ANOVA and Tukey's test (alpha = 0.05). The relationship between VHN and DTS was observed by Pearson correlation. The light source was not significant in both tests (VHN: P < 0.18; DTS: P < 0.92), but the factor storage showed significance (P < .001). Mechanical properties of the control group were statistically superior to those of the other storage groups (VHN = 102.2; DTS = 42.3 MPa). The alcohol group showed the lowest VHN (93.3) and DTS (33.8 MPa) values, which were similar to values for propionic (VHN = 97.5; DTS = 35.9 MPa) and acetic acids (VHN = 97.8; DTS = 36.1 MPa), but different from that of water (VHN = 102.2; DTS = 42.3 MPa). The relationship between VHN and DTS values presented a positive correlation (r2 = 0.90; P < 0.01). PMID:17429184

  5. Influence of different crosshead speeds on diametral tensile strength of a methacrylate based resin composite: An in-vitro study

    PubMed Central

    Sood, Anubhav; Ramarao, Sathyanarayanan; Carounanidy, Usha

    2015-01-01

    Aim: The aim was to evaluate the influence of different crosshead speeds on diametral tensile strength (DTS) of a resin composite material (Tetric N-Ceram). Materials and Methods: The DTS of Tetric N-Ceram was evaluated using four different crosshead speeds 0.5 mm/min (DTS 1), 1 mm/min (DTS 2), 5 mm/min (DTS 3), 10 mm/min (DTS 4). A total of 48 specimens were prepared and divided into four subgroups with 12 specimens in each group. Specimens were made using stainless steel split custom molds of dimensions 6 mm diameter and 3 mm height. The specimens were stored in distilled water at room temperature for 24 h. Universal testing machine was used and DTS values were calculated in MPa. Results: Analysis of variance was used to compare the four groups. Higher mean DTS value was recorded in DTS 2 followed by DTS 4, DTS 1, and DTS 3, respectively. However, the difference in mean tensile strength between the groups was not statistically significant (P > 0.05). Conclusion: The crosshead speed variation between 0.5 and 10 mm/min does not seem to influence the DTS of a resin composite. PMID:26069407

  6. Finite Element Simulation of Diametral Strength Test of Hydroxyapatite

    SciTech Connect

    Ozturk, Fahrettin; Toros, Serkan; Evis, Zafer

    2011-01-17

    In this study, the diametral strength test of sintered hydroxyapatite was simulated by the finite element software, ABAQUS/Standard. Stress distributions on diametral test sample were determined. The effect of sintering temperature on stress distribution of hydroxyapatite was studied. It was concluded that high sintering temperatures did not reduce the stress on hydroxyapatite. It had a negative effect on stress distribution of hydroxyapatite after 1300 deg. C. In addition to the porosity, other factors (sintering temperature, presence of phases and the degree of crystallinity) affect the diametral strength of the hydroxyapatite.

  7. A novel dentin bond strength measurement technique using a composite disk in diametral compression.

    PubMed

    Huang, Shih-Hao; Lin, Lian-Shan; Rudney, Joel; Jones, Rob; Aparicio, Conrado; Lin, Chun-Pin; Fok, Alex

    2012-04-01

    New methods are needed that can predict the clinical failure of dental restorations that primarily rely on dentin bonding. Existing methods have shortcomings, e.g. severe deviation in the actual stress distribution from theory and a large standard deviation in the measured bond strength. We introduce here a novel test specimen by examining an endodontic model for dentin bonding. Specifically, we evaluated the feasibility of using the modified Brazilian disk test to measure the post-dentin interfacial bond strength. Four groups of resin composite disks which contained a slice of dentin with or without an intracanal post in the center were tested under diametral compression until fracture. Advanced nondestructive examination and imaging techniques in the form of acoustic emission (AE) and digital image correlation (DIC) were used innovatively to capture the fracture process in real time. DIC showed strain concentration first appearing at one of the lateral sides of the post-dentin interface. The appearance of the interfacial strain concentration also coincided with the first AE signal detected. Utilizing both the experimental data and finite-element analysis, the bond/tensile strengths were calculated to be: 11.2 MPa (fiber posts), 12.9 MPa (metal posts), 8.9 MPa (direct resin fillings) and 82.6 MPa for dentin. We have thus established the feasibility of using the composite disk in diametral compression to measure the bond strength between intracanal posts and dentin. The new method has the advantages of simpler specimen preparation, no premature failure, more consistent failure mode and smaller variations in the calculated bond strength. PMID:22266033

  8. 7 CFR 29.3061 - Strength (tensile).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strength (tensile). 29.3061 Section 29.3061... Type 93) 29.3061 Strength (tensile). The stress a tobacco leaf can bear without tearing. Tensile strength is not an important element of quality in Burley tobacco....

  9. 7 CFR 29.6040 - Strength (tensile).

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Strength (tensile). 29.6040 Section 29.6040 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards... REGULATIONS TOBACCO INSPECTION Standards Definitions 29.6040 Strength (tensile). The stress a tobacco...

  10. Surfactant effects on soil aggregate tensile strength

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  11. CHARACTERIZATION OF TENSILE STRENGTH OF GLOVEBOX GLOVES

    SciTech Connect

    Korinko, P.; Chapman, G.

    2012-02-29

    A task was undertaken to compare various properties of different glovebox gloves, having various compositions, for use in gloveboxes at the Savannah River Site (SRS). One aspect of this project was to determine the tensile strength (TS) of the gloves. Longitudinal tensile samples were cut from 15 different gloves and tensile tested. The stress, load, and elongation at failure were determined. All of the gloves that are approved for glovebox use and listed in the glovebox procurement specification met the tensile and elongation requirements. The Viton{reg_sign} compound gloves are not listed in the specification, but exhibited lower tensile strengths than permissible based on the Butyl rubber requirements. Piercan Polyurethane gloves were the thinnest samples and exhibited the highest tensile strength of the materials tested.

  12. Method and apparatus for determining tensile strength

    DOEpatents

    Ratigan, Joe L.

    1984-01-01

    A method and apparatus for determining the statistical distribution of apparent tensile strength of rock, the size effect with respect to tensile strength, as well as apparent deformation modulus of both intact and fractured or jointed rock. The method is carried out by inserting a plug of deformable material, such as rubber, in an opening of a specimen to be tested. The deformable material is loaded by an upper and lower platen until the specimen ruptures, whereafter the tensile strength is calculated based on the parameters of the test specimen and apparatus.

  13. Method and apparatus for determining tensile strength

    DOEpatents

    Ratigan, J.L.

    1982-05-28

    A method and apparatus is described for determining the statistical distribution of apparent tensile strength of rock, the size effect with respect to tensile strength, as well as apparent deformation modulus of both intact and fractured or jointed rock. The method is carried out by inserting a plug of deformable material, such as rubber, in an opening of a specimen to be tested. The deformable material is loaded by an upper and lower platen until the specimen ruptures, whereafter the tensile strength is calculated based on the parameters of the test specimen and apparatus.

  14. Tensile Strength Measurements on Biopolymer Films

    NASA Astrophysics Data System (ADS)

    Stevens, Eugene S.; Poliks, Mark D.

    2003-07-01

    An experiment is described in which students prepare biopolymer (agar, gelatin, and starch) films from aqueous solution and measure the tensile strengths of the films using easily constructed equipment. Agar and gelatin form moderately strong films. Starch forms weak films but the strength is increased by combining with agar and gelatin.

  15. Making High-Tensile-Strength Amalgam Components

    NASA Technical Reports Server (NTRS)

    Grugel, Richard

    2008-01-01

    Structural components made of amalgams can be made to have tensile strengths much greater than previously known to be possible. Amalgams, perhaps best known for their use in dental fillings, have several useful attributes, including room-temperature fabrication, corrosion resistance, dimensional stability, and high compressive strength. However, the range of applications of amalgams has been limited by their very small tensile strengths. Now, it has been discovered that the tensile strength of an amalgam depends critically on the sizes and shapes of the particles from which it is made and, consequently, the tensile strength can be greatly increased through suitable choice of the particles. Heretofore, the powder particles used to make amalgams have been, variously, in the form of micron-sized spheroids or flakes. The tensile reinforcement contributed by the spheroids and flakes is minimal because fracture paths simply go around these particles. However, if spheroids or flakes are replaced by strands having greater lengths, then tensile reinforcement can be increased significantly. The feasibility of this concept was shown in an experiment in which electrical copper wires, serving as demonstration substitutes for copper powder particles, were triturated with gallium by use of a mortar and pestle and the resulting amalgam was compressed into a mold. The tensile strength of the amalgam specimen was then measured and found to be greater than 10(exp 4) psi (greater than about 69 MPa). Much remains to be done to optimize the properties of amalgams for various applications through suitable choice of starting constituents and modification of the trituration and molding processes. The choice of wire size and composition are expected to be especially important. Perusal of phase diagrams of metal mixtures could give insight that would enable choices of solid and liquid metal constituents. Finally, whereas heretofore, only binary alloys have been considered for amalgams, ternary additions to liquid or solid components should be considered as means to impart desired properties to amalgams.

  16. A comparison of pressure compaction and diametral compression tests for determining granule strengths

    SciTech Connect

    Glass, S.J.; Newton, C.

    1994-12-31

    Lightning strikes can cause structural damage, ignite flammable materials, and produce circuit malfunctions in missiles, aircraft, and ground systems. Lightning arrestor connectors (LACs) are used to divert harmful lightning energy away from these systems by providing less destructive breakdown paths. Ceramic granules in the size range of 150--200 {micro}m are used in LACs to provide physical and electrical separation of contacts (pins) from the surrounding metal web, and to control the voltage breakdown level. Pressure compaction (P-C) tests were used to characterize the strength of ceramic granules. When compaction data are plotted as relative density of the compact versus the compaction pressure two linear regions are generally observed. The intersection of these regions, which is known as the ``breakpoint,`` has been used as a semi-quantitative measure of granule strength. Comparisons were made between the P-C breakpoint and strengths of 150--200 {micro}m diameter ZnO, TiO{sub 2} (rutile), and lead magnesium niobate-lead titanate (PMN-PT) granules, where the strengths were determined by diametral compression (D-C) tests. At high compaction pressures the compliance of the die itself is significant and was accounted for in the analyses. Tests were conducted at different compaction rates, and with different aspect ratio compacts. High aspect ratios and loading rates decrease the slope of the second linear portion of the compaction curve and produce higher apparent P-C breakpoints. Comparison of the P-C breakpoint to the average D-C strength indicates that the D-C strength is approximately fifty percent higher for PMN-PT granules. To eliminate the uncertainty in results due to irregular granules sizes and shapes, comparisons were made for uniform size (210 {micro}m) glass spheres. In this case the average D-C strength coincided with a second breakpoint in the P-C data, which occurred after compaction by a mechanism of bridge formation and collapse had ceased.

  17. 49 CFR 230.26 - Tensile strength of shell plates.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of... 49 Transportation 4 2012-10-01 2012-10-01 false Tensile strength of shell plates. 230.26...

  18. 49 CFR 230.26 - Tensile strength of shell plates.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of... 49 Transportation 4 2011-10-01 2011-10-01 false Tensile strength of shell plates. 230.26...

  19. 49 CFR 230.26 - Tensile strength of shell plates.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of... 49 Transportation 4 2010-10-01 2010-10-01 false Tensile strength of shell plates. 230.26...

  20. 49 CFR 230.26 - Tensile strength of shell plates.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of... 49 Transportation 4 2014-10-01 2014-10-01 false Tensile strength of shell plates. 230.26...

  1. 49 CFR 230.26 - Tensile strength of shell plates.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of... 49 Transportation 4 2013-10-01 2013-10-01 false Tensile strength of shell plates. 230.26...

  2. The tensile strength of helium II

    SciTech Connect

    Xiong, Quan.

    1991-01-01

    The study of the negative pressure required to produce cavitation in liquid helium (i.e. the tensile strength of helium) has been of continuing interest for two reasons. Since all other elements have freezing temperatures of 14 K or higher, helium can be prepared free of gaseous impurities which can serve as centers for heterogeneous nucleation of bubbles which will reduce the tensile strength of the liquid. Secondly, helium remains a liquid even down to the absolute zero of temperature. Consequently, it has been considered that at sufficiently low temperatures there is the possibility that the rate of nucleation of bubbles is dominated by quantum tunneling. In this thesis, the authors reexamined the theory of homogeneous nucleation and made an estimate of the equation of state for negative pressure in helium. He found that the earlier theories were incorrect in that they took no account of the equation of state of liquid helium in the negative pressure regime. The tensile strength of helium at T = 0 K should be around [minus]9 bars instead of [minus]17 bars predicted by the standard theory.

  3. Tensile Bond Strength of Latex-Modified Bonded Concrete Overlays

    NASA Astrophysics Data System (ADS)

    Dubois, Cameron; Ramseyer, Chris

    2010-10-01

    The tensile bond strength of bonded concrete overlays was tested using the in-situ pull-off method described in ASTM C 1583 with the goal of determining whether adding latex to the mix design increases bond strength. One slab of ductile concrete (f'c > 12,000 psi) was cast with one half tined, i.e. roughened, and one half steel-troweled, i.e. smooth. The slab surface was sectioned off and overlay mixtures containing different latex contents cast in each section. Partial cores were drilled perpendicular to the surface through the overlay into the substrate. A tensile loading device applied a direct tensile load to each specimen and the load was increased until failure occurred. The tensile bond strength was then calculated for comparison between the specimens.

  4. Silicon nitride having a high tensile strength

    DOEpatents

    Pujari, V.K.; Tracey, D.M.; Foley, M.R.; Paille, N.I.; Pelletier, P.J.; Sales, L.C.; Willkens, C.A.; Yeckley, R.L.

    1996-11-05

    A silicon nitride ceramic is disclosed comprising: (a) inclusions no greater than 25 microns in length, (b) agglomerates no greater than 20 microns in diameter, and (c) a surface finish of less than about 8 microinches, said ceramic having a four-point flexural strength of at least about 900 MPa. 4 figs.

  5. Silicon nitride having a high tensile strength

    DOEpatents

    Pujari, Vimal K.; Tracey, Dennis M.; Foley, Michael R.; Paille, Norman I.; Pelletier, Paul J.; Sales, Lenny C.; Willkens, Craig A.; Yeckley, Russell L.

    1996-01-01

    A silicon nitride ceramic comprising: a) inclusions no greater than 25 microns in length, b) agglomerates no greater than 20 microns in diameter, and c) a surface finish of less than about 8 microinches, said ceramic having a four-point flexural strength of at least about 900 MPa.

  6. Water's tensile strength measured using an optofluidic chip.

    PubMed

    Li, Z G; Xiong, S; Chin, L K; Ando, K; Zhang, J B; Liu, A Q

    2015-05-21

    In this paper, for the first time, the tensile strength of water is directly measured using an optofluidic chip based on the displacement of air-water interface deformation with homogeneous nucleation. When water in a microchannel is stretched dynamically via laser-induced shock reflection at the air-water interface, the shock pressures are determined by measuring the displacements of the deformed interface. Observation of the vapor bubbles is used as a probe to identify the cavitation threshold with a critical distance, and the tensile strength of water at 20 °C is measured to be -33.3 ± 2.8 MPa. This method can be extended to investigate the tensile strength of other soft materials such as glycerol, which is measured to be -59.8 ± 10.7 MPa at 20 °C. PMID:25812076

  7. Covalent Crosslinking of Carbon Nanotube Materials for Improved Tensile Strength

    NASA Technical Reports Server (NTRS)

    Baker, James S.; Miller, Sandi G.; Williams, Tiffany A.; Meador, Michael A.

    2013-01-01

    Carbon nanotubes have attracted much interest in recent years due to their exceptional mechanical properties. Currently, the tensile properties of bulk carbon nanotube-based materials (yarns, sheets, etc.) fall far short of those of the individual nanotube elements. The premature failure in these materials under tensile load has been attributed to inter-tube sliding, which requires far less force than that needed to fracture individual nanotubes.1,2 In order for nanotube materials to achieve their full potential, methods are needed to restrict this tube-tube shear and increase inter-tube forces.Our group is examining covalent crosslinking between the nanotubes as a means to increase the tensile properties of carbon nanotube materials. We are working with multi-walled carbon nanotube (MWCNT) sheet and yarn materials obtained from commercial sources. Several routes to functionalize the nanotubes have been examined including nitrene, aryl diazonium, and epoxide chemistries. The functional nanotubes were crosslinked through small molecule or polymeric bridges. Additionally, electron beam irradiation induced crosslinking of the non-functional and functional nanotube materials was conducted. For example, a nanotube sheet material containing approximately 3.5 mol amine functional groups exhibited a tensile strength of 75 MPa and a tensile modulus of 1.16 GPa, compared to 49 MPa and 0.57 GPa, respectively, for the as-received material. Electron beam irradiation (2.2x 1017 ecm2) of the same amine-functional sheet material further increased the tensile strength to 120 MPa and the modulus to 2.61 GPa. This represents approximately a 150 increase in tensile strength and a 360 increase in tensile modulus over the as-received material with only a 25 increase in material mass. Once we have optimized the nanotube crosslinking methods, the performance of these materials in polymer matrix composites will be evaluated.

  8. Tensile strength of cementitious materials under triaxial loading

    NASA Astrophysics Data System (ADS)

    Tsubota, Shuji

    1998-11-01

    A general tension-compression-compression (sigmasb1, sigmasb2=sigmasb3) failure criterion for brittle materials is mathematically developed using FEM analysis and experimentally verified by use of the cementitious composite axial tensile test (CCATT). This tensile failure criterion is based on the stress concentration derived from the classical theory of elasticity. This analytical approach shows the upper bound of the tension-compression-compression failure surface for brittle materials. Since the CCATT applies confining hydraulic pressure, a tensile specimen is subjected to triaxial loading defined by the principal stress ratio sigmasb1/|sigmasb2|. When lateral pressure increases, tensile strength decreases; therefore, stress concentration is defined as a function of the principal stress ratio. The model has three distinct regions of behavior corresponding to the principal stress ratio, 0?sigmasb1/|sigmasb2|<0.9 (high-lateral pressure), 0.9?sigmasb1/|sigmasb2|<3.0 (medium-lateral pressure), 3.0?sigmasb1/|sigmasb2| (low-lateral pressure). The experimental failure line shows true tensile strength of cementitious materials under low-lateral pressure. The predicted nominal stress fsb{ta} with large size specimens for the CCATT is written as$fsb{ta}=gamma*{1/{Kt}}*alpha* pwhere gamma$ is the size effect obtained by experimental results; Kt is the stress concentration factor derived from triaxial loading. Tensile strength values from the CCATT are compared to experimental results from other tests such as the uniaxial tensile test and the split cylinder test. CCATT results are analyzed using Weibull theory to measure material reliability and to develop characteristic stresses for construction design. Failure analysis using fractography was conducted on fractured cementitious materials and composites. The failure analysis on test specimens correlated well with FEM stress distributions and with the principal stress ratio. The observed fracture behavior (fracture patterns) was correlated to different strength regions of the model. Additionally, a failure model of fiber wrapped cementitious composite is developed. Using data on load-extension behavior from the UTT and ultimate strength from the CCATT models for fiber wrapped cementitious composites were developed. These models predict the mechanical behavior of fiber sheets subjected to cycles of wetting and drying in a simulated seawater environment; therefore, the tensile strength using the CCATT is applicable to a wide range of brittle materials including cementitious composites.

  9. Improved molding process ensures plastic parts of higher tensile strength

    NASA Technical Reports Server (NTRS)

    Heier, W. C.

    1968-01-01

    Single molding process ensures that plastic parts /of a given mechanical design/ produced from a conventional thermosetting molding compound will have a maximum tensile strength. The process can also be used for other thermosetting compounds to produce parts with improved physical properties.

  10. Importance of Tensile Strength on the Shear Behavior of Discontinuities

    NASA Astrophysics Data System (ADS)

    Ghazvinian, A. H.; Azinfar, M. J.; Geranmayeh Vaneghi, R.

    2012-05-01

    In this study, the shear behavior of discontinuities possessing two different rock wall types with distinct separate compressive strengths was investigated. The designed profiles consisted of regular artificial joints molded by five types of plaster mortars, each representing a distinct uniaxial compressive strength. The compressive strengths of plaster specimens ranged from 5.9 to 19.5 MPa. These specimens were molded considering a regular triangular asperity profile and were designed so as to achieve joint walls with different strength material combinations. The results showed that the shear behavior of discontinuities possessing different joint wall compressive strengths (DDJCS) tested under constant normal load (CNL) conditions is the same as those possessing identical joint wall strengths, but the shear strength of DDJCS is governed by minor joint wall compressive strength. In addition, it was measured that the predicted values obtained by Barton's empirical criterion are greater than the experimental results. The finding indicates that there is a correlation between the joint roughness coefficient (JRC), normal stress, and mechanical strength. It was observed that the mode of failure of asperities is either pure tensile, pure shear, or a combination of both. Therefore, Barton's strength criterion, which considers the compressive strength of joint walls, was modified by substituting the compressive strength with the tensile strength. The validity of the modified criterion was examined by the comparison of the predicted shear values with the laboratory shear test results reported by Grasselli (Ph.D. thesis n.2404, Civil Engineering Department, EPFL, Lausanne, Switzerland, 2001). These comparisons infer that the modified criterion can predict the shear strength of joints more precisely.

  11. In vitro tensile strength of luting cements on metallic substrate.

    PubMed

    Orsi, Iara A; Varoli, Fernando K; Pieroni, Carlos H P; Ferreira, Marly C C G; Borie, Eduardo

    2014-01-01

    The aim of this study was to determine the tensile strength of crowns cemented on metallic substrate with four different types of luting agents. Twenty human maxillary molars with similar diameters were selected and prepared to receive metallic core castings (Cu-Al). After cementation and preparation the cores were measured and the area of crown's portion was calculated. The teeth were divided into four groups based on the luting agent used to cement the crowns: zinc phosphate cement; glass ionomer cement; resin cement Rely X; and resin cement Panavia F. The teeth with the crowns cemented were subjected to thermocycling and later to the tensile strength test using universal testing machine with a load cell of 200 kgf and a crosshead speed of 0.5 mm/min. The load required to dislodge the crowns was recorded and converted to MPa/mm(2). Data were subjected to Kruskal-Wallis analysis with a significance level of 1%. Panavia F showed significantly higher retention in core casts (3.067 MPa/mm(2)), when compared with the other cements. Rely X showed a mean retention value of 1.877 MPa/mm(2) and the zinc phosphate cement with 1.155 MPa/mm(2). Glass ionomer cement (0.884 MPa/mm(2)) exhibited the lowest tensile strength value. Crowns cemented with Panavia F on cast metallic posts and cores presented higher tensile strength. The glass ionomer cement showed the lowest tensile strength among all the cements studied. PMID:25140718

  12. Tensile and shear strength of porous dust agglomerates

    NASA Astrophysics Data System (ADS)

    Seizinger, A.; Speith, R.; Kley, W.

    2013-11-01

    Context. Within the sequential accretion scenario of planet formation, planets are built up through a sequence of sticking collisions. The outcome of collisions between porous dust aggregates is very important for the growth from very small dust particles to planetesimals. In this work we determine the necessary material properties of dust aggregates as a function of porosity. Aims: Continuum models such as SPH that are capable of simulating collisions of macroscopic dust aggregates require a set of material parameters. Some of them, such as the tensile and shear strength, are difficult to obtain from laboratory experiments. The aim of this work is to determine these parameters from ab initio molecular dynamics simulations. Methods: We simulated the behavior of porous dust aggregates using a detailed micro-physical model of the interaction of spherical grains that includes adhesion forces, rolling, twisting, and sliding. Using different methods of preparing the samples, we studied the strength behavior of our samples with varying porosity and coordination number of the material. Results: For the tensile strength, we can reproduce data from laboratory experiments very well. For the shear strength, there are no experimental data available. The results from our simulations differ significantly from previous theoretical models, which indicates that the latter might not be sufficient to describe porous dust aggregates. Conclusions: We have provided the functional behavior of tensile and shear strength of porous dust aggregates as a function of the porosity, which can be directly applied to continuum simulations of these objects in planet formation scenarios.

  13. Tensile Strength of Natural Fiber Reinforced Polyester Composite

    NASA Astrophysics Data System (ADS)

    Ismail, Al Emran; Awang, Muhd. Khairudin; Sa'at, Mohd Hisham

    2007-05-01

    Nowadays, increasing awareness of replacing synthetic fiber such as glass fiber has emerged due to environmental problems and pollutions. Automotive manufacturers also seek new material especially biodegradable material to be non-load bearing application parts. This present work discussed on the effect of silane treatment on coir fiber reinforced composites. From the results of tensile tests, fibers treated with silane have attained maximum material stiffness. However, to achieve maximum ultimate tensile strength and strain at failure performances, untreated fibers work very well through fiber bridging and internal friction between fiber and polymeric matrix. Scanning electron microscope (SEM) observations have coincided with these results.

  14. Dentin adhesive tensile strength after Nd:YAG laser application

    NASA Astrophysics Data System (ADS)

    Lizarelli, Rosane F. Z.; Miranda, Walter G., Jr.; Eduardo, Carlos d. P.

    1999-05-01

    The authors evaluated, in vitro, the tensile strength of a hydrophilic adhesive on dentin surface, with and without previous treatment with high power Nd:YAG laser. Power of 1.0 W and 2.0 W with respective frequencies of 25 Hz and 50 Hz were used. Thirteen human extracted molars were prepared and randomly separated in five groups: GI, Nd:YAG laser with 1.0 W plus SBMPP (3M) adhesive system; GII, laser with 2.0 W, plus adhesive system; GIII, laser with 1.0 W; GIV, laser with 2.0 W; GV, adhesive system to treat dentin surface. To each group five samples with a composite bottom each, totalling in 25 samples, which were kept in distilled water, by 37C, during 30 days. After that, thermal cycling was applied. After this period, the samples were submitted the tensile strength test to evaluate the necessary threshold of power to break up the adhesive bond of composite button from dentin surface. The statistical evaluation was done through variance analysis. Results showed that the values of tensile strength of the GV (26.4 kgf/cm2) were better than GI (4.6 kgf/cm2) which was the best laser group: GIII (2.4 kgf/cm2); GII (1.7 kgf/cm2) and GIV (1.2 kgf/cm2).

  15. Tensile Strength of Cell Walls of Living Cells 1

    PubMed Central

    Carpita, Nicholas C.

    1985-01-01

    A gas decompression technique was used to determine the breaking strength of cell walls of single cells. Breaking strengths of the bacterium Salmonella typhimurium and the unicellular green alga Chlamydomonas eugametos were 100 and 95 atmospheres, respectively, while those of sporophytes of the water mold Blastocladiella emersonii were 65 atmospheres, and those of suspension cultured cells of carrot were only 30 atmospheres. Estimation of wall tensile stress based on breaking pressures, cell radii, and estimation of wall thickness, indicates that microfibrillar walls are not necessarily stronger than walls of primitive organisms. Hence, alternative hypotheses for their evolution must be considered. PMID:16664436

  16. Effects of parachute-ribbon surface treatments on tensile strength

    SciTech Connect

    Auerbach, I.; Whinery, L.D.; Johnson, D.W.; Mead, K.E.; Sheldon, D.D.

    1986-01-01

    Routine quality-assurance evaluations of nylon ribbons used on test-deployed parachutes revealed tensile-strength degradation had occurred in some of the ribbons. The degradation occurred exclusively in some of the noncritical skirt ribbons with stenciled blue-ink identification markings. Although the strength loss was excessive, the reliability of the parachute was not affected. These results motivated an accelerated-aging study of the effects on tensile strength of not only the inks but also of the sizing chemicals that are used to coat fabrics in parachute construction. Nylon ribbons and Kevlar webbing were treated with these materials and stored both under ambient conditions and at 60/sup 0/C (140/sup 0/F) for periods of time up to eight months. Small increases in strength developed under ambient conditions whereas small decreases developed at elevated temperatures. Samples stored in glass degraded more than those stored in stainless steel. None of these laboratory results correlated with those obtained from parachutes. Possible explanations for the lack of a correlation are provided in this paper. Additional studies are in progress.

  17. Tensile strength of bilayered ceramics and corresponding glass veneers

    PubMed Central

    Champirat, Tharee; Jirajariyavej, Bundhit

    2014-01-01

    PURPOSE To investigate the microtensile bond strength between two all-ceramic systems; lithium disilicate glass ceramic and zirconia core ceramics bonded with their corresponding glass veneers. MATERIALS AND METHODS Blocks of core ceramics (IPS e.max Press and Lava Frame) were fabricated and veneered with their corresponding glass veneers. The bilayered blocks were cut into microbars; 8 mm in length and 1 mm2 in cross-sectional area (n = 30/group). Additionally, monolithic microbars of these two veneers (IPS e.max Ceram and Lava Ceram; n = 30/group) were also prepared. The obtained microbars were tested in tension until fracture, and the fracture surfaces of the microbars were examined with fluorescent black light and scanning electron microscope (SEM) to identify the mode of failure. One-way ANOVA and the Dunnett's T3 test were performed to determine significant differences of the mean microtensile bond strength at a significance level of 0.05. RESULTS The mean microtensile bond strength of IPS e.max Press/IPS e.max Ceram (43.40 5.51 MPa) was significantly greater than that of Lava Frame/Lava Ceram (31.71 7.03 MPa)(P<.001). Fluorescent black light and SEM analysis showed that most of the tested microbars failed cohesively in the veneer layer. Furthermore, the bond strength of Lava Frame/Lava Ceram was comparable to the tensile strength of monolithic glass veneer of Lava Ceram, while the bond strength of bilayered IPS e.max Press/IPS e.max Ceram was significantly greater than tensile strength of monolithic IPS e.max Ceram. CONCLUSION Because fracture site occurred mostly in the glass veneer and most failures were away from the interfacial zone, microtensile bond test may not be a suitable test for bonding integrity. Fracture mechanics approach such as fracture toughness of the interface may be more appropriate to represent the bonding quality between two materials. PMID:25006377

  18. Through-the-thickness tensile strength of textile composites

    NASA Technical Reports Server (NTRS)

    Jackson, Wade C.; Ifju, Peter G.

    1994-01-01

    A series of tests was run to characterize the through-the-thickness tensile strength for a variety of composites that included 2D and 3D braids, 2D and 3D weaves, and prepreg tapes. A new test method based on a curved beam was evaluated. The through-the-thickness deformations were characterized using moire interferometry. Failures were significantly different between the 2D and 3D materials. The 2D materials delaminated between layers due to out-of-plane tensile stresses. The strength of the 2D textile composites did not increase relative to the tapes. The 3D materials failed due to the formation of radial cracks caused by high circumferential stresses along the inner radius. A circumferential crack similar to the 2D materials produced the final failure. Final failure in the 3D materials occurred at a lower bending moment than in other materials. The early failures were caused by radial crack formation rather than low through-the-thickness strength.

  19. Dynamic compressive and tensile strengths of spark plasma sintered alumina

    SciTech Connect

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M. P.; Frage, N.

    2014-06-28

    Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1 km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100–1000 m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr{sub 2}O{sub 3} decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

  20. Dynamic compressive and tensile strengths of spark plasma sintered alumina

    NASA Astrophysics Data System (ADS)

    Girlitsky, I.; Zaretsky, E.; Kalabukhov, S.; Dariel, M. P.; Frage, N.

    2014-06-01

    Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1 km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100-1000 m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr2O3 decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.

  1. Tensile strengths of paracetamol and Avicel powders and their mixtures.

    PubMed

    Bangudu, A B; Pilpel, N

    1984-11-01

    Measurements were made of the tensile strengths of paracetamol and Avicel powders and of their mixtures. Two quantities were derived from the results; m, a universal constant whose value was 1.00 +/- 0.23 and alpha, a constant of the material. The value of alpha for paracetamol was much larger than that for Avicel and increased slightly with increase in particle size. Adding 25% w/w of Avicel to paracetamol produced a significant decrease in alpha and this fact may account for its use as an excipient in the tableting of paracetamol. PMID:6150973

  2. Strain rate effects on tensile strength of iron green bodies

    NASA Astrophysics Data System (ADS)

    Nishida, Masahiro; Kuroyanagi, Yuki; Hggblad, Hans-ke; Jonsn, Pr; Gustafsson, Gustaf

    2015-09-01

    Impact tensile strength of iron green bodies with densities of 7.2 and 7.4 g/cm3 was examined by Brazilian test using the split-Hopkinson pressure bar (Kolsky bar) method. The powder material used for the experiments was a press-ready premix containing Distaloy AE, graphite, and lubricant. During dynamic compression, the failure behavior of specimens was observed using a high-speed video camera. The failure stress and failure behavior of dynamic compressive tests were compared with those of static compressive tests.

  3. Size effect on flexural, splitting tensile, and torsional strengths of high-strength concrete

    SciTech Connect

    Zhou, F.P.; Balendran, R.V.; Jeary, A.P.

    1998-12-01

    This paper presents the results of an investigation into the size effect on flexural, splitting tensile, and torsional strengths of high-strength concrete (HSC) with normal aggregate (crushed limestone) and lightweight aggregate (sintered fly ash). The Bazant`s size effect law gives a very good fit to the flexural strengths of both normal and lightweight aggregate HSC measured from beams of different sizes. As observed in the size effect curve, the fracture behavior of the lightweight HSC seems more brittle than that of the normal HSC. Linear elastic fracture mechanics may still be less applicable to HSC in the normal size range than nonlinear fracture mechanics. A reverse size effect is observed in the prism splitting tensile strengths of both normal and light-weight HSC and possible mechanisms of the reverse size effect are discussed. The torsional strength of the lightweight HSC appears to have a stronger size dependency than that of the normal HSC.

  4. Effects of conventional welding and laser welding on the tensile strength, ultimate tensile strength and surface characteristics of two cobalt-chromium alloys: a comparative study.

    PubMed

    Madhan Kumar, Seenivasan; Sethumadhava, Jayesh Raghavendra; Anand Kumar, Vaidyanathan; Manita, Grover

    2012-06-01

    The purpose of this study was to evaluate the efficacy of laser welding and conventional welding on the tensile strength and ultimate tensile strength of the cobalt-chromium alloy. Samples were prepared with two commercially available cobalt-chromium alloys (Wironium plus and Diadur alloy). The samples were sectioned and the broken fragments were joined using Conventional and Laser welding techniques. The welded joints were subjected to tensile and ultimate tensile strength testing; and scanning electron microscope to evaluate the surface characteristics at the welded site. Both on laser welding as well as on conventional welding technique, Diadur alloy samples showed lesser values when tested for tensile and ultimate tensile strength when compared to Wironium alloy samples. Under the scanning electron microscope, the laser welded joints show uniform welding and continuous molt pool all over the surface with less porosity than the conventionally welded joints. Laser welding is an advantageous method of connecting or repairing cast metal prosthetic frameworks. PMID:23858281

  5. Predicting yield strength and tensile strength after forming for automotive integral body structural rail type parts

    SciTech Connect

    Levy, B.S.

    1984-01-01

    Samples of cold rolled and hot dip galvanized mild steel, microalloyed high strength steel, and dual phase steel were prestrained by bending and straightening, bending and straightening with superimposed tensile strain in a die, and cold rolling (dual phase steels only). In all three cases, the strain state was approximately plane strain. Stress-strain behavior was evaluated by conventional tensile testing of as-received and prestrained samples. For the mild and the high strength microalloyed steels, it is shown that the use of effective prestrain calculated assuming isotropy coupled with simple parabolic work hardening provides reasonable engineering estimates of the yield and tensile strength after prestraining if K and n are taken from as-received tensile tests oriented coaxially to the restrain direction. It was also found that in bending and straightening, only the absolute average value of the bending strain should be used in calculating the effective prestrain. For steels with dual phase microstructures, this approach to predicting cold work strengthening does not provide useful engineering estimates.

  6. Improved Tensile Adhesion Specimens for High Strength Epoxy Systems in Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Haddock, M. Reed; McLennan, Michael L.

    2000-01-01

    An improved tensile adhesion button has been designed and tested that results in higher measured tensile adhesion strength while providing increased capability for testing high strength epoxy adhesive systems. The best attributes of two well-established tensile button designs were combined and refined into an optimized tensile button. The most significant design change to the tensile button was to improve alignment of the bonded tensile button specimens during tensile testing by changing the interface between the tensile button and the tensile test machine. The established or old button design uses a test fixture that pulls from a grooved annulus or anvil head while the new button design pulls from a threaded hole in the centerline of the button. Finite element (FE) analysis showed that asymmetric loading of the established anvil head tensile button significantly increases the stress concentration in the adhesive, causing failure at lower tensile test loads. The new tensile button was designed to eliminate asymmetric loading and eliminate misalignment sensitivity. Enhanced alignment resulted in improved tensile adhesion strength measurement up to 13.8 MPa (2000psi) over the established button design. Another design change increased the capability of the button by increasing the threaded hole diameter allowing it to test high strength epoxy systems up to 85 MPa(less than 12,000 psi). The improved tensile button can be used in button- to-button or button-to-panel configurations.

  7. ZERODUR: bending strength data for tensile stress loaded support structures

    NASA Astrophysics Data System (ADS)

    Bizjak, Tanja; Hartmann, Peter; Westerhoff, Thomas

    2012-03-01

    In the past ZERODUR was mainly used for mirror and substrate applications, where mechanical loads were given by its own weight. Nowadays substrates become more sophisticated and subject to higher stresses as consequences of high operational accelerations or vibrations. The integrity of structures such as reticle and wafer stages e.g. must be guaranteed with low failure probability over their full intended life time. Their design requires statistically relevant strength data and information. The usual way determining the design strength employs statistical Weibull distributions obtained from a set of experimental data extrapolating the results to low acceptable failure probability values. However, in many cases this led to allowable stress values too low for the intended application. Moreover, the experimental basis has been found to be too small for reliable calculations. For these reasons measurement series on the strength of ZERODUR have been performed with different surface conditions employing a standardized ring-on-ring test setup. The numbers of specimens per sample have been extended from about 20 to 100 or even much more. The results for surfaces ground with different diamond grain sizes D151, D64 and D25 as well as for etched surfaces are presented in this paper. Glass ceramics like all glassy materials exhibit some strength reduction when being exposed to loads above a tensile stress threshold over long time periods. The strength change of ZERODUR with time will be discussed on the basis of known and newly determined stress corrosion data. The results for samples with large numbers of specimens contribute new aspects to the common practice of extrapolation to low failure probability, since they provide evidence for the existence of minimum strength values depending on the structures surface conditions. For ground surfaces the evidence for minimum strength values is quite obvious. For etched surfaces minimum values are to be expected also. However, here closer observation is still needed. The systematic deviations from Weibull distributions lie below about 5 % failure probability and thus could not be seen in small samples as they were common in the past.

  8. The relation between the tensile strength and the hardness of metals

    NASA Technical Reports Server (NTRS)

    Schwarz, O

    1930-01-01

    This report presents methods determining the hardness and tensile strength of metals by showing the effect and dependence of the hardness numbers on the strain-hardening. Relations between the hardness numbers and the ordinary stress-strain diagrams and tensile strength are given. Procedures for finding the Brinell strength are also presented.

  9. Thermal degradation and tensile strength of sansevieria trifasciata-polypropylene composites

    NASA Astrophysics Data System (ADS)

    Abral, H.; Kenedy, E.

    2015-07-01

    The paper exhibits thermal degradation and tensile strength of Sansevieria Trifasciata (ST) fibers and polypropylene (PP) composites. Thermal degradation of ST fibers PP composites was conducted by using thermogravimetry (TGA) instrument, meanwhile tensile strength of the composite was done by using tensile equipment. The results show that the thermal resistance of ST fibers PP composites was higher than that of virgin PP only. Increases in volume fraction of fibers in the composites enhance the tensile strength. Scanning Electron Microscope (SEM) observation exhibits good interface bonding between ST fibers and PP matrix.

  10. Asteroids With Tensile Strength: The Case of 2015 HM10

    NASA Astrophysics Data System (ADS)

    Busch, Michael W.; Benner, Lance A. M.; Naidu, Shantanu P.; Brozovic, Marina; Richardson, James E.; Rivera-Valentin, Edgard G.; Taylor, Patrick A.; Ford, H. Alyson; Ghigo, Frank D.; Giorgini, Jon D.; Jao, Joseph S.; Teitelbaum, Lawrence

    2015-11-01

    Near-Earth asteroid 2015 HM10 was discovered on 2015 April 19 with the 4-m Blanco Telescope at Cerro Tololo (MPEC 2015-H90). HM10 made a 0.00295 AU / 1.14 lunar distance flyby of Earth on July 7. This was the asteroid’s closest approach to Earth until at least 2419.We observed HM10 with radar between July 5 and July 8 using Arecibo, the 70 m DSS-14 and 34 m DSS-13 antennas at Goldstone, Green Bank, and elements of the Very Long Baseline Array (VLBA). Bistatic observations were crucial to obtain high-resolution images of HM10 due to the short round-trip travel time of the radar signal, which was as low as 2.95 s on July 7. Our finest image resolution was 3.75 m/pixel in range, obtained on July 7 with the new 80 kW C-band (7190 MHz, 4.2 cm) transmitter on DSS-13 and receiving at Green Bank with the new radar backend.Optical lightcurves obtained prior to closest approach indicated that HM10 has a spin period of ~22.2 minutes and an elongated shape (W. Ryan, pers. comm). The delay-Doppler radar images confirm the rotation period estimated from photometry and reveal that HM10 has a long-axis extent of 80-100 m with an equatorial aspect ratio of about 2:1. Radar speckle tracking transmitting from Arecibo and receiving with the VLBA on July 6 rule out any non-principal axis ‘wobble’ with an amplitude greater than ~10º.HM10’s rapid rotation implies significant cohesion, with a minimum tensile strength of 25-150 Pa required at its center to prevent disruption, assuming overall bulk density between 0.7 and 3.9 g cm-3. This is comparable to strength predictions for rubble-pile aggregates (e.g. Scheeres, Britt, Carry, & Holsapple 2015, Asteroids IV, in press). HM10 is not necessarily a ‘monolith’.HM10’s shape is complex and irregular. The radar images show angular features and ‘facets’ up to ~30 m across. There is also a cluster of radar-bright pixels that tracks with HM10’s rotation, consistent with a high standing feature 15-20 m across. This feature is similar in appearance to radar images of decameter-scale boulders on other asteroids.

  11. Correlation of tensile and shear strengths of metals with their friction properties

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1982-01-01

    The relation between the theoretical tensile and the shear strengths and the friction properties of metals in contact with diamond, boron nitride, silicon carbide, manganese-zinc ferrite, and the metals themselves in vacuum was investigated. The relationship between the actual shear strength and the friction properties of the metal was also investigated. An estimate of the theoretical uniaxial tensile strength was obtained in terms of the equilibrium surface energy, interplanar spacing of the planes perpendicular to the tensile axis, and the Young's modulus of elasticity. An estimate of the theoretical shear strength for metals was obtained from the shear modulus, the repeat distance of atoms in the direction of shear of the metal and the interplanar spacing of the shear planes. The coefficient of friction for metals was found to be related to the theoretical tensile, theoretical shear, and actual shear strengths of metals. The higher the strength of the metal, the lower the coefficient of friction.

  12. Increased Tensile Strength of Carbon Nanotube Yarns and Sheets through Chemical Modification and Electron Beam Irradiation

    NASA Technical Reports Server (NTRS)

    Miller, Sandi G.; Williams, Tiffany S.; Baker, James S.; Sola, Francisco; Lebron-Colon, Marisabel; McCorkle, Linda S.; Wilmoth, Nathan G.; Gaier, James; Chen, Michelle; Meador, Michael A.

    2014-01-01

    The inherent strength of individual carbon nanotubes offers considerable opportunity for the development of advanced, lightweight composite structures. Recent work in the fabrication and application of carbon nanotube (CNT) forms such as yarns and sheets has addressed early nanocomposite limitations with respect to nanotube dispersion and loading; and has pushed the technology toward structural composite applications. However, the high tensile strength of an individual CNT has not directly translated to macro-scale CNT forms where bulk material strength is limited by inter-tube electrostatic attraction and slippage. The focus of this work was to assess post processing of CNT sheet and yarn to improve the macro-scale strength of these material forms. Both small molecule functionalization and e-beam irradiation was evaluated as a means to enhance tensile strength and Youngs modulus of the bulk CNT material. Mechanical testing results revealed a tensile strength increase in CNT sheets by 57 when functionalized, while an additional 48 increase in tensile strength was observed when functionalized sheets were irradiated; compared to unfunctionalized sheets. Similarly, small molecule functionalization increased yarn tensile strength up to 25, whereas irradiation of the functionalized yarns pushed the tensile strength to 88 beyond that of the baseline yarn.

  13. Tensile and flexural strength of commercially pure titanium submitted to laser and tungsten inert gas welds.

    PubMed

    Atoui, Juliana Abdallah; Felipucci, Daniela Nair Borges; Pagnano, Valéria Oliveira; Orsi, Iara Augusta; Nóbilo, Mauro Antônio de Arruda; Bezzon, Osvaldo Luiz

    2013-01-01

    This study evaluated the tensile and flexural strength of tungsten inert gas (TIG) welds in specimens made of commercially pure titanium (CP Ti) compared with laser welds. Sixty cylindrical specimens (2 mm diameter x 55 mm thick) were randomly assigned to 3 groups for each test (n=10): no welding (control), TIG welding (10 V, 36 A, 8 s) and Nd:YAG laser welding (380 V, 8 ms). The specimens were radiographed and subjected to tensile and flexural strength tests at a crosshead speed of 1.0 mm/min using a load cell of 500 kgf applied on the welded interface or at the middle point of the non-welded specimens. Tensile strength data were analyzed by ANOVA and Tukey's test, and flexural strength data by the Kruskal-Wallis test (α=0.05). Non-welded specimens presented significantly higher tensile strength (control=605.84 ± 19.83) (p=0.015) and flexural strength (control=1908.75) (p=0.000) than TIG- and laser-welded ones. There were no significant differences (p>0.05) between the welding types for neither the tensile strength test (TIG=514.90 ± 37.76; laser=515.85 ± 62.07) nor the flexural strength test (TIG=1559.66; laser=1621.64). As far as tensile and flexural strengths are concerned, TIG was similar to laser and could be suitable to replace laser welding in implant-supported rehabilitations. PMID:24474361

  14. Increased tensile strength of carbon nanotube yarns and sheets through chemical modification and electron beam irradiation.

    PubMed

    Miller, Sandi G; Williams, Tiffany S; Baker, James S; Sol, Francisco; Lebron-Colon, Marisabel; McCorkle, Linda S; Wilmoth, Nathan G; Gaier, James; Chen, Michelle; Meador, Michael A

    2014-05-14

    The inherent strength of individual carbon nanotubes (CNTs) offers considerable opportunity for the development of advanced, lightweight composite structures. Recent work in the fabrication and application of CNT forms such as yarns and sheets has addressed early nanocomposite limitations with respect to nanotube dispersion and loading and has pushed the technology toward structural composite applications. However, the high tensile strength of an individual CNT has not directly translated into that of sheets and yarns, where the bulk material strength is limited by intertube electrostatic attractions and slippage. The focus of this work was to assess postprocessing of CNT sheets and yarns to improve the macro-scale strength of these material forms. Both small-molecule functionalization and electron-beam irradiation were evaluated as means to enhance the tensile strength and Young's modulus of the bulk CNT materials. Mechanical testing revealed a 57% increase in tensile strength of CNT sheets upon functionalization compared with unfunctionalized sheets, while an additional 48% increase in tensile strength was observed when functionalized sheets were irradiated. Similarly, small-molecule functionalization increased tensile strength of yarn by up to 25%, whereas irradiation of the functionalized yarns pushed the tensile strength to 88% beyond that of the baseline yarn. PMID:24720450

  15. Small screw study: Interim report on fastener tensile strength and optimum thread depth

    SciTech Connect

    Diegert, K.V.; Dorrell, L.R.; Reese, R.T.; Lazarus, L.J.; Allied-Signal Aerospace Co., Kansas City, MO . Kansas City Div.)

    1989-10-01

    This report summarizes about 1260 tests performed on small threaded fasteners (equal to or less than 1/4 inch in diameter and designated as 1/4-20 UNC, {number sign}4-40 UNC, {number sign}2-56 UNC, and 1.0 UNM). Tests determined the tensile strengths of the screws, the lengths of engagement needed to develop the full tensile strengths when the screws were engaged in 6061-T6 Aluminum, Hiperco 50, and 303 Stainless Steel, and whether relationships existed between the tensile strengths and Knoop Micro-Hardness measurements taken on the threaded ends of the screws. 17 figs., 13 tabs.

  16. Ideal Strength of graphene under general states of tensile strain

    NASA Astrophysics Data System (ADS)

    Cha, Moon-Hyun; Hwang, Jeongwoon; Ihm, Jisoon; Kim, Kyung-Suk

    2014-03-01

    Phonon softening of graphene under general directional tensile strain is investigated based on ab initio density functional theory calculations. Under a wide range of tensile strain configurations, we demonstrate that phonon instabilities are responsible for the mechanical failure of graphene through the strain-induced enhancement of phonon softening. It is shown that there are two types of phonon instabilities which induce symmetry-breaking structural distortions, and both of them lead to mechanical failure prior to the elastic failure commonly expected when the structural symmetry is retained. This work was supported by the Korea Institute of Science and Technology (KIST) and Extreme Science and Engineering Discovery Environment (XSEDE).

  17. An Experimental Study of the Rate Dependence of Tensile Strength Softening of Longyou Sandstone

    NASA Astrophysics Data System (ADS)

    Huang, Sheng; Xia, Kaiwen; Yan, Fei; Feng, Xiating

    2010-11-01

    It is well-known that the strengths of sandstones measured under fully saturated conditions are smaller than those measured under nominally dry conditions. This strength softening phenomenon has profound implications to rock engineering. In this work we investigate the tensile strength softening of Longyou sandstone from China. Defining the strength softening factor as the ratio of the strength under nominally dry conditions over that under saturated conditions, the static compressive strength softening factor of Longyou sandstone is close to 2 and the static tensile strength softening factor is about 7.9. To further address the applications, where the load may be dynamic, we examine the rate dependence of the tensile strength softening of this sandstone. The dynamic tensile strength is measured using the split Hopkinson pressure bar system in combination with the Brazilian disc sample geometry. The results show that the tensile strength softening factor decreases with the loading rate. Because the saturated sample shows stronger loading rate sensitivity than the dry sample, the softening factor decreases with the loading rate.

  18. Residual Stress Distribution of 600MPa Grade High Tensile Strength Steel Pipe Using Welding fe Simulation

    NASA Astrophysics Data System (ADS)

    Chang, Kyong-Ho; Jang, Gab-Chul

    2011-06-01

    This paper aims to determine the residual stress distribution of 600MPa grade high tensile strength steel pipe (STKT590) by girth welding. Welding FE simulation is achieved considering temperature dependent physical constants and mechanical properties, obtained by the temperature elevated tensile tests. Comparative analyses clarify the characteristics of residual stress profile near weld joint of STKT590 pipe.

  19. Experimental and Numerical Study on Tensile Strength of Concrete under Different Strain Rates

    PubMed Central

    Min, Fanlu; Yao, Zhanhu; Jiang, Teng

    2014-01-01

    The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10−7 s−1 to 10−4 s−1 in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates. PMID:24883355

  20. Experimental and numerical study on tensile strength of concrete under different strain rates.

    PubMed

    Min, Fanlu; Yao, Zhanhu; Jiang, Teng

    2014-01-01

    The dynamic characterization of concrete is fundamental to understand the material behavior in case of heavy earthquakes and dynamic events. The implementation of material constitutive law is of capital importance for the numerical simulation of the dynamic processes as those caused by earthquakes. Splitting tensile concrete specimens were tested at strain rates of 10(-7) s(-1) to 10(-4) s(-1) in an MTS material test machine. Results of tensile strength versus strain rate are presented and compared with compressive strength and existing models at similar strain rates. Dynamic increase factor versus strain rate curves for tensile strength were also evaluated and discussed. The same tensile data are compared with strength data using a thermodynamic model. Results of the tests show a significant strain rate sensitive behavior, exhibiting dynamic tensile strength increasing with strain rate. In the quasistatic strain rate regime, the existing models often underestimate the experimental results. The thermodynamic theory for the splitting tensile strength of concrete satisfactorily describes the experimental findings of strength as effect of strain rates. PMID:24883355

  1. Optimization and Prediction of Ultimate Tensile Strength in Metal Active Gas Welding.

    PubMed

    Ampaiboon, Anusit; Lasunon, On-Uma; Bubphachot, Bopit

    2015-01-01

    We investigated the effect of welding parameters on ultimate tensile strength of structural steel, ST37-2, welded by Metal Active Gas welding. A fractional factorial design was used for determining the significance of six parameters: wire feed rate, welding voltage, welding speed, travel angle, tip-to-work distance, and shielded gas flow rate. A regression model to predict ultimate tensile strength was developed. Finally, we verified optimization of the process parameters experimentally. We achieved an optimum tensile strength (558 MPa) and wire feed rate, 19 m/min, had the greatest effect, followed by tip-to-work distance, 7 mm, welding speed, 200 mm/min, welding voltage, 30 V, and travel angle, 60°. Shield gas flow rate, 10 L/min, was slightly better but had little effect in the 10-20 L/min range. Tests showed that our regression model was able to predict the ultimate tensile strength within 4%. PMID:26491719

  2. Anisotropy of tensile strength and fracture mode of perfect face-centered-cubic crystals

    NASA Astrophysics Data System (ADS)

    Wang, R. F.; Xu, J.; Qu, R. T.; Liu, Z. Q.; Zhang, Z. F.

    2015-06-01

    This study presents an effective method to calculate the ideal tensile strength of six face-centered-cubic (fcc) crystals (Cu, Au, Ni, Pt, Al, and Ir) along an arbitrary tensile direction by considering the coupling effect of normal stress and shear stress on a given crystallographic plane. Meanwhile, the fracture modes of the six crystals can also be derived from the competition between shear and cleavage fracture along different crystallographic planes. The results show that both the intrinsic factors (the ideal shear strength and cleavage strength of low-index planes) and the orientation may affect the tensile strength and fracture modes of ideal fcc crystals, which may give the reliable strength limit of fcc metals and well interpret the observed high strength in nano-scale mechanical experiments.

  3. High efficient preparation of carbon nanotube-grafted carbon fibers with the improved tensile strength

    NASA Astrophysics Data System (ADS)

    Fan, Wenxin; Wang, Yanxiang; Wang, Chengguo; Chen, Jiqiang; Wang, Qifen; Yuan, Yan; Niu, Fangxu

    2016-02-01

    An innovative technique has been developed to obtain the uniform catalyst coating on continuously moving carbon fibers. Carbon nanotube (CNT)-grafted carbon fibers with significantly improved tensile strength have been succeeded to produce by using chemical vapor deposition (CVD) when compared to the tensile strength of untreated carbon fibers. The critical requirements for preparation of CNT-grafted carbon fibers with high tensile strength have been found, mainly including (i) the obtainment of uniform coating of catalyst particles with small particle size, (ii) the low catalyst-induced and mechano-chemical degradation of carbon fibers, and (iii) the high catalyst activity which could facilitate the healing and strengthening of carbon fibers during the growth of CNTs. The optimum growth temperature was found to be about 500 °C, and the optimum catalyst is Ni due to its highest activity, there is a pronounced increase of 10% in tensile strength of carbon fibers after CNT growth at 500 °C by using Ni catalyst. Based on the observation from HRTEM images, a healing and crosslink model of neighboring carbon crystals by CNTs has been formulated to reveal the main reason that causes an increase in tensile strength of carbon fibers after the growth of CNTs. Such results have provided the theoretical and experimental foundation for the large-scale preparation of CNT-grafted carbon fibers with the improved tensile strength, significantly promoting the development of CNT-grafted carbon fiber reinforced polymer composites.

  4. Development on the Tensile Fatigue Test Apparatus and Strength Evaluation of Thin Metal Films

    NASA Astrophysics Data System (ADS)

    Fukushi, Miyuki; Miyata, Hiroshi; Murakami, Akira

    Recently, development of medical devices such as catheter and stent are advanced in the low invasion medical field. Considering the functions of human body are affected severely by the medical devices, the high strength reliability of devices must be secured. In these circumstances, the thin metal film, which has high reliability of strength, is useful structural material for further development of low invasion medical device. As the strength characteristics of a thin film depend on thickness and formation process of itself, there is little strength database concerning a thin metal film. In this study, a tensile fatigue testing apparatus with cyclic loading frequency up to 30Hz and maximum loading 8 N for the thin metal film has been developed, and thin rolled films Ti and SUS304 were evaluated on tensile and load-controlled fatigue strength. The static tensile tests give that both are also over the twice of the bulk material on the tensile strength, and the proof stress is high-strength with over 90% of tensile strength respectively. The fatigue test shows that Ti thin film has long life in comparison with the bulk material, however, the fatigue characteristic itself is similar like that of bulk material.

  5. Modeling of statistical tensile strength tensile of short-fiber composites

    SciTech Connect

    Zhu, Y.T.; Blumenthal, W.R.; Stout, M.G.; Lowe, T.C.

    1995-10-05

    This Paper develops a statistical strength theory for three-dimensionally (3-D) oriented short-fiber reinforced composites. Short-fiber composites are usually reinforced with glass and ceramic short fibers and whiskers. These reinforcements are brittle and display a range of strength values, which can be statistically characterized by a Weibull distribution. This statistical nature of fiber strength needs to be taken into account in the prediction of composite strength. In this paper, the statistical nature of fiber strength is incorporated into the calculation of direct fiber strengthening, and a maximum-load composite failure criterion is adopted to calculate the composite strength. Other strengthening mechanisms such as residual thermal stress, matrix work hardening, and short-fiber dispersion hardening are also briefly discussed.

  6. Tensile and tear strength of carrageenan film from Philippine eucheuma species.

    PubMed

    Briones, Annabelle V; Ambal, Wilhelmina O; Estrella, Romulo R; Pangilinan, Rolando; De Vera, Carlos J; Pacis, Raymund L; Rodriguez, Ner; Villanueva, Merle A

    2004-01-01

    The tensile and tear strength of carrageenan film from Philippines Eucheuma species were investigated using NEC tensilon universal-testing machine according to American Society for Testing Materials methods. These properties are important for assessing carrageenan film as packaging material. The kappa and iota types were used in the study. The effect of glycerine on the tensile and tear strength including elongation was also evaluated. Addition of glycerine tended to lower the tensile strength of the film and increase its elongation properties including the tear strength. Carrageenan film without glycerine was much stronger. Glycerine made the film more flexible and easy to deform. The composite film of carrageenan and konjac gum did not exhibit elongation. It also showed higher tensile strength than did the composite film of carrageenan and xanthan gum. Compared with iota-type carrageenan film, kappa-type carrageenan film without glycerine was more comparable to low-density polyethylene (LDPE) film in terms of tensile strength as was the composite film of carrageenan-konjac gum. The kappa-type carrageenan film with glycerine was more comparable to LDPE film in terms of tear strength. The elongation reading for carrageenan film was lower than that for LDPE film. Morphologic studies showed that the carrageenan film had sets of pores distributed randomly at different places as compared to LDPE film. It also showed that the carrageenan film was more fibrous than LDPE film. PMID:15085409

  7. Impact tensile properties and strength development mechanism of glass for reinforcement fiber

    NASA Astrophysics Data System (ADS)

    Kim, T.; Oshima, K.; Kawada, H.

    2013-07-01

    In this study, impact tensile properties of E-glass were investigated by fiber bundle testing under a high strain rate. The impact tests were performed employing two types of experiments. One is the tension-type split Hopkinson pressure bar system, and the other is the universal high-speed tensile-testing machine. As the results, it was found that not only the tensile strength but also the fracture strain of E-glass fiber improved with the strain rate. The absorbed strain energy of this material significantly increased. It was also found that the degree of the strain rate dependency of E-glass fibers on the tensile strength was varied according to fiber diameter. As for the strain rate dependency of the glass fiber under tensile loading condition, change of the small crack-propagation behaviour was considered to clarify the development of the fiber strength. The tensile fiber strength was estimated by employing the numerical simulation based on the slow crack-growth model (SCG). Through the parametric study against the coefficient of the crack propagation rate, the numerical estimation value was obtained for the various testing conditions. It was concluded that the slow crack-growth behaviour in the glass fiber was an essential for the increase in the strength of this material.

  8. Computer simulation of fatigue under diametrical compression

    SciTech Connect

    Carmona, H. A.; Kun, F.; Andrade, J. S. Jr.; Herrmann, H. J.

    2007-04-15

    We study the fatigue fracture of disordered materials by means of computer simulations of a discrete element model. We extend a two-dimensional fracture model to capture the microscopic mechanisms relevant for fatigue and we simulate the diametric compression of a disc shape specimen under a constant external force. The model allows us to follow the development of the fracture process on the macrolevel and microlevel varying the relative influence of the mechanisms of damage accumulation over the load history and healing of microcracks. As a specific example we consider recent experimental results on the fatigue fracture of asphalt. Our numerical simulations show that for intermediate applied loads the lifetime of the specimen presents a power law behavior. Under the effect of healing, more prominent for small loads compared to the tensile strength of the material, the lifetime of the sample increases and a fatigue limit emerges below which no macroscopic failure occurs. The numerical results are in a good qualitative agreement with the experimental findings.

  9. The Effect of Gap Angle on Tensile Strength of Preceramic Base Metal Solder Joints

    PubMed Central

    Fattahi, Farnaz; Hashemi Ardakani, Zahra; Hashemi Ardakani, Maryam

    2015-01-01

    Statement of the Problem Soldering is a process commonly used in fabricating dental prosthesis. Since most soldered prosthesis fail at the solder joints; the joint strength is of utmost importance. Purpose The purpose of this study was to evaluate the effect of gap angle on the tensile strength of base metal solder joints. Materials and Method A total number of 40 Ni-Cr samples were fabricated according to ADA/ISO 9693 specifications for tensile test. Samples were cut at the midpoint of the bar, and were placed at the considered angles by employing an explicitly designed device. They were divided into 4 groups regarding the gap angle; Group C (control group) with parallel gap on steady distance of 0.2mm, Group 1: 10°, Group 2: 20°, and Group3: 30° gap angles. When soldered, the specimens were all tested for tensile strength using a universal testing machine at a cross-head speed of 0.5 mm/min with a preload of 10N. Kruskal-Wallis H test was used to compare tensile strength among the groups (p< 0.05). Results The mean tensile strength values obtained from the study groups were respectively 307.84, 391.50, 365.18, and 368.86 MPa. The tensile strength was not statistically different among the four groups in general (p≤ 0.490). Conclusion Making the gap angular at the solder joints and the subsequent unsteady increase of the gap distance would not change the tensile strength of the joint. PMID:26636118

  10. Effects of Thermal Treatment on Tensile Strength of Laurentian Granite Using Brazilian Test

    NASA Astrophysics Data System (ADS)

    Yin, Tubing; Li, Xibing; Cao, Wenzhuo; Xia, Kaiwen

    2015-11-01

    The effect of thermal treatment on several physical properties and the tensile strength of Laurentian granite (LG) are measured in this study. Brazilian disc LG specimens are treated at temperatures of up to 850 °C. The physical properties such as grain density, relative volume change per degree, and P-wave velocity are investigated under the effect of heat treatment. The results indicate that both the density and the P-wave velocity decrease with the increase in heating temperature. However, the relative volume change per degree is not sensitive below 450 °C, while a remarkable increase appears from 450 to 850 °C. All cases are explained by the increase in both number and width of the thermally induced microcracks with the heating temperature. Brazilian tests are carried out statically with an MTS hydraulic servo-control testing system and dynamically with a modified split Hopkinson pressure bar (SHPB) system to measure both static and dynamic tensile strength of LG. The relationship between the tensile strength and treatment temperatures shows that static tensile strength decreases with temperature while the dynamic tensile strength first increases and then decreases with a linear increase in the loading rate. However, the increase in dynamic tensile strength with treatment temperatures from 25 to 100 °C is due to slight dilation of the grain boundaries as the initial thermal action, which leads to compaction of rock. When the treatment temperature rises above 450 °C, the quartz phase transition results in increased size of microcracks due to the differential expansion between the quartz grains and other minerals, which is the main cause of the sharp reduction in tensile strength.

  11. Ideal tensile and shear strength of a gum metal approximant: Ab initio density functional calculations

    NASA Astrophysics Data System (ADS)

    Nagasako, Naoyuki; Asahi, Ryoji; Hafner, Jrgen

    2012-01-01

    The ideal tensile and shear strengths of binary ?-phase Ti3Nb alloys have been investigated using ab initio density functional calculations. The binary alloy is considered as an approximant to the multifunctional Ti-Nb-Ta-Zr-O alloy known as gum metal, which displays high strength, low elastic modulus, high yield strain, and very good ductility. This alloy has been reported to deform elastically until the stress approaches the ideal tensile strength. Our calculations have been performed for an optimized chemical decoration of the body-centered cubic (bcc) structure of the ? phase. Previous work has demonstrated that this model yields elastic constants in very good agreement with those measured for gum metal specimens and leads to a reasonably accurate description of the martensitic transformations between the bcc ?, the orthorhombic ?'' and the hexagonal ? phases [Lazar , Phys. Rev. BPLRBAQ0556-280510.1103/PhysRevB.84.054202 84, 054202 (2011)]. The simulations of the response to tensile and shear loading have been performed for large supercells which account also for the different orientations of the -Nb-Nb- chains characteristic for the ?-phase structure relative to the direction of the applied load. The energy-strain and stress-strain curves are found to be very different from those reported for all bcc metals. Under uniaxial <100> loading we find an ideal tensile strength of 2.4 GPa, the upper limit to the tensile stress arising from a shear instability of the structure. Under uniaxial <110> load we calculate an ideal tensile strength of 2.2 or 2.8 GPa, depending on the orientation of the -Nb-Nb- chains relative to the loading direction. For a realistic multidomain structure the ideal strength is expected to correspond to the average of these values. An ideal strength of 2.6 GPa under <110> loading is roughly the same as under <100> load, despite a considerable anisotropy of the tensile moduli. For {211}<111> shear we calculate an ideal shear strength of 1.6 GPa, again as an average over different possible shearing directions relative to the Nb-Nb bonds. For the {110}<110> shear system we find a lower strength of 0.9 GPa. The structures reached at the stress maximum under <100> uniaxial tension and {211}<111> shear are identical, and since the maximal shear stress is much lower than the tensile stress, the alloy will fail by shear even under strictly uniaxial tension. The values of the ideal tensile and shear strengths are significantly low, even in comparison with those calculated for bcc V and Nb with very small shear moduli and approach the values reported for gum metal alloys.

  12. Mller glia provide essential tensile strength to the developing retina.

    PubMed

    MacDonald, Ryan B; Randlett, Owen; Oswald, Julia; Yoshimatsu, Takeshi; Franze, Kristian; Harris, William A

    2015-09-28

    To investigate the cellular basis of tissue integrity in a vertebrate central nervous system (CNS) tissue, we eliminated Mller glial cells (MG) from the zebrafish retina. For well over a century, glial cells have been ascribed a mechanical role in the support of neural tissues, yet this idea has not been specifically tested in vivo. We report here that retinas devoid of MG rip apart, a defect known as retinoschisis. Using atomic force microscopy, we show that retinas without MG have decreased resistance to tensile stress and are softer than controls. Laser ablation of MG processes showed that these cells are under tension in the tissue. Thus, we propose that MG act like springs that hold the neural retina together, finally confirming an active mechanical role of glial cells in the CNS. PMID:26416961

  13. Characterization of Optical Fiber Strength Under Applied Tensile Stress and Bending Stress

    SciTech Connect

    P.E. Klingsporn

    2011-08-01

    Various types of tensile testing and bend radius tests were conducted on silica core/silica cladding optical fiber of different diameters with different protective buffer coatings, fabricated by different fiber manufacturers. The tensile tests were conducted to determine not only the average fiber strengths at failure, but also the distribution in fracture strengths, as well as the influence of buffer coating on fracture strength. The times-to-failure of fiber subjected to constant applied bending stresses of various magnitudes were measured to provide a database from which failure times of 20 years or more, and the corresponding minimum bend radius, could be extrapolated in a statistically meaningful way. The overall study was done to provide an understanding of optical fiber strength in tensile loading and in applied bending stress as related to applications of optical fiber in various potential coizfgurations for weapons and enhanced surveillance campaigns.

  14. Effect of Silver Nano-particles on Tensile Strength of Acrylic Resins

    PubMed Central

    Ghaffari, Tahereh; Hamedi-rad, Fahimeh

    2015-01-01

    Background and aims. Polymethyl methacrylate (PMMA) is widely used for the fabrication of removable prostheses. Silver nano-particles (AgNps) have been added to PMMA because of their antimicrobial properties, but their effect on the mechanical properties of PMMA is unknown. The aim of this study was to investigate the effects of AgNps on the tensile strength of PMMA. Materials and methods. For this study, 12 specimens were prepared and divided into two groups. Group 1 included PMMA without AgNps and group 2 included PMMA mixed with 5 wt% of AgNps. Tensile strength of the specimens was measured by Zwick Z100 apparatus. Statistical analysis was carried out by SPSS using t-test. Statistical significance was defined at P<0.05. Results. This study showed that the mean tensile strength of PMMA in group 2 was significantly lower than that in group 1. Therefore, the tensile strength decreased significantly after incorporation of silver nano-particles. Conclusion. Within the limitations of this study, tensile strength of acrylic resin specimens was influenced by silver nano-particles. PMID:25973153

  15. Modeling of the temperature-dependent ideal tensile strength of solids

    NASA Astrophysics Data System (ADS)

    Cheng, Tianbao; Li, Weiguo; Fang, Daining

    2014-08-01

    To reveal the fracture failure mechanisms of single crystals at elevated temperatures, a new temperature-dependent ideal tensile strength model for solids has been developed, based on the critical strain principle. At the same time, the uniaxial tensile strength model, based on the critical failure energy density principle for isotropic materials that was presented in the previous study, is generalized to multi-axial loading and to cubic single crystals. The relationship between the two models is discussed, and how to obtain the material properties needed in the calculations is summarized. The two well-established models are used to predict the temperature-dependent ideal tensile strength of W, Fe and Al single crystals. The predictions from the critical strain principle agree well with the predictions from the critical failure energy density principle. The theoretical values from the critical strain principle at 0 K is in reasonable agreement with the ab initio results. The study shows that the temperature dependence of the ideal tensile strength is similar to that of Youngs modulus; that is, the ideal tensile strength firstly remains approximately constant and then decreases linearly with the temperature. The fracture failure for single crystals at elevated temperatures has been identified, for the first time, as a strain-controlled criterion.

  16. Acceleration of tensile strength of incisions treated with EGF and TGF-beta.

    PubMed Central

    Brown, G L; Curtsinger, L J; White, M; Mitchell, R O; Pietsch, J; Nordquist, R; von Fraunhofer, A; Schultz, G S

    1988-01-01

    The ability of surgeons to accelerate wound healing through pharmacologic intervention is limited. The effects of locally applied, biosynthetic human epidermal growth factor (EGF) and transforming growth factor-beta (TGF-beta) on tensile strength of experimental incisions were investigated. A single dose of EGF in saline failed to increase tensile strength over controls. Thus, EGF was incorporated into multilamellar liposomes, which prolonged the exposure of incisions to EGF (p less than 0.001). A single dose of EGF in multilamellar liposomes produced a 200% increase in wound tensile strength over controls between 7 and 14 days (p less than 0.05). Light and electron microscopy of the wounds revealed increased collagen formation and fibroblast proliferation. A single dose of TGB-beta in a collagen vehicle stimulated a 51% increase in wound tensile strength at 9 days (p less than 0.01). We conclude that addition of EGF and TGF-beta in appropriate vehicles stimulates early transient increases in wound tensile strength in normal rats. PMID:3264140

  17. Specimen type and size effects on lithium hydride tensile strength distributions

    SciTech Connect

    Oakes, Jr, R E

    1991-12-01

    Weibull's two-parameter statistical-distribution function is used to account for the effects of specimen size and loading differences on strength distributions of lithium hydride. Three distinctly differing uniaxial specimen types (i.e., an elliptical-transition pure tensile specimen, an internally pressurized ring tensile, and two sizes of four-point-flexure specimens) are shown to provide different strength distributions as expected, because of their differing sizes and modes of loading. After separation of strengths into volumetric- and surface-initiated failure distributions, the Weibull characteristic strength parameters for the higher-strength tests associated with internal fracture initiations are shown to vary as predicted by the effective specimen volume Weibull relationship. Lower-strength results correlate with the effective area to much lesser degree, probably because of the limited number of surface-related failures and the different machining methods used to prepare the specimen. The strength distribution from the fourth specimen type, the predominantly equibiaxially stressed disk-flexure specimen, is well below that predicted by the two-parameter Weibull-derived effective volume or surface area relations. The two-parameter Weibull model cannot account for the increased failure probability associated with multiaxial stress fields. Derivations of effective volume and area relationships for those specimens for which none were found in the literature, the elliptical-transition tensile, the ring tensile, and the disk flexure (including the outer region), are also included.

  18. Thermal degradation of the tensile strength of unidirectional boron/aluminum composites

    NASA Technical Reports Server (NTRS)

    Grimes, H. H.; Lad, R. A.; Maisel, J. E.

    1977-01-01

    The variation of ultimate tensile strength with thermal treatment of B-Al composite materials and of boron fibers chemically removed from these composites in an attempt to determine the mechanism of the resulting strength degradation was studied. Findings indicate that thermally cycling B-Al represents a more severe condition than equivalent time at temperature. Degradation of composite tensile strength from about 1.3 GN/m squared to as low as 0.34 GN/m squared was observed after 3,000 cycles to 420 C for 203 micrometers B-1100 Al composite. In general, the 1100 Al matrix composites degraded somewhat more than the 6061 matrix material studied. Measurement of fiber strengths confirmed a composite strength loss due to the degradation of fiber strength. Microscopy indicated a highly flawed fiber surface.

  19. Environmental effects on the tensile strength of chemically vapor deposited silicon carbide fibers

    NASA Technical Reports Server (NTRS)

    Bhatt, R. T.; Kraitchman, M. D.

    1985-01-01

    The room temperature and elevated temperature tensile strengths of commercially available chemically vapor-deposited (CVD) silicon carbide fibers were measured after 15 min heat treatment to 1600 C in various environments. These environments included oxygen, air, argon and nitrogen at one atmosphere and vacuum at 10/9 atmosphere. Two types of fibers were examined which differed in the SiC content of their carbon-rich coatings. Threshold temperature for fiber strength degradation was observed to be dependent on the as-received fiber-flaw structure, on the environment and on the coating. Fractographic analyses and flexural strength measurements indicate that tensile strength losses were caused by surface degradation. Oxidation of the surface coating is suggested as one possible degradation mechanism. The SiC fibers containing the higher percentage of SiC near the surface of the carbon-rich coating show better strength retention and higher elevated temperature strength.

  20. An investigation into geometry and microstructural effects upon the ultimate tensile strengths of butt welds

    NASA Technical Reports Server (NTRS)

    Gordon, Stephen S.

    1992-01-01

    A mathematical theory was evaluated empirically. This theory predicts weld ultimate tensile strength based on material properties and fusion line angles, mismatch, peaking, and weld widths. Welds were made on 1/4 and 1/2 in. aluminum 2219-T87, their geometries were measured, they were tensile tested, and these results were compared to theoretical predictions. Statistical analysis of results was performed to evaluate correlation of theory to results for many different categories of weld geometries.

  1. Estimating the tensile strength of super hard brittle materials using truncated spheroidal specimens

    NASA Astrophysics Data System (ADS)

    Serati, Mehdi; Alehossein, Habib; Williams, David J.

    2015-05-01

    New approaches need to be introduced to measure the tensile capacity of super hard materials since the standard methods are not effective. To pursue this objective, a series of laboratory tests were constructed to replicate the fracture mechanism of diamond-based materials. Experiments indicate that under a certain compressive test condition, stresses normal to the axisymmetric line in truncated spheroidal specimens (bullet-shaped specimens) are in tension contributing to the tensile fracture of the material. From experimental and numerical studies, it is concluded that semi-prolate spheroidal specimens can be used to determine precisely the tensile strength of brittle stiff diamond-like composites.

  2. SIZE EFFECTS IN THE TENSILE STRENGTH OF UNIDIRECTIONAL FIBER COMPOSITES

    SciTech Connect

    M. SIVASAMBU; ET AL

    1999-08-01

    Monte Carlo simulation and theoretical modeling are used to study the statistical failure modes in unidirectional composites consisting of elastic fibers in an elastic matrix. Both linear and hexagonal fiber arrays are considered, forming 2D and 3D composites, respectively. Failure is idealized using the chain-of-bundles model in terms of {delta}-bundles of length {delta}, which is the length-scale of fiber load transfer. Within each {delta}-bundle, fiber load redistribution is determined by local load-sharing models that approximate the in-plane fiber load redistribution from planar break clusters as predicted from 2D and 3D shear-lag models. As a result these models are 1D and 2D, respectively. Fiber elements have random strengths following either the Weibull or the power-law distribution with shape and scale parameters {rho} and {sigma}{sub {delta}}, respectively. Simulations of {delta}-bundle failure, reveal two regimes. When fiber strength variability is low (roughly {rho} > 2) the dominant failure mode is by growing clusters of fiber breaks up to instability. When this variability is high (roughly 0 < {rho} < 1) cluster formation is suppressed by a dispersed fiber failure mode. For these two cases, closed-form approximations to the strength distribution of a {delta}-bundle are developed under the local load-sharing model and an equal load-sharing model of Daniels, respectively. The results compare favorably with simulations on {delta}-bundles with up to 1500 fibers. The location of the transition in terms of {rho} is affected by the upper tail properties of the fiber strength distributions as well as the number of fibers.

  3. Effective Size Analysis of the Diametral Compression (Brazil) Test Specimen

    SciTech Connect

    Jadaan, Osama M.; Wereszczak, Andrew A

    2009-04-01

    This study considers the finite element analysis (FEA) simulation and Weibull effective size analysis for the diametral compression (DC) or Brazil specimen loaded with three different push-rod geometries. Those geometries are a flat push-rod, a push-rod whose radius of curvature is larger than that for the DC specimen, and a push-rod whose radius of curvature matches that of the DC specimen. Such established effective size analysis recognizes that the tensile strength of structural ceramics is typically one to two orders of magnitude less than its compressive strength. Therefore, because fracture is much more apt to result from a tensile stress than a compressive one, this traditional analysis only considers the first principal tensile stress field in the mechanically loaded ceramic component for the effective size analysis. The effective areas and effective volumes were computed as function of Weibull modulus using the CARES/Life code. Particular attention was devoted to the effect of mesh sensitivity and localized stress concentration. The effect of specimen width on the stress state was also investigated. The effects of push-rod geometry, the use of steel versus WC push-rods, and considering a frictionless versus no-slip interface between push-rod and specimen on the maximum stresses, where those stresses are located, and the effective area and effective volume results are described. Of the three push-rod geometries, it is concluded that the push-rod (made from WC rather than steel) whose radius of curvature matches that of the DC specimen is the most apt to cause fracture initiation within the specimen's bulk rather than at the loading interface. Therefore, its geometry is the most likely to produce a valid diametral compression strength test. However, the DC specimen remains inefficient in terms of its area and volume efficiencies; namely, the tensile strength of only a few percent of the specimen's entire area or volume is sampled. Given the high probability that a valid (or invalid) test can be proven by ceramic fractographic practices suggests that this test method and specimen is questionable for use with relatively strong structural ceramics.

  4. Experimental Study On The Effect Of Micro-Cracks On Brazilian Tensile Strength

    NASA Astrophysics Data System (ADS)

    Wang, Xiangyu

    2015-12-01

    For coal mine ground control issues, it is necessary to propose a failure criteria accounting for the transversely isotropic behaviors of rocks. Hence, it is very helpful to provide experimental data for the validation of the failure criteria. In this paper, the method for preparing transversely isotropic specimens and the scheme of the Brazilian tensile strength test are presented. Results obtained from Brazilian split tests under dry and water-saturated conditions reflect the effect of the development direction β of the structural plane, such as the bedding fissure, on the tensile strength, ultimate displacement, failure mode, and the whole splitting process. The results show that the tensile strength decreases linearly with increasing β. The softening coefficient of the tensile strength shows a sinusoidal function. The values of the slope and inflection point for the curve vary at the different stages of the Brazilian test. The failure mode of the rock specimen presented in this paper generally coincides with the standard Brazilian splitting failure mode. Based on the test results, the major influencing factors for the Brazilian splitting strength are analyzed and a mathematical model for solving the Brazilian splitting strength is proposed. The findings in this paper would greatly benefit the coal mine ground control studies when the surrounding rocks of interest show severe transversely isotropic behaviors.

  5. Comparison of the Tensile, Creep, and Rupture Strength Properties of Stoichiometric SiC Fibers

    NASA Technical Reports Server (NTRS)

    Yun, H. M.; DiCarlo, J. A.

    1999-01-01

    Tensile strength, creep strength, and rupture strength properties were measured for the following types of polymer-derived stoichiometric SiC fibers: Hi-Nicalon Type S from Nippon Carbon, Tyranno SA from Ube, and Sylramic from Dow Corning. Also included in this study were an earlier version of the SA fiber plus two recent developmental versions of the Sylramic fiber. The tensile strength measurements were made at room temperature on as-received fibers and on fibers after high-temperature inert exposure. The creep-rupture property data were obtained at 1400 deg C in air as well as, argon. Some fiber types showed strong effects of environment on their strength properties. These results are compared and discussed in terms of underlying mechanisms and implications for ceramic composites.

  6. Predicting the tensile modulus and strength of single and hybrid natural fibre reinforced thermoplastic composites

    NASA Astrophysics Data System (ADS)

    Facca, Angelo George

    Natural fibre reinforced thermoplastics (NFRT) are used in a variety of commercial applications, but there is little theoretical modeling of structure/property relationships in these materials. In this thesis, micromechanical models available in the short-fibre literature were adapted to predict the tensile modulus and strength of some NFRT formulations. Hemp, 20 and 40-mesh hardwood, rice hulls and E-glass fibres were blended into HDPE to produce single and hybrid composites. Changes in fibre density and moisture content that occur during composite manufacturing were included in the micromechanical models. To account for fibre densification, the Young's modulus of the natural fibres was determined on a cell wall basis. A modified hybrid rule of mixtures (HROM) equation that uses experimental data from single NFRT was developed and found to adequately predict the tensile modulus of the hybrid composites. The tensile modulus for both the single and hybrid composites was found to linearly increase with an increase in fibre loading. The failure mechanism for all composite specimens was due to fibre pullout followed by matrix failure. Consequently the tensile strength of the NFRT was predicted using a ROM strength equation, which was modified with a derived semi-empirical fibre clustering parameter. The clustering parameter correctly predicted that as fibre loading increased, the average fibre stress would decrease. By assuming no contact between different types of fibres it was possible to use a modified HROM strength equation to predict the tensile strength of the hybrid composites. As a result parameters taken from the respective single fibre systems could be applied directly to the HROM equation. The modified ROM and HROM strength equations adequately predicted the tensile strength of various single and hybrid fibre reinforced composites over a wide range of composite loading. In this study experiments were conducted to shed light on the effect of a coupling agent (maleic anhydride) on the tensile strength and stiffness of various NFRT. Coupling agents, which alter the interfacial shear strength between the fibre and matrix, were determined to have a minimal effect on composite stiffness but produced increases in composite strength.

  7. Instrumented impact and residual tensile strength testing of eight-ply carbon eopoxy specimens

    NASA Technical Reports Server (NTRS)

    Nettles, A. T.

    1990-01-01

    Instrumented drop weight impact testing was utilized to examine a puncture-type impact on thin carbon-epoxy coupons. Four different material systems with various eight-ply lay-up configurations were tested. Specimens were placed over a 10.3-mm diameter hole and impacted with a smaller tup (4.2-mm diameter) than those used in previous studies. Force-time plots as well as data on absorbed energy and residual tensile strength were gathered and examined. It was found that a critical impact energy level existed for each material tested, at which point tensile strength began to rapidly decrease with increasing impact energy.

  8. Tensile strength of dome rocks and lavas at Santiaguito dome complex, Guatemala

    NASA Astrophysics Data System (ADS)

    Hornby, Adrian; Lamb, Oliver; Lamur, Anthony; Lavallée, Yan

    2015-04-01

    Lava domes are inherently unstable structures, subject to intense gas flux and rapid variations in the state of stress. At shallow depths confining stresses are minimal and deformation is dilatant, occurring predominantly through tensile fractures. This fracture mode facilitates outgassing and contributes to the development of gas-and-ash activity as well as vulcanian eruptions. However, there is a paucity of tensile strength data for volcanic materials in the published literature, and we know of no paper which addresses this at high temperatures. We study the tensile strength of dome rocks collected at the Santiaguito dome complex, Guatemala, over a porosity range of 3-25%. Indirect tensile (Brazilian) tests were conducted on 40-mm diameter cores, by imposing a compressive displacement rate (radial to the core) of 4 micron/s at room temperature as well as an eruptive temperature of ca. 850 °C. An acoustic monitoring system is employed to track the nucleation, propagation and coalescence of fractures leading to complete sample failure. We find that the rocks' tensile strength exhibits a nonlinear decrease with porosity. Preliminary tests at high temperature indicate that some rocks exhibit a higher tensile strength (than at room temperature); in these experiments, samples containing a higher fraction of interstitial melt revealed an additional component of viscous flow. Further experiments conducted at higher strain rates will define the brittle response of the liquid during tensile failure. The data is compared against similar datasets for volcanic rocks. We will discuss implications for shallow volcanic processes ranging from dilation bands and tuffisite formation to gas-and-ash explosions and dome structural stability.

  9. Development of Yield and Tensile Strength Design Curves for Alloy 617

    SciTech Connect

    Nancy Lybeck; T. -L. Sham

    2013-10-01

    The U.S. Department of Energy Very High Temperature Reactor Program is acquiring data in preparation for developing an Alloy 617 Code Case for inclusion in the nuclear section of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code. A draft code case was previously developed, but effort was suspended before acceptance by ASME. As part of the draft code case effort, a database was compiled of yield and tensile strength data from tests performed in air. Yield strength and tensile strength at temperature are used to set time independent allowable stress for construction materials in B&PV Code, Section III, Subsection NH. The yield and tensile strength data used for the draft code case has been augmented with additional data generated by Idaho National Laboratory and Oak Ridge National Laboratory in the U.S. and CEA in France. The standard ASME Section II procedure for generating yield and tensile strength at temperature is presented, along with alternate methods that accommodate the change in temperature trends seen at high temperatures, resulting in a more consistent design margin over the temperature range of interest.

  10. Modeling the Tensile Strength of Carbon Fiber - Reinforced Ceramic - Matrix Composites Under Multiple Fatigue Loading

    NASA Astrophysics Data System (ADS)

    Li, Longbiao

    2015-09-01

    An analytical method has been developed to investigate the effect of interface wear on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs) under multiple fatigue loading. The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure and the difference existed in the new and original interface debonded region. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The interface shear stress degradation model and fibers strength degradation model have been adopted to analyze the interface wear effect on the tensile strength of the composite subjected to multiple fatigue loading. Under tensile loading, the fibers failure probabilities were determined by combining the interface wear model and fibers failure model based on the assumption that the fiber strength is subjected to two - parameter Weibull distribution and the loads carried by broken and intact fibers satisfy the Global Load Sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength corresponding to multiple fatigue peak stress levels and different cycle number have been analyzed.

  11. Scale effects on the transverse tensile strength of graphite epoxy composites

    NASA Technical Reports Server (NTRS)

    Obrien, T. Kevin; Salpekar, Satish A.

    1992-01-01

    The influence of material volume on the transverse tensile strength of AS4/3501-6 graphite epoxy composites was investigated. Tensile tests of 90 degree laminates with 3 different widths and 5 different thicknesses were conducted. A finite element analysis was performed to determine the influence of the grip on the stress distribution in the coupons and explain the tendency for the distribution of failure locations to be skewed toward the grip. Specimens were instrumented with strain gages and extensometers to insure good alignment and to measure failure strains. Data indicated that matrix dominated strength properties varied with the volume of material that was stressed, with the strength decreasing as volume increased. Transverse strength data were used in a volumetric scaling law based on Weibull statistics to predict the strength of 90 degree laminates loaded in three point bending. Comparisons were also made between transverse strength measurements and out-of-plane interlaminar tensile strength measurements from curved beam bending tests. The significance of observed scale effects on the use of tests for material screening, quality assurance, and design allowables is discussed.

  12. Tensile Strength of Carbon Nanotubes Under Realistic Temperature and Strain Rate

    NASA Technical Reports Server (NTRS)

    Wei, Chen-Yu; Cho, Kyeong-Jae; Srivastava, Deepak; Biegel, Bryan (Technical Monitor)

    2002-01-01

    Strain rate and temperature dependence of the tensile strength of single-wall carbon nanotubes has been investigated with molecular dynamics simulations. The tensile failure or yield strain is found to be strongly dependent on the temperature and strain rate. A transition state theory based predictive model is developed for the tensile failure of nanotubes. Based on the parameters fitted from high-strain rate and temperature dependent molecular dynamics simulations, the model predicts that a defect free micrometer long single-wall nanotube at 300 K, stretched with a strain rate of 1%/hour, fails at about 9 plus or minus 1% tensile strain. This is in good agreement with recent experimental findings.

  13. Nanoindentation cannot accurately predict the tensile strength of graphene or other 2D materials

    NASA Astrophysics Data System (ADS)

    Han, Jihoon; Pugno, Nicola M.; Ryu, Seunghwa

    2015-09-01

    Due to the difficulty of performing uniaxial tensile testing, the strengths of graphene and its grain boundaries have been measured in experiments by nanoindentation testing. From a series of molecular dynamics simulations, we find that the strength measured in uniaxial simulation and the strength estimated from the nanoindentation fracture force can differ significantly. Fracture in tensile loading occurs simultaneously with the onset of crack nucleation near 5-7 defects, while the graphene sheets often sustain the indentation loads after the crack initiation because the sharply concentrated stress near the tip does not give rise to enough driving force for further crack propagation. Due to the concentrated stress, strength estimation is sensitive to the indenter tip position along the grain boundaries. Also, it approaches the strength of pristine graphene if the tip is located slightly away from the grain boundary line. Our findings reveal the limitations of nanoindentation testing in quantifying the strength of graphene, and show that the loading-mode-specific failure mechanism must be taken into account in designing reliable devices from graphene and other technologically important 2D materials.Due to the difficulty of performing uniaxial tensile testing, the strengths of graphene and its grain boundaries have been measured in experiments by nanoindentation testing. From a series of molecular dynamics simulations, we find that the strength measured in uniaxial simulation and the strength estimated from the nanoindentation fracture force can differ significantly. Fracture in tensile loading occurs simultaneously with the onset of crack nucleation near 5-7 defects, while the graphene sheets often sustain the indentation loads after the crack initiation because the sharply concentrated stress near the tip does not give rise to enough driving force for further crack propagation. Due to the concentrated stress, strength estimation is sensitive to the indenter tip position along the grain boundaries. Also, it approaches the strength of pristine graphene if the tip is located slightly away from the grain boundary line. Our findings reveal the limitations of nanoindentation testing in quantifying the strength of graphene, and show that the loading-mode-specific failure mechanism must be taken into account in designing reliable devices from graphene and other technologically important 2D materials. Electronic ESI (ESI) available: Modelling of polycrystalline graphene, verification of loading speed, biaxial tensile simulations, comparison of stress distribution, size effects of indenter radius, force-deflection curves, and stability analysis of crack propagation. See DOI: 10.1039/c5nr04134a

  14. Effects of reclaimed asphalt pavement on indirect tensile strength test of conditioned foamed asphalt mix

    NASA Astrophysics Data System (ADS)

    Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela

    2013-06-01

    This paper presents the results of Indirect Tensile Strength (ITS) Test for samples prepared with reclaimed asphalt pavement (RAP). Samples were conditioned in water at 25C for 24 hours prior to testing. Results show that recycled aggregate from reclaimed asphalt pavement performs as well as virgin aggregate.

  15. Different characteristics of circular staplers make the difference in anastomotic tensile strength.

    PubMed

    Giaccaglia, V; Antonelli, M S; Franceschilli, L; Salvi, P F; Gaspari, A L; Sileri, P

    2016-01-01

    Anastomotic leak after gastrointestinal surgery is a severe complication associated with relevant short and long-term sequelae. Most of the anastomoses are currently performed with a surgical stapler that is required to have appropriate characteristics in order to guarantee good performances. The aim of our study was to evaluate, ex vivo, pressure resistance and tensile strength of anastomosis performed with different circular staplers available in the market. We studied 7 circular staplers of 3 different companies, 3 of them used for gastrointestinal anastomosis and 4 staplers for hemorrhoidal prolapse excision. A total of 350 anastomoses, 50 for each of the 7 staplers, were performed using healthy pig fresh intestine, then injected saline solution and recorded the leaking pressure. There were no statistically significant differences between the mean pressure necessary to induce an anastomotic leak in the various instruments (p>0.05). For studying tensile strength, we performed a total of 350 anastomoses with 7 different circular staplers on a special strong paper (Tyvek), and then recorded the maximal tensile force that could open the anastomosis. There were statistically significant differences between one brand stapler vs other 2 companies staplers about the strength necessary to open the staple line (p<0.05). In conclusion, we demonstrated that different circular staplers of three companies available in the market give comparable anastomotic pressure resistance but different tensile strengths. This is probably due to different technical characteristics. PMID:26379251

  16. Optimization and Prediction of Ultimate Tensile Strength in Metal Active Gas Welding

    PubMed Central

    Ampaiboon, Anusit; Lasunon, On-Uma; Bubphachot, Bopit

    2015-01-01

    We investigated the effect of welding parameters on ultimate tensile strength of structural steel, ST37-2, welded by Metal Active Gas welding. A fractional factorial design was used for determining the significance of six parameters: wire feed rate, welding voltage, welding speed, travel angle, tip-to-work distance, and shielded gas flow rate. A regression model to predict ultimate tensile strength was developed. Finally, we verified optimization of the process parameters experimentally. We achieved an optimum tensile strength (558 MPa) and wire feed rate, 19 m/min, had the greatest effect, followed by tip-to-work distance, 7 mm, welding speed, 200 mm/min, welding voltage, 30 V, and travel angle, 60°. Shield gas flow rate, 10 L/min, was slightly better but had little effect in the 10–20 L/min range. Tests showed that our regression model was able to predict the ultimate tensile strength within 4%. PMID:26491719

  17. Developmental exposure to xenoestrogens at low doses alters femur length and tensile strength in adult mice.

    PubMed

    Pelch, Katherine E; Carleton, Stephanie M; Phillips, Charlotte L; Nagel, Susan C

    2012-03-01

    Developmental exposure to high doses of the synthetic xenoestrogen diethylstilbestrol (DES) has been reported to alter femur length and strength in adult mice. However, it is not known if developmental exposure to low, environmentally relevant doses of xenoestrogens alters adult bone geometry and strength. In this study we investigated the effects of developmental exposure to low doses of DES, bisphenol A (BPA), or ethinyl estradiol (EE(2)) on bone geometry and torsional strength. C57BL/6 mice were exposed to DES, 0.1 ?g/kg/day, BPA, 10 ?g/kg/day, EE(2), 0.01, 0.1, or 1.0 ?g/kg/day, or vehicle from Gestation Day 11 to Postnatal Day 12 via a mini-osmotic pump in the dam. Developmental Xenoestrogen exposure altered femoral geometry and strength, assessed in adulthood by micro-computed tomography and torsional strength analysis, respectively. Low-dose EE(2), DES, or BPA increased adult femur length. Exposure to the highest dose of EE(2) did not alter femur length, resulting in a nonmonotonic dose response. Exposure to EE(2) and DES but not BPA decreased tensile strength. The combined effect of increased femur length and decreased tensile strength resulted in a trend toward decreased torsional ultimate strength and energy to failure. Taken together, these results suggest that exposure to developmental exposure to environmentally relevant levels of xenoestrogens may negatively impact bone length and strength in adulthood. PMID:22088916

  18. Effect of TiO2 Nanoparticles on Tensile Strength of Dental Acrylic Resins

    PubMed Central

    Shirkavand, Saeed; Moslehifard, Elnaz

    2014-01-01

    Background and aims. Adding further fillers to dental resins may enhance their physical characteristics. The aim of this study was to evaluate the tensile strength of heat-curing acrylic resin reinforced by TiO2nanoparticles added into the resin matrix. Materials and methods. Commercially available TiO2 nanoparticles were obtained and characterized using X-ray diffrac-tion (XRD) and scanning electron microscopy (SEM) to determine their crystalline structure, particle size and morphology. TiO2-acrylic resin nanocomposite was prepared by mixing 0.5, 1 and 2 (wt%) of surface modified TiO2 nanoparticles in an amalgamator providing three groups of samples. Before curing, the obtained paste was packed into steel molds. After cur-ing, the specimens were removed from the molds. The tensile strength test samples were prepared according to ISO 1567. Results. Two crystalline phases were found in TiO2 nanoparticles including: (i) anatase as the major one, and (ii) rutile. The average particle size calculated according to the Scherrer equation was 20.4 nm, showing a normal size distribution. According to SEM images, the nanocomposite with 1wt% TiO2 nanoparticles had a better distribution compared to other groups. In addition, the group by 1wt% TiO2 exhibited higher tensile strength with a significant difference compared to other groups. ANOVA showed significant differences between the contents of TiO2 particles in acrylic resin (F = 22.19; P < 0.001). Conclusion. A considerable increase in tensile strength was observed with titania NPs reinforcement agents in 1wt% by weight. Further increase of TiO2 nanoparticles decreased the tensile strength. PMID:25587380

  19. Influence of surface defects on the tensile strength of carbon fibers

    NASA Astrophysics Data System (ADS)

    Vautard, F.; Dentzer, J.; Nardin, M.; Schultz, J.; Defoort, B.

    2014-12-01

    The mechanical properties of carbon fibers, especially their tensile properties, are affected by internal and surface defects. In order to asses in what extent the generation of surface defects can result in a loss of the mechanical properties, non-surface treated carbon fibers were oxidized with three different surface treatment processes: electro-chemical oxidation, oxidation in nitric acid, and oxidation in oxygen plasma. Different surface topographies and surface chemistries were obtained, as well as different types and densities of surface defects. The density of surface defects was measured with both a physical approach (Raman spectroscopy) and a chemical approach (Active Surface Area). The tensile properties were evaluated by determining the Weibull modulus and the scale parameter of each reference, after measuring the tensile strength for four different gauge lengths. A relationship between the tensile properties and the nature and density of surface defects was noticed, as large defects largely control the value of the tensile strength. When optimized, some oxidation surface treatment processes can generate surface functional groups as well as an increase of the mechanical properties of the fibers, because of the removal of the contamination layer of pyrolytic carbon generated during the carbonization of the polyacrylonitrile precursor. Oxidation in oxygen plasma revealed to be a promising technology for alternative surface treatment processes, as high levels of functionalization were achieved and a slight improvement of the mechanical properties was obtained too.

  20. Tensile properties of carbon nanotubes grown on ultrahigh strength polyacrylonitrile-based and ultrahigh modulus pitch-based carbon fibers

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi; Yang, Jenn-Ming; Tanaka, Yoshihisa; Kagawa, Yutaka

    2008-06-01

    The tensile properties and fracture behavior of carbon nanotubes (CNTs) grown on ultrahigh tensile strength polyacrylonitrile (PAN)-based (T1000GB) and ultrahigh modulus pitch-based (K13D) carbon fibers have been investigated. The CNTs were grown on the carbon fiber surface using chemical vapor deposition. The statistical scattering of the tensile strength was also evaluated. The results clearly show that grafting of CNTs improves the mechanical properties and the Weibull modulus of ultrahigh tensile strength PAN-based and ultrahigh modulus pitch-based carbon fibers.

  1. Correlation of Fiber Composite Tensile Strength with the Ultrasonic Stress Wave Factor

    NASA Technical Reports Server (NTRS)

    Vary, A.; Lark, R. F.

    1978-01-01

    An ultrasonic-acoustic technique was used to indicate the strength variations of tensile specimens of a graphite-epoxy composite. A stress wave factor was determined and its value was found to depend on variations of the fiber-resin bonding as well as fiber orientation. The fiber orientations studied were 0 deg (longitudinal), 10 deg (off-axis), 90 deg (transverse), 0 deg + or - 45 deg/0 deg symmetrical, and + or - 45 deg] symmetrical. The stress wave factor can indicate variations of the tensile and shear strengths of composite materials. The stress wave factor was also found to be sensitive to strength variations associated with microporosity and differences in fiber-resin ratio.

  2. Effects of processing induced defects on laminate response - Interlaminar tensile strength

    NASA Technical Reports Server (NTRS)

    Gurdal, Zafer; Tomasino, Alfred P.; Biggers, S. B.

    1991-01-01

    Four different layup methods were used in the present study of the interlaminar tensile strength of AS4/3501-6 graphite-reinforced epoxy as a function of defects from manufacturing-induced porosity. The methods were: (1) baseline hand layup, (2) solvent wipe of prepreg for resin removal, (3) moisture-introduction between plies, and (4) a low-pressure cure cycle. Pore characterization was conducted according to ASTM D-2734. A significant reduction is noted in the out-of-plane tensile strength as a function of increasing void content; the porosity data were used in an empirical model to predict out-of-plane strength as a function of porosity.

  3. Evaluation of tensile strength of hybrid fiber (jute/gongura) reinforced hybrid polymer matrix composites

    NASA Astrophysics Data System (ADS)

    Venkatachalam, G.; Gautham Shankar, A.; Vijay, Kumar V.; Chandan, Byral R.; Prabaharan, G. P.; Raghav, Dasarath

    2015-07-01

    The polymer matrix composites attract many industrial applications due to its light weight, less cost and easy for manufacturing. In this paper, an attempt is made to prepare and study of the tensile strength of hybrid (two natural) fibers reinforced hybrid (Natural + Synthetic) polymer matrix composites. The samples were prepared with hybrid reinforcement consists of two different fibers such as jute and Gongura and hybrid polymer consists of polyester and cashew nut shell resins. The hybrid composites tensile strength is evaluated to study the influence of various fiber parameters on mechanical strength. The parameters considered here are the duration of fiber treatment, the concentration of alkali in fiber treatment and nature of fiber content in the composites.

  4. High Tensile Strength Amalgams for In-Space Repair and Fabrication

    NASA Technical Reports Server (NTRS)

    Grugel, R. N.

    2005-01-01

    Amalgams are defined as an alloy of mercury with one or more other metals. These, along with those based on gallium (also liquid at near room temperature), are widely used in dental practice as a tooth filling material. Amalgams have a number of useful attributes that indude room temperature compounding. corrosion resistance, dimensional stability, and good compressive strength. These properties well serve dental needs but, unfortunately, amalgams have extremely poor tensile strength, a feature that severely limits their applications. The work presented here demonstrates how, by modifying particle geometry, the tensile strength of amalgams can be increased and thus extending the range of potential applications. This is relevant to, for example, the freeform fabrication of replacement parts that might be necessary during an extended space mission. Advantages, i.e. Figures-of-Merit. include the ability to produce complex parts, minimum crew interaction, high yield - minimum wasted material, reduced gravity compatibility, minimum final finishing, safety, and minimum power consumption.

  5. Predictive model for tensile strength of pharmaceutical tablets based on local hardness measurements.

    PubMed

    Juban, Audrey; Nouguier-Lehon, Ccile; Briancon, Stphanie; Hoc, Thierry; Puel, Franois

    2015-07-25

    In the pharmaceutical field, tablets are the most common dosage forms for oral administration. During the manufacture of tablets, measures are taken to assure that they possess a suitable mechanical strength to avoid crumbling or breaking when handling while ensuring disintegration after administration. Accordingly, the tensile strength is an essential parameter to consider. In the present study, microscopic hardness and macroscopic tensile strength of binary tablets made from microcrystalline cellulose and caffeine in various proportions were measured. A relationship between these two mechanical properties was found for binary mixture. The proposed model was based on two physical measurements easily reachable: hardness and tablet density. Constants were determined from the two extreme compositions of this given system. This model was validated with experimental results, and a comparison was made with the one developed by Wu et al. (2005). Both models are relevant for this studied system. Nonetheless, with this model, the tablet tensile strength can be connected with a tablet characteristic at microscopic scale in which porosity is not needed. PMID:26043825

  6. Effects of porosity on weld-joint tensile strength of aluminum alloys

    NASA Technical Reports Server (NTRS)

    Lovoy, C. V.

    1974-01-01

    Tensile properties in defect-free weldments of aluminum alloys 2014-T6 and 2219-T87 (sheet and plate) are shown to be related to the level or concentration of induced simulated porosity. The scatter diagram shows that the ultimate tensile strength of the weldments displays the most pronounced linear relationship with the level of porosity. The relationships between yield strength or elongation and porosity are either trivial or inconsequential in the lower and intermediate levels of porosity content. In highly concentrated levels of porosity, both yield strength and elongation values decrease markedly. Correlation coefficients were obtained by simple straight line regression analysis between the variables of ultimate tensile strength and pore level. The coefficients were greater, indicating a better correlation, using a pore area accumulation concept or pore volume accumulation than the accumulation of the pore diameters. These relationships provide a useful tool for assessing the existing aerospace radiographic acceptance standards with respect to permissible porosity. In addition, these relationships, in combination with known design load requirements, will serve as an engineering guideline in determining when a weld repair is necessary based on accumulative pore level as detected by radiographic techniques.

  7. Modelling weathering induced retreat of c-φ cliffs with limited tensile strength

    NASA Astrophysics Data System (ADS)

    Voulgari, C.

    2015-09-01

    Natural cliffs subject to weathering induced retreat are typically made of hard soils and / or weak rocks exhibiting limited tensile strength. In this paper, the morphologic evolution of uniform c, φ slopes subject to weathering is investigated for a range of values of tensile strengths employing the limit analysis upper bound method. This paper extends the analytical framework set up in [1, 2] by accounting for the limited tensile strength of the ground which was previously disregarded. The solutions were obtained by employing the kinematic method of limit analysis providing rigorous upper bounds to the true collapse values. The inclusion of tension cracks leads to modified analytical expressions of the energy balance equation (the balance between external work and dissipated energy) and as a consequence, of the function whose minimum provides the solution in terms of failure mechanisms and associated values of soil strength. Pre-existing cracks are considered, as well as cracks that form as part of the failure mechanism. It turns out that the presence of tension cracks may significantly alter the size of each landslide contributing to the retrogression of the slope. Results in the form of dimensionless ready-to-use charts are produced for any value of engineering interest of friction angle and slope inclination for the case of dry cracks. Moreover, upper bounds for values not included in the charts can be achieved either by interpolation from the charts or by running the minimisation of the analytical functions provided in the paper.

  8. Microtensile and tensile bond strength of single-bottle adhesives: a new test method.

    PubMed

    Abdalla, A I

    2004-04-01

    To evaluate the tensile and microtensile bond strength of five single-bottle adhesives to dentine, extracted human molar teeth were used. For each tooth dentine was exposed on the occlusal surface by cutting with an isomet saw and the remaining part was mounted in a plastic ring using dental stone. The tested adhesive materials were: Scotchbond 1, Syntac SC, One-Step, Prime & Bond 2.1 and Clearfil SE Bond. The adhesive was applied to either 1 mm(2) of dentine or a circular area with a diameter of 3.9 mm. Composite resin Clearfil AP-X was placed to the adhesives using a Teflon split mould 3.9 mm in diameter and 2.5 mm in height. Tensile and microtensile bond strengths were measured using a universal testing machine at a crosshead speed of 0.5 mm min(-1). Under tensile mode, the bond strengths were 16.7 +/- 3.5, 15.2 +/- 2.5, 11.5 +/- 3.2, 13.7 +/- 2.6, 20.9 +/- 4.2 MPa for each material. Under microtensile mode, the bond strengths were 52.5 +/- 9.5, 55.3 +/- 8.3, 40.5 +/- 5.2, 37.5 +/- 8.7, 60 +/- 6.21 MPa. Fracture pattern of bonded specimens showed 66% cohesive dentine failure in samples tested for tensile bond strength. For the microtensile test, failures were mainly adhesive at the interface between adhesive and dentine (94%). PMID:15089946

  9. Powder flow studies III: tensile strength, consolidation ratio, flow rate, and capsule-filling-weight variation relationships.

    PubMed

    Chowhan, Z T; Yang, I C

    1981-08-01

    The tensile strength of consolidated powder beds was studied by applying a series of loads to the surface of the powder beds in a tensile tester. The results were plotted as tensile strength versus consolidation pressure. The linearity of these plots suggests a direct relationship between tensile strength and consolidation pressure. The following plots gave linear relationships: (1) tensile strength versus consolidation ratio, (b) tensile strength versus coefficient of variation of the filled weight of the capsules, and (c) logarithm of the tensile strength versus logarithm of the flow rate. These results suggest a direct relationship between tensile strength and consolidation ratio and their usefulness in studying powder flow. The physical significance of the empirical equation used in consolidation studies was explored. A comparison of the empirical equation with a theoretically derived equation, under certain assumptions, suggests that the consolidation ratio is a function of the ratio of the initial volume to the net volume and a function of the coefficient of Rankine. The coefficient of Rankine is a function of the angle of internal friction in the static powder bed. PMID:7310665

  10. Casting behavior and tensile strength of cast BaTiO sub 3 tape

    SciTech Connect

    Karas, A.; Kumagai, Toshiya; Cannon, W.R. )

    1988-07-01

    The casting behavior and properties of thin, unsintered BaTiO{sub 3} tapes were studied by measuring viscosity of the slip, green density, ultimate tensile stress, and strain to failure. It was found that increasing the binder to plasticizer ratio increased slip viscosity and strength as expected but also increased strain to failure, and that increasing the poly(ethylene glycol) to benzyl butyl phthalate ratio improved tape release and tape strength, but a small amount of benzyl butyl phthalate improved strain to failure. In addition, increasing the powder to organics ratio increased slip viscosity and green density but strength passed through a maximum and strain to failure decreased. Both slip viscosity and green density were optimized at a particular dispersant concentration but strength decreased monotonically with increased dispersant addition. Finally, an optimum cyclohexanone addition led to a maximum density and strength.

  11. FE Analysis of Buckling Behavior Caused by Welding in Thin Plates of High Tensile Strength Steel

    NASA Astrophysics Data System (ADS)

    Wang, Jiangchao; Rashed, Sherif; Murakawa, Hidekazu

    2014-09-01

    The target of this study was to investigate buckling behavior during the entire welding process which consists of the heating and the cooling processes. For thin plate structures made of high tensile strength steel, not only residual buckling during or after cooling down but also transient buckling during heating may occur. The thermal elastic plastic FE analysis to investigate welding-induced buckling during the entire welding process is presented. Because of the high yield stress of high tensile strength steel, larger longitudinal compressive thermal stress is produced near the welding line compared with that in the case of carbon steel. Therefore, the plate may buckle due to thermal expansion, before the material nears yielding. During cooling down, the longitudinal compressive thermal stress close to the welding line disappears, and longitudinal tensile residual stress is produced due to contraction. Meanwhile, longitudinal compressive residual stress occurs far from the welding line to balance the tensile stress close to the welding line. This distribution of longitudinal residual stress would change the deformed dish shape of transient buckling into a saddle buckling type when the stress exceeds the critical buckling condition.

  12. FE Analysis of Buckling Behavior Caused by Welding in Thin Plates of High Tensile Strength Steel

    NASA Astrophysics Data System (ADS)

    Wang, Jiangchao; Rashed, Sherif; Murakawa, Hidekazu

    2014-12-01

    The target of this study was to investigate buckling behavior during the entire welding process which consists of the heating and the cooling processes. For thin plate structures made of high tensile strength steel, not only residual buckling during or after cooling down but also transient buckling during heating may occur. The thermal elastic plastic FE analysis to investigate welding-induced buckling during the entire welding process is presented. Because of the high yield stress of high tensile strength steel, larger longitudinal compressive thermal stress is produced near the welding line compared with that in the case of carbon steel. Therefore, the plate may buckle due to thermal expansion, before the material nears yielding. During cooling down, the longitudinal compressive thermal stress close to the welding line disappears, and longitudinal tensile residual stress is produced due to contraction. Meanwhile, longitudinal compressive residual stress occurs far from the welding line to balance the tensile stress close to the welding line. This distribution of longitudinal residual stress would change the deformed dish shape of transient buckling into a saddle buckling type when the stress exceeds the critical buckling condition.

  13. Shear and tensile strength of hydroxyapatite coating under loading conditions. An experimental study in dogs.

    PubMed

    Mller, R T; Patsalis, T

    1997-01-01

    The shear and tensile strength of a hydroxyapatite (HA) coating on a femoral component was studied after physiological loading conditions in 8 German Shepherds. A proximal macrostructure on the stem was used to protect this region from shear stresses. Another four implantations with uncoated components were used as controls. In vitro testing of the HA layer demonstrated excellent tensile strength and stability to surface deformation. The loaded implants were tested at 6, 12, and 24 weeks. At 6 weeks the HA-coated components could easily be removed by axial loading, whereas the HA layer remained undamaged on the metal. However, pull out tests of implants older than 12 weeks showed complete debonding of the HA layer from the non-macrostructured surface due to shear forces in all cases. Debonding of the HA layer was also observed with microradiography. The macrostructured surface prevented dislodging of the component from this area at pull out test by distributing shear forces. Unlike in uncoated implants, considerable amounts of bone remained attached onto the HA macrostructure when the surrounding femur was pulled out. Shear forces cause debonding of the HA layer, while tensile stress affects failure within the bone. Physiological loading partially produces gaps at the interface so direct transmission of tensile forces onto the bone is lost, and the coating-metal interface becomes the weak point in the system. PMID:9266035

  14. Laser solder repair technique for nerve anastomosis: temperatures required for optimal tensile strength

    NASA Astrophysics Data System (ADS)

    McNally-Heintzelman, Karen M.; Dawes, Judith M.; Lauto, Antonio; Parker, Anthony E.; Owen, Earl R.; Piper, James A.

    1998-01-01

    Laser-assisted repair of nerves is often unsatisfactory and has a high failure rate. Two disadvantages of laser assisted procedures are low initial strength of the resulting anastomosis and thermal damage of tissue by laser heating. Temporary or permanent stay sutures are used and fluid solders have been proposed to increase the strength of the repair. These techniques, however, have their own disadvantages including foreign body reaction and difficulty of application. To address these problems solid protein solder strips have been developed for use in conjunction with a diode laser for nerve anastomosis. The protein helps to supplement the bond, especially in the acute healing phase up to five days post- operative. Indocyanine green dye is added to the protein solder to absorb a laser wavelength (approximately 800 nm) that is poorly absorbed by water and other bodily tissues. This reduces the collateral thermal damage typically associated with other laser techniques. An investigation of the feasibility of the laser-solder repair technique in terms of required laser irradiance, tensile strength of the repair, and solder and tissue temperature is reported here. The tensile strength of repaired nerves rose steadily with laser irradiance reaching a maximum of 105 plus or minus 10 N.cm-2 at 12.7 W.cm-2. When higher laser irradiances were used the tensile strength of the resulting bonds dropped. Histopathological analysis of the laser- soldered nerves, conducted immediately after surgery, showed the solder to have adhered well to the perineurial membrane, with minimal damage to the inner axons of the nerve. The maximum temperature reached at the solder surface and at the solder/nerve interface, measured using a non-contact fiber optic radiometer and thermocouple respectively, also rose steadily with laser irradiance. At 12.7 W.cm-2, the temperatures reached at the surface and at the interface were 85 plus or minus 4 and 68 plus or minus 4 degrees Celsius respectively. This study demonstrates the feasibility of the laser-solder repair technique for nerve anastomosis resulting in improved tensile strength. The welding temperature required to achieve optimal tensile strength has been identified.

  15. Nanoindentation cannot accurately predict the tensile strength of graphene or other 2D materials.

    PubMed

    Han, Jihoon; Pugno, Nicola M; Ryu, Seunghwa

    2015-10-14

    Due to the difficulty of performing uniaxial tensile testing, the strengths of graphene and its grain boundaries have been measured in experiments by nanoindentation testing. From a series of molecular dynamics simulations, we find that the strength measured in uniaxial simulation and the strength estimated from the nanoindentation fracture force can differ significantly. Fracture in tensile loading occurs simultaneously with the onset of crack nucleation near 5-7 defects, while the graphene sheets often sustain the indentation loads after the crack initiation because the sharply concentrated stress near the tip does not give rise to enough driving force for further crack propagation. Due to the concentrated stress, strength estimation is sensitive to the indenter tip position along the grain boundaries. Also, it approaches the strength of pristine graphene if the tip is located slightly away from the grain boundary line. Our findings reveal the limitations of nanoindentation testing in quantifying the strength of graphene, and show that the loading-mode-specific failure mechanism must be taken into account in designing reliable devices from graphene and other technologically important 2D materials. PMID:26350786

  16. Enhancement of tensile strength of lignocellulosic jute fibers by alkali-steam treatment.

    PubMed

    Saha, Prosenjit; Manna, Suvendu; Chowdhury, Sougata Roy; Sen, Ramkrishna; Roy, Debasis; Adhikari, Basudam

    2010-05-01

    The physico-chemical properties of jute fibers treated with alkali (NaOH) solution have been investigated in this study. The treatments were applied under ambient and elevated temperatures and high pressure steaming conditions. To the knowledge of these authors the influence of alkali-steam treatment on the uniaxial tensile strength of natural ligno-cellulosic fibers, such as jute, has not been investigated earlier. The results from this investigation indicate that a 30 min dipping of the fibers in 0.5% alkali solution followed by 30 min alkali-steam treatment leads to an increase in the tensile strength of up to 65%. The increase appears to be due to fiber separation and removal of non-cellulosic materials, which, in turn, resulted in an increased crystallinity. PMID:20074944

  17. Coating of carbon nanotube fibers: variation of tensile properties, failure behavior and adhesion strength

    NASA Astrophysics Data System (ADS)

    Mäder, Edith; Liu, Jian-Wen; Hiller, Janett; Lu, Weibang; Li, Qingwen; Zhandarov, Serge; Chou, Tsu-Wei

    2015-07-01

    An experimental study of the tensile properties of CNT fibers and their interphasial behavior in epoxy matrices is reported. One of the most promising applications of CNT fibers is their use as reinforcement in multifunctional composites. For this purpose, an increase of the tensile strength of the CNT fibers in unidirectional composites as well as strong interfacial adhesion strength is desirable. However, the mechanical performance of the CNT fiber composites manufactured so far is comparable to that of commercial fiber composites. The interfacial properties of CNT fiber/polymer composites have rarely been investigated and provided CNT fiber/epoxy interfacial shear strength of 14.4 MPa studied by the microbond test. In order to improve the mechanical performance of the CNT fibers, an epoxy compatible coating with nano-dispersed aqueous based polymeric film formers and low viscous epoxy resin, respectively, was applied. For impregnation of high homogeneity, low molecular weight epoxy film formers and polyurethane film formers were used. The aqueous based epoxy film formers were not crosslinked and able to interdiffuse with the matrix resin after impregnation. Due to good wetting of the individual CNT fibers by the film formers, the degree of activation of the fibers was improved leading to increased tensile strength and Young’s modulus. Cyclic tensile loading and simultaneous determination of electric resistance enabled to characterize the fiber’s durability in terms of elastic recovery and hysteresis. The pull-out tests and SEM study reveal different interfacial failure mechanisms in CNT fiber/epoxy systems for untreated and film former treated fibers, on the one hand, and epoxy resin treated ones, on the other hand. The epoxy resin penetrated between the CNT bundles in the reference or film former coated fiber, forming a relatively thick CNT/epoxy composite layer and thus shifting the fracture zone within the fiber. In contrast to this, shear sliding along the

  18. Flexor tenorrhaphy tensile strength: reduction by cyclic loading: in vitro and ex vivo porcine study.

    PubMed

    Gibbons, C E R; Thompson, D; Sandow, M J

    2009-06-01

    The integrity of the repair is critical to maintain coaptation of the severed flexor tendon end until healing has advanced sufficiently. In our hospital, we use a modified Savage repair (four-strand Adelaide technique) using 3-0 Ethibond (Ethicon, Somerville, NJ, USA) for acute flexor tenorrhaphy and an active postrepair mobilization protocol. To explain the apparent differences between the theoretical and actual repair strength of a multistrand repair in a single tension test and the reduced strength of a repair subjected to cyclic loading, we compared single and cyclical tensile loading with different suture in vitro configurations of 3-0 Ethibond (Ethicon, Somerville, NJ, USA; one, two, and four strands) and an ex vivo four-strand repair of freshly divided porcine tendon to calculate the ultimate tensile strength (UTS). Mechanical testing was repeated 15 times with both single tensile and cyclical loading for each suture configuration and porcine repair. In the in vitro model, the presence of a knot in a single strand reduced the UTS by 50%. The stiffness of a knotted strand was substantially less than the unknotted strand but became identical after cyclical loading. There was no statistical significance of the UTS between single and cyclical loading with different numbers of strands in this model. In the ex vivo four-strand porcine repair model, there was a significant reduction in UTS with cyclical loading, which equated to the number of strands times the strength of the knotted strand. This discrepancy can be explained by the change in stiffness of the knotted strand after cyclical loading and has important implications for previous studies of suture tendon repair using single tensile loading where the UTS may have been overestimated. We believe that cyclical loading is more representative of physiological loading after acute flexor tendon repair and should be the testing model of choice in suture tenorrhaphy studies. PMID:19089497

  19. Tensile strength of simulated and welded butt joints in W-Cu composite sheet

    NASA Technical Reports Server (NTRS)

    Moore, Thomas J.; Watson, Gordon K.

    1994-01-01

    The weldability of W-Cu composite sheet was investigated using simulated and welded joints. The welded joints were produced in a vacuum hot press. Tensile test results showed that simulated joints can provide strength and failure mode data which can be used in joint design for actual weldments. Although all of the welded joints had flaws, a number of these joints were as strong as the W-Cu composite base material.

  20. Effect of laser welding on the titanium ceramic tensile bond strength

    PubMed Central

    GALO, Rodrigo; RIBEIRO, Ricardo Faria; RODRIGUES, Renata Cristina Silveira; PAGNANO, Valéria de Oliveira; de MATTOS, Maria da Glória Chiarello

    2011-01-01

    Titanium reacts strongly with elements, mainly oxygen at high temperature. The high temperature of titanium laser welding modifies the surface, and may interfere on the metal-ceramic tensile bond strength. Objective The influence of laser welding on the titanium-ceramic bonding has not yet been established. The purpose of this in vitro study was to analyze the influence of laser welding applied to commercially pure titanium (CpTi) substructure on the bond strength of commercial ceramic. The influence of airborne particle abrasion (Al2O3) conditions was also studied. Material and Methods Forty CpTi cylindrical rods (3 mm x 60 mm) were cast and divided into 2 groups: with laser welding (L) and without laser welding (WL). Each group was divided in 4 subgroups, according to the size of the particles used in airborne particle abrasion: A - Al2O3 (250 µm); B - Al2O3 (180 µm); C - Al2O3 (110 µm); D - Al2O3 (50 µm). Ceramic rings were fused around the CpTi rods. Specimens were invested and their tensile strength was measured at fracture with a universal testing machine at a crosshead speed of 2.0 mm/min and 200 kgf load cell. Statistical analysis was carried out with analysis of variance and compared using the independent t test (p≤0.05). Results Significant differences were found among all subgroups (p<0.05). The highest and the lowest bond strength means were recorded in subgroups WLC (52.62 MPa) and LD (24.02 MPa), respectively. Conclusion Airborne particle abrasion yielded significantly lower bond strength as the Al2O3 particle size decreased. Mechanical retention decreased in the laser-welded specimens, i.e. the metal-ceramic tensile bond strength was lower. PMID:21956585

  1. The dependence of bedrock erodibility on rock material properties: is tensile strength enough?

    NASA Astrophysics Data System (ADS)

    Beyeler, J. D.; Sklar, L. S.; Litwin, K.; Johnson, J. P.; Collins, G. C.; Whipple, K. X.

    2009-12-01

    Rock resistance to fluvial abrasion by bedload sediment impacts has been shown experimentally to depend on the square of rock tensile strength across the full range of rock strengths encountered in the field. This result is consistent with fracture mechanics theory which predicts that fractures propagate when the capacity of brittle materials to store impact energy by elastic deformation is exceeded. Strain energy depends on the square of tensile strength, but also on the elastic modulus. Log-log linear regression of laboratory measurements of bedrock erosion rates against tensile strength shows order-of -magnitude variability about the power-law fit, particularly for stronger rocks. In this investigation we seek to explain this variability in terms of other rock material properties. In particular we are examining elastic modulus, crystal grain size, mineralogy, degree of cementation, rock bulk density and porosity. We have access to the same rocks used in previous bedrock abrasion experiments, as well as artificial bedrock made from controlled mixtures of sand and portland cement. We measure tensile strength by the Brazilian splitting test, and estimate elastic modulus from measurements of the velocity of ultrasonic pulses through core samples. We are analyzing thin sections and photomicrographs to measure crystal grain size, and mineral and cement composition. Bulk density, as well as porosity, are measured by comparison of dry and saturated weights for known volumes of material. Preliminary results suggest that coarse-grained rocks, such as granite and some sandstones, are less erodible for a given measured tensile strength than the fine-grained rocks tested, which include greenstone, andesite and limestone. We also find, with a small subset of rock types tested to-date, that inclusion of elastic modulus in a multiple regression reduces the uncertainty in the regression slope estimate, but that substantial variability remains to be explained. This work may have broad applicability in understanding erodibility of terrestrial bedrock by fluvial as well as eolian mechanisms, as well as controls on the surface erodibility of ice bedrock on outer solar system satellites such as Titan.

  2. The effect of bacterial endotoxin on the early tensile strength of healing surgical wounds.

    PubMed

    Metzger, Zvi; Nitzan, Daniel; Pitaru, Sandu; Brosh, Tamar; Teicher, Shlomo

    2002-01-01

    Wound healing in the oral cavity occurs in a bacteria-rich environment, which may affect its outcome. Furthermore, it takes place where forces are frequently applied to the healing tissue. The effect of bacterial endotoxin on the development of tensile strength in healing wounds was studied using surgical skin wounds in rats as a model. Collagen membranes soaked with 0.01 microg of bacterial endotoxin were inserted into surgical skin wounds, and their effect was studied on days 6 and 10. Membranes with no endotoxin served as controls. Endotoxin inhibited the early development of tensile strength in 6 days, healing wounds by 38%, whereas the collagen membrane alone had no effect. Dexamethasone (0.5 mg/kg every 72 h) had a suppressive effect on the development of tensile strength in healing noncontaminated wounds, but not in those containing bacterial endotoxin. These results suggest that bacterial endotoxin may interfere with the early healing of wounds. Understanding the mechanisms of this inhibition may result in treatments that will allow this response to be faster and more reproducible. PMID:11806645

  3. Influence of Tm:YAP laser irradiation on tensile strength for bracket debonding

    NASA Astrophysics Data System (ADS)

    Dostalova, Tatjana; Jelinkova, Helena; Sulc, Jan; Koranda, Petr; Nemec, Michal; Fibrich, Martin; Jelinek, Michal; Michalik, Pavel; Miyagi, Mitsunobu

    2011-03-01

    The investigation of tensile strength needed for bracket debonding was the aim of study. A diode pumped Tm: YAP microchip laser generating a continuous 2um radiation with the maximum output power of 4W was used for debonding purposes. The group of 60 brackets was debonded using classical and laser irradiation methods - the doze from 1W to 4 W, 60s. The tensile strength without laser irradiation was in the range from 39.6 N (full ceramic bracket group) to 63.7 N (ceramic bracket with metal slot group). After irradiation the tensile strength was decreased from 35.1 N (full ceramic bracket group) to 48.8 N (ceramic bracket with metal slot group). The results of our study generally agree with the previous studies, substantiating the fact that lasers can be used effectively to thermally soften the adhesive resin for removal of ceramic brackets. From the practical point of view is conclusion that during laser irradiation, thermal ablation occurs and the bracket is removed from the enamel together with the rest of the adhesive resin. Laser debonding is easier and little heat diffusion occurred.

  4. Effect of dimethylpolysiloxane liquid on the cryogenic tensile strength and thermal contraction behavior of epoxy resins

    NASA Astrophysics Data System (ADS)

    Yi, Jin Woo; Lee, Yu Jin; Lee, Sang Bok; Lee, Wonoh; Um, Moon Kwang

    2014-05-01

    Dimethylpolysiloxane liquid was blended with diglycidyl ether of bisphenol-A epoxy resin including anhydride curing agent to improve the tensile strength of the epoxy resin at 77 K without any increase in its coefficient of thermal expansion (CTE). A bifunctional polymer, silicone-modified epoxy resin (SME), was also added to the mixture as a compatibilizer. The results of UV transmittance for the blend resin showed that the incorporation of the SME could stabilize effectively spherical domains of the siloxane liquid which was immiscible with the epoxy matrix. The tensile strengths of the blend resins at both room temperature and 77 K were measured and SEM analysis for the fractured cross sections was carried out to verify the toughening behavior of the liquid droplets. The results indicated that even small amount of addition of the siloxane liquid (0.05 phr) coupled with SME (20 phr) could enhance the tensile strength at 77 K by 77.6% compared to that of the neat epoxy resin. This improvement is attributed to the fact that the solid and s droplets can disperse the localized stress and interrupt the crack propagation by cavitation mechanism followed by multiple generation of numerous micro-deformation. From the CTE measurement, the siloxane liquid has no influence on the thermal contraction behavior of the blend resin.

  5. Studies on the reduction of tensile strength of tablets after roll compaction/dry granulation.

    PubMed

    Herting, Michael G; Kleinebudde, Peter

    2008-09-01

    Roll compaction/dry granulation is a widely used technique for granulation. A major drawback is the reduction of tablet tensile strength compared to other granulation methods. The purpose of this study was to determine the reasons for the partial loss in compactibility. Microcrystalline cellulose of different particle sizes was roll-compacted/dry-granulated. The granules were sieved to obtain two sieve cuts and then compressed into tablets. The particle-size distribution within the sieve cut was determined using image analysis. The specific surface area of sieve cut was obtained by nitrogen adsorption. Heckel equation was used to determine the change in compressibility. The work-hardening phenomenon was found to be caused by a combination of particle-size enlargement and hardening of material. Although particle size of granules was equal, the use of smaller particles as raw material resulted in tablets with higher tensile strength due to higher specific surface area. Both work-hardening and particle-size enlargement cause the partial loss in compactibility. The reduction in tensile strength could be compensated by producing smaller granules or using raw materials with small particle sizes. PMID:18511247

  6. Effects of HF Treatments on Tensile Strength of Hi-Nicalon Fibers

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.

    1998-01-01

    Tensile strengths of as-received Hi-Nicalon fibers and those having a dual BN/SiC surface coating, deposited by chemical vapor deposition, have been measured at room temperature. These fibers were also treated with HF for 24 h followed by tensile strength measurements. Strengths of uncoated and BN/SiC coated Hi-Nicalon fibers extracted from celsian matrix composites, by dissolving away the matrix in HF for 24 h, were also determined. The average tensile strength of uncoated Hi-Nicalon was 3.19 +/- 0.73 GPa with a Weibull modulus of 5.41. The Hi-Nicalon/BN/SiC fibers showed an average strength of 3.04 q 0.53 GPa and Weibull modulus of 6.66. After HF treatments, the average strengths of the uncoated and BN/SiC coated Hi-Nicalon fibers were 2.69 +/- 0.67 GPa and 2.80 +/- 0.53 GPa and the Weibull moduli were 4.93 and 5.96, respectively. The BN/SiC coated fibers extracted from the celsian matrix composite exhibited a strength of 2.38 +/- 0.40 GPa and a Weibull modulus of 7.15. The strength of the uncoated Hi-Nicalon fibers in the composite was so severely degraded that they disintegrated into small fragments during extraction with HF. The uncoated fibers probably undergo mechanical surface damage during hot pressing of the composites. Also, the BN layer on the coated fibers acts as a compliant layer which protects the fibers from mechanical damage during composite processing. The elemental composition and thickness of the fiber coatings were deten-nined using scanning Auger analysis. Microstructural analyses of the fibers and the coatings were done by scanning electron microscopy and transmission electron microscopy. Strengths of fibers calculated using average and measured fiber diameters were in good agreement. Thus, the strength of fibers can be evaluated using an average fiber diameter instead of the measured diameter of each filament.

  7. Surface morphology changes of lignin filled natural rubber latex films investigated using AFM in relation to tensile strengths

    NASA Astrophysics Data System (ADS)

    Asrul, M.; Othman, M.; Zakaria, M.

    2015-07-01

    The paper describes the preparation of lignin filled natural rubber latex composite and the consequential changes in tensile strength observed with varying lignin loading. The changes in tensile strength were shown to be associated with the changes in surface morphology as investigated via AFM. From the AFM analysis it can be inferred that lignin filled rubber latex film which exhibited an increase in tensile strength also demonstrated better phase homogeneity with lowest surface roughness value in comparison to the rest of the lignin filled rubber latex films analysed.

  8. Tensile strength of fiber reinforced plastics at 77K irradiated by various radiation sources

    SciTech Connect

    Humer, K.; Weber, H.W.; Tschegg, E.K.; Egusa, S.; Birtcher, R.C.; Gerstenberg, H.

    1993-08-01

    The influence of radiation damage on the mechanical properties of fiber reinforced plastics (FRPs), which are considered as candidate materials for the insulation of superconducting magnets for nuclear fusion reactors, has been investigated. Different types of FRPs (epoxies, bismaleimides; two- and three-dimensional reinforcement structures with E-, S-, or T-glass fibers) has been included in the test program. Three aspects of our present results will be discussed in detail. The first is related to an assessment of the tensile strength and its radiation dependence under the influence of strongly varying radiation conditions. The second aspect refers to low temperature ({approx}5 K) reactor irradiation of selected materials. In this case, identical sets of tensile test samples were transferred into the tensile testing machine, one without warming-up to room temperature and the other after an annealing cycle to room temperature. Finally, a comparison between the radiation response of different materials is made. It turns out that the three-dimensionally reinforced bismaleimide shows the smallest degradation of its tensile properties under all irradiation conditions.

  9. Modeling approach for tensile strength of interphase layers in polymer nanocomposites.

    PubMed

    Zare, Yasser

    2016-06-01

    At the first step, this paper describes a developed model for tensile strength of interphase layers (σk) in polymer nanocomposites. The "σk" is expressed as linear, exponential and power functions of the distance between nanoparticles and polymer matrix (xk). Afterwards, the predictions of these equations at the central layer of interphase (the average strength) are compared to the calculations of interphase strength (σi) by several micromechanical models including the developed Leidner-Woodhams and Pukanszky models to choose the best equation which expresses "σk". The calculations are carried out for several reported samples. The equation which expresses the "σk" as a power function of "xk" shows the best results compared to others. Also, its predictions significantly depend to an exponent as "Z" which demonstrates the level of interphase properties. According to the chosen equation, the "σm" and "σp" play positive roles in "σi" predictions at low "Z" value, but a high "Z" eliminates the effect of "σm" on the tensile strength of interphase layers. PMID:26990956

  10. Tensile Bond Strength of Self Adhesive Resin Cement After Various Surface Treatment of Enamel

    PubMed Central

    Sekhri, Sahil; Garg, Sandeep

    2016-01-01

    Introduction In self adhesive resin cements adhesion is achieved to dental surface without surface pre-treatment, and requires only single step application. This makes the luting procedure less technique-sensitive and decreases postoperative sensitivity. Aim The purpose of this study was to evaluate bond strength of self adhesive resin after surface treatment of enamel for bonding base metal alloy. Materials and Methods On the labial surface of 64 central incisor rectangular base metal block of dimension 6 mm length, 5mm width and 1 mm height was cemented with RelyX U200 and Maxcem Elite self adhesive cements with and without surface treatment of enamel. Surface treatment of enamel was application of etchant, one step bonding agent and both. Tensile bond strength of specimen was measured with universal testing machine at a cross head speed of 1mm/min. Results Least tensile bond strength (MPa) was in control group i.e. 1.33 (0.32) & 1.59 (0.299), Highest bond strength observed when enamel treated with both etchant and bonding agent i.e. 2.72 (0.43) & 2.97 (0.19) for Relyx U200 and Elite cement. When alone etchant and bonding agent were applied alone bond strength is 2.19 (0.18) & 2.24 (0.47) for Relyx U200, and 2.38 (0.27) 2.49 (0.16) for Max-cem elite. Mean bond strength was higher in case of Max-cem Elite as compared to RelyX U200 resin cement, although differences were non–significant (p > 0.05). Conclusion Surface treatment of enamel increases the bond strength of self adhesive resin cement. PMID:26894165

  11. Chitosan films with improved tensile strength and toughness from N-acetyl-cysteine mediated disulfide bonds.

    PubMed

    Miles, Kevin Barrett; Ball, Rebecca Lee; Matthew, Howard William Trevor

    2016-03-30

    To improve the mechanical properties of chitosan (Ct) materials without the use of cytotoxic crosslinkers, disulfide cross-linkable Ct was synthesized by grafting N-acetyl-cysteine (NAC) to Ct using carbodiimide chemistry. Cast films of NAC-Ct conjugates were prepared with degrees of substitution (DS) of 0%, 6%, 15%, and 20%, and the disulfide bond formation was induced by increasing the reaction media pH to 11. The tensile strength, breaking strain, elastic moduli and toughness of disulfide cross-linked polymers were analyzed by monotonic tensile testing of hydrated NAC-Ct films. Crystallinity was determined via XRD. Results demonstrated that NAC incorporation and crosslinking in chitosan produced tougher polymer films with 4-fold higher tensile strength (10MPa) and 6-fold greater elongation (365%), but reduced crystallinity, compared to unmodified chitosan. The resilience of NAC-Ct films was evaluated by cyclic testing, and results demonstrate that increasing NAC content produced a more resilient material that dissipated less energy when deformed. These improved mechanical properties broaden chitosan's applicability towards the construction of mechanically robust implantable scaffolds for tissue regeneration. PMID:26794940

  12. Strength properties of visible-light-cured resin-modified glass-ionomer cements.

    PubMed

    Kerby, R E; Knobloch, L; Thakur, A

    1997-01-01

    A new generation of glass ionomers containing polymerizable methacrylate monomers and/or prepolymers are now available for use as direct esthetic restorative materials. Proper clinical application of these new resin-modified glass ionomers requires an understanding of their benefits and limitations. The purpose of this investigation was to compare the compressive and diametral tensile strength at 1 hour, 24 hours, and 7 days of three visible-light-cured glass-ionomer cements, a polyacid-modified composite resin, and a composite resin core build-up material under both light-cure and dark-cure conditions. Statistical analysis indicated significant differences between several of the cements tested for both compressive and diametral tensile strengths at all three testing times (P > 0.05). Prosthodent composite resin and Vitremer tricure visible-light-cured glass-ionomer cement are significantly greater in both compressive and diametral tensile strength than any of the other materials tested after 7 days. PMID:9484165

  13. Bulk metallic glass composite with good tensile ductility, high strength and large elastic strain limit

    NASA Astrophysics Data System (ADS)

    Wu, Fu-Fa; Chan, K. C.; Jiang, Song-Shan; Chen, Shun-Hua; Wang, Gang

    2014-06-01

    Bulk metallic glasses exhibit high strength and large elastic strain limit but have no tensile ductility. However, bulk metallic glass composites reinforced by in-situ dendrites possess significantly improved toughness but at the expense of high strength and large elastic strain limit. Here, we report a bulk metallic glass composite with strong strain-hardening capability and large elastic strain limit. It was found that, by plastic predeformation, the bulk metallic glass composite can exhibit both a large elastic strain limit and high strength under tension. These unique elastic mechanical properties are attributed to the reversible B2<-->B19' phase transformation and the plastic-predeformation-induced complicated stress state in the metallic glass matrix and the second phase. These findings are significant for the design and application of bulk metallic glass composites with excellent mechanical properties.

  14. High Tensile Strength Amalgams for In-Space Fabrication and Repair

    NASA Technical Reports Server (NTRS)

    Grugel, Richard N.

    2006-01-01

    Amalgams are well known for their use in dental practice as a tooth filling material. They have a number of useful attributes that include room temperature fabrication, corrosion resistance, dimensional stability, and very good compressive strength. These properties well serve dental needs but, unfortunately, amalgams have extremely poor tensile strength, a feature that severely limits other potential applications. Improved material properties (strength and temperature) of amalgams may have application to the freeform fabrication of repairs or parts that might be necessary during an extended space mission. Advantages would include, but are not limited to: the ability to produce complex parts, a minimum number of processing steps, minimum crew interaction, high yield - minimum wasted material, reduced gravity compatibility, minimum final finishing, safety, and minimum power consumption. The work presented here shows how the properties of amalgams can be improved by changing particle geometries in conjunction with novel engineering metals.

  15. Tensile strength of carbyne chains in varied chemical environments and structural lengths

    NASA Astrophysics Data System (ADS)

    Mirzaeifar, Reza; Qin, Zhao; Buehler, Markus J.

    2014-09-01

    Carbyne and carbyne-based low-dimensional structures are promising for several applications including ultra-compact circuits and purification devices. Designing any applied carbyne-based structure requires a fundamental understanding of the mechanical strength of carbyne chains with different lengths at different temperatures and operating chemical environment. Here we use molecular dynamics simulations to investigate the strength of carbyne chains with different lengths at different temperatures. A theoretical framework based on statistical mechanics and molecular dynamics results is presented, proving a fast and insightful method for predicting the rupture force and its physical mechanism. The effect of water molecules interaction is also studied on the mechanical properties and it is shown that both the tensile strength and rupture strain are improved by the water interaction. The results of this work can be used for designing and analyzing the robustness and reliability of various carbyne-based materials and applied devices for varies working conditions.

  16. Tensile and fatigue strength properties of Kevlar 29 aramid/epoxy unidirectional composites

    SciTech Connect

    Zweben, C.

    1981-07-22

    Static and fatigue tensile strength properties of filament wound undirectional Kevlar 29/epoxy, typical of filament wound material used in flywheel rotors, were studied. Machining techniques were developed to minimize fiber fuzzing on edges. The static modulus, normalized to 70% fiber volume fraction is 8.87 x 10/sup 6/ psi. The major Poisson's ratio is 0.37. The static composite tensile strength, normalized to 70% fiber volume fraction is 200 x 10/sup 3/ psi, corresponding to a fiber stress at failure of 286 x 10/sup 3/ psi, which is good for materials having a very high fiber volume fraction. The S-N curve for R = 0.7 was found to be quite flat. Although the techniques used in this program had previously been employed successfully to study the fatigue behavior of Kevlar 29/epoxy and Kevlar 49/epoxy unidirectional materials, we were unable to overcome the persistent problem of cohesive material failure in the tab regions. The apparent reason for this is the very low interlaminar shear strength of the filament wound material. 16 figures.

  17. Tensile Strength and Microstructural Characterization of Uncoated and Coated HPZ Ceramic Fibers

    NASA Technical Reports Server (NTRS)

    Bansal, Narottam P.; Wheeler, Donald R.; Dickerson, Robert M.

    1996-01-01

    Tensile strengths of as-received HPZ fiber and those surface coated with BN, BN/SiC, and BN/Si3N4 have been determined at room temperature using a two-parameter Weibull distribution. Nominally approx. 0.4 micron BN and 0.2 micron SiC or Si3N4 coatings were deposited on the fibers by chemical vapor deposition using a continuous reactor. The average tensile strength of uncoated HPZ fiber was 2.0 +/- 0.56 GPa (290 +/- 81 ksi) with a Weibull modulus of 4.1. For the BN coated fibers, the average strength and the Weibull modulus increased to 2.39 +/- 0.44 GPa (346 +/- 64 ksi) and 6.5, respectively. The HPZ/BN/SiC fibers showed an average strength of 2.0 +/- 0.32 GPa (290 +/- 47 ksi) and Weibull modulus of 7.3. Average strength of the fibers having a dual BN/Si3N4 surface coating degraded to 1.15 +/- 0.26 GPa (166 +/- 38 ksi) with a Weibull modulus of 5.3. The chemical composition and thickness of the fiber coatings were determined using scanning Auger analysis. Microstructural analysis of the fibers and the coatings was carried out by scanning electron microscopy and transmission electron microscopy. A microporous silica-rich layer approx. 200 nm thick is present on the as-received HPZ fiber surface. The BN coatings on the fibers are amorphous to partly turbostratic and contaminated with carbon and oxygen. Silicon carbide coating was crystalline whereas the silicon nitride coating was amorphous. The silicon carbide and silicon nitride coatings are non-stoichiometric, non-uniform, and granular. Within a fiber tow, the fibers on the outside had thicker and more granular coatings than those on the inside.

  18. Relationship between the ideal tensile strength and the friction properties of metals in contact with nonmetals and themselves

    NASA Technical Reports Server (NTRS)

    Miyoshi, K.; Buckley, D. H.

    1981-01-01

    The adhesion and friction properties of metals in contact with diamond, boron nitride, silicon carbide, manganese-zinc ferrite, and the metals themselves in vacuum was investigated. An estimate of the ideal uniaxial tensile was obtained in terms of the equilibrium surface energy, interplanar spacing of the planes perpendicular to the tensile axis, and the Young's modulus of elasticity. The coefficient of friction for metals was found to be related to the ideal tensile strength of metals. The higher the strength of the metal, the lower the coefficient of friction.

  19. Tensile Strength and Hardness Correlations with Microscopy in Friction welded Aluminium to Copper

    NASA Astrophysics Data System (ADS)

    Satish, Rengarajan; Seshagiri Rao, Vaddi; Ananthapadmanaban, Dattaguru; Ravi, Balappa

    2016-01-01

    Aluminium and copper are good conductors of heat and electricity, copper being the better conductor, is a costly metal indeed. On the other hand, aluminium is cheap, easily available and also has a lower density than copper. Hence, worldwide efforts are being made to partially replace copper wire. Solid state welding should be used to join aluminium to copper. This is because the use of fusion welding results in brittle phases formed in the weld interface. One of the solid state welding techniques used for joining aluminium to copper is friction welding. In this paper, an attempt has been made to join aluminium to copper by friction welding by varying the friction welding parameters, namely friction pressure, upset pressure, burn-off length and speed of rotation of the workpiece. Nine different friction welding parameter combinations were used during welding in accordance with ASTM standards and results have been reported. Tensile strength and hardness tests were carried out for each parameter combination. Optimum friction welding parameter combination was identified with respect to tensile strength. Scanning Electron Microscopy and Electron dispersive spectroanalysis were obtained to identify modes of fracture and presence of intermetallic phases for each friction welding combination with the aim to narrow down friction welding parameters that give good properties on the whole.

  20. Tensile strength of glass fiber posts submitted to different surface treatments.

    PubMed

    Faria, Maria Isabel A; Gomes, Érica Alves; Messias, Danielle Cristine; Silva Filho, João Manoel; Souza Filho, Celso Bernardo; Paulino, Silvana Maria

    2013-01-01

    The aim of this in vitro study was to evaluate the tensile strength of glass fiber posts submitted to different surface treatments. Forty-eight maxillary canines had their crowns sectioned and root canals endodontically treated. The roots were embedded in acrylic resin and distributed into 3 groups according to the surface treatment: Group I: the posts were treated with silane agent for 30 s and adhesive; Group II: the posts were cleaned with alcohol before treatment with silane agent and adhesive; Group III: the posts were submitted to conditioning with 37% phosphoric acid for 30 s before treatment with silane agent and adhesive. Each group was divided into 2 subgroups for adhesive polymerization or not before insertion into the canal: A - adhesive was not light cured and B - adhesive was light cured. All posts were cemented with Panavia F and the samples were subjected to tensile strength test in a universal testing machine at crosshead speed of 1 mm/min. Data were submitted to one-way ANOVA and Tukey's test at 5% significance level. There was statistically significant difference (p<0.01) only between group GIII-B and groups GI-A and GI-B. No significant difference was found among the other groups (p>0.05). It was concluded that the products used for cleaning the posts influenced the retention regardless of adhesive light curing. PMID:24474360

  1. Tensile Strength and Hardness Correlations with Microscopy in Friction welded Aluminium to Copper

    NASA Astrophysics Data System (ADS)

    Satish, Rengarajan; Seshagiri Rao, Vaddi; Ananthapadmanaban, Dattaguru; Ravi, Balappa

    2015-03-01

    Aluminium and copper are good conductors of heat and electricity, copper being the better conductor, is a costly metal indeed. On the other hand, aluminium is cheap, easily available and also has a lower density than copper. Hence, worldwide efforts are being made to partially replace copper wire. Solid state welding should be used to join aluminium to copper. This is because the use of fusion welding results in brittle phases formed in the weld interface. One of the solid state welding techniques used for joining aluminium to copper is friction welding. In this paper, an attempt has been made to join aluminium to copper by friction welding by varying the friction welding parameters, namely friction pressure, upset pressure, burn-off length and speed of rotation of the workpiece. Nine different friction welding parameter combinations were used during welding in accordance with ASTM standards and results have been reported. Tensile strength and hardness tests were carried out for each parameter combination. Optimum friction welding parameter combination was identified with respect to tensile strength. Scanning Electron Microscopy and Electron dispersive spectroanalysis were obtained to identify modes of fracture and presence of intermetallic phases for each friction welding combination with the aim to narrow down friction welding parameters that give good properties on the whole.

  2. TENSILE STRENGTH AND FRACTURE SURFACE CHARACTERIZATION OF HI-NICALONTM SIC FIBERS

    SciTech Connect

    Youngblood, Gerald E.; Lewinsohn, Charles A.; Jones, Russell H.; Kohyama, Akira

    2000-06-30

    Dimensional, tensile strength and fracture surface characterizations were carried out for a particular batch (51 samples) of unirradiated Hi-Nicalon™ SiC fiber. This batch of SiC fibers is included in the radiation test matrix as part of the JUPITER 12J and 14J experiments. In general, filaments of Hi-Nicalon™ fiber with larger cross-sectional areas (equivalent diameters) had lower strengths than filaments with smaller cross-sectional areas. During tensile tests at room temperature, fracture originated at critical flaws that typically consisted of internal pores or carbonaceous inclusions. Well-demarcated mirror and hackle regions usually surrounded the critical flaws. With a few exceptions, the critical flaw size (ac) was linearly related to the mirror size (rm) by ac » 0.33rm. From fracture mechanics principles, values for the average mirror constant (Am) and effective fracture toughness for this batch of Hi-NicalonÔ fiber were estimated to be 2.99 ± 0.33 and 1.1 ± 0.2 MPa m1/2, respectively.

  3. Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes.

    PubMed

    Liu, Jie; Lu, Xiaolong; Wu, Chunrui

    2013-01-01

    Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of α and β phases, the overall membranes were predominantly α phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of α and β phases, the overall membranes were predominantly α phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 °C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

  4. Effect of Preparation Methods on Crystallization Behavior and Tensile Strength of Poly(vinylidene fluoride) Membranes

    PubMed Central

    Liu, Jie; Lu, Xiaolong; Wu, Chunrui

    2013-01-01

    Poly(vinylidene fluoride) (PVDF) membranes were prepared by non solvent induced phase separation (NIPS), melt spinning and the solution-cast method. The effect of preparation methods with different membrane formation mechanisms on crystallization behavior and tensile strength of PVDF membranes was investigated. Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and X-ray diffraction (XRD) were employed to examine the crystal form of the surface layers and the overall membranes, respectively. Spherulite morphologies and thermal behavior of the membranes were studied by polarized light optical microscopy (PLO) and differential scanning calorimetry (DSC) separately. It was found that the crystallization behavior of PVDF membranes was closely related to the preparation methods. For membranes prepared by the NIPS method, the skin layers had a mixture of ? and ? phases, the overall membranes were predominantly ? phase, and the total crystallinity was 60.0% with no spherulite. For melt spinning membranes, the surface layers also showed a mixture of ? and ? phases, the overall membranes were predominantly ? phase. The total crystallinity was 48.7% with perfect spherulites. Whereas the crystallization behavior of solution-cast membranes was related to the evaporation temperature and the additive, when the evaporation temperature was 140 C with a soluble additive in the dope solution, obvious spherulites appeared. The crystalline morphology of PVDF exerted a great influence on the tensile strength of the membranes, which was much higher with perfect spherulites. PMID:24957064

  5. Change of Tensile Strength due to Non-uniform Thermal Deterioration of XLPE Sheets

    NASA Astrophysics Data System (ADS)

    Kurihara, Takashi; Takahashi, Toshihiro; Homma, Hiroya; Okamoto, Tatsuki

    Cross-linked polyethylene (XLPE) sheets were thermally deteriorated in atmospheric air at 180C for at most 100 hours, and their depth profiles of the oxidation degrees were investigated with a micro FT-IR, and the relationships between the oxidation degree and mechanical properties such as tensile strength and elongation at break were examined. The oxidation degree was defined as the ratio of the IR absorption peak for the C=O bond to that for the C-H bond. When tensile strength and elongation at break of XLPE sheets decreased, the oxidation degree increased and the oxidation degree distributed non-uniformly with depth. That is, the oxidation degree was the largest on the upper surface of XLPE sheets where air supply was sufficient during heating, and it was the smallest on the lower surface that contacted with a metal plate during heating. Since the mechanical characteristics such as the hardness and the Young's modulus decreased in the oxidized region of XLPE sheets, it was pointed out that the oxidized region became a weak point against the mechanical stress. It was also pointed out that the micro FT-IR was useful in evaluating the depth profile of oxidation in polymer materials.

  6. Origin of tensile strength of a woven sample cut in bias directions

    PubMed Central

    Pan, Ning; Kovar, Radko; Dolatabadi, Mehdi Kamali; Wang, Ping; Zhang, Diantang; Sun, Ying; Chen, Li

    2015-01-01

    Textile fabrics are highly anisotropic, so that their mechanical properties including strengths are a function of direction. An extreme case is when a woven fabric sample is cut in such a way where the bias angle and hence the tension loading direction is around 45 relative to the principal directions. Then, once loaded, no yarn in the sample is held at both ends, so the yarns have to build up their internal tension entirely via yarnyarn friction at the interlacing points. The overall fabric strength in such a sample is a result of contributions from the yarns being pulled out and those broken during the process, and thus becomes a function of the bias direction angle ?, sample width W and length L, along with other factors known to affect fabric strength tested in principal directions. Furthermore, in such a bias sample when the major parameters, e.g. the sample width W, change, not only the resultant strengths differ, but also the strength generating mechanisms (or failure types) vary. This is an interesting problem and is analysed in this study. More specifically, the issues examined in this paper include the exact mechanisms and details of how each interlacing point imparts the frictional constraint for a yarn to acquire tension to the level of its strength when both yarn ends were not actively held by the testing grips; the theoretical expression of the critical yarn length for a yarn to be able to break rather than be pulled out, as a function of the related factors; and the general relations between the tensile strength of such a bias sample and its structural properties. At the end, theoretical predictions are compared with our experimental data. PMID:26064655

  7. Theoretical investigations into the influence of the position of a breaking line on the tensile failure of flat, round, bevel-edged tablets using finite element methodology (FEM) and its practical relevance for industrial tablet strength testing.

    PubMed

    Podczeck, Fridrun; Newton, J Michael; Fromme, Paul

    2014-12-30

    Flat, round tablets may have a breaking ("score") line. Pharmacopoeial tablet breaking load tests are diametral in their design, and industrially used breaking load testers often have automatic tablet feeding systems, which position the tablets between the loading platens of the machine with the breaking lines in random orientation to the applied load. The aim of this work was to ascertain the influence of the position of the breaking line in a diametral compression test using finite element methodology (FEM) and to compare the theoretical results with practical findings using commercially produced bevel-edged, scored tablets. Breaking line test positions at an angle of 0, 22.5, 45, 67.5 and 90 relative to the loading plane were studied. FEM results obtained for fully elastic and elasto-plastic tablets were fairly similar, but they highlighted large differences in stress distributions depending on the position of the breaking line. The stress values at failure were predicted to be similar for tablets tested at an angle of 45 or above, whereas at lower test angles the predicted breaking loads were up to three times larger. The stress distributions suggested that not all breaking line angles would result in clean tensile failure. Practical results, however, did not confirm the differences in the predicted breaking loads, but they confirmed differences in the way tablets broke. The results suggest that it is not advisable to convert breaking loads obtained on scored tablets into tablet tensile strength values, and comparisons between different tablets or batches should carefully consider the orientation of the breaking line with respect to the loading plane, as the failure mechanisms appear to vary. PMID:25455775

  8. Size effects on tensile and compressive strengths in metallic glass nanowires

    NASA Astrophysics Data System (ADS)

    Zhou, Xiaoling; Zhou, Haofei; Li, Xiaoyan; Chen, Changqing

    2015-11-01

    Shear localization induced brittleness is the main drawback of metallic glasses which restricts their practical applications. Previous experiments have provided insights on how to suppress shear localization by reducing the sample size of metallic glasses to the order of 100 nm. In order to reveal the size effects and associated deformation mechanisms of metallic glasses in an even finer scale, we perform large-scale atomistic simulations for the uniaxial compression and tension of metallic glass nanowires. The simulation results show that, as the diameter of metallic glass samples decreases from 45 nm to 8 nm, the tensile yield strength increases while the compressive yield strength decreases. Homogeneous flow is observed as the governing deformation mechanism in all simulated metallic glass samples, where plastic shearing tends to initiate on the sample surface and propagate into the interior. To rationalize the size dependence of yield strengths, we propose a theoretical model based on the concept of surface stress and Mohr-Coulomb criterion. The theoretical predictions agree well with the simulation results, implying the important role of surface stress on the yielding of MGs below 100 nm. Finally, a discussion about the size effects of strength in metallic glasses at different length scales is provided. Our results suggest that the shear band energy and surface stress might be the two crucial parameters in determining the critical size required for the transition from shear localization to homogeneous deformation in MGs.

  9. Tensile Bond Strengths of Two Adhesives on Irradiated and Nonirradiated Human Dentin

    PubMed Central

    Bernard, Cécile; Abouelleil, Hazem; Gustin, Marie-Paule; Grosgogeat, Brigitte

    2015-01-01

    The aim of this study was to assess the effect of radiotherapy on bond efficiency of two different adhesive systems using tensile bond strength test. Twenty extracted teeth after radiotherapy and twenty nonirradiated extracted teeth were used. The irradiation was applied in vivo to a minimal dose of 50 Gy. The specimens of each group were randomly assigned to two subgroups to test two different adhesive systems. A three-step/etch-and-rinse adhesive system (Optibond FL) and a two-steps/self-etch adhesive system (Optibond XTR) were used. Composite buildups were performed with a nanohybrid composite (Herculite XTR). All specimens were submitted to thermocycling ageing (10000 cycles). The specimens were sectioned in 1 mm2 sticks. Microtensile bond strength tests were measured. Nonparametric statistical analyses were performed due to nonnormality of data. Optibond XTR on irradiated and nonirradiated teeth did not show any significant differences. However, Optibond FL bond strength was more effective on nonirradiated teeth than on irradiated teeth. Within the limitations of an in vitro study, it can be concluded that radiotherapy had a significant detrimental effect on bond strength to human dentin. However, it seems that adhesive choice could be adapted to the substrata. According to the present study, the two-steps/self-etch (Optibond XTR) adhesive system tested could be more effective on irradiated dentin compared to three-steps/etch-and-rinse adhesive system (Optibond FL). PMID:26783528

  10. Relationship between apposition pressure during welding and tensile strength of the acute weld

    NASA Astrophysics Data System (ADS)

    Wu, Paul J.; Walsh, Joseph T., Jr.

    2001-05-01

    Dye-assisted photothermal welding is a technique used to close wounds by thermally cross-linking collagen across apposed tissue edges. For a successful weld, not only do laser parameters have to be optimized, but also apposition of the incision has to be consistent and controlled. The objective of this study was to quantify the relationship between the applied apposition pressure (i.e., the compressive force holding the wound closed during the welding procedure divided by the area of the skin-to-skin interface) and the tensile strength of the wound following the welding procedure. By using a clamping device made of two complementary pieces, each 3 cm wide with a row of 10 equally spaced blunt wire mesh tips, the apposition pressure along a 2-cm-long incision in each albino guinea pig was quantified using a 127-micrometers -thick load cell and varied from 0-1.8 kgf/cm2. A continuous wave, Nd:YAG laser emitting 10.0 W of 1.06-micrometers radiation from a 600-micrometers -diameter fiber irradiating a 5-mm-diameter spot size was scanned across the incision in order to deliver 300 J of total energy. As the apposition pressure of the incisions was increased, the resulting tensile strength of welded skin increased in a sigmoidal manner. For this welding technique, an apposition pressure of at least 1.2 kgf/cm2 is necessary to obtain maximum weld strength of the skin (2.56+/- 0.36 kg/cm2).

  11. Effect of thermal treatments on tensile strength of commercially cast pure titanium and Ti-6Al-4V alloys.

    PubMed

    da Rocha, Sicknan Soares; Adabo, Gelson Luis; Vaz, Luis Geraldo; Henriques, Guilherme Elias Pessanha

    2005-08-01

    Heating titanium structures is assumed to relieve tensions induced by the casting process as well as possibly optimizing some mechanical properties. The aim of this investigation was to evaluate the effect of thermal treatments on tensile strength of commercially pure titanium (CP Ti) and Ti-6Al-4V alloy. Thirty dumbbell rods, with diameters of 3.0 mm at the central segment and lengths of 42 mm, were cast for each metal using the Rematitan System. CP Ti and Ti-6Al-4V specimens were randomly divided into three groups of ten: a control group that received no thermal treatment and two test groups. One (T1) was heated at 750 degrees C for 2 h and the other (T2) was annealed at 955 degrees C for 1 h and aged at 620 degrees C for 2 h. Tensile strength was measured with a universal testing machine (MTS model 810). Tensile strength means and standard deviations were statistically compared using a Kruskal-Wallis test at a alpha=0.05 significance level. No statistically significant differences in tensile strength were observed among CP Ti groups. For the Ti-6Al-4V alloy, the control and T1 groups revealed statistically higher tensile strengths when compared to the T2 group, with no significant difference between the control and T1 groups. PMID:15965747

  12. Hot-press consolidation and tensile strength characterization of mechanically alloyed nanostructured Fe-Al and Fe-C powder

    SciTech Connect

    Rawers, J.C.; Slavens, G.J.; Krabbe, R.A.; Groza, J.

    1997-01-01

    Previous studies of nanostructured materials have typically concentrated on characterization of microscopic properties, principally because of the inability to produce samples of sufficient size to determine macroscopic properties. In this study consolidation of mechanically alloyed Fe-AI and Fe-C powders was accomplished by hot-pressing. Microstructure characterizations of both the attritor-processed powder and the consolidated material were determined using X-ray diffraction and SEM. Consolidated samples were of sufficient size (25 mm in diameter and 5-7mm thick) to determine macroscopic properties, most notably tensile strengths. Tensile strength increased with increasing density, reaching a optimal strength of 700 to 900 MPa as the compacts reached full density. The maximum nanostructure tensile strength is consistent with tensile properties of HSLA steels. Compact characteristics (density, hardness, tensile strength) were determined as a function of hot-pressing conditions (processing temperature, time, pressure). During consolidation, Fe-C samples developed second phase spinel and carbide precipitates. During consolidation, Fe-AI samples developed a duplex submicron- and nanograin bcc-Fe microstructures and nanograins of (Fe,Al)3O4. The grains of the consolidated samples were free of grain disorder, e.g., dislocations, twins, etc. With few exceptions, density and grain size increased with increasing hot-press processing time, temperature, and/or pressure.

  13. The tensile strength of the union between various glass ionomer cements and various composite resins.

    PubMed

    Mount, G J

    1989-04-01

    Increasing use is being made of the glass ionomer cements as a lining for composite resin restorations, particularly when restoring posterior teeth. It has been suggested that it is possible to obtain a mechanical union between the two materials by etching the surface of the cement. This paper discusses the result of testing a broad variety of combinations of different glass ionomer cements and composite resins that have been reported on previously, and suggests that a number of factors need to be taken into account if the optimum physical properties are to be achieved from the union. There would appear to be four main factors which dictate the final strength of the union. The tensile strength of the cement itself is of primary importance and it seems the wettability of the resin bonding agent is also significant. When using some of the less heavily filled composite resins, the stresses set up by the setting contraction of the resin may be too great and, finally, the more heavily filled composite resins for restoration of posterior teeth often prove difficult to adapt to the underlying cement. With careful clinical handling, the so-called 'sandwich' technique is very useful. However, not all combinations of glass ionomer cement and composite resin will unite with sufficient strength to be successful clinically. PMID:2658936

  14. Tensile Strength of Liquids: Equivalence of Temporal and Spatial Scales in Cavitation.

    PubMed

    Cai, Y; Huang, J Y; Wu, H A; Zhu, M H; Goddard, W A; Luo, S N

    2016-03-01

    It is well known that strain rate and size effects are both important in material failure, but the relationships between them are poorly understood. To establish this connection, we carry out molecular dynamics (MD) simulations of cavitation in Lennard-Jones and Cu liquids over a very broad range of size and strain rate. These studies confirm that temporal and spatial scales play equivalent roles in the tensile strengths of these two liquids. Predictions based on smallest-scale MD simulations of Cu for larger temporal and spatial scales are consistent with independent simulations, and comparable to experiments on liquid metals. We analyze these results in terms of classical nucleation theory and show that the equivalence arises from the role of both size and strain rate in the nucleation of a daughter phase. Such equivalence is expected to hold for a wide range of materials and processes and to be useful as a predictive bridging tool in multiscale studies. PMID:26885747

  15. Galactans and cellulose in flax fibres: putative contributions to the tensile strength.

    PubMed

    Girault, R; Bert, F; Rihouey, C; Jauneau, A; Morvan, C; Jarvis, M

    1997-08-01

    The proton spin-spin relaxation time, T2, measured from solid-state NMR, indicates a greater rigidity for cellulose than for the adhesive matrix between the microfibrils of flax ultimate fibres. Cytochemical and biochemical analyses allow the identification of: (1) EDTA-soluble RG I-polymers in the primary walls and cell junctions of fibres; (2) long 1 --> 4-beta-D-galactan chains between primary and secondary wall layers; and (3) arabinogalactan-proteins throughout the secondary walls. These polymers in the adhesive matrix between microfibrils and/or cellulose layers ensure that cracks propagate along the matrix rather than across the fibres and play an important role in allowing flax fibres to approach the tensile strength of advanced synthetic fibres like carbon and Kevlar. PMID:9283034

  16. Influence of residual stresses on the tensile strength of composite-metal sandwich laminates

    NASA Technical Reports Server (NTRS)

    Herakovich, C. T.; Wong, D. M.

    1977-01-01

    The tensile strength of boron-epoxy/aluminum sandwich laminates is discussed relative to the residual thermal stresses generated by curing and bonding at elevated temperatures. It is shown that the sandwich laminates investigated exhibit three dinstinct modes of failure, depending upon the fiber orientation of the composite. Sandwich laminates with moderate to high percentage of 0-deg fibers exhibit early failures initiated by edge effect; laminates with moderate to high percentage of 90-deg fibers fail according to a first-ply failure criterion; laminates with moderate to high percentages of plus or minus 45 deg plies fail at strains equal to or greater than the failure strain of the corresponding all-composite laminate.

  17. Analysis of Ninety Degree Flexure Tests for Characterization of Composite Transverse Tensile Strength

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin; Krueger, Ronald

    2001-01-01

    Finite element (FE) analysis was performed on 3-point and 4-point bending test configurations of ninety degree oriented glass-epoxy and graphite-epoxy composite beams to identify deviations from beam theory predictions. Both linear and geometric non-linear analyses were performed using the ABAQUS finite element code. The 3-point and 4-point bending specimens were first modeled with two-dimensional elements. Three-dimensional finite element models were then performed for selected 4-point bending configurations to study the stress distribution across the width of the specimens and compare the results to the stresses computed from two-dimensional plane strain and plane stress analyses and the stresses from beam theory. Stresses for all configurations were analyzed at load levels corresponding to the measured transverse tensile strength of the material.

  18. Tensile strength and impact resistance properties of materials used in prosthetic check sockets, copolymer sockets, and definitive laminated sockets.

    PubMed

    Gerschutz, Maria J; Haynes, Michael L; Nixon, Derek M; Colvin, James M

    2011-01-01

    Prosthetic sockets serve as the interface between people with amputations and their prostheses. Although most materials used to make prosthetic sockets have been used for many years, knowledge of these materials' properties is limited, especially after they are subjected to fabrication processes. This study evaluated tensile and impact properties of the current state-of-the-art materials used to fabricate prosthetic check sockets, copolymer sockets, and definitive laminated sockets. Thermolyn Rigid and Orfitrans Stiff check socket materials produced significantly lower tensile strength and impact resistance than polyethylene terephthalate glycol (PETG). Copolymer socket materials exhibited greater resistance to impact forces than the check socket materials but lower tensile strengths than PETG. The heated molding processes, for the check socket and copolymer materials, reduced both tensile strength and elongation at break. Definitive laminated sockets were sorted according to fabrication techniques. Nyglass material had significantly higher elongation, indicating a more ductile material than carbon-based laminations. Carbon sockets with pigmented resin had higher tensile strength and modulus at break than nonpigmented carbon sockets. Elongation at yield and elongation at break were similar for both types of carbon-based laminations. The material properties determined in this study provide a foundation for understanding and improving the quality of prosthetic sockets using current fabrication materials and a basis for evaluating future technologies. PMID:22068374

  19. Correlation analysis of the variation of weld seam and tensile strength in laser welding of galvanized steel

    NASA Astrophysics Data System (ADS)

    Sinha, Amit Kumar; Kim, Duck Young; Ceglarek, Darek

    2013-10-01

    Many advantages of laser welding technology such as high speed and non-contact welding make the use of the technology more attractive in the automotive industry. Many studies have been conducted to search the optimal welding condition experimentally that ensure the joining quality of laser welding that relies both on welding system configuration and welding parameter specification. Both non-destructive and destructive techniques, for example, ultrasonic inspection and tensile test are widely used in practice for estimating the joining quality. Non-destructive techniques are attractive as a rapid quality testing method despite relatively low accuracy. In this paper, we examine the relationship between the variation of weld seam and tensile shear strength in the laser welding of galvanized steel in a lap joint configuration in order to investigate the potential of the variation of weld seam as a joining quality estimator. From the experimental analysis, we identify a trend in between maximum tensile shear strength and the variation of weld seam that clearly supports the fact that laser welded parts having larger variation in the weld seam usually have lower tensile strength. The discovered relationship leads us to conclude that the variation of weld seam can be used as an indirect non-destructive testing method for estimating the tensile strength of the welded parts.

  20. Tensile strength as a function of thermal history of Inconel 718 and Inconel 625 alloys for glass-ceramic headers

    SciTech Connect

    Rey, M.C.; Henderson, W.R.

    1982-06-11

    Tensile strength tests were conducted on Inconel 718 specimens following a variety of heat treatments, and on as-received and heat-treated specimens of Inconel 625. A heat treatment cycle for Inconel 718 was found that represents an acceptable compromise between a thermal cycle that yields the strongest metal and one that least taxes a glass-ceramic material to which the Inconel 718 is bonded. Heat treating resulted in a moderate decrease in the tensile strength of the as-received Inconel 625.

  1. First-principles Calculations of Ideal Tensile and Shear Strengths for Gum-Metal Approximants

    NASA Astrophysics Data System (ADS)

    Nagasako, Naoyuki; Jahnatek, Michal; Asahi, Ryoji; Hafner, Jrgen

    2010-03-01

    A newly developed bcc-type Ti-23Nb-0.7Ta-2Zr-O (mol%) alloy named Gum-Metal showed unusual properties including ultralow elastic modulus, ultrahigh strength, super-elastic-like behavior, and super-plastic-like behavior, in particular, accompanied by dislocation-free plastic deformation. [1]. As proposed in first-principles calculations, one of the requirements for the Gum-Metal is dramatic softening of the elastic shear modulus C'=(C11-C12)/2 0, which happens at a valence electron concentration around 4.24. We also study ideal tensile and shear strengths for Gum-Metal approximants to understand microscopic origin of such unique mechanical properties. The most stable Gum-metal approximant among all the possible 1820 atomic configurations of Ti12Nb4 has been determined, and showed good agreement with the experimental elastic constants of Gum-Metal.[4pt] [1] T. Saito et al., Science 300, 464 (2003).

  2. Tensile strengths of polyamide based 3D printed polymers in liquid nitrogen

    NASA Astrophysics Data System (ADS)

    Cruz, P.; Shoemake, E. D.; Adam, P.; Leachman, J.

    2015-12-01

    Advances in additive manufacturing technology have made 3D printing a viable solution for many industries, allowing for the manufacture of designs that could not be made through traditional subtractive methods. Applicability of additive manufacturing in cryogenic applications is hindered, however, by a lack of accurate material properties information. Nylon is available for printing using fused deposition modeling (FDM) and selective laser sintering (SLS). We selected 5 SLS (DuraForm® EX, DuraForm® HST, DuraForm® PA, PA 640-GSL, and PA 840-GSL) and 2 FDM (Nylon 12, ULTEM) nylon variants based on the bulk material properties and printed properties at room temperature. Tensile tests were performed on five samples of each material while immersed in liquid nitrogen at approximately 77 Kelvin. Samples were tested in XY and, where available, Z printing directions to determine influence on material properties. Results show typical SLS and FDM nylon ultimate strength retention at 77 K, when compared to (extruded or molded) nylon ultimate strength.

  3. Modeling the Effect of Oxidation on Tensile Strength of Carbon Fiber-Reinforced Ceramic-Matrix Composites

    NASA Astrophysics Data System (ADS)

    Longbiao, Li

    2015-12-01

    An analytical method has been developed to investigate the effect of oxidation on the tensile strength of carbon fiber - reinforced ceramic - matrix composites (CMCs). The Budiansky - Hutchinson - Evans shear - lag model was used to describe the micro stress field of the damaged composite considering fibers failure. The statistical matrix multicracking model and fracture mechanics interface debonding criterion were used to determine the matrix crack spacing and interface debonded length. The fiber strength degradation model and oxidation region propagation model have been adopted to analyze the oxidation effect on tensile strength of the composite, which is controlled by diffusion of oxygen gas through matrix cracks. Under tensile loading, the fibers failure probabilities were determined by combining oxidation model and fiber statistical failure model based on the assumption that fiber strength is subjected to two-parameter Weibull distribution and the loads carried by broken and intact fibers statisfy the global load sharing criterion. The composite can no longer support the applied load when the total loads supported by broken and intact fibers approach its maximum value. The conditions of a single matrix crack and matrix multicrackings for tensile strength considering oxidation time and temperature have been analyzed.

  4. Laboratory measurements of ice tensile strength dependence on density and concentration of silicate and polymer impurities at low temperatures

    NASA Astrophysics Data System (ADS)

    Litwin, K. L.; Beyeler, J. D.; Polito, P. J.; Zygielbaum, B. R.; Sklar, L. S.; Collins, G. C.

    2009-12-01

    The tensile strength of ice bedrock on Titan should strongly influence the effectiveness of the erosional processes responsible for carving the extensive fluvial drainage networks and other surface features visible in images returned by the Cassini and Huygens probes. Recent measurements of the effect of temperature on the tensile strength of low-porosity, polycrystalline ice, without impurities, suggest that ice bedrock at the Titan surface temperature of 93 K may be as much as five times stronger than ice at terrestrial surface temperatures. However, ice bedrock on Titan and other outer solar system bodies may have significant porosity, and impurities such silicates or polymers are possible in such ices. In this laboratory investigation we are exploring the dependence of tensile strength on the density and concentration of impurities, for polycrystalline ice across a wide range of temperatures. We use the Brazilian tensile splitting test to measure strength, and control temperature with dry ice and liquid nitrogen. The 50 mm diameter ice cores are made from a log-normally distributed seed crystal mixture with a median size of 1.4 mm. To control ice density and porosity we vary the packing density of the seed grains in core molds and vary the degree of saturation of the matrix with added near-freezing distilled water. We also vary ice density by blending in a similarly-sized mixture of angular fragments of two types of impurities, a fine-grained volcanic rock and a polyethylene polymer. Because both types of impurities have greater tensile strength than ice at Earth surface temperatures, we expect higher concentrations of impurities to correlate with increased strength for ice-rock and ice-polymer mixtures. However, at the ultra-cold temperatures of the outer planets, we expect significant divergence in the temperature dependence of ice tensile strength for the various mixtures and resulting densities. These measurements will help constrain the range of possible ice tensile strengths that might occur on Titan and other solar system bodies.

  5. Effects of reclaimed asphalt pavement on indirect tensile strength test of foamed asphalt mix tested in dry condition

    NASA Astrophysics Data System (ADS)

    Yati Katman, Herda; Rasdan Ibrahim, Mohd; Yazip Matori, Mohd; Norhisham, Shuhairy; Ismail, Norlela

    2013-06-01

    Indirect tensile strength (ITS) test was conducted to analyse strength of the foamed asphalt mixes incorporating reclaimed asphalt pavement. Samples were tested for ITS after cured in the oven at 40C for 72 hours. This testing condition known as dry condition or unconditioned. Laboratory results show that reclaimed asphalt pavement (RAP) contents insignificantly affect the ITS results. ITS results significantly affected by foamed bitumen contents.

  6. Water Saturation Effects on the Brazilian Tensile Strength of Gypsum and Assessment of Cracking Processes Using High-Speed Video

    NASA Astrophysics Data System (ADS)

    Wong, Louis Ngai Yuen; Jong, Ming Chuan

    2014-07-01

    This study investigates the water weakening effect on the tensile strength, as well as the fracturing behavior, of an artificially molded Hydrocal B-11 gypsum rock. Brazilian disc tests, with the aid of a high-speed video system to monitor and record the cracking processes, are conducted on dry and wet specimens to determine their tensile strengths. The dry specimens are oven-dried, while the wet specimens are prepared by soaking in water for 1, 3, and 10 weeks to achieve different levels of water content. The test results show that the tensile strength drops to nearly half of its dry value after being soaked in water for only 1 week. The tensile strength reduces only slightly further after the specimens have been immersed in water for 3 and 10 weeks. An analysis of the recorded high-speed footage shows that the primary crack initiates at the center as observed from the surface for the majority of the tested specimens. Most importantly, the cracking processes of dry and wet specimens are distinctly different with regard to the speed of crack propagation and the number of cracks developed.

  7. Evaluation of Surface Roughness and Tensile Strength of Base Metal Alloys Used for Crown and Bridge on Recasting (Recycling)

    PubMed Central

    Hashmi, Syed W.; Rao, Yogesh; Garg, Akanksha

    2015-01-01

    Background Dental casting alloys play a prominent role in the restoration of the partial dentition. Casting alloys have to survive long term in the mouth and also have the combination of structure, molecules, wear resistance and biologic compatibility. According to ADA system casting alloys were divided into three groups (wt%); high noble, Noble and predominantly base metal alloys. Aim To evaluate the mechanical properties such as tensile strength and surface roughness of the new and recast base metal (nickel-chromium) alloys. Materials and Methods Recasting of the base metal alloys derived from sprue and button, to make it reusable has been done. A total of 200 test specimens were fabricated using specially fabricated jig of metal and divided into two groups- 100 specimens of new alloy and 100 specimens of recast alloys, which were tested for tensile strength on universal testing machine and surface roughness on surface roughness tester. Results Tensile strength of new alloy showed no statistically significant difference (p-value>0.05) from recast alloy whereas new alloy had statistically significant surface roughness (Maximum and Average surface roughness) difference (p-value<0.01) as compared to recast alloy. Conclusion Within the limitations of the study it is concluded that the tensile strength will not be affected by recasting of nickel-chromium alloy whereas surface roughness increases markedly. PMID:26393194

  8. A new derivation of the tensile strength of cometary nuclei: Application to comet Shoemaker-Levy 9

    NASA Technical Reports Server (NTRS)

    Greenberg, J. Mayo; Mizutani, Hitoshi; Yamamoto, Tetsuo

    1994-01-01

    The splitting of comets as exemplified by comet Shoemaker-Levy 9, when it passed near Jupiter, is a common phenomenon. Multiple splitting is also not an uncommon occurrence. It is clear that the comet nucleus is fragile, i.e., its tensile strength is small compared with that of solid materials. We show that aggregates of sub-micron interstellar dust particles presumed to consist of a silicate core, an inner mantle of complex organic refractory molecules, and an outer mantle dominated by H2O ice (Greenberg, 1982) provide the basis for a quantitative derivation of the tensile strength of comet SL9 using molecular interactions at the contact interfaces. In fact, using a mean particle size representing interstellar dust as it would appear in its final presolar state one derives a tensile strength which describes remarkably well the multiple splitting phenomenon. This derivation of the tensile strength of a particle aggregate resulting from molecular interactions is quite general and can be applied to physical situations involving any sorts of aggregates as well as those representing comet nuclei.

  9. Developmental Exposure to Xenoestrogens at Low Doses Alters Femur Length and Tensile Strength in Adult Mice1

    PubMed Central

    Pelch, Katherine E.; Carleton, Stephanie M.; Phillips, Charlotte L.; Nagel, Susan C.

    2011-01-01

    ABSTRACT Developmental exposure to high doses of the synthetic xenoestrogen diethylstilbestrol (DES) has been reported to alter femur length and strength in adult mice. However, it is not known if developmental exposure to low, environmentally relevant doses of xenoestrogens alters adult bone geometry and strength. In this study we investigated the effects of developmental exposure to low doses of DES, bisphenol A (BPA), or ethinyl estradiol (EE2) on bone geometry and torsional strength. C57BL/6 mice were exposed to DES, 0.1 μg/kg/day, BPA, 10 μg/kg/day, EE2, 0.01, 0.1, or 1.0 μg/kg/day, or vehicle from Gestation Day 11 to Postnatal Day 12 via a mini-osmotic pump in the dam. Developmental Xenoestrogen exposure altered femoral geometry and strength, assessed in adulthood by micro-computed tomography and torsional strength analysis, respectively. Low-dose EE2, DES, or BPA increased adult femur length. Exposure to the highest dose of EE2 did not alter femur length, resulting in a nonmonotonic dose response. Exposure to EE2 and DES but not BPA decreased tensile strength. The combined effect of increased femur length and decreased tensile strength resulted in a trend toward decreased torsional ultimate strength and energy to failure. Taken together, these results suggest that exposure to developmental exposure to environmentally relevant levels of xenoestrogens may negatively impact bone length and strength in adulthood. PMID:22088916

  10. In vitro Comparative Evaluation of Tensile Bond Strength of 6th, 7th and 8th Generation Dentin Bonding Agents

    PubMed Central

    Kamble, Suresh S; Kandasamy, Baburajan; Thillaigovindan, Ranjani; Goyal, Nitin Kumar; Talukdar, Pratim; Seal, Mukut

    2015-01-01

    Background: Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6th, 7th and 8th generation bonding agents by in vitro method. Materials and Methods: Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6th generation bonding agent-Adper SE plus 3M ESPE, Group II: 7th generation bonding agent-G-Bond GC Corp Japan and Group III: 8th generation dentin adhesives-FuturaBond, DC, Voco, Germany). With high-speed diamond disc, coronal dentin was exposed, and selected dentin bonding agents were applied, followed by composite restoration. All samples were saved in saline for 24 h and tensile bond strength testing was done using a universal testing machine. The obtained data were tabulated and statistically analyzed using ANOVA test. Results: The tensile bond strength readings for 6th generation bonding agent was 32.2465, for 7th generation was 31.6734, and for 8th-generation dentine bonding agent was 34.74431. The highest tensile bond strength was seen in 8th generation bonding agent compared to 6th and 7th generation bonding agents. Conclusion: From the present study it can be conclude that 8th generation dentine adhesive (Futura DC, Voco, Germany) resulted in highest tensile bond strength compared to 6th (Adper SE plus, 3M ESPE) and 7th generation (G-Bond) dentin bonding agents. PMID:26028901

  11. Microstructure of high-tensile strength brasses containing silicon and manganese

    NASA Astrophysics Data System (ADS)

    Sun, Y. S.; Lorimer, G. W.; Ridley, N.

    1989-07-01

    The morphology, crystallography, chemistry, and distribution of the phases in commercial high-tensile strength brasses containing manganese and silicon with compositions conforming to U.S.A. Specifications C67300 (Cu-35Zn-2.5Mn-lSi) and C67400 (Cu-35Zn-2.5Mn-lSi-l.5Al) have been studied. The wrought and cast microstructures of both types of alloys consist of the copper-rich fee a phase, ordered B2 ? phase, and a manganese silicide Mn5Si3, with the crystal structure D88. Particles of Mn5Si3 are distributed uniformly in the as-cast alloy C67300 but tend to concentrate at the ?' boundaries in alloy C67400. Studies of the development of the microstructure show that Mn5Si3 particles form from the liquid and are also precipitated from solid solution. During cooling, the ? phase precipitates at a higher temperature in alloy C67300 (800 C) than in alloy C67400 (500 C); nucleation of the ? phase occurs on Mn5Si3 particles in alloy C67400. Tiny Mn5Si3 precipitates are formed in both alloys upon quenching from temperatures near the solidus. When the quenched specimens are tempered at temperatures between 400 C and 500 CC, all of the ?' phase transforms to ? in alloy C67300, while in alloy C67400, ? precipitation occurs at the ?' boundaries and shows a Widmansttten morphology.

  12. Research on tensile strength characteristics of bridge deck pavement bonding layers

    NASA Astrophysics Data System (ADS)

    Wu, Shaopeng; Han, Jun

    2010-03-01

    As the development of the traffic in the world, the bridge deck pavement is playing a more and more important role in the whole traffic system. Big span bridge has become more and more especially cement concrete bridge, therefore the bridge deck pavement bonding layers are emphasized as an important part of bridge traffic system, which can mitigate travel impact to bridge and magnify stationary or traffic amenity. The quality and durability of deck pavement bonding layer has directly effect on traffic safety, comfort, durability and investment of bridge. It represents the first line of defence against the ingress of water, road de-icing salts and aggressive chemicals. In real project, many early age damage of bridge deck pavement has become serious disease that affecting the function of bridge. During the construction of the bridge deck, many types of asphalt binders were used, such as styrene-butadiene-styrene (SBS) modified asphalt, styrene-butadiene rubber (SBR) modified asphalt, neoprene latex asphalt, etc. In this paper UTM-25 was used to test the tensile strength of different bridge deck pavement bonding layers with the different treatment methods to inter-surface.

  13. Research on tensile strength characteristics of bridge deck pavement bonding layers

    NASA Astrophysics Data System (ADS)

    Wu, Shaopeng; Han, Jun

    2009-12-01

    As the development of the traffic in the world, the bridge deck pavement is playing a more and more important role in the whole traffic system. Big span bridge has become more and more especially cement concrete bridge, therefore the bridge deck pavement bonding layers are emphasized as an important part of bridge traffic system, which can mitigate travel impact to bridge and magnify stationary or traffic amenity. The quality and durability of deck pavement bonding layer has directly effect on traffic safety, comfort, durability and investment of bridge. It represents the first line of defence against the ingress of water, road de-icing salts and aggressive chemicals. In real project, many early age damage of bridge deck pavement has become serious disease that affecting the function of bridge. During the construction of the bridge deck, many types of asphalt binders were used, such as styrene-butadiene-styrene (SBS) modified asphalt, styrene-butadiene rubber (SBR) modified asphalt, neoprene latex asphalt, etc. In this paper UTM-25 was used to test the tensile strength of different bridge deck pavement bonding layers with the different treatment methods to inter-surface.

  14. Hydrogen Embrittlement of a 1500-MPa Tensile Strength Level Steel with an Ultrafine Elongated Grain Structure

    NASA Astrophysics Data System (ADS)

    Nie, Yihong; Kimura, Yuuji; Inoue, Tadanobu; Yin, Fuxing; Akiyama, Eiji; Tsuzaki, Kaneaki

    2012-05-01

    A deformation of a tempered martensitic structure ( i.e., tempforming) at 773 K (500 °C) was applied to a 0.6 pct C-2 pct Si-1 pct Cr steel. The hydrogen embrittlement (HE) property of the tempformed (TF) steel was investigated by a slow strain rate test (SSRT) and an accelerated atmospheric corrosion test (AACT). Hydrogen content within the samples after SSRT and AACT was measured by thermal desorption spectrometry (TDS). The tempforming at 773 K (500 °C) using multipass caliber rolling with an accumulative are reduction of 76 pct resulted in the evolution of an ultrafine elongated grain (UFEG) structure with a strong <110>//rolling direction (RD) fiber deformation texture and a dispersion of spheroidized cementite particles. The SSRT of the pre-hydrogen-charged notched specimens and the AACT demonstrated that the TF sample had superior potential for HE resistance to the conventional quenched and tempered (QT) sample at a tensile strength of 1500 MPa. The TDS analysis also indicated that the hydrogen might be mainly trapped by reversible trapping sites such as grain boundaries and dislocations in the TF sample, and the hydrogen trapping states of the TF sample were similar to those of the QT sample. The QT sample exhibited hydrogen-induced intergranular fracture along the boundaries of coarse prior-austenite grains. In contrast, the hydrogen-induced cracking occurred in association with the UFEG structure in the TF sample, leading to the higher HE resistance of the TF sample.

  15. Thermal dilatation, density, porosity and tensile strength of porous Miocene limestone

    NASA Astrophysics Data System (ADS)

    Pápay, Zita; Török, Ákos

    2015-04-01

    Porous Miocene limestone is one of the most important stone that have been used as in the monuments from Roman times in the present territory of Hungary. Thermal behaviour of these structures plays an important role in the structural integrity of the monument. Very limited data is available on the thermal dilatation of porous limestone and to bridge this information gap limestone from Sóskút quarry was analyzed. The present study focuses on the thermal dilatation and its relationship with other physical properties and fabric. Three different lithotypes were tested: i) fine-grained, ii) medium-grained and iii) coarse-grained porous limestone. Prismatic test specimens were placed in thermal dilatometers and were subjected to thermal cycles within the temperature range of 20°C - 100°C. Thermal dilation and shrinkage was recorded. Measurements on bulk density, porosity and indirect tensile strength of the three different lithologies were also made. Data set suggests that the thermal dilatation of porous limestone is in the order of 0.2-0.8 mm/m. The differences are related to different fabric and also suggest an oriented micro-fabric, since thermal expansion in the X,Y Z direction is different.

  16. Tensile bond strength of veneering resins to PEEK: impact of different adhesives.

    PubMed

    Stawarczyk, Bogna; Keul, Christine; Beuer, Florian; Roos, Malgorzata; Schmidlin, Patrick R

    2013-01-01

    This study tested tensile bond strength (TBS) between veneering resins and polyetheretherketone (PEEK) after pre-treatment with adhesive systems. Five-hundred-seventy-six PEEK disks were fabricated, air-abraded and divided into six pre-treatment groups (n=96/group): Z-Prime Plus, Ambarino P60, Monobond Plus, Visio.link, Signum PEEK Bond, and control group without pre-treatment. Each group was divided into three subgroups of different veneering resins (n=32): Sinfony, GC Gradia and VITA VM LC. After specimen preparation with a bond area of 6.6 mm(2), half of each subgroup (n=16) was tested initially, and the other half was thermo-cycled. TBS measurements were analysed by three-way and one-way ANOVA, t-test and Weibull statistics. Groups without pre-treatment and groups pre-treated by Z-Prime Plus and Ambarino P60 showed no TBS. Pre-treatment with Monobond Plus increased the TBS values. The highest TBS before and after thermo-cycling between PEEK and all tested veneering resins was observed for groups pre-treated with Visio.link and Signum PEEK Bond. PMID:23719006

  17. Effect of cooling rate on eutectic cell count, grain size, microstructure, and ultimate tensile strength of hypoeutectic cast iron

    SciTech Connect

    Hemanth, J.; Rao, K.V.S. . Dept. of Mechanical Engineering)

    1999-08-01

    This article describes a series of microstructural and strength studies performed on hypoeutectic cast iron, which was sand cast using a variety of end chills (metallic, nonmetallic, water-cooled, and subzero, respectively). The effects of cooling rate on the eutectic cell count (ECC), grain size, and the ultimate tensile strength (UTS) were evaluated. Attempts were also made to explain these effects and to correlate the UTS with ECC. It was found that subzero chilled and water-cool, chilled cast iron exhibit severe undercooling compared to normal sand cast iron. It was concluded from this investigation that nucleation conditions are completely altered but growth conditions prevail as usual. Therefore, undercooling during solidification is considered to be responsible for variation in ECC, grain size, and microstructure, and tensile strength.

  18. Tensile and shear strength measurements on brazed "T" joints used in construction of intra- and intermaxillary hooks.

    PubMed

    Davies, E H; Kuhn, A T; Oleschenko, S V

    1982-10-01

    Silver-brazed "T" joints, representing the first stage in the construction of intermaxillary hooks were fabricated under rigorously controlled conditions. Their tensile and shear strengths were then measured using specially developed test jigs. It was found that the braze joint itself was stronger than the component wires (under tensile load) while in shear mode, fracture occurred in one of a number of well-defined ways. The effect of prolonged heating was investigated using microhardness measurements and recommendations are made for the optimum brazing conditions. PMID:6958322

  19. Open and filled hole static tensile strength characterization of metal matrix composite SCS-9/Beta21s. Master's thesis

    SciTech Connect

    Roush, J.T.

    1992-12-01

    SCS-9/Beta 21s has a reduced gauge thickness, in comparison with other metal matrix composites, due to a smaller diameter fiber. This reduced gauge thickness makes it an attractive candidate for the skin of hypersonic vehicles. Tensile testing of (0/90) sub 2s and (O/+ or -45/90) sub s laminates was performed at room temperature, 482 deg C, and 650 deg C. Both notched and unnotched specimens were tested. Notched specimens, open and filled hole, had a width-to-diameter ratio of six. Materials 7075-T6 and Mar-m-246 were used as pins in the filled hole tensile testing. Analytical work was completed to predict material properties, elastic and plastic stress concentration factors, residual stresses, and failure strengths. Damage was documented in the form of fiber-matrix debonding, matrix cracking, fiber failure, and plasticity.... SCS-9, Beta 21s, Open Hole, Filled Hole, Metal Matrix Composite, Notch, Static Tensile.

  20. Effect of Saliva on the Tensile Bond Strength of Different Generation Adhesive Systems: An In-Vitro Study

    PubMed Central

    Tripathi, Abhay Mani; Saha, Sonali; Dhinsa, Kavita; Garg, Aarti

    2015-01-01

    Background Newer development of bonding agents have gained a better understanding of factors affecting adhesion of interface between composite and dentin surface to improve longevity of restorations. Objective The present study evaluated the influence of salivary contamination on the tensile bond strength of different generation adhesive systems (two-step etch-and-rinse, two-step self-etch and one-step self-etch) during different bonding stages to dentin where isolation is not maintained. Materials and Methods Superficial dentin surfaces of 90 extracted human molars were randomly divided into three study Groups (Group A: Two-step etch-and-rinse adhesive system; Group B: Two-step self-etch adhesive system and Group C: One-step self-etch adhesive system) according to the different generation of adhesives used. According to treatment conditions in different bonding steps, each Group was further divided into three Subgroups containing ten teeth in each. After adhesive application, resin composite blocks were built on dentin and light cured subsequently. The teeth were then stored in water for 24 hours before sending for testing of tensile bond strength by Universal Testing Machine. The collected data were then statistically analysed using one-way ANOVA and Tukey HSD test. Results One-step self-etch adhesive system revealed maximum mean tensile bond strength followed in descending order by Two-step self-etch adhesive system and Two-step etch-and-rinse adhesive system both in uncontaminated and saliva contaminated conditions respectively. Conclusion Unlike One-step self-etch adhesive system, saliva contamination could reduce tensile bond strength of the two-step self-etch and two-step etch-and-rinse adhesive system. Furthermore, the step of bonding procedures and the type of adhesive seems to be effective on the bond strength of adhesives contaminated with saliva. PMID:26393214

  1. The Disulfide Bonds within BST-2 Enhance Tensile Strength during Viral Tethering.

    PubMed

    Du Pont, Kelly E; McKenzie, Aidan M; Kokhan, Oleksandr; Sumner, Isaiah; Berndsen, Christopher E

    2016-02-16

    Human BST-2/tetherin is a host factor that inhibits the release of enveloped viruses, including HIV-1, HIV-2, and SIV, from the cell surface by tethering viruses to the host cell membrane. BST-2 has an ?-helical ectodomain that forms disulfide-linked dimers between two monomers forming a coiled coil. The ectodomain contains three cysteine residues that can participate in disulfide bond formation and are critical for viral tethering. The role of the disulfides in viral tethering is unknown but proposed to be for maintaining the dimer. We explored the role of the disulfides in the structure of BST-2 using experimental, biophysical methods. To understand the role of the disulfides in viral tethering, we used a new approach in viral tethering, steered molecular dynamics. We find that the disulfides coordinate the unfolding of the BST-2 monomers, which adds tensile strength to the coiled coil. Structural differences between oxidized and reduced BST-2 are apparent during unfolding, showing the monomers slide past each other in the absence of the disulfides. We found no evidence to support dissociation of the dimer upon reduction of the disulfide bonds. Moreover, the structure of BST-2 in the absence of the disulfides is similar to that of the oxidized form of BST-2, supporting previous X-ray crystallography and cellular work that showed the disulfides are not required for expression of BST-2. These data provide new insights into viral tethering by using novel techniques in the analysis of BST-2 to give amino acid level insight into functions of BST-2. PMID:26789136

  2. A Simple Test Method to Compare the Tensile Strengths of Metallic Substrates Used in YBa2Cu3O7-x Coated Conductors

    NASA Astrophysics Data System (ADS)

    Varanasi, Chakrapani V.; Chuck, Leon; Chaney, Andrew D.; Barnes, Paul N.

    2006-03-01

    A simple method is developed and used to compare the tensile strengths of metallic substrates used in the YBa2Cu3O7-x (YBCO) coated conductor technology. This method is developed based on the ASTM D3379 tensile test standard method that is recommended for single filament materials. Two different biaxially textured samples, pure Cu and Cu-Fe alloy, are tested by this new method and the tensile strengths are compared. The copper samples showed average yield strength of 36 MPa, and the Cu-Fe samples showed average yield strength of 72 MPadouble that of the pure copper.

  3. A Unified Model for Predicting the Open Hole Tensile and Compressive Strengths of Composite Laminates for Aerospace Applications

    NASA Technical Reports Server (NTRS)

    Davidson, Paul; Pineda, Evan J.; Heinrich, Christian; Waas, Anthony M.

    2013-01-01

    The open hole tensile and compressive strengths are important design parameters in qualifying fiber reinforced laminates for a wide variety of structural applications in the aerospace industry. In this paper, we present a unified model that can be used for predicting both these strengths (tensile and compressive) using the same set of coupon level, material property data. As a prelude to the unified computational model that follows, simplified approaches, referred to as "zeroth order", "first order", etc. with increasing levels of fidelity are first presented. The results and methods presented are practical and validated against experimental data. They serve as an introductory step in establishing a virtual building block, bottom-up approach to designing future airframe structures with composite materials. The results are useful for aerospace design engineers, particularly those that deal with airframe design.

  4. Orthodontic brackets removal under shear and tensile bond strength resistance tests - a comparative test between light sources

    NASA Astrophysics Data System (ADS)

    Silva, P. C. G.; Porto-Neto, S. T.; Lizarelli, R. F. Z.; Bagnato, V. S.

    2008-03-01

    We have investigated if a new LEDs system has enough efficient energy to promote efficient shear and tensile bonding strength resistance under standardized tests. LEDs 470 10 nm can be used to photocure composite during bracket fixation. Advantages considering resistance to tensile and shear bonding strength when these systems were used are necessary to justify their clinical use. Forty eight human extracted premolars teeth and two light sources were selected, one halogen lamp and a LEDs system. Brackets for premolar were bonded through composite resin. Samples were submitted to standardized tests. A comparison between used sources under shear bonding strength test, obtained similar results; however, tensile bonding test showed distinct results: a statistical difference at a level of 1% between exposure times (40 and 60 seconds) and even to an interaction between light source and exposure time. The best result was obtained with halogen lamp use by 60 seconds, even during re-bonding; however LEDs system can be used for bonding and re-bonding brackets if power density could be increased.

  5. EFFECT OF CONVENTIONAL AND EXPERIMENTAL GINGIVAL RETRACTION SOLUTIONS ON THE TENSILE STRENGTH AND INHIBITION OF POLYMERIZATION OF FOUR TYPES OF IMPRESSION MATERIALS

    PubMed Central

    Sábio, Sérgio; Franciscone, Paulo Afonso; Mondelli, José

    2008-01-01

    In the present study, two types of tests (tensile strength test and polymerization inhibition test) were performed to evaluate the physical and chemical properties of four impression materials [a polysulfide (Permlastic), a polyether (Impregum), a condensation silicone (Xantopren) and a polyvinylsiloxane (Aquasil)] when polymerized in contact with of one conventional (Hemostop) and two experimental (Vislin and Afrin) gingival retraction solutions. For the tensile strength test, the impression materials were mixed and packed into a steel plate with perforations that had residues of the gingival retraction solutions. After polymerization, the specimens were tested in tensile strength in a universal testing machine. For the polymerization inhibition test, specimens were obtained after taking impressions from a matrix with perforations that contained 1 drop of the gingival retraction solutions. Two independent examiners decided on whether or not impression material remnants remained unpolymerized, indicating interference of the chemical solutions. Based on the analysis of the results of both tests, the following conclusions were reached: 1. The tensile strength of the polysulfide decreased after contact with Hemostop and Afrin. 2. None of the chemical solutions inhibited the polymerization of the polysulfide; 3. The polyether presented lower tensile strength after polymerization in contact with the three gingival retraction agents; 4. The polyether had its polymerization inhibited only by Hemostop; 5. None of the chemical solutions affected the tensile strength of the condensation silicone; 6. Only Hemostop inhibited the polymerization of the condensation silicone; 7. The polyvinylsiloxane specimens polymerized in contact with Hemostop had significantly lower tensile strength; 8. Neither of the chemical solutions (Afrin and Vislin) affected the tensile strength of the polyvinylsiloxane and the condensation silicone; 9. Results of the tensile strength and polymerization inhibition tests suggest that Vislin can be used as substance of gingival retraction without affecting the tested properties of four impression materials. PMID:19089261

  6. Weathering effects on tensile and stress rupture strength of glass fiber reinforced vinylester and epoxy thermoset pipes

    NASA Astrophysics Data System (ADS)

    Nizamuddin, Syed

    Glass fiber reinforced vinylester (GFRE) and epoxy (GFRE) pipes have been used for more than three decades to mitigate corrosion problems in oil fields, chemical and industrial plants. In these services, both GFRV and GFRE pipes are exposed to various environmental conditions. Long-term mechanical durability of these pipes after exposure to environmental conditions, which include natural weathering exposure to seasonal temperature variation, sea water, humidity and other corrosive fluids like crude oil, should be well known. Although extensive research has been undertaken, several major issues pertaining to the performance of these pipes under a number of environmental conditions still remain unresolved. The main objective of this study is to investigate the effects of natural weathering, combined natural weathering with seawater and crude oil exposure, for time periods ranging from 3 to 36 months respectively, on the tensile and stress rupture behavior of GFRV and GFRE pipes. Ring specimens are machined from GFRV and GFRE pipes and tested before and after exposure to different weathering conditions prevalent in the eastern region (Dhahran) of Saudi Arabia and present under service conditions. The natural weathering and combined natural weathering with crude oil exposure of GFRV specimens revealed increased tensile strength even after 36 months of exposure when compared with that of the as received samples. However, the combined natural weathering with seawater exposure of GFRV samples revealed better tensile behavior till 24 months of exposure, and after 36 months their tensile strength was seen to be below that of the as received GFRV samples. The stress rupture behavior of natural weather exposed GFRV samples showed an improvement after 12 months of exposure and it decreased after 24 and 36 months of exposure when compared with the as received GFRV samples. The combined natural weathering with crude oil and seawater exposure of GFRV sample revealed improved stress rupture behavior after 12 months of exposure. The as received GFRE pipe specimens revealed higher average tensile strength when compared to the as received GFRV sample, whereas the stress rupture behavior was comparatively low. The seawater exposure of the GFRE specimens resulted in drastic reduction in both tensile and stress rupture properties. Fractographic analysis was performed using an optical microscope and SEM in order to explain the possible controlling mechanisms of failure.

  7. An investigation into the effects of metal primer and surface topography on the tensile bond strength between cobalt chromium alloy and composite resin.

    PubMed

    Newsum, David; Juszczyk, Andrzej; Clark, Robert K F; Radford, David R

    2011-03-01

    This study examined the influence of surface preparation and metal primer on the tensile bond strength between cobalt chromium alloy and composite resin. The bond strength between 168 cobalt chromium alloy dumb-bells with one of three test surfaces (beaded, machined or sandblasted) to composite resin were tested. Half of each group were treated with metal primer. The weakest bond strength was produced by the unprimed machined surface, many specimens failing before testing. The metal primer increased the bond strengths of all groups tested. The greatest bond strengths were achieved with the primed beaded and sandblasted surfaces. Within the limits of the study it has been shown that the surface preparation of the cobalt-chromium alloy did influence tensile bond strengths with composite resin and Metal Primer II increased the tensile bond strengths for all groups tested. The sandblasted surface treated with Metal Primer II is recommended for the bonding of composite resin to cobalt chromium alloy. PMID:21528688

  8. Modelling and Simulation of Tensile Fracture in High Velocity Compacted Metal Powder

    SciTech Connect

    Jonsen, P.; Haeggblad, H.-A.

    2007-05-17

    In cold uniaxial powder compaction, powder is formed into a desired shape with rigid tools and a die. After pressing, but before sintering, the compacted powder is called green body. A critical property in the metal powder pressing process is the mechanical properties of the green body. Beyond a green body free from defects, desired properties are high strength and uniform density. High velocity compaction (HVC) using a hydraulic operated hammer is a production method to form powder utilizing a shock wave. Pre-alloyed water atomised iron powder has been HVC-formed into circular discs with high densities. The diametral compression test also called the Brazilian disc test is an established method to measure tensile strength in low strength material like e.g. rock, concrete, polymers and ceramics. During the test a thin disc is compressed across the diameter to failure. The compression induces a tensile stress perpendicular to the compressed diameter. In this study the test have been used to study crack initiation and the tensile fracture process of HVC-formed metal powder discs with a relative density of 99%. A fictitious crack model controlled by a stress versus crack-width relationship is utilized to model green body cracking. Tensile strength is used as a failure condition and limits the stress in the fracture interface. The softening rate of the model is obtained from the corresponding rate of the dissipated energy. The deformation of the powder material is modelled with an elastic-plastic Cap model. The characteristics of the tensile fracture development of the central crack in a diametrically loaded specimen is numerically studied with a three dimensional finite element simulation. Results from the finite element simulation of the diametral compression test shows that it is possible to simulate fracturing of HVC-formed powder. Results from the simulation agree reasonably with experiments.

  9. Influence of different brazing and welding methods on tensile strength and microhardness of orthodontic stainless steel wire.

    PubMed

    Bock, Jens Johannes; Fraenzel, Wolfgang; Bailly, Jacqueline; Gernhardt, Christian Ralf; Fuhrmann, Robert Andreas Werner

    2008-08-01

    The aim of this study was to compare the mechanical strength and microhardness of joints made by conventional brazing and tungsten inert gas (TIG) and laser welding. A standardized end-to-end joint configuration of the orthodontic wire material in spring hard quality was used. The joints were made using five different methods: brazing (soldering > 450 degrees C) with universal silver solder, two TIG, and two laser welders. Laser parameters and welding conditions were used according to the manufacturers' guidance. The tensile strengths were measured with a universal testing machine (Zwick 005). The microhardness measurements were carried out with a hardness tester (Zwick 3202). Data were analysed using one-way analysis of variance and Bonferroni's post hoc correction (P < 0.05). In all cases, brazing joints ruptured at low levels of tensile strength (198 +/- 146 MPa). Significant differences (P < 0.001) between brazing and TIG or laser welding were found. The highest means were observed for TIG welding (699-754 MPa). Laser welding showed a significantly lower mean tensile strength (369-520 MPa) compared with TIG welding. Significant differences (P < 0.001) were found between the original orthodontic wire and the mean microhardness at the centre of the welded area. The mean microhardness differed significantly between brazing (1.99 GPa), TIG (2.22-2.39 GPa) and laser welding (2.21-2.68 GPa). For orthodontic purposes, laser and TIG welding are solder-free alternatives to joining metal. TIG welding with a lower investment cost is comparable with laser welding. However, while expensive, the laser technique is a sophisticated and simple method. PMID:18617503

  10. A scaffold-enhanced light-activated surgical adhesive technique: surface selection for enhanced tensile strength in wound repair

    NASA Astrophysics Data System (ADS)

    Soller, Eric C.; Hoffman, Grant T.; Heintzelman, Douglas L.; Duffy, Mark T.; Bloom, Jeffrey N.; McNally-Heintzelman, Karen M.

    2004-07-01

    An ex vivo study was conducted to determine the effect of the irregularity of the scaffold surface on the tensile strength of repairs formed using our Scaffold-Enhanced Biological Adhesive (SEBA). Two different scaffold materials were investigated: (i) a synthetic biodegradable material fabricated from poly(L-lactic-co-glycolic acid); and (ii) a biological material, small intestinal submucosa, manufactured by Cook BioTech. The scaffolds were doped with protein solder composed of 50%(w/v) bovine serum albumin solder and 0.5mg/ml indocyanine green dye mixed in deionized water, and activated with an 808-nm diode laser. The tensile strength of repairs performed on bovine thoracic aorta, liver, spleen, small intestine and lung, using the smooth and irregular surfaces of the above scaffold-enhanced materials were measured and the time-to-failure was recorded. The tensile strength of repairs formed using the irregular surfaces of the scaffolds were consistently higher than those formed using the smooth surfaces of the scaffolds. The largest difference was observed on repairs formed on the aorta and small intestine, where the repairs were, on average, 50% stronger using the irregular versus the smooth scaffold surfaces. In addition, the time-to-failure of repairs formed using the irregular surfaces of the scaffolds were between 50% and 100% longer than that achieved using the smooth surfaces of the scaffolds. It has previously been shown that distributing or dispersing the adhesive forces over the increased surface area of the scaffold, either smooth or irregular, produces stronger repairs than albumin solder alone. The increase in the absolute strength and longevity of repairs seen in this new study when the irregular surfaces of the scaffolds are used is thought to be due to the distribution of forces between the many independent micro-adhesions provided by the irregular surfaces.

  11. Study of austenitic stainless steel welded with low alloy steel filler metal. [tensile and impact strength tests

    NASA Technical Reports Server (NTRS)

    Burns, F. A.; Dyke, R. A., Jr.

    1979-01-01

    The tensile and impact strength properties of 316L stainless steel plate welded with low alloy steel filler metal were determined. Tests were conducted at room temperature and -100 F on standard test specimens machined from as-welded panels of various chemical compositions. No significant differences were found as the result of variations in percentage chemical composition on the impact and tensile test results. The weldments containing lower chromium and nickel as the result of dilution of parent metal from the use of the low alloy steel filler metal corroded more severely in a marine environment. The use of a protective finish, i.e., a nitrile-based paint containing aluminum powder, prevented the corrosive attack.

  12. Influence of Specimen Preparation and Specimen Size on Composite Transverse Tensile Strength and Scatter

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin; Chawan, Arun D.; DeMarco, Kevin; Paris, Isabelle

    2001-01-01

    The influence of specimen polishing, configuration, and size on the transverse tension strength of two glass-epoxy materials, and one carbon-epoxy material, loaded in three and four point bending was evaluated. Polishing machined edges, arid/or tension side failure surfaces, was detrimental to specimen strength characterization instead of yielding a higher, more accurate, strength as a result of removing inherent manufacture and handling flaws. Transverse tension strength was typically lower for longer span lengths due to the classical weakest link effect. However, strength was less sensitive to volume changes achieved by increasing specimen width. The Weibull scaling law typically over-predicted changes in transverse tension strengths in three point bend tests and under-predicted changes in transverse tension strengths in four point bend tests. Furthermore, the Weibull slope varied with specimen configuration, volume, and sample size. Hence, this scaling law was not adequate for predicting transverse tension strength of heterogeneous, fiber-reinforced, polymer matrix composites.

  13. Ultimate Tensile Strength as a Function of Test Rate for Various Ceramic Matrix Composites at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Bansal, Narottam P.; Gyekenyesi, John P.

    2002-01-01

    Ultimate tensile strength of five different continuous fiber-reinforced ceramic composites, including SiC/BSAS (2D 2 types), SiC/MAS-5 (2D), SiC/SiC (2D enhanced), and C/SiC(2D) was determined as a function of test rate at I 100 to 1200 'C in air. All five composite materials exhibited a significant dependency of ultimate strength on test rate such that the ultimate strength decreased with decreasing test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress rate) to another (constant stress loading) for SiC/BSAS suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law type of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics.

  14. Effects of polymerization and briquetting parameters on the tensile strength of briquettes formed from coal coke and aniline-formaldehyde resin

    SciTech Connect

    Demirbas, A.; Simsek, T.

    2006-10-15

    In this work, the utilization of aniline (C{sub 6}H{sub 7}N) formaldehyde (HCHO) resins as a binding agent of coke briquetting was investigated. Aniline (AN) formaldehyde (F) resins are a family of thermoplastics synthesized by condensing AN and F in an acid solution exhibiting high dielectric strength. The tensile strength sharply increases as the ratio of F to AN from 0.5 to 1.6, and it reaches the highest values between 1.6 and 2.2 F/AN ratio; it then slightly decreases. The highest tensile strength of F-AN resin-coke briquette (23.66 MN/m{sup 2}) was obtained from the run with 1.5 of F/AN ratio by using (NH4){sub 2}S{sub 2}O{sub 8} catalyst at 310 K briquetting temperature. The tensile strength of F-AN resin-coke briquette slightly decreased with increasing the catalyst percent to 0.10%, and then it sharply decreased to zero with increasing the catalyst percent to 0.2%. The effect of pH on the tensile strength is irregular. As the pH of the mixture increases from 9.0 to 9.2, the tensile strength shows a sharp increase, and the curve reaches a plateau value between pH 9.3 and 9.9; then the tensile strength shows a slight increase after pH = 9.9.

  15. Experimental assessments of notch ductility and tensile strength of stainless steel weldments after 120/sup 0/C neutron irradiation

    SciTech Connect

    Hawthorne, J.R.; Menke, B.H.; Awadalla, N.G.; O'Kula, K.R.

    1986-01-01

    The Charpy-V (C/sub v/) properties of AISI 300 series stainless steel plate, weld, and weld heat-affected zone (HAZ) materials from commercial production weldments in 406-mm-diameter pipe (12.7-mm wall) were investigated in unirradiated and irradiated conditions. Weld and HAZ tensile properties were also assessed in the two conditions. The plates and weld filler wires represent different steel melts; the welds were produced using the multipass MIG process. Weldment properties in two test orientations were evaluated. Specimens were irradiated in the UBR reactor to 1 x 10/sup 20/ n/cm/sup 2/, E >0.1 MeV in a controlled temperature assembly. Specimen tests were performed at 25/sup 0/C and 125/sup 0/C. The radiation-induced reductions in C/sub v/ energy absorption at 25/sup 0/C were about 42 percent for the weld and HAZ materials evaluated. A trend of energy increase with temperature was observed. The concomitant elevation in yield strength was about 53%. In contrast, the increase in tensile strength was only 16%. The postirradiation yield strength of the axial test orientation in the pipe was less than that of the circumferential test orientation. Results for the HAZ indicate that this component may be the weakest link in the weldment from a fracture resistant viewpoint.

  16. The tensile strength of black bear (Ursus americanus) cortical bone is not compromised with aging despite annual periods of hibernation.

    PubMed

    Harvey, Kristin B; Drummer, Thomas D; Donahue, Seth W

    2005-11-01

    Black bears (Ursus americanus) may not develop disuse osteoporosis during long periods of disuse (i.e. hibernation) because they may be able to maintain bone formation. Previously, we found that cortical bone bending strength was not compromised with age in black bears' tibias, despite annual periods of disuse. Here we showed that cortical bone tensile strength (166-198MPa) also does not decrease with age (2-14 years) in black bear tibias. There were also no significant age-related changes in cortical bone porosity in black bear tibias. It is likely that the ability of black bears to maintain bone formation during hibernation keeps bone porosity low (2.3-8.6%) with aging, notwithstanding annual periods of disuse. This low porosity likely preserves ultimate stress with aging. Female bears give birth and nurse during hibernation; however, we found no significant differences between male and female tensile material properties, mineral content, or porosity. Our findings support the idea that black bears, which hibernate 5-7 months annually, have evolved biological mechanisms to mitigate the adverse effects of disuse on bone porosity and strength. PMID:16115638

  17. Development of a new method to determine dynamic tensile strength of ballistic yarns

    NASA Astrophysics Data System (ADS)

    Nussbaum, J.; Faderl, N.; Nuesing, R.; Ha-Minh, C.; Boussu, F.

    2012-08-01

    Since the design of new soft protections is getting intensive, the study of the dynamic behavior of ballistic yarns becomes more and more important. This paper deals with the development of a new experimental method in order to obtain some dynamic parameters by performing dynamic tensile tests. The concept is quite simple: two projectiles, linked together by the ballistic yarn we want to study, are accelerated together with the help of a gas gun. The first one flies freely while the second one is suddenly stopped. The yarn is then loaded in tensile. Several measurements are performed during each test with the help of a high speed camera. First results on a polyethylene yarn are presented here and several improvements are proposed in order to improve the accuracy of the results.

  18. Uncertainty analysis of mechanical properties from miniature tensile testing of high strength steels

    NASA Astrophysics Data System (ADS)

    Malpally, Deepthi Rao

    Boat samples extracted from scheduled maintenance shutdowns of piping and pressure vessels provide opportunities for testing for mechanical properties of the service exposed components. However, it is not clear whether testing of miniature specimens machined from boat samples which are about 2 in. long can be a viable replacement for the standard-sized mechanical testing. Three steels, stainless steel Type 304, sensitized Type 304, and SA516 Grade 70 carbon steel, are tested by standard-sized specimen and miniature specimen tensile tests. Mechanical properties as affected by the specimen geometry and tensile testing procedure for miniature specimen testing are compared to that of conventional specimens tested according to ASTM A370-10. The miniature tensile testing results are analyzed by using Monte Carlo Method (MCM) for uncertainty estimation in order to quantify the probability distribution of mechanical properties. For the steels under study, miniature specimens with a cross-sectional area of 3 mm2 and 12 mm gauge length are found to produce equivalent mechanical properties as tested from standard-sized specimens.

  19. Tensile and electrical properties of high-strength high-conductivity copper alloys

    SciTech Connect

    Zinkle, S.J.; Eatherly, W.S.

    1998-09-01

    Electrical conductivity and tensile properties have been measured on an extruded and annealed CuCrNb dispersion strengthened copper alloy which has been developed for demanding aerospace high heat flux applications. The properties of this alloy are somewhat inferior to GlidCop dispersion strengthened copper and prime-aged CuCrZr over the temperature range of 20--500 C. However, if the property degradation in CuCrZr due to joining operations and the anisotropic properties of GlidCop in the short transverse direction are taken into consideration, CuCrNb may be a suitable alternative material for high heat flux structural applications in fusion energy devices. The electrical conductivity and tensile properties of CuCrZr that was solution annealed and then simultaneously aged and diffusion bonded are also summarized. A severe reduction in tensile elongation is observed in the diffusion bonded joint, particularly if a thin copper shim is not placed in the diffusion bondline.

  20. The Value Compressive Strength and Split Tensile Strength on Concrete Mixture With Expanded Polystyrene Coated by Surfactant Span 80 as a Partial Substitution of Fine Aggregate

    NASA Astrophysics Data System (ADS)

    Hidayat, Irpan; Siauwantara, Alice

    2014-03-01

    The value of the density normal concrete which ranges between 2200-2400 kg/m3. Therefore the use of Expanded Polystyrene (EPS) as a subitute to fine aggregate can reduce the density of concrete. The purpose this research is to reduce the density of normal concrete but increase compressive strength of EPS concrete, with use surfactant as coating for the EPS. Variables of substitution percentage of EPS and EPS coated by surfactant are 5%,10%,15%,20%,25%. Method of concrete mix design based on SNI 03-2834-2000 "Tata Cara Pembuatan Rencana Campuran Beton Normal (Provisions for Proportioning Normal Concrete Mixture)". The result of testing, every increase percentage of EPS substitution will decrease the compressive strength around 1,74 MPa and decrease density 34,03 kg/m3. Using Surfactant as coating of EPS , compressive strength increase from the EPS's compressive strength. Average of increasing compressive strength 0,19 MPa and increase the density 20,03 kg/m3,average decrease of the tensile split strength EPS coated surfaktan is 0,84 MPa.

  1. Validity of using average diameter for determination of tensile strength and Weibull modulus of ceramic filaments

    SciTech Connect

    Petry, M.D.; Mah, T.I.; Kerans, R.J.

    1997-10-01

    Strengths and Weibull moduli for alumina/yttrium aluminum garnet eutectic (AYE) filaments and for Si-C-O (Nicalon) filaments were calculated using measured and average filament diameters. The strengths agreed closely. Thus an average filament diameter could be used instead of the measured filament diameter in calculating strengths. The Weibull modulus obtained from an average filament diameter approximates the Weibull modulus obtained using the measured filament diameter.

  2. A Comparative Study of the Shear and Tensile Bond Strength using three types of Direct Bonding Adhesives on Stainless Steel Brackets - An In Vitro Study

    PubMed Central

    Sunilkumar, P; Patil, Chandrashekhara; H, Baswaraj; Putturaj, KT; Sangolgi, Vijaykumar C; Jayasudha, K

    2013-01-01

    Background: The purpose of this study was to compare the shear and tensile bond strength of three adhesive systems with increasing concentrations of filler for bonding brackets. Materials & Methods: The study was carried out on 120 extracted human premolars; randomly divided into six groups, three groups for shear bond strength & three for tensile bond strength, each subgroup consisting of 20 teeth; using light cured adhesive systems: Group 1: FORTIFY Unfilled, (unfilled penetrating resin) Group 2: ALITEF Low Filled (filler load 58% by weight) Group 3: PYRAMID Highly Filled (filler load greater than 80% by weight) with metal brackets (TP 256-650. TP orthodontic inc. Po.box 73,La Porte 46350,USA). Results: The findings showed that in vitro tensile bond strength and shear bond strength of PYRAMID [9.88/11.46 MPa resp.] is significantly greater than ALITEFLO[5.34/9.50 MPa resp.] and FORTIFY [2.65/5.39 MPa resp.]. Conclusion: Using the same bracket and force mode but different adhesive filler concentrations revealed increased shear and tensile bond strength with increased filler concentration. How to cite this article: Kumar PS, Patil C, Hullal B, Putturaj KT, Sangolgi VC, Jayasudha K. A Comparative Study of the Shear and Tensile Bond Strength using three types of Direct Bonding Adhesives on Stainless Steel Brackets - An In Vitro Study. J Int Oral Health 2013; 5(4):26-29. PMID:24155616

  3. Development of Cold-Rolled Dual-Phase Steels with Tensile Strength Above 1000 MPa and Good Bendability

    NASA Astrophysics Data System (ADS)

    Rosenberg, Gejza; Sinaiová, Iveta; Hvizdoš, Pavol; Juhar, L'uboš

    2015-10-01

    This paper presents the most important results of the study oriented on development of low-silicon (<0.03Si), precipitation-strengthened, fine-grained, cold-rolled dual-phase (DP) steels with tensile strength greater than 1000 MPa, primarily intended for the automotive industry. For this purpose, extensive systematic investigations were conducted with the aim to optimize the composition/processing conditions with regard to the microstructural effects on tensile properties and bendability of DP steels. Within this study, influence of the addition of Mn, Cr, Mo and/or both Mo and Ti on the microstructure and tensile properties of eight steels molded in the form of ~20 kg ingots processed by controlled rolling has been investigated. The effect of simulated coiling temperature on hot-rolled steels followed by cold rolling and intercritical annealing at temperatures 1023 K and 1073 K (750 °C and 800 °C) as well as the interaction between ferrite recrystallization and austenite formation were examined. Investigation of the effect of intercritical annealing on the structure-property relationships was carried out on steels in both the hot-rolled and cold-rolled states. It was found that in spite of strength above 1000 MPa, good bendability (steel strip may have been bent to 180 deg at radius of 0.5 mm) can be achieved in the cold-rolled intercritically annealed steel with nominal composition 0.15-C-1.2Mn-0.02Si-0.2Mo-0.1Ti by more or less homogeneous distribution of fine Ti precipitates (<5 nm) within fine ferrite grains (<2 μm) and about 35 pct martensite volume fraction in the microstructure of DP steel.

  4. Breaking Badly: DFT-D2 Gives Sizeable Errors for Tensile Strengths in Palladium-Hydride Solids.

    PubMed

    Ilawe, Niranjan V; Zimmerman, Jonathan A; Wong, Bryan M

    2015-11-10

    Dispersion interactions play a crucial role in noncovalently bound molecular systems, and recent studies have shown that dispersion effects are also critical for accurately describing covalently bound solids. While most studies on bulk solids have solely focused on equilibrium properties (lattice constants, bulk moduli, and cohesive energies), there has been little work on assessing the importance of dispersion effects for solid-state properties far from equilibrium. In this work, we present a detailed analysis of both equilibrium and highly nonequilibrium properties (tensile strengths leading to fracture) of various palladium-hydride systems using representative DFT methods within the LDA, GGA, DFT-D2, DFT-D3, and nonlocal vdw-DFT families. Among the various DFT methods, we surprisingly find that the empirically constructed DFT-D2 functional gives extremely anomalous and qualitatively incorrect results for tensile strengths in palladium-hydride bulk solids. We present a detailed analysis of these effects and discuss the ramifications of using these methods for predicting solid-state properties far from equilibrium. Most importantly, we suggest caution in using DFT-D2 (or other coarse-grained parametrizations obtained from DFT-D2) for computing material properties under large stress/strain loads or for evaluating solid-state properties under extreme structural conditions. PMID:26574331

  5. Effect of varying chromophores used in light-activated protein solders on tensile strength and thermal damage profile of repairs.

    PubMed

    Hoffman, Grant T; Byrd, Brian D; Soller, Eric C; Heintzelman, Douglas L; McNally-Heintzelman, Karen M

    2003-01-01

    Clinical adoption of laser tissue welding (LTW) techniques has been beleaguered by problems associated with thermal damage of tissue and insufficient strength of the resulting tissue bond. The magnitude of these problems has been significantly reduced with the incorporation of indocyanine green (ICG)-doped protein solders into the LTW procedure to form a new technique known as laser tissue soldering (LTS). With the addition of ICG, a secondary concern has arisen relating to the potential harmful effects of the degradation products of the chromophore upon thermal denaturation of the protein solder with a laser. In this study, two different food colorings were investigated, including blue #1 and green consisting of yellow #5 and blue #1, as alternative chromophores for use in LTS techniques. Food coloring has been found to have a suitable stability and safety profile for enteral use when heated to temperatures above 200 degrees C; thus, it is a promising candidate chromophore for LTS which typically requires temperatures between 50 degrees C and 100 degrees C. Experimental investigations were conducted to test the tensile strength of ex vivo repairs formed using solders doped with these alternative chromophores in a bovine model. Two commonly used chromophores, ICG and methylene blue (MB), were investigated as a reference. In addition, the temperature rise, depth of thermal coagulation in the protein solder, and the extent of thermal damage in the surrounding tissue were measured. Temperature rise at the solder/tissue interface, and consequently the degree of solder coagulation and collateral tissue thermal damage, was directly related to the penetration depth of laser light in the protein solder. Variation of the chromophore concentration such that the laser light penetrated to a depth approximately equal to half the thickness of the solder resulted in uniform results between each group of chromophores investigated. Optimal tensile strength of repairs was achieved by optimizing laser and solder parameters to obtain a temperature of approximately 65 degrees C at the solder/tissue interface. The two alternative chromophores tested in this study show considerable promise for application in LTS techniques, with equivalent tensile strength to solders doped with ICG or MB, and the potential advantage of eliminating the risks associated with harmful byproducts. PMID:12724861

  6. Effect of test temperature and strain rate on the tensile properties of high-strength, high-conductivity copper alloys

    SciTech Connect

    Zinkle, S.J.; Eatherly, W.S.

    1997-04-01

    The unirradiated tensile properties of wrought GlidCop AL25 (ITER grade zero, IGO) solutionized and aged CuCrZr, and cold-worked and aged and solutionized and aged Hycon 3HP{trademark} CuNiBe have been measured over the temperature range of 20-500{degrees}C at strain rates between 4 x 10{sup {minus}4} s{sup {minus}1} and 0.06 s{sup {minus}1}. The measured room temperature electrical conductivity ranged from 64 to 90% IACS for the different alloys. All of the alloys were relatively insensitive to strain rate at room temperature, but the strain rate sensitivity of GlidCop Al25 increased significantly with increasing temperature. The CuNiBe alloys exhibited the best combination of high strength and high conductivity at room temperature. The strength of CuNiBe decreased slowly with increasing temperature. However, the ductility of CuNiBe decreased rapidly with increasing temperature due to localized deformation near grain boundaries, making these alloy heats unsuitable for typical structural applications above 300{degrees}C. The strength and uniform elongation of GlidCop Al25 decreased significantly with increasing temperature at a strain rate of 1 x 10{sup {minus}3} s{sup {minus}1}, whereas the total elongation was independent of test temperature. The strength and ductility of CuCrZr decreased slowly with increasing temperature.

  7. Effects on stress rupture life and tensile strength of tin additions to Inconel 718

    NASA Technical Reports Server (NTRS)

    Dreshfield, R. L.; Johnson, W.

    1982-01-01

    Because Inconel 718 represents a major use of columbium and a large potential source of columbium for aerospace alloys could be that of columbium derived from tin slags, the effects of tin additions to Inconel 718 at levels which might be typical of or exceed those anticipated if tin slag derived columbium were used as a melting stock were investigated. Tin was added to 15 pound Inconel 718 heats at levels varying from none added to approximately 10,000 ppm (1 wt%). Limited 1200 F stress rupture testing was performed at stresses from 68,000 to 115,000 psi and a few tensile tests were performed at room temperature, 800 and 1200 F. Additions of tin in excess of 800 ppm were detrimental to ductility and stress rupture life.

  8. Relevance of impacter shape to nonvisible damage and residual tensile strength of a thick graphite/epoxy laminate

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1990-01-01

    A study was made to determine the relevance of impacter shape to nonvisible damage and tensile residual strength of a 36 mm (1.4 in.) thick graphite/epoxy motor case. The shapes of the impacters were as follows: 12.7 mm (0.5 in.) and 25.4 mm (1.0 in.) diameter hemispheres, a sharp corner, and a 6.3 mm (0.25 in.) diameter bolt-like rod. The investigation revealed that damage initiated when the contact pressure exceeded a critical level. However, the damage was not visible on the surface until an even higher pressure was exceeded. The damage on the surface consisted of a crater shaped like the impacter, and the damage below the surface consisted of broken fibers. The impact energy to initiate damage or cause visible damage on the surface increased approximately with impacter diameter to the third power. The reduction in strength for nonvisible damage increased with increasing diameter, 9 and 30 percent for the 12.7 mm (0.5 in.) and 25.4 mm (1.0 in.) diameter hemispheres, respectively. The corner impacter made visible damage on the surface for even the smallest impact energy. The rod impacter acted like a punch and sliced through the composite. Even so, the critical level of pressure to initiate damage was the same for the rod and hemispherical impacters. Factors of safety for nonvisible damage increased with increasing kinetic energy of impact. The effects of impacter shape on impact force, damage size, damage visibility, and residual tensile strength were predicted quite well assuming Hertzian contact and using maximum stress criteria and a surface crack analysis.

  9. Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

    PubMed Central

    TRKMEN, Cafer; DURKAN, Meral; C?M?LL?, Hale; KSZ, Mustafa

    2011-01-01

    Objective The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM. Material and Methods Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student's t-test. The failure modes of all groups were also evaluated. Results The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure. Conclusion The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces. PMID:21710095

  10. Role of coatings in axial tensile strength of long fibre-reinforced metal-matrix composites

    SciTech Connect

    Zhenhai Xia . Dept. of Metallic Materials Science and Engineering)

    1993-07-01

    A model that includes effects of coatings, interfacial behavior, plastic deformation of matrix and reaction zone has been developed for analysis of the behavior of metal-matrix composites reinforced by coated fibres. The stress concentration caused by the cracks in the reaction zone was calculated from the model and the results show that it can be relaxed by choosing coatings of low modulus and controlling interfacial strength to a relatively low value. The predictions of the model in composite strength are consistent with that from the Griffith relationship with strong interfacial bonding and the experimental results for SiC-coated C/Al composites. Both the theory and the experiment show that high strength of the composites can be maintained by SiC coating even when there is a serious reaction at the coating/matrix interface.

  11. Tensile strength of composite sheets with unidirectional stringers and crack-like damage: A brief report

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1984-01-01

    The residual strength of composite sheets with bonded composite stringers loaded in tension was determined. The results are summarized. About 50 graphite/epoxy composite panels with crack-like slots were monotonically loaded in tension to failure. Both sheet layup and stringer configuration were varied. The composite panels have considerable damage tolerance. The stringers arrested cracks that ran from the crack-like slots, and the residual strengths were considerably greater than those of unstiffened composite sheets. A stress-intensity factor analysis was developed to predict the failing strains of the stiffened panels. Using the analysis, a single design curve was produced for composite sheets with bonded stringers of any configuration.

  12. Tensile strength of composite sheets with unidirectional stringers and crack-like damage

    NASA Technical Reports Server (NTRS)

    Poe, C. C., Jr.

    1984-01-01

    The damage tolerance characteristics of metal tension panels with riveted and bonded stringers are well known. The stringers arrest unstable cracks and retard propagation of fatigue cracks. Residual strengths and fatigue lives are considerably greater than those of unstiffened or integrally stiffened sheets. The damage tolerance of composite sheets with bonded composite stringers loaded in tension was determined. Cracks in composites do not readily propagate in fatigue, at least not through fibers. Moreover, the residual strength of notched composites is sometimes even increased by fatigue loading. Therefore, the residual strength aspect of damage tolerance, and not fatigue crack propagation, was investigated. About 50 graphite/epoxy composite panels were made with two sheet layups and several stringer configurations. Crack-like slots were cut in the middle of the panels to simulate damage. The panels were instrumented and monotonically loaded in tension to failure. The tests indicate that the composite panels have considerable damage tolerance, much like metal panels. The stringers arrested cracks that ran from the crack-like slots, and the residual strengths were considerably greater than those of unstiffened composite sheets. A stress intensity factor analysis was developed to predict the failing strains of the stiffened panels. Using the analysis, a single design curve was produced for composite sheets with bonded stringers of any configuration.

  13. [Tensile strength of various anchor systems in surgical correction of instability of the shoulder joint].

    PubMed

    Gohlke, F; Schneider, P; Siegel, K; Balzer, C

    1993-10-01

    Commercially available fixation devices used for reattachment of capsuloligamentous tissue to the glenoid rim were tested until they failed in 42 human cadaveric shoulders, and compared to the tension strength of the standard Bankart procedure and that of the intact anterior capsule. The bone quality in the glenoid was measured by quantitative computed tomography, which allowed selective quantification of cortical and cancellous quantification of cortical and cancellous bone. The mean load at failure perpendicular to the bone surface varied from 90 to 115 N and was lower than in the standard Bankart procedure (127 N). All suture anchors demonstrated similar holding strength with the exception of an absorbable wedge (P < 0.05). Due to reduced mineral content in the inferior part of the glenoid, the fixation strength of all suture anchors was significantly decreased. In more than 20% a tension load of 100 N caused the suture anchor to pull out, but in general the fixation strength was limited by the suture attachment and the quality of the soft tissues. These data together with the first clinical results of 49 cases of anterior instability operated on between 1988 and 1992 allow the conclusion to be made that this modification will provide sufficient stability for early mobilization after surgical repair. PMID:8235676

  14. Evaluation of a sugar based edible adhesive utilizing a tensile strength tester

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A new method to evaluate adhesives has been developed and utilized to formulate a recently patented adhesive based on sugar and citric acid. Factors affecting adhesive performance were uncovered, such as reduced strength due to improper heating time, and an optimal curing temperature of 60oC was ac...

  15. Micro-tensile bond strength of different adhesive systems on sound dentin and resin-based composite: An in-vitro study

    PubMed Central

    Mallick, Rashmirekha; Sarangi, Priyanka; Mohanty, Sandhyarani; Behera, Subasish; Nanda, Soumyaranjan; Satapathy, Sukanta Kumar

    2015-01-01

    Aim: To analyze the difference in the micro-tensile bond strength of specimens made with two different adhesive systems and compare them with two homogenous substrates. Materials and Methods: Sixty permanent mandibular molars were mounted in acrylic blocks and sectioned with exposed dentin surfaces. Samples were then divided into four groups. To Group-I Adper Single Bond 2 and to Group-II Adper Self-Etch plus bonding agents were applied. For Group-I and Group-II beams consisted of resin composite in the upper half and dentin in the lower half. In Group-III beams were made of only dentin. In Group-IV beams were made of only composite. Fifteen specimens of each group were taken for the micro-tensile bond strength test. Statistical Analysis: The results are analyzed using one-way analysis of variance and Critical Difference test. Results: The interface bonded with the two adhesive systems had lower micro-tensile bond strength than those of dentin and resin composite and the self-etching adhesive Adper Self-Etch plus had comparable bond strength with total-etch adhesive Adper Single Bond 2. Conclusion: The bond strength values for current adhesive systems cannot be compared to the micro-tensile bond strength of dentin and resin composite, and self-etching adhesives have comparable bond strength with total-etch adhesives. PMID:26430301

  16. Semi-analytical and Numerical Studies on the Flattened Brazilian Splitting Test Used for Measuring the Indirect Tensile Strength of Rocks

    NASA Astrophysics Data System (ADS)

    Huang, Y. G.; Wang, L. G.; Lu, Y. L.; Chen, J. R.; Zhang, J. H.

    2015-09-01

    Based on the two-dimensional elasticity theory, this study established a mechanical model under chordally opposing distributed compressive loads, in order to perfect the theoretical foundation of the flattened Brazilian splitting test used for measuring the indirect tensile strength of rocks. The stress superposition method was used to obtain the approximate analytic solutions of stress components inside the flattened Brazilian disk. These analytic solutions were then verified through a comparison with the numerical results of the finite element method (FEM). Based on the theoretical derivation, this research carried out a contrastive study on the effect of the flattened loading angles on the stress value and stress concentration degree inside the disk. The results showed that the stress concentration degree near the loading point and the ratio of compressive/tensile stress inside the disk dramatically decreased as the flattened loading angle increased, avoiding the crushing failure near-loading point of Brazilian disk specimens. However, only the tensile stress value and the tensile region were slightly reduced with the increase of the flattened loading angle. Furthermore, this study found that the optimal flattened loading angle was 20-30; flattened load angles that were too large or too small made it difficult to guarantee the central tensile splitting failure principle of the Brazilian splitting test. According to the Griffith strength failure criterion, the calculative formula of the indirect tensile strength of rocks was derived theoretically. This study obtained a theoretical indirect tensile strength that closely coincided with existing and experimental results. Finally, this paper simulated the fracture evolution process of rocks under different loading angles through the use of the finite element numerical software ANSYS. The modeling results showed that the Flattened Brazilian Splitting Test using the optimal loading angle could guarantee the tensile splitting failure initiated by a central crack.

  17. Comparison of Tensile Strength of Composite Material Elements with Drilled and Molded-in Holes

    NASA Astrophysics Data System (ADS)

    Langella, A.; Durante, M.

    2008-11-01

    Holes are generally obtained through drilling operations; this causes a property decrease for polymer composites reinforced by fibers, brought about by damage due to fiber continuity interruption, and to delamination between the laminate layers. In this study, specimens with circular holes, both drilled and molded-in, obtained in different ways, are tested in order to investigate on whether it is possible to avoid the decrease in mechanical properties of components with holes. In particular, a number of laminates were manufactured by RIFT (Resin Infusion under Flexible Tool), a closed mold process capable of obtaining large and complex forms, impregnating, under vacuum, a dry preform placed on the rigid mold. At specific points of these laminates, molded-in holes are generated during the resin infusion phase, operating in two different ways: displacing or cutting the fibers in the dry preform. Tensile tests were carried out in order to compare the mechanical properties of elements in composite materials which have molded-in holes generated during the impregnation process, with the properties of those with holes produced after the resin cure by drill operations.

  18. An Investigation of the Tensile Strength of a Composite-To-Metal Adhesive Joint

    NASA Astrophysics Data System (ADS)

    Tsouvalis, Nicholas G.; Karatzas, Vassilios A.

    2011-04-01

    The present study examines the feasibility of a simple concept composite-to-metal butt joint through the performance of both numerical and experimental studies. The composite part is made of glass/epoxy unidirectional layers made with the vacuum bag method. The geometry of the joint is typical for marine applications and corresponds to a low stiffness ratio. Two major parameters are investigated, namely the overlap length and the surface preparation of the steel adherent. Manufacturing of specimens and the procedure of the tensile tests are described in detail, giving hints for obtaining a better quality joint. Axial elongation and strains at various places of the joint were monitored and also numerically calculated. The tests revealed that the joint is quite effective, irrespectively of the steel surface preparation method. The failure loads are comparable and in some cases superior to other corresponding values found in the literature. The numerical models proved to adequately predict the structural response of the joint up to the loading where debonding starts.

  19. Ultrasonic Spot Welding of Aluminum to High-Strength Low-Alloy Steel: Microstructure, Tensile and Fatigue Properties

    NASA Astrophysics Data System (ADS)

    Patel, V. K.; Bhole, S. D.; Chen, D. L.

    2014-04-01

    The structural applications of lightweight aluminum alloys inevitably involve dissimilar welding with steels and the related durability issues. This study was aimed at evaluating the microstructural change, lap shear tensile load, and fatigue resistance of dissimilar ultrasonic spot-welded joints of aluminum-to-galvanized high-strength low-alloy (HSLA) steel. Two non-uniform layers were identified in between Al and HSLA steel via SEM/EDS and XRD. One was an Al-Zn eutectic layer and the other was a thin (<2 μm) layer of intermetallic compound (IMC) of Al and Fe in the nugget zone. The lap shear tensile testing gave a maximum load of 3.7 kN and the sample failed initially in between the Al-Zn eutectic film and Al-Fe IMC, and afterward from the region containing Al on both matching fracture surfaces. The fatigue test results showed a fatigue limit of about 0.5 kN (at 1 × 107 cycles). The maximum cyclic stress at which transition of the fatigue fracture from transverse through-thickness crack growth mode to the interfacial failure mode occurs increases with increasing energy input.

  20. Investigation of uplift pressures and shear and tensile strengths for concrete gravity dams

    SciTech Connect

    Meisenheimer, J.K. )

    1990-12-01

    This report presents a discussion of concrete gravity dam stability parameters such as uplift pressure and strength test results of lift joints and concrete-to-rock contact areas from several older dams. The purpose of the report is to present the importance of site foundation investigations in the interpretation of uplift pressure readings and to discuss the application of site test results to get the maximum benefit of actual conditions when submitting dam stability calculations for the consideration of regulatory agencies. Uplift pressure behavior and its response to reservoir level fluctuations are discussed with case study examples. The feasibility of using actual strength data from existing dams as a benchmark database to give credibility to site-specific values is demonstrated. 69 refs., 47 figs., 6 tabs.

  1. Effect of reactive adhesives on the tensile bond strength of polyvinyl siloxane impression materials to methyl methacrylate tray material.

    PubMed

    Ona, Masahiro; Takahashi, Hidekazu; Sato, Masayuki; Igarashi, Yoshimasa; Wakabayashi, Noriyuki

    2010-05-01

    The effect of new adhesives on the bond strength of elastomeric impression materials to acrylic trays was evaluated. Two polyvinyl siloxane impression materials (Fusion and Imprinsis) with reactive adhesives and one (Examix) with a conventional adhesive were tested. Flat, double-sided plates of auto-polymerizing methyl methacrylate (10 x 10 x 2.5 mm) were prepared with one of the adhesives. Five specimens were prepared by injecting each impression material into a 2-mm gap between the two plates. Tensile tests were conducted until separation failure occurred. The mean bond strengths of Fusion (1.0 MPa) and Imprinsis (0.8 MPa) were significantly greater than that of Examix (0.2 MPa). On the contrary, one of five Fusion showed adhesive failure mode while all the Imprinsis exhibited mixed failure. The conflicting results were presumably attributed to the mean tear strength of Fusion (0.8 N/mm) being higher than that of Imprinsis (0.5 N/mm). PMID:20484844

  2. Effect of Load Rate on Ultimate Tensile Strength of Ceramic Matrix Composites at Elevated Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.

    2001-01-01

    The strengths of three continuous fiber-reinforced ceramic composites, including SiC/CAS-II, SiC/MAS-5 and SiC/SiC, were determined as a function of test rate in air at 1100 to 1200 C. All three composite materials exhibited a strong dependency of strength on test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress-rate) to another (constant stress loading) suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law type of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics. It was further found that constant stress-rate testing could be used as an alternative to life prediction test methodology even for composite materials, at least for short range of lifetimes and when ultimate strength is used as the failure criterion.

  3. Effect of the fiber-matrix interphase on the transverse tensile strength of the unidirectional composite material

    NASA Technical Reports Server (NTRS)

    Tsai, H. C.; Arocho, A. M.

    1992-01-01

    A simple one-dimensional fiber-matrix interphase model has been developed and analytical results obtained correlated well with available experimental data. It was found that by including the interphase between the fiber and matrix in the model, much better local stress results were obtained than with the model without the interphase. A more sophisticated two-dimensional micromechanical model, which included the interphase properties was also developed. Both one-dimensional and two-dimensional models were used to study the effect of the interphase properties on the local stresses at the fiber, interphase and matrix. From this study, it was found that interphase modulus and thickness have significant influence on the transverse tensile strength and mode of failure in fiber reinforced composites.

  4. Diametrical diseases reflect evolutionary-genetic tradeoffs

    PubMed Central

    Crespi, Bernard J.; Go, Matthew C.

    2015-01-01

    Tradeoffs centrally mediate the expression of human adaptations. We propose that tradeoffs also influence the prevalence and forms of human maladaptation manifest in disease. By this logic, increased risk for one set of diseases commonly engenders decreased risk for another, diametric, set of diseases. We describe evidence for such diametric sets of diseases from epidemiological, genetic and molecular studies in four clinical domains: (i) psychiatry (autism vs psychotic-affective conditions), (ii) rheumatology (osteoarthritis vs osteoporosis), (iii) oncology and neurology (cancer vs neurodegenerative disorders) and (iv) immunology (autoimmunity vs infectious disease). Diametric disorders are important to recognize because genotypes or environmental factors that increase risk for one set of disorders protect from opposite disorders, thereby providing novel and direct insights into disease causes, prevention and therapy. Ascertaining the mechanisms that underlie disease-related tradeoffs should also indicate means of circumventing or alleviating them, and thus reducing the incidence and impacts of human disease in a more general way. PMID:26354001

  5. Gas bubble retention and its effect on waste properties: Retention mechanisms, viscosity, and tensile and shear strengths

    SciTech Connect

    Gauglitz, P.A.; Rassat, S.D.; Powell, M.R.

    1995-08-01

    Several of the underground nuclear storage tanks at Hanford have been placed on a flammable gas watch list, because the waste is either known or suspected to generate, store, and episodically release flammable gases. Because retention and episodic release of flammable gases from these tanks containing radioactive waste slurries are critical safety concerns, Pacific Northwest Laboratory (PNL) is studying physical mechanisms and waste properties that contribute to the episodic gas release from these storage tanks. This study is being conducted for Westinghouse Hanford Company as part of the PNL Flammable Gas project. Previous investigations have concluded that gas bubbles are retained by the slurry or sludge that has settled at the bottom of the tanks; however, the mechanisms responsible for the retention of these bubbles are not well understood. Understanding the rheological behavior of the waste, particularly of the settled sludge, is critical to characterizing the tendency of the waste to retain gas bubbles and the dynamics of how these bubbles are released from the waste. The presence of gas bubbles is expected to affect the rheology of the sludge, specifically its viscosity and tensile and shear strengths, but essentially no literature data are available to assess the effect of bubbles. The objectives of this study were to conduct experiments and develop theories to understand better how bubbles are retained by slurries and sludges, to measure the effect of gas bubbles on the viscosity of simulated slurries, and to measure the effect of gas bubbles on the tensile and shear strengths of simulated slurries and sludges. In addition to accomplishing these objectives, this study developed correlations, based on the new experimental data, that can be used in large-scale computations of waste tank physical phenomena.

  6. Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study

    PubMed Central

    Lau, Mayank; Amarnath, G S; Muddugangadhar, B C; Swetha, M U; Das, Kopal Anshuraj Ashok Kumar

    2014-01-01

    Background: The condition of the denture bearing tissues may be adversely affected by high stress concentration during function. Chairside Denture (Hard and Soft) reliners are used to distribute forces applied to soft tissues during function. Tensile and shear bond strength has been shown to be dependent on their chemical composition. A weak bond could harbor bacteria, promote staining and delamination of the lining material. To investigate tensile and shear bond strength of 4 different commercially available denture relining materials to conventional heat cured acrylic denture base resin. Materials & Methods: 4 mm sections in the middle of 160 Acrylic cylindrical specimens (20 mm x 8 mm) were removed, packed with test materials (Mollosil, G C Reline Soft, G C Reline Hard (Kooliner) and Ufi Gel Hard and polymerized. Specimens were divided into 8 groups of 20 each. Tensile and shear bond strength to the conventional heat cured acrylic denture base resin were examined by Instron Universal Tensile Testing Machine using the equation F=N/A (F-maximum force exerted on the specimen (Newton) and A-bonding area= 50.24 mm2). One-way ANOVA was used for multiple group comparisons followed by Bonferroni Test and Hsu’s MCB for multiple pairwise comparisons to asses any significant differences between the groups. Results: The highest mean Tensile bond strength value was obtained for Ufi Gel Hard (6.49+0.08 MPa) and lowest for G C Reline Soft (0.52+0.01 MPa). The highest mean Shear bond strength value was obtained for Ufi Gel Hard (16.19+0.1 MPa) and lowest for Mollosil (0.59+0.05 MPa). The Benferroni test showed a significant difference in the mean tensile bond strength and the mean shear bond strength when the two denture soft liners were compared as well as when the two denture hard liners were compared. Hsu’s MCB implied that Ufi gel hard is better than its other closest competitors. Conclusion: The Tensile and Shear bond strength values of denture soft reliners were significantly lower than denture hard reliners. How to cite the article: Lau M, Amarnath GS, Muddugangadhar BC, Swetha MU, Das KA. Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study. J Int Oral Health 2014;6(2):55-61. PMID:24876703

  7. Evaluation of a sugar-based edible adhesive using a tensile strength tester.

    PubMed

    Doll, Kenneth M; Erhan, Sevim Z

    2011-04-01

    A method to evaluate adhesives has been developed and used to reformulate a recently patented adhesive which is based on sugar and citric acid. Factors affecting adhesive performance were uncovered, such as an optimal curing temperature of 60°C. The addition of maltodextrin and soy protein at optimized levels was shown to nearly double the bonding strength of the adhesive, from 0.46 ± 0.076 to 0.74 ± 0.26 kN, under our test conditions. Also discussed is the potential for this method to be automated using commercially available equipment. PMID:21609697

  8. A comparison of tensile bond strengths of resin-retained prostheses made using five alloys.

    PubMed

    Rubo, J H; Pegoraro, L F; Ferreira, P M

    1996-01-01

    This in vitro study evaluated the bond strength of metal frameworks cast using Ni-Cr, Ni-Cr-Be, Cu-Al, type IV gold, and noble metal ceramic alloy with and without tin electroplating. The castings were luted to human teeth using Panavia Ex resin. It was found that tin electroplating had a negative effect for the Cu-Al and type IV gold alloys and a positive effect for gold for metal ceramic restorations. The best results were obtained using the Ni-Cr alloy. PMID:8957864

  9. An evaluation of the +/-45 deg tensile test for the determination of the in-plane shear strength of composite materials

    NASA Technical Reports Server (NTRS)

    Kellas, S.; Morton, J.; Jackson, K. E.

    1991-01-01

    The applicability of the +/-45 deg tensile test for the determination of the in-plane shear strength of advanced composite laminates is studied. The assumptions used for the development of the shear strength formulas were examined, and factors such as the specimen geometry and stacking sequence were assessed experimentally. It was found that the strength of symmetric and balanced +/-45 deg laminates depends primarily upon the specimen thickness rather than the specimen width. These findings have important implications for the +/-45 deg tensile test which is recommended by several organizations for the determination of the in-plane shear stress/strain response and the shear strength of continuous fiber reinforced composites. Modifications to the recommended practices for specimen selection and shear strength determination are suggested.

  10. Ultimate tensile strength of embedded I-sections: a comparison of experimental and numerical results

    NASA Astrophysics Data System (ADS)

    Heristchian, Mahmoud; Pourakbar, Pouyan; Imeni, Saeed; Ramezani, M. Reza Adib

    2014-12-01

    Exposed baseplates together with anchor bolts are the customary method of connection of steel structures to the concrete footings. Post-Kobe studies revealed that the embedded column bases respond better to the earthquake uplift forces. The embedded column bases also, offer higher freedom in achieving the required strength, rigidity and ductility. The paper presents the results of the pullout failure of three embedded IPE140 sections, tested under different conditions. The numerical models are then, generated in Abaqus 6.10-1 software. It is concluded that, the steel profiles could be directly anchored in concrete without using anchor bolts as practiced in the exposed conventional column bases. Such embedded column bases can develop the required resistance against pullout forces at lower constructional costs.

  11. On the determination of tensile and compressive strengths of unidirectional fiber composites

    SciTech Connect

    Chatterjee, S.N.; Yen, C.F.; Oplinger, D.W.

    1997-12-31

    Stress fields in tabbed unidirectional composite coupons and in cross-ply specimens are examined with a goal towards improving the methods for determining the axial strengths of the unidirectional material. Results of parametric studies for evaluation of the influence of tab materials and geometries as well as adhesive properties on the stress peaks in unidirectional tension coupons are presented. Use of ductile (but tough) adhesives, soft tabs, and low taper angles is recommended to reduce failures near tab ends. Data reduction schemes for evaluation of cross-ply test data are critically examined with due consideration to subcritical damages (such as ply cracks) and expected failure modes. Test results from cross-ply and unidirectional tension and compression specimens of carbon and glass-fiber composites are compared. Some recommendations are made based on the results reported. Tests and data correlations for other composites are suggested for selecting a data reduction scheme acceptable to the composites community.

  12. Metalloproteases meprin ? and meprin ? are C- and N-procollagen proteinases important for collagen assembly and tensile strength

    PubMed Central

    Broder, Claudia; Arnold, Philipp; Vadon-Le Goff, Sandrine; Konerding, Moritz A.; Bahr, Kerstin; Mller, Stefan; Overall, Christopher M.; Bond, Judith S.; Koudelka, Tomas; Tholey, Andreas; Hulmes, David J. S.; Moali, Catherine; Becker-Pauly, Christoph

    2013-01-01

    Type I fibrillar collagen is the most abundant protein in the human body, crucial for the formation and strength of bones, skin, and tendon. Proteolytic enzymes are essential for initiation of the assembly of collagen fibrils by cleaving off the propeptides. We report that Mep1a?/? and Mep1b?/? mice revealed lower amounts of mature collagen I compared with WT mice and exhibited significantly reduced collagen deposition in skin, along with markedly decreased tissue tensile strength. While exploring the mechanism of this phenotype, we found that cleavage of full-length human procollagen I heterotrimers by either meprin ? or meprin ? led to the generation of mature collagen molecules that spontaneously assembled into collagen fibrils. Thus, meprin ? and meprin ? are unique in their ability to process and release both C- and N-propeptides from type I procollagen in vitro and in vivo and contribute to the integrity of connective tissue in skin, with consequent implications for inherited connective tissue disorders. PMID:23940311

  13. Parametric studies on tensile strength in joining AA6061- T6 and AA7075-T6 by gas metal arc welding process

    NASA Astrophysics Data System (ADS)

    Ishak, M.; Noordin, N. F. M.; Shah, L. H.

    2015-12-01

    Proper selection of the welding parameters can result in better joining. In this study, the effects of various welding parameters on tensile strength in joining dissimilar aluminum alloys AA6061-T6 and AA7075-T6 were investigated. 2 mm thick samples of both base metals were welded by semi-automatic gas metal arc welding (GMAW) using filler wire ER5356. The welding current, arc voltage and welding speed were chosen as variables parameters. The strength of each specimen after the welding operations were tested and the effects of these parameters on tensile strength were identified by using Taguchi method. The range of parameter for welding current were chosen from 100 to 115 A, arc voltage from 17 to 20 V and welding speed from 2 to 5 mm/s. L16 orthogonal array was used to obtained 16 runs of experiments. It was found that the highest tensile strength (194.34 MPa) was obtained with the combination of a welding current of 115 A, welding voltage of 18 V and welding speed of 4 mm/s. Through analysis of variance (ANOVA), the welding voltage was the most effected parameter on tensile strength with percentage of contribution at 41.30%.

  14. The influence of impurities in Titan ice bedrock on tensile strength and resistance to fluvial erosion: experimental results

    NASA Astrophysics Data System (ADS)

    Litwin, K. L.; Polito, P.; Zygielbaum, B.; Sklar, L. S.; Collins, G. C.

    2010-12-01

    Images of the surface of Titan returned by the Cassini-Huygens mission show extensive fluvial drainage networks, which may be eroded by low-velocity impacts by ice clasts moving as bedload in rivers of liquid methane. Recent work has shown that the strength of polycrystalline water ice at Titan surface temperature of 93K is comparable to moderate strength rocks on Earth, and is significantly stronger than ice at terrestrial temperatures. However, the ice bedrock on Titan is likely to contain impurities such as silicates, atmospherically-derived hydrocarbon polymers and compounds of cryovolcanic origin. In this laboratory investigation, we examine the dependence of ice erosion resistance on the concentration of impurities, across a wide range of temperatures. The polycrystalline ice is made from a log-normally distributed seed crystal material with a median size of 1.4mm, which we combine with particles of basalt, ammonium-sulfate, and a urea polymer. We use the Brazilian tensile splitting test to measure the strength of the ice as a function of the concentration of each impurity. We erode 57-cm diameter drums of ice by repeatedly dropping a clast of known mass from a constant height and measure volume eroded with a topographic scanning technique where photographs are taken at an oblique angle to a vertically-oriented laser sheet. We control the temperature of the ice with dry ice and liquid nitrogen, as well as by conducting experiments in a walk-in freezer. The strength tests indicate that the ice strengthens with decreasing temperature and increasing concentration of impurity, for all impurity types. Additionally, the grain size of the added impurities is a strongly influences ice strength. The results of the erosion tests indicate that ice, regardless of composition, becomes stronger, and becomes more resistant to erosion, as it gets colder. However, the ice containing impurities is more resistant to erosion as compared to pure ice. Combining the results of both the strength tests and erosion experiments, we conclude that the resistance to erosion of the ice increases with increasing concentration of each impurity. These results will help constrain estimates of ice resistance to erosion, and possible erosion rates, that may occur on Titan and other icy satellites.

  15. Diametric Quadrilaterals with Two Equal Sides

    ERIC Educational Resources Information Center

    Beauregard, Raymond A.

    2009-01-01

    If you take a circle with a horizontal diameter and mark off any two points on the circumference above the diameter, then these two points together with the end points of the diameter form the vertices of a cyclic quadrilateral with the diameter as one of the sides. We refer to the quadrilaterals in question as diametric. In this note we consider

  16. Diametric Quadrilaterals with Two Equal Sides

    ERIC Educational Resources Information Center

    Beauregard, Raymond A.

    2009-01-01

    If you take a circle with a horizontal diameter and mark off any two points on the circumference above the diameter, then these two points together with the end points of the diameter form the vertices of a cyclic quadrilateral with the diameter as one of the sides. We refer to the quadrilaterals in question as diametric. In this note we consider…

  17. Tensile strength of a surgeons or a square knot

    PubMed Central

    Muffly, Tyler M.; Boyce, Jamie; Kieweg, Sarah L.; Bonham, Aaron J.

    2014-01-01

    Objective To test the integrity of surgeons knots and flat square knots using four different suture materials. Study Design Chromic catgut, polyglactin 910, silk, and polydioxanone sutures were tied in the two types of knot configurations. For all sutures, a 0-gauge United States Pharmacopeia suture was used. Knots were tied by a single investigator (JB). Suture was soaked in 0.9 % sodium chloride for 60 seconds and subsequently transferred to a tensiometer where the tails were cut to 3 mm length. We compared the knots, measuring knot strength using a tensiometer until the sutures broke or untied. Results A total of 119 knots were tied. We found no difference in mean tension at failure between a surgeons knot (79.7 Newtons) and a flat square knot (82.9 Newtons). Using a Chi-square test, we did not find a statistically significant difference in the likelihood of knots coming untied between surgeons knots (29%) and flat square knots (38%). Conclusions Under laboratory conditions, surgeons knots and flat square knots did not differ in tension at failure or likelihood of untying. PMID:20816357

  18. Effect of different stages of tensile deformation on micromagnetic parameters in high-strength, low-alloy steel

    SciTech Connect

    Vaidyanathan, S.; Moorthy, V.; Kalyanasundaram, P.; Jayakumar, T.; Raj, B.

    1999-08-01

    The influence of tensile deformation on the magnetic Barkhausen emissions (MBE) and hysteresis loop has been studied in a high-strength, low-alloy steel (HSLA) and its weldment. The magnetic measurements were made both in loaded and unloaded conditions for different stress levels. The root-mean-square (RMS) voltage of the MBE has been used for analysis. This study shows that the preyield and postyield deformation can be identified from the change in the MBE profile. The initial elastic deformation showed a linear increase in the MBE level in the loaded condition, and the MBE level remained constant in the unloaded condition. The microplastic yielding, well below the macroyield stress, significantly reduces the MBE, indicating the operation of grain-boundary dislocation sources below the macroyield stress. This is indicated by the slow increase in the MBE level in the loaded condition and the decrease in the MBE level in the unloaded condition. The macroyielding resulted in a significant increase in the MBE level in the loaded condition and, more clearly, in the unloaded condition. The increase in the MBE level during macroyielding has been attributed to the grain rotation phenomenon, in order to maintain the boundary integrity between adjacent grains, which would preferentially align the magnetic domains along the stress direction. This study shows that MBE during tensile deformation can be classified into four stages: (1) perfectly elastic, (2) microplastic yielding, (3) macroyielding, and (4) progressive plastic deformation. A multimagnetic parameter approach, combining the hysteresis loop and MBE, has been suggested to evaluate the residual stresses.

  19. In-plane tensile strength and residual stress in thick Al{sub 2}O{sub 3} coatings on aluminum alloy

    SciTech Connect

    Uenal, O.; Sordelet, D.J.

    2000-03-17

    Three types of strength are important for coating materials; bond (adhesive) strength, cohesive strength and in-plane strength. The distinction between the first two can be made by failure location; if failure occurs at the coating/substrate interface, the corresponding strength value is adhesive; and if it occurs within the ceramic coating, the strength value is cohesive. Between the two, adhesive strength is the most important since coatings often fail by debonding at the interface. In fact, there is a standard test procedure to determine both of these strengths, ASTM C633-79. In-plane strength characterizes the point of coating failure under in-plane applied loads. Since it is not the primary failure parameter, little attention has been given for its measurement. Therefore, work in the area of in-plane properties is limited. However, the knowledge of in-plane strength could be important for weaker coatings, but there is no simple way of measuring it. In this study as attempt was made to determine in-plane tensile strength of thick Al{sub 2}O{sub 3} coatings on Al-alloy through straightforward strength of materials approach. The residual stresses, which invariably occur in coatings, affect the in-plant strength. The magnitude of apparent average residual stress in Al{sub 2}O{sub 3} was determined indirectly by comparing the in-plane strength of coating/substrate system with the intrinsic strength of coating (no substrate).

  20. Editorial Commentary: High-Tensile Strength Polyblend Tape Outperforms Suture for Whip and Krackow Stitch Models at Time Zero, Which Is No Surprise.

    PubMed

    Rossi, Michael J

    2016-02-01

    The matched, head-to-head comparison of high-tensile strength tape versus suture shows a higher load to failure for tape. This may be the first step to showing the advantage of polyblend tape in clinical models as we await further cyclic load testing to extend beyond time zero in cadaveric biomechanical modeling. PMID:26814398

  1. Low-output carbon dioxide laser for cutaneous wound closure of scalpel incisions: comparative tensile strength studies of the laser to the suture and staple for wound closure

    SciTech Connect

    Garden, J.M.; Robinson, J.K.; Taute, P.M.; Lautenschlager, E.P.; Leibovich, S.J.; Hartz, R.S.

    1986-01-01

    The low-output carbon dioxide (CO/sub 2/) laser was used for cutaneous wound closure of scalpel incisions. Cutaneous scalpel incisions were placed over the dorsum of three minipigs and were then closed by either the laser, sutures, or staples. At multiple time points after wound closure, up to day 90, the tensile strengths of these wounds were comparatively evaluated. All wounds, including those closed with the laser, clinically appeared to heal similarly with no evidence of wound dehiscence or infection. Tensile strength studies revealed similar sigmoid curves for all wound closure modalities with low initial tensile strengths up to days 14 to 21, which afterwards increased rapidly, with a plateau toward day 90. From our study, it appears that the CO/sub 2/ laser, in the low-output mode, can be used for cutaneous wound closure and that similar clinical healing and tensile strength measurements are obtained relative to the conventional cutaneous wound closure modalities of the suture or staple.

  2. Effects of excipients on the tensile strength, surface properties and free volume of Klucel free films of pharmaceutical importance

    NASA Astrophysics Data System (ADS)

    Gottnek, Mihly; Svegh, Kroly; Pintye-Hdi, Klra; Regdon, Gza

    2013-08-01

    The physicochemical properties of polymers planned to be applied as mucoadhesive films were studied. Two types of Klucel hydroxypropylcellulose (LF and MF) were used as film-forming polymers. Hydroxypropylcellulose was incorporated in 2 w/w% with glycerol and xylitol as excipients and lidocaine base as an active ingredient at 5, 10 or 15 w/w% of the mass of the film-forming polymer. The free volume changes of the films were investigated by positron annihilation lifetime spectroscopy, the mechanical properties of the samples were measured with a tensile strength tester and contact angles were determined to assess the surface properties of the films. It was found that the Klucel MF films had better physicochemical properties than those of the LF films. Klucel MF as a film-forming polymer with lidocaine base and both excipients at 5 w/w% exhibited physicochemical properties and good workability. The excipients proved to exert strong effects on the physicochemical properties of the tested systems and it is very important to study them intensively in preformulation studies in the pharmaceutical technology in order to utilise their benefits and to avoid any disadvantageous effects.

  3. INFLUENCE OF THE FINAL TEMPERATURE OF INVESTMENT HEALTING ON THE TENSILE STRENGTH AND VICKERS HARDNESS OF CP TI AND TI-6AL-4V ALLOY

    PubMed Central

    Oliveira, Pedro Csar Garcia; Adabo, Gelson Luis; Ribeiro, Ricardo Faria; da Rocha, Sicknan Soares; vila, Fabiano Arajo; do Valle, Acccio Lins

    2007-01-01

    The aim of the work was to evaluate the influence of the temperature of investment healting on the tensile strength and Vickers hardness of CP Ti and Ti-6Al-4V alloy casting. Were obtained for the tensile strength test dumbbell rods that were invested in the Rematitan Plus investment and casting in the Discovery machine cast. Thirty specimens were obtained, fiftten to the CP Titanium and fifteen to the Ti-6Al-4V alloy, five samples to each an of the three temperatures of investment: 430C (control group), 480C and 530C. The tensile test was measured by means of a universal testing machine, MTS model 810, at a strain of 1.0 mm/min. After the tensile strenght test the specimens were secctioned, embedded and polished to hardness measurements, using a Vickers tester, Micromet 2100. The means values to tensile tests to the temperatures 430C, 480 and 530: CP Ti (486.1 501.16 498.14 mean 495.30 MPa) and Ti-6Al-4V alloy (961.33 958.26 1005.80 mean 975.13 MPa) while for the Vickers hardness the values were (198.06, 197.85, 202.58 mean 199.50) and (352.95, 339.36, 344.76 mean 345.69), respectively. The values were submitted to Analysis of Variance (ANOVA) and Tukey,s Test that indicate differences significant only between the materials, but not between the temperature, for both the materias. It was conclued that increase of the temperature of investment its not chance the tensile strength and the Vickers hardness of the CP Titanium and Ti-6Al-4V alloy. PMID:19089099

  4. Direct Tensile Strength and Characteristics of Dentin Restored with All-Ceramic, Resin-Composite, and Cast Metal Prostheses Cemented with Resin Adhesives.

    PubMed

    Piemjai, Morakot; Nakabayashi, Nobuo

    2015-01-01

    A dentin-cement-prosthesis complex restored with either all-porcelain, cured resin-composite, or cast base metal alloy and cemented with either of the different resin cements was trimmed into a mini-dumbbell shape for tensile testing. The fractured surfaces and characterization of the dentin-cement interface of bonded specimens were investigated using a Scanning Electron Microscope. A significantly higher tensile strength of all-porcelain (12.5 2.2?MPa) than that of cast metal (9.2 3.5?MPa) restorations was revealed with cohesive failure in the cement and failure at the prosthesis-cement interface in Super-Bond C&B group. No significant difference in tensile strength was found among the types of restorations using the other three cements with adhesive failure on the dentin side and cohesive failure in the cured resin. SEM micrographs demonstrated the consistent hybridized dentin in Super-Bond C&B specimens that could resist degradation when immersed in hydrochloric acid followed by NaOCl solutions whereas a detached and degraded interfacial layer was found for the other cements. The results suggest that when complete hybridization of resin into dentin occurs tensile strength at the dentin-cement is higher than at the cement-prosthesis interfaces. The impermeable hybridized dentin can protect the underlying dentin and pulp from acid demineralization, even if detachment of the prosthesis has occurred. PMID:26539520

  5. Restoration of tensile strength in bark samples of Ficus benjamina due to coagulation of latex during fast self-healing of fissures

    PubMed Central

    Bauer, Georg; Speck, Thomas

    2012-01-01

    Background and Aims The functions of plant latex have been discussed for a long time. Today, many studies support a defence mechanism as being its main function. A role as a self-healing mechanism was never attributed to the coagulation of latex. In this study we quantified the contribution of the coagulation of Ficus benjamina (weeping fig) latex to a restoration of the mechanical properties of the bark after external lesions. Methods Tensile tests of F. benjamina bark were conducted either immediately after injury or at various latency times after injury. Key Results A significant increase in the tensile strength of bark samples until 30 min after injury was found, and this effect could be attributed to the coagulation of plant latex alone. The tensile strength remains nearly constant until several hours or days after injury. Then, very probably due to other mechanisms such as cell growth and cell proliferation, the tensile strength begins to increase slightly again. Conclusions The coagulation of latex seals lesions and serves as a quick and effective pre-step of subsequent, more effective, long-lasting self-healing mechanisms such as cell growth and proliferation. Thus, a fast self-healing effect can be included in the list of functions of plant latex. PMID:22207613

  6. Direct Tensile Strength and Characteristics of Dentin Restored with All-Ceramic, Resin-Composite, and Cast Metal Prostheses Cemented with Resin Adhesives

    PubMed Central

    Piemjai, Morakot; Nakabayashi, Nobuo

    2015-01-01

    A dentin-cement-prosthesis complex restored with either all-porcelain, cured resin-composite, or cast base metal alloy and cemented with either of the different resin cements was trimmed into a mini-dumbbell shape for tensile testing. The fractured surfaces and characterization of the dentin-cement interface of bonded specimens were investigated using a Scanning Electron Microscope. A significantly higher tensile strength of all-porcelain (12.5 ± 2.2 MPa) than that of cast metal (9.2 ± 3.5 MPa) restorations was revealed with cohesive failure in the cement and failure at the prosthesis-cement interface in Super-Bond C&B group. No significant difference in tensile strength was found among the types of restorations using the other three cements with adhesive failure on the dentin side and cohesive failure in the cured resin. SEM micrographs demonstrated the consistent hybridized dentin in Super-Bond C&B specimens that could resist degradation when immersed in hydrochloric acid followed by NaOCl solutions whereas a detached and degraded interfacial layer was found for the other cements. The results suggest that when complete hybridization of resin into dentin occurs tensile strength at the dentin-cement is higher than at the cement-prosthesis interfaces. The impermeable hybridized dentin can protect the underlying dentin and pulp from acid demineralization, even if detachment of the prosthesis has occurred. PMID:26539520

  7. Influence Of Holes On The In-Plane Tensile Strength And Fatigue Durability Of A NICALON(Trademark)/Si-N-C Ceramic Matrix Composite

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Verrilli, Michael J.

    2003-01-01

    Effects of different sizes of holes as well as different percentages of open areas on the in-plane tensile strength and fatigue durability of the SiC/Si-N-C composite were investigated in this study. Test specimens with no holes, four different diameters of holes (1.0 to 3.2 mm), and four different open areas (20 to 35%) were machined. All mechanical testing was performed in air at a temperature of 910 C. Fatigue tests were conducted with a load ratio, R = 0.05, and a frequency of 0.33 Hz. In general, both the in-plane tensile strength of the composite and its fatigue durability decreased with an increase in the size of the hole and percentage of the open area. Reductions in the in-plane tensile strength and cyclic fatigue life of the composite were described by empirical equations with the diameter of the hole and the percent open area as the independent variables. The validity of these two empirical equations was verified with additional tensile and fatigue test data generated on the composite specimens.

  8. To evaluate and compare the effect of different Post Surface treatments on the Tensile Bond Strength between Fiber Posts and Composite Resin.

    PubMed Central

    Shori, Deepa; Pandey, Swapnil; Kubde, Rajesh; Rathod, Yogesh; Atara, Rahul; Rathi, Shravan

    2013-01-01

    Background: Fiber posts are widely used for restoration of mutilated teeth that lack adequate coronal tooth structure to retain a core for definitive restoration, bond between the fiber post and composite material depends upon the chemical reaction between the post surface and the resin material used for building up the core. In attempt to maximize the resin bonding with fiber post, different post surface conditioning is advocated. Therefore the purpose of the study is to examine the interfacial strength between fiber post and composite, as core build-up material after different surface treatments of fiber posts. Materials & Methods:Twenty fiber posts were split into four groups off five each according to different surface treatments viz. Group I-(Negative Control), Group II-Silanization (Positive control), Group III-(37% Phosphoric Acid & Silanization) ,Group IV- (10% Hydrogen Peroxide and Silanization). With the preformed plastic mould, a core of dual cure composite resin around the fiber post having the uniform thickness was created. Tensile bond strength of each specimen was measured under Universal Testing Machine (UTM) at the cross head speed of 3mm/min. Results: The results achieved with 10% Hydrogen peroxide had a marked effect on micro tensile bond strength values between the tested materials. Conclusion: Immense enhancement in the silanization efficiency of quartz fiber phase was observed with different surface chemical treatment of the resin phase of fiber posts with the marked increase in the micro-tensile bond strength between fiber post and composite core. How to cite this article: Shori D, Pandey S, Kubde R, Rathod Y, Atara R, Rathi S. To evaluate and compare the effect of different Post Surface treatments on the Tensile Bond Strength between Fiber Posts and Composite Resin. J Int Oral Health 2013; 5(5):27-32. PMID:24324301

  9. Pre-heated dual-cured resin cements: analysis of the degree of conversion and ultimate tensile strength.

    PubMed

    Frana, Flvio lvares; Oliveira, Michele de; Rodrigues, Jos Augusto; Arrais, Csar Augusto Galvo

    2011-01-01

    This study evaluated the degree of conversion (DC) and ultimate tensile strength (UTS) of dual-cured resin cements heated to 50 C prior to and during polymerization. Disc- and hourglass-shaped specimens of Rely X ARC (RX) and Variolink II (VII) were obtained using addition silicon molds. The products were manipulated at 25 C or 50 C and were subjected to 3 curing conditions: light-activation through a glass slide or through a pre-cured 2-mm thick resin composite disc, or they were allowed to self-cure (SC). All specimens were dark-stored dry for 15 days. For DC analysis, the resin cements were placed into the mold located on the center of a horizontal diamond on the attenuated total reflectance element in the optical bench of a Fourier Transformed Infrared spectrometer. Infrared spectra (n = 6) were collected between 1680 and 1500 cm-1, and DC was calculated by standard methods using changes in ratios of aliphatic-to-aromatic C=C absorption peaks from uncured and cured states. For UTS test, specimens (n = 10) were tested in tension in a universal testing machine (crosshead speed of 1 mm/min) until failure. DC and UTS data were submitted to 2-way ANOVA, followed by Tukey's test (?= 5%). Both products showed higher DC at 50 C than at 25 C in all curing conditions. No significant difference in UTS was noted between most light-activated groups at 25 C and those at 50 C. VII SC groups showed higher UTS at 50 C than at 25 C (p < 0.05). Increased temperature led to higher DC, but its effects on resin cement UTS depended on the curing condition. PMID:21537644

  10. Molecular-Level Study of the Effect of Prior Axial Compression/Torsion on the Axial-Tensile Strength of PPTA Fibers

    NASA Astrophysics Data System (ADS)

    Grujicic, M.; Yavari, R.; Ramaswami, S.; Snipes, J. S.; Yen, C.-F.; Cheeseman, B. A.

    2013-11-01

    A comprehensive all-atom molecular-level computational investigation is carried out in order to identify and quantify: (i) the effect of prior longitudinal-compressive or axial-torsional loading on the longitudinal-tensile behavior of p-phenylene terephthalamide (PPTA) fibrils/fibers; and (ii) the role various microstructural/topological defects play in affecting this behavior. Experimental and computational results available in the relevant open literature were utilized to construct various defects within the molecular-level model and to assign the concentration to these defects consistent with the values generally encountered under "prototypical" PPTA-polymer synthesis and fiber fabrication conditions. When quantifying the effect of the prior longitudinal-compressive/axial-torsional loading on the longitudinal-tensile behavior of PPTA fibrils, the stochastic nature of the size/potency of these defects was taken into account. The results obtained revealed that: (a) due to the stochastic nature of the defect type, concentration/number density and size/potency, the PPTA fibril/fiber longitudinal-tensile strength is a statistical quantity possessing a characteristic probability density function; (b) application of the prior axial compression or axial torsion to the PPTA imperfect single-crystalline fibrils degrades their longitudinal-tensile strength and only slightly modifies the associated probability density function; and (c) introduction of the fibril/fiber interfaces into the computational analyses showed that prior axial torsion can induce major changes in the material microstructure, causing significant reductions in the PPTA-fiber longitudinal-tensile strength and appreciable changes in the associated probability density function.

  11. Break-up in Capillary Thinning Experiments: Using the CaBER to Determine Maximum Tensile Strength at Low Stressing Rates

    NASA Astrophysics Data System (ADS)

    Lubansky, Alex S.; Brad, Rhodri; Williams, P. Rhodri; Deganello, Davide; Claypole, Tim C.; Gethin, David T.

    2008-07-01

    The maximum tensile strength of fluids is an important guide to the onset of cavitation. Being able to predict the onset of cavitation is important in formulation for industries as diverse as printing and automotive industries. A technique has been developed to use break-up at the end of a capillary thinning experiment to determine the maximum tensile strength of the test fluid. The technique has been applied to a range of concentrations and molecular weights of polyethylene glycol. The results have been validated by comparison with the values and behaviours observed from the bullet piston apparatus. Some discussion regarding the advantages, differences and applicability of using the CaBER is also provided. Some discussion is also provided regarding break-up in capillary thinning experiments.

  12. In Vitro Comparison of Compressive and Tensile Strengths ofAcrylic Resins Reinforced by Silver Nanoparticles at 2% and0.2% Concentrations.

    PubMed

    Ghaffari, Tahereh; Hamedirad, Fahimeh; Ezzati, Baharak

    2014-01-01

    Background and aims. Polymethyl methacrylate, PMMA, is widely used in prosthodontics for fabrication of removable prostheses. This study was undertaken to investigate the effect of adding silver nanoparticles (AgNPs) to PMMA at 2% and 0.2% concentrations on compressive and tensile strengths of PMMA. Materials and methods. The silver nanoparticles were mixed with heat-cured acrylic resin in an amalgamator in two groups at 0.2 and 2 wt% of AgNPs. Eighteen 220200-mm samples were prepared for tensile strength test, 12 samples containing silver nanoparticle and 6 samples for the control group. Another 18 cylindrical 2538-mm samples were prepared for compressive strength test. Scanning electron microscopy was used to verify homogeneous distribution of particles. The powder was manually mixed with a resin monomer and then the mixture was properly blended. Before curing, the paste was packed into steel molds. After curing, the specimens were removed from the molds. One-way ANOVA was used for statistical analysis, followed by multiple comparison test (Scheff's test). Results. This study showed that the mean compressive strength of PMMA reinforced with AgNPs was significantly higher than that of the unmodified PMMA (P<0.05). It was not statistically different between the two groups reinforced with AgNPs. The tensile strength was not significantly different between the 0.2% group and unmodified PMMA and it de-creased significantly after incorporation of 2% AgNPs (P<0.05). Conclusion. Based on the results and the desirable effect of nanoparticles of silver on improvement of compressive strength of PMMA, use of this material with proper concentration in the palatal area of maxillary acrylic resin dentures is recommended. PMID:25587381

  13. In Vitro Comparison of Compressive and Tensile Strengths ofAcrylic Resins Reinforced by Silver Nanoparticles at 2% and0.2% Concentrations

    PubMed Central

    Ghaffari, Tahereh; Hamedirad, Fahimeh; Ezzati, Baharak

    2014-01-01

    Background and aims. Polymethyl methacrylate, PMMA, is widely used in prosthodontics for fabrication of removable prostheses. This study was undertaken to investigate the effect of adding silver nanoparticles (AgNPs) to PMMA at 2% and 0.2% concentrations on compressive and tensile strengths of PMMA. Materials and methods. The silver nanoparticles were mixed with heat-cured acrylic resin in an amalgamator in two groups at 0.2 and 2 wt% of AgNPs. Eighteen 220200-mm samples were prepared for tensile strength test, 12 samples containing silver nanoparticle and 6 samples for the control group. Another 18 cylindrical 2538-mm samples were prepared for compressive strength test. Scanning electron microscopy was used to verify homogeneous distribution of particles. The powder was manually mixed with a resin monomer and then the mixture was properly blended. Before curing, the paste was packed into steel molds. After curing, the specimens were removed from the molds. One-way ANOVA was used for statistical analysis, followed by multiple comparison test (Scheffs test). Results. This study showed that the mean compressive strength of PMMA reinforced with AgNPs was significantly higher than that of the unmodified PMMA (P<0.05). It was not statistically different between the two groups reinforced with AgNPs. The tensile strength was not significantly different between the 0.2% group and unmodified PMMA and it de-creased significantly after incorporation of 2% AgNPs (P<0.05). Conclusion. Based on the results and the desirable effect of nanoparticles of silver on improvement of compressive strength of PMMA, use of this material with proper concentration in the palatal area of maxillary acrylic resin dentures is recommended. PMID:25587381

  14. High-Temperature Tensile Strength of Al10Co25Cr8Fe15Ni36Ti6 Compositionally Complex Alloy (High-Entropy Alloy)

    NASA Astrophysics Data System (ADS)

    Daoud, H. M.; Manzoni, A. M.; Wanderka, N.; Glatzel, U.

    2015-06-01

    Homogenizing at 1220°C for 20 h and subsequent aging at 900°C for 5 h and 50 h of a novel Al10Co25Cr8Fe15Ni36Ti6 compositionally complex alloy (high-entropy alloy) produces a microstructure consisting of an L12 ordered γ' phase embedded in a face-centered cubic solid-solution γ matrix together with needle-like B2 precipitates (NiAl). The volume fraction of γ' phase is ~46% and of needle-like B2 precipitates <5%, which is in accordance with the prediction of calculation of phase diagram method (CALPHAD using Thermo-Calc software with TTNi7 database; Thermo-Calc Software, Stockholm, Sweden). The high-temperature tensile tests were carried out at room temperature, 600°C, 700°C, 800°C, and 1000°C. The tensile strength as well as the elongation to failure of both heat-treated specimens is very high at all tested temperatures. The values of tensile strength has been compared with literature data of well-known Alloy 800H and Inconel 617, and is discussed in terms of the observed microstructure.

  15. An in vitro Comparative Evaluation of Micro Tensile Bond Strength of Two metal bonding Resin Cements bonded to Cobalt Chromium alloy

    PubMed Central

    Musani, Smita; Musani, Iqbal; Dugal, Ramandeep; Habbu, Nitin; Madanshetty, Pallavi; Virani, Danish

    2013-01-01

    Background: The purpose of this study was to evaluate and compare the micro tensile bond strength of two metal bonding resin cements to sandblasted cobalt chromium alloy. Materials & Methods: Eight, Cobalt chromium alloy blocks of dimensions 10x5x5 mm were cast, finished and polished. One of the faces of each alloy block measuring 5x5mm was sandblasted with 50 ?m grit alumina particles. The alloy blocks were then cleaned in an ultrasonic cleaner for 1 min and then air dried with an air stream. The Sandblasted surfaces of the two alloy blocks were bonded together with 2 different metal bonding resin systems (Panavia F Kuraray and DTK Kleber Bredent). The samples were divided into 2 groups (n=4). Group 1- Two Co-Cr blocks were luted with Panavia cement. Group 2- Two Co-Cr blocks were luted with DTK Kleber-Bredent cement. The bonded samples were cut with a diamond saw to prepare Microtensile bars of approximately 1mm x 1mm x 6mm. Thirty bars from each group were randomly separated into 2 subgroups (n=15) and left for 3hrs (baseline) as per manufacturer's instructions while the other group was aged for 24hrs in 370C water, prior to loading to failure under tension at a cross head speed of 1mm/min. Failure modes were determined by means of stereomicroscopy (sm). Statistical analysis was performed through one way ANOVA. Results: Significant variation in micro-tensile bond strength was observed between the two metal bonding resin systems. Conclusion: DTK showed higher mean bond strength values than Panavia F cement both at baseline and after aging. How to cite this article: Musani S, Musani I, Dugal R, Habbu N, Madanshetty P, Virani D. An in vitro Comparative Evaluation of Micro Tensile Bond Strength of Two metal bonding Resin Cements bonded to Cobalt Chromium alloy. J Int Oral Health 2013;5(5):73-8. PMID:24324308

  16. Influence of Specimen Preparation and Specimen Size on the Transverse Tensile Strength and Scatter of Glass Epoxy Laminates

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin; Chawan, Arun D.; DeMarco, Kevin

    1999-01-01

    The influence of specimen polishing, specimen configuration, and specimen size on the transverse tension strength of two glass epoxy materials loaded in three and four point bending was evaluated. Polishing machined edges, and/or tension side failure surfaces, was detrimental to specimen strength characterization instead of yielding a higher, more accurate, strength as a result of removing inherent manufacture and handling flaws. Transverse tension strength was sensitive to span length due to the classical weakest link effect. However, strength was less sensitive to volume changes achieved by increasing specimen width. The Weibull scaling law over-predicted changes in transverse tension strengths in three point bend tests and under-predicted changes in transverse tension strengths in four point bend tests. Furthermore, the Weibull slope varied with specimen configuration, volume, and sample size. Hence, the utility of this scaling law for predicting transverse tension strength is unclear.

  17. Root tensile strength of grey alder and mountain maple grown on a coarse grained eco-engineered slope in the Swiss Alps related to wood anatomical features

    NASA Astrophysics Data System (ADS)

    Kink, Dimitri; Bast, Alexander; Meyer, Christine; Meier, Wolfgang; Egli, Markus; Gärtner, Holger

    2014-05-01

    Steep, vegetation free slopes are a common feature in alpine areas. The material covering these slopes is prone to all kind of erosional processes, resulting in a high risk potential for population and infrastructure. This risk potential is likely to increase with the predicted change in the spatiotemporal distribution of precipitation events. A potential increase in extreme precipitation events will also result in a higher magnitude and frequency of erosional processes. In the Swiss Alps as in many other mountainous areas, there is a need to stabilize these slopes to reduce their direct or indirect hazard potential. In this regard, eco-engineering is a very promising and sustainable approach for slope stabilization. Planting trees and shrubs is a central task in eco-engineering. A developing vegetation cover will on one hand reduce the mechanical effects of rainfall by an increased interception, on the other hand, the root systems cause modifications of soil properties. Roots not only provide anchorage for the plants, they also promote soil aggregation and are able to penetrate possible shear horizons. Overall, anchorage of plants is at the same extend also stabilizing the near subsurface. When rainfall occurs, the saturated soil exerts downhill pressure to a tree or shrub. As long as the root distribution supports anchorage, the respective slope area remains stable. At this point, the tensile strength of the roots is a critical measure, because it is more likely that the supporting roots break than the entire root system being pulled out of the soil completely. As a consequence, root tensile strength is an important parameter in characterizing the soil stabilization potential of trees and shrubs. It is known that tree roots show a high variability in their anatomical structure depending on their depth below soil surface as well as their distance to the main stem. Therefore, we assume that these structural changes affect the tensile strength of every single root. In order to confirm this assumption and possibly find more important root properties which have an influence on soil stabilization, the root systems of seven trees (three grey alder, four mountain maple) were excavated and analyzed. The study site is a catchment, where shallow landslides are common. It is located in the Prättigau valley in the Eastern Swiss Alps and was eco-engineered in 1997. The substrate is coarse-grained morainic material, mean annual air temperature reaches 4.64°C, average precipitation is 1170 mm, and the altitude is about 1000 m a.s.l.. The root system of each tree was uncovered carefully by hand to keep the roots undamaged, before removal it was photographed in situ to document the root distribution. The root systems were then cut into single root pieces of about 20 cm length and the position of each sample was documented. The root samples were then hierarchically classified in several root classes. The tensile strength of more than 500 samples was determined. In addition, the values for age, diameter, and root moisture were ascertained. Since it was assumed, that the cellular structure of the roots has an influence on the tensile strength, two microscopic thin-sections were prepared from all successfully tested root samples. The microscopic analysis focused on anatomical parameters such as the size and number of vessels, their distribution as well as their conductivity. The results for the final correlation between the anatomical characteristics and the root's tensile strength are presented for both tree species.

  18. Effects of Cooling Conditions on Microstructure, Tensile Properties, and Charpy Impact Toughness of Low-Carbon High-Strength Bainitic Steels

    NASA Astrophysics Data System (ADS)

    Sung, Hyo Kyung; Shin, Sang Yong; Hwang, Byoungchul; Lee, Chang Gil; Lee, Sunghak

    2013-01-01

    In this study, four low-carbon high-strength bainitic steel specimens were fabricated by varying finish cooling temperatures and cooling rates, and their tensile and Charpy impact properties were investigated. All the bainitic steel specimens consisted of acicular ferrite, granular bainite, bainitic ferrite, and martensite-austenite constituents. The specimens fabricated with higher finish cooling temperature had a lower volume fraction of martensite-austenite constituent than the specimens fabricated with lower finish cooling temperature. The fast-cooled specimens had twice the volume fraction of bainitic ferrite and consequently higher yield and tensile strengths than the slow-cooled specimens. The energy transition temperature tended to increase with increasing effective grain size or with increasing volume fraction of granular bainite. The fast-cooled specimen fabricated with high finish cooling temperature and fast cooling rate showed the lowest energy transition temperature among the four specimens because of the lowest content of coarse granular bainite. These findings indicated that Charpy impact properties as well as strength could be improved by suppressing the formation of granular bainite, despite the presence of some hard microstructural constituents such as bainitic ferrite and martensite-austenite.

  19. Evaluation of the tensile bond strength of an adhesive system self-etching in dentin irradiated with Er:YAG laser

    NASA Astrophysics Data System (ADS)

    de Mello, Andrea M. D.; Mello, Fabiano A. S.; Matson, Edmir; Mattos, Adriana B.; Mello, Guilerme S.

    2001-04-01

    Since Buonocore, several researchers have been seeking for the best adhesive system and treatment for the enamel and dentin surfaces. The use of the acid has been presented as one of the best techniques of dentin conditioning, because this promotes the removal of the 'smear layer' and exhibition of dentinal structure, for a best penetration and micro-retention of the adhesive system. However, some conditioning methods have been appearing in the literature, for the substitution or interaction with the acid substances, as the laser. The objective of this work is to evaluate the tensile bond strength of the adhesive system 'self-etching' associated to a composed resin, in dentin surfaces conditioned with the Er:YAG laser. For this study, freshly extracted human teeth were used and in each one the dentinal surfaces, which were treated with three sandpapers of different granulations to obtain a standard of the smear layer, before the irradiation of the laser and of the restoring procedure. After these procedures the specimens were storage in distilled water at 37 degrees for 24 hours. Soon after, they were submitted to the tensile strength test. After analyzing the results, we can conclude that the use of the Er:YAG laser can substitute the drill without the need of conditioning, when using the adhesive system 'self etching' in the dentinal surfaces because there was a decline in the strength of adhesion in the groups conditioned with the laser.

  20. Tensile and fracture toughness properties of SiCp reinforced Al alloys: Effects of particle size, particle volume fraction, and matrix strength

    NASA Astrophysics Data System (ADS)

    Milan, M. T.; Bowen, P.

    2004-12-01

    The goal of this work was to evaluate the effects of particle size, particle volume fraction, and matrix strength on the monotonic fracture properties of two different Al alloys, namely T1-Al2124 and T1-Al6061, reinforced with silicon carbide particles (SiCp). From the tensile tests, an increase in particle volume fraction and/or matrix strength increased strength and decreased ductility. On the other hand, an increase in particle size reduced strength and increased the composite ductility. In fracture toughness tests, an increase in particle volume fraction reduced the toughness of the composites. An increase in matrix strength reduced both K crit and ?crit values. However, in terms of K Q (5%) values, the Al6061 composite showed a value similar to the corresponding Al2124 composite. This was mainly attributed to premature yielding caused by the high ductility/low strength of the Al6061 matrix and the testpiece dimensions. The effect of particle size on the fracture toughness depends on the type of matrix and toughness parameter used. In general, an increase in particle size decreased the K Q (5%) value, but simultaneously increased the amount of plastic strain that the matrix is capable of accommodating, increasing both ?crit and K crit values.

  1. The influences of impurity content, tensile strength, and grain size on in-service temper embrittlement of CrMoV steels

    SciTech Connect

    Cheruvu, N.S.; Seth, B.B. )

    1989-11-01

    The influences of impurity levels, grain size, and tensile strength on in-service temper embrittlement of CrMoV steels have been investigated. The samples for this study were taken from steam turbine CrMoV rotors which had operated for 15 to 26 years. The effects of grain size and tensile strength on embrittlement susceptibility were separated by evaluating the embrittlement behavior of two rotor forgings made from the same ingot after an extended step-cooling treatment. Among the residual elements in the steels, only P produces a significant embrittlement. The variation of P and tensile strength has no effect on in-service temper embrittlement susceptibility, as measured by the shift in fracture appearance transition temperature (FATT). However, the prior austenite grain size plays a major role in service embrittlement. The fine grain steels with a grain size of ASTM No. 9 or higher are virtually immune to in-service embrittlement. In steels having duplex grain sizes, embrittlement susceptibility is controlled by the size of coarser grains. For a given steel chemistry, the coarse grain steel is more susceptible to in-service embrittlement, and a decrease in ASTM grain size number from 4 to 0/1 increases the shift in FATT by 61{degrees}C (10/10{degrees}F). It is demonstrated that long-term service embrittlement can be simulated, except in very coarse grain steels, by using the extended step-cooling treatment. The results of step-cooling studies show that the coarse grain rotor steels take longer time during service to reach a fully embrittled state than the fine grain rotor steels.

  2. Damage Initiation and Ultimate Tensile Strength of Scaled [0 deg n/90 deg n/0 deg n]sub T Graphite-Epoxy Coupons

    NASA Technical Reports Server (NTRS)

    Jackson, Karen E.; Prosser, William H.

    1997-01-01

    Previous research on scaling effects in composite materials has demonstrated that the stress levels at first ply failure and ultimate failure of composite laminates are dependent on the size of the laminate. In particular, the thickness dimension has been shown to be the most influential parameter in strength scaling of composite coupons loaded in tension. Geometrically and constitutively scaled laminates exhibit decreasing strength with increasing specimen size, and the magnitude of the strength-size effect is a function of both material properties and laminate stacking sequence. Some of the commonly used failure criteria for composite materials such as maximum stress, maximum strain, and tensor polynomial (e.g., Tsai-Wu) cannot account for the strength-size effect. In this paper, three concepts are developed and evaluated for incorporating size dependency into failure criteria for composite materials. An experimental program of limited scope was performed to determine the first ply failure stress in scaled cross-ply laminates loaded in tension. Test specimens were fabricated of AS-4/3502 graphite-epoxy composite material with laminate stacking sequences of [0 deg n/90 deg n/o deg n]subT where n=1-6. Two experimental techniques were used to determine first ply failure, defined as a transverse matrix crack in the 90 deg ply: (1) step loading with dye penetrant x-ray of the specimen at each load interval, and (2) acoustic emission. The best correlation between first ply failure analysis and experimental data was obtained using a modified Weibull approach which incorporated the residual thermal stress and the outer ply constraint, as well as the ply thickness effect. Finally, a second set of experiments was performed to determine the tensile response and ultimate failure of the scaled cross-ply laminates. The results of these experiments indicated no influence of specimen size on tensile response or ultimate strength.

  3. Data Qualification and Data Summary Report: Intact Rock Properties Data on Tensile Strength, Schmidt Hammer Rebound Hardness, and Rock Triaxial Creep

    SciTech Connect

    E.M. Cikanek; R.J. Blakely; T.A. Grant; L.E. Safley

    2003-07-29

    This report presents a systematic review of the available data in the TDMS that are relevant to the following intact rock properties: rock tensile strength, Schmidt hammer rebound hardness, and rock triaxial creep. Relevant data are compiled from qualified and unqualified sources into the summary DTNs and these DTNs are evaluated for qualification using the method of corroborating data as defined in AP-SIII.2Q, ''Qualification of Unqualified Data''. This report also presents a summary of the compiled information in the form of descriptive statistics and recommended values that will be contained in a Reference Information Base (RIB) item prepared in accordance with AP-SIII.4Q, ''Development, Review, Online Placement, and Maintenance of Individual Reference Information Base Data Items''. The primary purpose of this report is to produce qualified sets of data that include all relevant intact rock tensile strength, Schmidt hammer rebound hardness, and rock triaxial creep testing done over the course of the Yucca Mountain Project (YMP). A second purpose is to provide a qualified summary (i.e., a RIB data item) of the test results using descriptive statistics. The immediate purpose of the report is to support the data needs of repository design; however, the products are designed to be appropriate for general use by the YMP. The appropriateness and limitations, if any, of the data, with respect to the intended use, are addressed in this report.

  4. Incorporating Turbula mixers into a blending scale-up model for evaluating the effect of magnesium stearate on tablet tensile strength and bulk specific volume.

    PubMed

    Kushner, Joseph

    2012-06-15

    Turbula bottle blenders are often used in lab-scale experiments during early-stage pharmaceutical product development. Unfortunately, applying knowledge gained with these blenders to larger-sized diffusion mixers is limited by the lack of blending models that include Turbula mixers. To address this need for lubrication blending scale-up, 2:1 blends of microcrystalline cellulose and spray-dried lactose or dibasic calcium phosphate were mixed with 1% magnesium stearate using Turbula bottle blenders, varying bottle volume, V (30-1250mL); bottle headspace fraction, F(headspace) (30-70%); and the number of blending cycles, r (24 to ∼190,000 cycles). The impact of lubrication blending on tensile strength and bulk specific volume quality attributes, QA, was modeled by:where QA(0) is initial QA value, β is sensitivity of QA to lubrication, γ is formulation-specific lubrication rate constant, and L is characteristic mixing length scale (i.e. 1.5V(1/3) for Turbula blenders, V(1/3) for simple diffusion mixers). The factor of 1.5 captures the bottle dimensions and the more complex mixing dynamics of the Turbula blender. This lubrication blending process model is valid for scale-up from 30-mL to 200-L blenders. Assessing bulk specific volume may provide a simpler, more material-sparing means for determining γ than tensile strength, since these QAs exhibited similar γ values. PMID:22405966

  5. A comparative evaluation of the tensile strength of silver soldered joints of stainless steel and cobalt chromium orthodontic wires with band material--an in vitro study.

    PubMed

    Dua, R; Nandlal, B

    2004-03-01

    The present study was conducted to compare and evaluate the tensile strength of silver soldered joints of stainless steel and cobalt-chromium orthodontic wires with band material. An attempt was made to observe the effect of joint site preparation by incorporation of tack welding and increasing metal to metal surface contact area by flattening an end of the wire prior to soldering along with the regularly used round wires without tack welding. A total of 180 wire specimens were soldered to 180 band specimens. Fifteen samples according to joint site preparation were included for each of the wire groups i.e. Gloria (S.S.), Remanium (S.S.) and Remaloy (Co-Cr) wires of 0.036" in diameter. The findings of the study were suggestive that all three wires may be used for preparing silver soldered joints irrespective of the quality of the wire. However, when subjecting the wire to joint site preparation, Gloria (S.S.) wire showed less tensile strength as compared to Remanium and Remaloy. PMID:15255439

  6. Root tensile strength assessment of Dryas octopetala L. and implications for its engineering mechanism on lateral moraine slopes (Turtmann Valley, Switzerland)

    NASA Astrophysics Data System (ADS)

    Eibisch, Katharina; Eichel, Jana; Dikau, Richard

    2015-04-01

    Geomorphic processes and properties are influenced by vegetation. It has been shown that vegetation cover intercepts precipitation, enhances surface detention and storage, traps sediment and provides additional surface roughness. Plant roots impact the soil in a mechanical and hydrological manner and affect shear strength, infiltration capacity and moisture content. Simultaneously, geomorphic processes disturb the vegetation development. This strong coupling of the geomorphic and ecologic system is investigated in Biogeomorphology. Lateral moraine slopes are characterized by a variety of geomorphic processes, e. g. sheet wash, solifluction and linear erosion. However, some plant species, termed engineer species, possess specific functional traits which allow them to grow under these conditions and also enable them to influence the frequency, magnitude and even nature of geomorphic processes. For lateral moraine slopes, Dryas octopetala L., an alpine dwarf shrub, was identified as a potential engineer species. The engineering mechanism of D. octopetala, based on its morphological (e.g., growth form) and biomechanical (e.g., root strength) traits, yet remains unclear and only little research has been conducted on alpine plant species. The objectives of this study are to fill this gap by (A) quantifying D. octopetala root tensile strength as an important trait considering anchorage in and stabilization of the slope and (B) linking plant traits to the geomorphic process they influence on lateral moraine slopes. D. octopetala traits were studied on a lateral moraine slope in Turtmann glacier forefield, Switzerland. (A) Root strength of single root threads of Dryas octopetala L. were tested using the spring scale method (Schmidt et al., 2001; Hales et al., 2013). Measurement equipment was modified to enable field measurements of roots shortly after excavation. Tensile strength of individual root threads was calculated and statistically analyzed. First results show that Dryas roots appear to be quite strong compared to other alpine species with a mean tensile strength of 22,63 N mm -. (B) On a micro scale, morphological and biomechanical features of above and below-ground biomass were qualitatively studied through field observations on D. octopetala individuals. Findings indicate that D. octopetala's dense cushions, covering many square meters of the moraines surface, traps fine sediment, stores moisture and significantly reduces erosion through wind and water. Furthermore, Dryas is well adapted to rock fall or burial by forming stabilized patches of ground despite steep slope inclinations and strong, episodic surface runoff and creep processes. Anchorage is provided by its strong root, which in all studied cases grew upslope parallel to the moraines surface. Insights from this study allow to relate root tensile strength and other specific plant traits of Dryas octopetala to an engineering mechanism and effect on geomorphic processes on lateral moraine slopes. Knowledge about Dryas as an engineering species may help to understand its biotic influence on the geomorphic system of a lateral moraine and aid in the selection of species for erosion control or rehabilitation of ecosystems, where Dryas is native.

  7. Comparative Evaluation of Tensile – Bond Strength of An Orthodontic Adhesive with and without Fluoride Application, After Acid Etching -An Invitro Study

    PubMed Central

    Yugandhar, G; Ramana, I Venkata; Srinivas, K; Yadav, S. Sarjeev Singh

    2015-01-01

    Background Fixed appliances hinder the effective control of plaque accumulation and white spot lesions may develop under the ill fitting bands or adjacent to the stainless steel brackets during orthodontic treatment particularly the etching process. Aims and Objectives Comparative study of tensile bond strength of an orthodontic adhesive with and without fluoride application after acid etching to know the effect of fluoride on bond strength. Materials and Methods This study is carried out on 90 non carious human premolar teeth, and divided in 6 groups with each group of 15 specimens. In those Groups I and IV were control group acid etch treatment, Group II and V is 1.23% APF gel (acid etch plus APF gel treatment,) and group III and VI is 8% SnF2 (acid etch plus SnF2 treatment). Samples of Group I, II and III bond strength were tested after 24 h and groups IV, V and VI after one month on microtechtensometer machine. The scanning electron microscope (SEM) investigation was carried out for the 2 specimens for the control group after acid etch and 4 specimens after acid etch with fluoride application for fluoride groups. Results Control and SnF2 treated groups was found to be nearly similar to the control group whereas APF treated group showed less focal holes than the other 2 groups. Conclusion Fluoride application after acid etching without having an adverse effect on bond strength but we can prevent the white spot lesions and caries. PMID:26023648

  8. Role of matrix microstructure on room-temperature tensile properties and fiber-strength utilization of an orthorhombic ti-alloy-based composite

    NASA Astrophysics Data System (ADS)

    Boehlert, C. J.; Majumdar, B. S.; Krishnamurthy, S.; Miracle, D. B.

    1997-02-01

    Microstructure-property understanding obtained for a nominally Ti-25Al-17Nb (at. pct) monolithic sheet alloy was used to heat treat a unidirectional four-ply SCS-6/Ti-25Al-17Nb metal-matrix composite (MMC) and a fiberless neat material of the same alloy for enhancing mechanical properties. The unreinforced alloy and [0]4 composite recorded significant improvements in ductility and strength, which were related to the microstructural condition. Modeling of the tensile strength based on fiber fracture statistics helped in understanding how improved matrix microstructure provided more efficient utilization of fiber strength. In comparison to the [0]4 MMC, improvement of the [90]4 response was negligible, which was related to an ?2 stabilized zone around the fiber. A Nb coating on the fiber was used to modify the local microstructure, and it produced a modest improvement in strength and ductility in the transverse direction. Structure-property relations of the matrix under different heat-treatment conditions are described in terms of deformation and failure mechanisms of the constituent phases; ?2 (ordered hexagonal close-packed), B2 (ordered body-centered cubic), and O (ordered orthorhombic based on Ti2AlNb).

  9. Effect of low fluency dentin conditioning on tensile bond strength of composite bonded to Er:YAG laser-prepared dentin: a preliminary study.

    PubMed

    Bahrami, B; Askari, N; Tielemans, M; Heysselaer, D; Lamard, L; Peremans, A; Nyssen-Behets, C; Nammour, S

    2011-03-01

    Several studies in the literature have previously shown that the bond strength of a composite bonded to dentin is almost equivalent as when dentin is prepared by either bur or Er:YAG laser. The aim of this preliminary study is to assess the hypothesis that dentin conditioning at low fluency by means of Er:YAG laser can improve the value of adhesion of composites resin to dentin. Sixty surfaces of caries-free human third molars extracted for orthodontic purposes were randomly divided into five groups of 12 teeth. The bur group was the control, prepared using bur, group L was prepared using Er:YAG 200mJ, SSP (50s), 20Hz, 15 seconds of sweeping, for groups L80, L100, L120, they were prepared first, with the same parameters of the group L 200, and then they received a conditioning, which is, respectively, 15 s of irradiations at: 80mJ (SSP, 10Hz), 100mJ (SSP, 10Hz), and 120mJ (SSP, 10Hz). All samples were restored in a single-component adhesive system: Xenon (DENTSPLY), and ceramX (DENTSPLY) as the resin composite. The specimens were submitted to tensile bond strength test using a universal testing machine. Data were submitted to statistical analysis using ANOVA coupled to a Tukey-Kramer test at the 95% level. The mean values in MPa were 33.3 for group B, 36.73 for group L 200, 41.7 for group L80, 37.9 for group L100, and 39.1 for group L120. Our results showed that dentin conditioning at a low fluency of 12.58J/cm(2) per pulse, with 80mJ output energy and 50-s pulse duration can significantly improve tensile bond strength of a composite bonded to Er:YAG laser-prepared dentine. PMID:20309596

  10. Compressive and tensile failure at high fluid pressure where preexisting fractures have cohesive strength, with application to the San Andreas fault

    USGS Publications Warehouse

    Fournier, R.O.

    1996-01-01

    In thrusting and strike-slip situations, when the maximum principal horizontal stress S1 acts nearly normal to a fault (a misoriented fault, such as the San Andreas), pore-fluid pressure > the lithostatic load, Pf > Sv, is required to reactivate movement on that fault. Pf > Sv may be achieved without causing hydraulic tensile fracturing if (1) previously existing cracks have regained cohesive strength by chemical processes, (2) subcritical crack growth has been blunted, and (3) the least principal horizontal stress S3 nearly equals Sv. Where Pf > Sv has been attained within a misaligned fault, increasing the stress difference (S1 - S3) at constant Pf > Sv will not lead to shear failure, while a decrease in (S1 - S3) can lead to shear failure of that fault. However, where the cohesive strength of material in a broad misaligned fault zone is less than that of the surrounding intact rock, increasing (S1 - S3) while Pf > Sv can result in shear failure of fractures at near optimum angles to S1, but confined within this weak fault zone. If this faulting results in the local short-lived attainment of Pf > Sv (cataclastic deformation and frictional heating overcoming dilation) and a simultaneous decrease in (S1 - S3), this combination of effects can trigger movement along the main trace of the misaligned fault. When increasing Pf results in hydraulic failure, anisotropy in tensile strength or fracture toughness resulting from foliation within faults allows fractures to propagate along the planes of weakness rather than across the foliation perpendicular to S3.

  11. Tensile bond strength of different adhesive systems to primary dentin treated by Er:YAG laser and conventional high-speed drill

    NASA Astrophysics Data System (ADS)

    Marques, Barbara A.; Navarro, Ricardo S.; Silvestre, Fellipe D.; Pinheiro, Sergio L.; Freitas, Patricia M.; Imparato, Jose Carlos P.; Oda, Margareth

    2005-03-01

    The aim of this study was to evaluate the tensile strength of different adhesive systems to primary tooth dentin prepared by high-speed drill and Er:YAG laser (2.94?m). Buccal surfaces of 38 primary canines were ground and flattened with sand paper disks (#120-600 grit) and distributed into five groups (n=15): G1: diamond bur in high-speed drill (HD)+ 35% phosphoric acid (PA)+Single Bond (SB); G2: HD+self-etching One Up Bond F (OUB);G3: Er:YAG laser (KaVo 3- LELO-FOUSP)(4Hz, 80mJ, 25,72J/cm2) (L)+PA+SB, G4: L+SB, G5: L+OUB. The inverted truncated cone samples built with Z-100 composite resin after storage in water (37C/24h) were submitted to tensile bond strength test on Mini Instron 4442 (0.5mm/min, 500N). The data were analyzed with ANOVA and Tukey Test (p<0.05). The mean (MPa) were: G1-3.18(+/-1.24) G2-1.79(+/-0.73) G3-3.17(+/-0.44) G4-8.29(+/-1.86) G5-7.11(+/-2.07). The data analyzed with ANOVA and Tukey Test showed that Laser associated with PA+SB, SB or OUB lead to increased bonding values when compared to HD+PA+SB and HD+OUB (p=0.000), L+SB showed higher values than L+PA+SB and L+OUB (p=0.0311). Er:YAG laser radiation promoted significant increase of bond strength of different adhesive systems evaluated in the dentin of primary teeth.

  12. Effect of a ductility layer on the tensile strength of TiAl-based multilayer composite sheets prepared by EB-PVD

    SciTech Connect

    Zhang, Rubing; Zhang, Yaoyao; Liu, Qiang; Chen, Guiqing; Zhang, Deming

    2014-09-15

    TiAl/Nb and TiAl/NiCoCrAl laminate composite sheets with a thickness of 0.4–0.6 mm and dimensions of 150 mm × 100 mm were successfully fabricated by electron beam physical vapor deposition. The microstructures of the sheets were examined, and their mechanical properties were compared with those of TiAl monolithic sheet produced by electron beam physical vapor deposition. Tensile testing was performed at room temperature and 750 °C, and the fracture surfaces were examined by scanning electron microscopy. Among the three microlaminate sheets, the TiAl/NiCoCrAl micro-laminate sheet had the best comprehensive properties at room temperature, and the TiAl/Nb micro-laminate sheet showed the ideal high-temperature strength and plasticity at 750 °C. The result was discussed in terms of metal strengthening mechanism. - Highlights: • TiAl-based multilayer foils was fabricated successfully by using EB-PVD method; • The tensile properties and micro-fracture morphologies of the sheet were investigated; • The deformation behavior of the multilayer foils was discussed.

  13. Time/Temperature Dependent Tensile Strength of SiC and Al2O3-Based Fibers

    NASA Technical Reports Server (NTRS)

    Yun, Hee Mann; DiCarlo, James A.

    1997-01-01

    In order to understand and model the thermomechanical behavior of fiber-reinforced composites, stress-rupture, fast-fracture, and warm-up rupture studies were conducted on various advanced SiC and Al2O3-based fibers in the,temperature range from 20 to 1400 C in air as well as in inert environments. The measured stress-rupture, fast fracture, and warm-up rupture strengths were correlated into a single master time/temperature-dependent strength plot for each fiber type using thermal activation and slow crack growth theories. It is shown that these plots are useful for comparing and selecting fibers for CMC and MMC reinforcement and that, in comparison to stress rupture tests, the fast-fracture and warm-up tests can be used for rapid generation of these plots.

  14. Effect of Load Rate on Tensile Strength of Various CFCCs at Elevated Temperatures: An Approach to Life Prediction Testing

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.

    2001-01-01

    Strength of three continuous fiber-reinforced ceramic composites, including SiC/CAS-11, SiC/MAS-5 and SiC/SiC, was determined as a function of test rate in air at 1100 - 1200 C. All three composite materials exhibited a strong dependency of strength on test rate, similar to the behavior observed in many advanced monolithic ceramics at elevated temperatures. The application of the preloading technique as well as the prediction of life from one loading configuration (constant stress-rate) to another (constant stress loading) suggested that the overall macroscopic failure mechanism of the composites would be the one governed by a power-law tyw of damage evolution/accumulation, analogous to slow crack growth commonly observed in advanced monolithic ceramics. It was further found that constant stress-rate testing could be used as an alternative to life prediction test methodology even for the composite materials at least for the short range of lifetime.

  15. Role of matrix microstructure on room-temperature tensile properties and fiber-strength utilization of an orthorhombic Ti-alloy-based composite

    SciTech Connect

    Boehlert, C.J.; Majumdar, B.S.; Krishnamurthy, S.; Miracle, D.B.

    1997-02-01

    Microstructure-property understanding obtained for a nominally Ti-25Al-17Nb (at. pct) monolithic sheet alloy was used to heat treat a unidirectional four-ply SCS-6/Ti-25Al-17Nb metal-matrix composite (MMC) and a fiberless neat material of the same alloy for enhancing mechanical properties. The unreinforced alloy and [0]{sub 4} composite recorded significant improvements in ductility and strength, which were related to the microstructural condition. Modeling of the tensile strength based on fiber fracture statistics helped in understanding how improved matrix microstructure provided more efficient utilization, which was related to an {alpha}{sub 2} stabilized zone around the fiber. A Nb coating on the fiber was used to modify the local microstructure, and it produced a modest improvement in strength and ductility in the transverse direction. Structure-property relations of the matrix under different heat-treatment conditions are described in terms of deformation and failure mechanisms of the constituent phases; {alpha}{sub 2} (ordered hexagonal close-packed), B2 (ordered body-centered cubic), and O (ordered orthorhombic based on Ti{sub 2}AlNb).

  16. Mechanical Strength and Failure Characteristics of Cast Mg-9 pctAl-1 pctZn Alloys Produced by a Heated-Mold Continuous Casting Process: Tensile Properties

    NASA Astrophysics Data System (ADS)

    Okayasu, Mitsuhiro; Takeuchi, Shuhei; Ohfuji, Hiroaki

    2014-11-01

    The mechanical properties and failure characteristics of a cast Mg alloy (AZ91: Mg-Al8.9-Zn0.6-Mn0.2) produced by a heated-mold continuous casting process (HMC) are investigated. In a modification of the original HMC process, the cooling of the liquid alloy by direct water spray is carried out in an atmosphere of high-purity argon gas. The HMC-AZ91 alloy exhibits excellent mechanical properties (high strength and high ductility) that are about twice as high as those for the same alloy produced by conventional gravity casting. The increased material strength and ductility of the HMC sample are attributed to nanoscale and microscale microstructural characteristics. The fine grains and tiny spherical eutectic structures ( e.g., Mg17Al12 and Al6Mn) distributed randomly in the matrix of the HMC alloy result in resistance to dislocation movement, leading to high tensile strength. Basal slip on (0001) planes in the relatively organized crystal orientation of the HMC alloy, as well as grain boundary sliding through tiny spherical eutectic structures, results in high ductility. Details of the failure mechanism under static loading in the HMC alloy are also discussed using failure models.

  17. Effects of Rolling and Cooling Conditions on Microstructure and Tensile and Charpy Impact Properties of Ultra-Low-Carbon High-Strength Bainitic Steels

    NASA Astrophysics Data System (ADS)

    Sung, Hyo Kyung; Shin, Sang Yong; Hwang, Byoungchul; Lee, Chang Gil; Kim, Nack J.; Lee, Sunghak

    2011-07-01

    Six ultra-low-carbon high-strength bainitic steel plates were fabricated by controlling rolling and cooling conditions, and effects of bainitic microstructure on tensile and Charpy impact properties were investigated. The microstructural evolution was more critically affected by start cooling temperature and cooling rate than by finish rolling temperature. Bainitic microstructures such as granular bainites (GBs) and bainitic ferrites (BFs) were well developed as the start cooling temperature decreased or the cooling rate increased. When the steels cooled from 973 K or 873 K (700 C or 600 C) were compared under the same cooling rate of 10 K/s (10 C/s), the steels cooled from 973 K (700 C) consisted mainly of coarse GBs, while the steels cooled from 873 K (600 C) contained a considerable amount of BFs having high strength, thereby resulting in the higher strength but the lower ductility and upper shelf energy (USE). When the steels cooled from 673 K (400 C) at a cooling rate of 10 K/s (10 C/s) or 0.1 K/s (0.1 C/s) were compared under the same start cooling temperature of 873 K (600 C), the fast cooled specimens were composed mainly of coarse GBs or BFs, while the slowly cooled specimens were composed mainly of acicular ferrites (AFs). Since AFs had small effective grain size and contained secondary phases finely distributed at grain boundaries, the slowly cooled specimens had a good combination of strength, ductility, and USE, together with very low energy transition temperature (ETT).

  18. Hardness and tensile strength of zircon particles and TiB 2 reinforced Al-A356.1 alloy matrix composites: comparative study

    NASA Astrophysics Data System (ADS)

    Shirvani Moghaddam, K.; Abdizadeh, H.; Baharvandi, H. R.; Ehsani, N.; Abdi, F.

    2007-07-01

    Aluminum matrix composites are important engineering materials in automotive, aerospace, thermal, wear, and other applications because of excellent low weight, high specific strength, and better physical and mechanical properties compared to pure aluminum. In this paper, zircon and TiB II ceramic particles with different amounts were incorporated into Al-A356.1 alloy by stir-casting route. The ceramic particles size and adding temperature were 1 micron and 750C respectively. Microstructure of samples has been investigated by scanning electron microscopy (SEM); hence the dispersion of reinforcement was noted. Situation of compounds of composites was examined by XRD. Mechanical tests such as hardness measurement, tensile and physical (density) tests were used. Results showed that the mechanical properties and microstructure behavior of composites have improved compared to monolithic alloy. Microstructures of the composites in as-cast conditions show uniform distribution particles and reveal better bonding in the case of zircon reinforced composite compare to TiB II, but increasing the amount of reinforcement shows better conditions in the case of TiB II reinforced composite. It is observed that TiB II reinforced composites have a better wetting condition compare to zircon reinforced composites.

  19. Comparison of tensile bond strengths of four one-bottle self-etching adhesive systems with Er:YAG laser-irradiated dentin.

    PubMed

    Jiang, Qianzhou; Chen, Minle; Ding, Jiangfeng

    2013-12-01

    This study aimed to investigate the interaction of current one-bottle self-etching adhesives and Er:YAG laser with dentin using a tensile bond strength (TBS) test and scanning electron microscopy (SEM) in vitro. Two hundred and thirteen dentin discs were randomly distributed to the Control Group using bur cutting and to the Laser Group using an Er:YAG laser (200mJ, VSP, 20Hz). The following adhesives were investigated: one two-step total-etch adhesive [Prime & Bond NT (Dentsply)] and four one-step self-etch adhesives [G-Bond plus (GC), XENO V (Dentsply), iBond Self Etch (Heraeus) and Adper Easy One (3M ESPE)]. Samples were restored with composite resin, and after 24-hour storage in distilled water, subjected to the TBS test. For morphological analysis, 12 dentin specimens were prepared for SEM. No significant differences were found between the control group and laser group (p=0.899); dentin subjected to Prime & Bond NT, XENOV and Adper Easy One produced higher TBS. In conclusion, this study indicates that Er:YAG laser-prepared dentin can perform as well as bur on TBS, and some of the one-step one-bottle adhesives are comparable to the total-etch adhesives in TBS on dentin. PMID:24190486

  20. Temperature-dependent tensile strength, surface roughness diagnostics, and magnetic support and positioning of polymer ICF shells. Final report, October 1, 1993--April 30, 1995

    SciTech Connect

    Honig, A.

    1995-12-15

    During the course of this grant, we perfected emissivity and accommodation coefficient measurements on polymer ICF shells in the temperature range 250 to 350 K. Values for polystyrene shells are generally between 10{sup -2} and 10{sup -3}, which are very advantageous for ICF at cryogenic temperatures. Preliminary results on Br doped target shells indicate an accommodation coefficient, presumably associated with surface roughness on an atomic scale, about an order of magnitude larger than for ordinary polystyrene target shells. We also constructed apparatus with optical access for low temperature tensile strength and emissivity measurements, and made preliminary tests on this system. Magnetic shells were obtained both from GDP coating and from doping styrene with 10 manometer size ferromagnetic particles. The magnetic properties were measured through electron spin resonance (ESR). These experiments confirm the applicability of the Curie law, and establish the validity of using ESR measurements to determine shell temperature in the low temperature regime from 4K to 250K, thus complementing our presently accessible range. The high electron spin densities (> 10{sup 20}/CM{sup 3}) suggest magnetic levitation should be feasible at cryogenic temperatures. This work has resulted in two conference presentations, a Technical Report, a paper to be published in Fusion Technology, and a Master`s Thesis.

  1. Advances in experimental assessment of dynamic tensile strength of concrete by the spalling technique. in tribute to Janusz Roman Klepaczko, Emeritus Professor at the Universit Paul Verlaine in Metz, passed away on August 15, 2008.

    NASA Astrophysics Data System (ADS)

    Brara, Ahmed

    2015-09-01

    An experimental method to test concrete in dynamic tension by spalling with a Hopkinson bar as loading and measuring tool was developed in 1999. The dynamic strength of concrete specimen and strain rate were indirectly derived from an accurate data processing of the signals measured on the Hopkinson bar surface. This method suggested by late Prof. Klepaczko, allowed for reaching the highest strain rate reported in literature for which an intriguing tensile strength increase was highlighted. This simple and efficient technique has been adopted by many researchers around the world. Some significant improvements in terms of definition and reproducibility of the incident loading pulse travelling along the bar and direct and/or contactless measurements on concrete specimens have been introduced. The very high rate sensitivity of concrete tensile strength was corroborated by the additional experimental data obtained with this experimental technique during the last fifteen years.

  2. High-strain rate tensile characterization of graphite platelet reinforced vinyl ester based nanocomposites using split-Hopkinson pressure bar

    NASA Astrophysics Data System (ADS)

    Pramanik, Brahmananda

    The dynamic response of exfoliated graphite nanoplatelet (xGnP) reinforced and carboxyl terminated butadiene nitrile (CTBN) toughened vinyl ester based nanocomposites are characterized under both dynamic tensile and compressive loading. Dynamic direct tensile tests are performed applying the reverse impact Split Hopkinson Pressure Bar (SHPB) technique. The specimen geometry for tensile test is parametrically optimized by Finite Element Analysis (FEA) using ANSYS Mechanical APDLRTM. Uniform stress distribution within the specimen gage length has been verified using high-speed digital photography. The on-specimen strain gage installation is substituted by a non-contact Laser Occlusion Expansion Gage (LOEG) technique for infinitesimal dynamic tensile strain measurements. Due to very low transmitted pulse signal, an alternative approach based on incident pulse is applied for obtaining the stress-time history. Indirect tensile tests are also performed combining the conventional SHPB technique with Brazilian disk test method for evaluating cylindrical disk specimens. The cylindrical disk specimen is held snugly in between two concave end fixtures attached to the incident and transmission bars. Indirect tensile stress is estimated from the SHPB pulses, and diametrical transverse tensile strain is measured using LOEG. Failure diagnosis using high-speed digital photography validates the viability of utilizing this indirect test method for characterizing the tensile properties of the candidate vinyl ester based nanocomposite system. Also, quasi-static indirect tensile response agrees with previous investigations conducted using the traditional dog-bone specimen in quasi-static direct tensile tests. Investigation of both quasi-static and dynamic indirect tensile test responses show the strain rate effect on the tensile strength and energy absorbing capacity of the candidate materials. Finally, the conventional compressive SHPB tests are performed. It is observed that both strength and energy absorbing capacity of these candidate material systems are distinctively less under dynamic tension than under compressive loading. Nano-reinforcement appears to marginally improve these properties for pure vinyl ester under dynamic tension, although it is found to be detrimental under dynamic compression.

  3. Evaluation of nondestructive tensile testing

    NASA Technical Reports Server (NTRS)

    Bowe, J. J.; Polcari, S. M.

    1971-01-01

    The results of a series of experiments performed in the evaluation of nondestructive tensile testing of chip and wire bonds are presented. Semiconductor devices were subjected to time-temperature excursions, static-load life testing and multiple pre-stressing loads to determine the feasibility of a nondestructive tensile testing approach. The report emphasizes the importance of the breaking angle in determining the ultimate tensile strength of a wire bond, a factor not generally recognized nor implemented in such determinations.

  4. Light-curing efficiency of dental adhesives by gallium nitride violet-laser diode determined in terms of ultimate micro-tensile strength.

    PubMed

    Kameyama, Atsushi; Kato, Junji; De Munck, Jan; Hatayama, Hitoshi; Haruyama, Akiko; Yoshinari, Masao; Takase, Yasuaki; Van Meerbeek, Bart; Tsunoda, Masatake

    2011-01-01

    The purpose of this study was to evaluate whether violet-laser diode (VLD) can be used as light-curing source. The ultimate (micro-)tensile strength (μTS) of three adhesives was determined when cured by VLD in comparison with curing by two different types of commercial LED light-curing units. One VLD (VLM 500) and two LED units (Curenos and G-Light Prima) were used to cure the adhesive resin of the two-step self-etch adhesives Clearfil SE Bond, Tokuso Mac Bond II, and FL-Bond II. A 0.6-mm thick acrylic mould was filled with adhesive resin and cured for 60 s. After 24-h water storage, specimens were trimmed into an hourglass shape with a width of 1.2 mm at the narrowest part, after which the μTS was determined (n=10). In addition, the light transmittance of each adhesive was characterized using a UV-vis-NIR spectrometer. No significant difference in curing efficiency between VLD and LED were observed for both Tokuso Mac Bond II and FL-Bond II (p>0.05). For Clearfil SE Bond, the μTS of VLD-cured specimens was higher than that of the specimens cured by the LED Curenos unit (p<0.05). Spectrometry revealed that this marked difference must be attributed to a different light transmittance of Clearfil SE Bond for visible blue light versus for the lower area of UV and visible violet light. In conclusion, A GaN-based violet laser diode can be used as light-curing source to initiate polymerization of dental resins. PMID:22561254

  5. Optical diametric drive acceleration through action-reaction symmetry breaking

    NASA Astrophysics Data System (ADS)

    Wimmer, Martin; Regensburger, Alois; Bersch, Christoph; Miri, Mohammad-Ali; Batz, Sascha; Onishchukov, Georgy; Christodoulides, Demetrios N.; Peschel, Ulf

    2013-12-01

    Newton's third law of motion is one of the pillars of classical physics. This fundamental principle states that the forces two bodies exert on each other are equal and opposite. Had the resulting accelerations been oriented in the same direction, this would have instead led to a counterintuitive phenomenon, that of diametric drive. In such a hypothetical arrangement, two interacting particles constantly accelerate each other in the same direction through a violation of the action-reaction symmetry. Although in classical mechanics any realization of this process requires one of the two particles to have a negative mass and hence is strictly forbidden, it could nevertheless be feasible in periodic structures where the effective mass can also attain a negative sign. Here we report the first experimental observation of such diametric drive acceleration for pulses propagating in a nonlinear optical mesh lattice. The demonstrated reversal of action-reaction symmetry could enable altogether new possibilities for frequency conversion and pulse-steering applications.

  6. Comparative evaluation of tensile bond strength of a polyvinyl acetate-based resilient liner following various denture base surface pre-treatment methods and immersion in artificial salivary medium: An in vitro study

    PubMed Central

    Philip, Jacob M.; Ganapathy, Dhanraj M.; Ariga, Padma

    2012-01-01

    Background and Aim: This study was formulated to evaluate and estimate the influence of various denture base resin surface pre-treatments (chemical and mechanical and combinations) upon tensile bond strength between a poly vinyl acetate-based denture liner and a denture base resin. Materials and Methods: A universal testing machine was used for determining the bond strength of the liner to surface pre-treated acrylic resin blocks. The data was analyzed by one-way analysis of variance and the t-test (? =.05). Results: This study infers that denture base surface pre-treatment can improve the adhesive tensile bond strength between the liner and denture base specimens. The results of this study infer that chemical, mechanical, and mechano-chemical pre-treatments will have different effects on the bond strength of the acrylic soft resilient liner to the denture base. Conclusion: Among the various methods of pre-treatment of denture base resins, it was inferred that the mechano-chemical pre-treatment method with air-borne particle abrasion followed by monomer application exhibited superior bond strength than other methods with the resilient liner. Hence, this method could be effectively used to improve bond strength between liner and denture base and thus could minimize delamination of liner from the denture base during function. PMID:23293485

  7. High-temperature tensile tester for ceramics

    NASA Technical Reports Server (NTRS)

    Smith, M.

    1974-01-01

    Apparatus measures tensile strength of rigid, low-density ceramic materials at temperatures up to 1375 K. Tensile grips mate with tensile specimen and form top and bottom of lightweight furnace. Apparatus can only be used with rigid materials and grips must be stronger than material under test.

  8. In-Plane Cracking Behavior and Ultimate Strength for 2D Woven and Braided Melt-Infiltrated SiC/SiC Composites Tensile Loaded in Off-Axis Fiber Directions

    NASA Technical Reports Server (NTRS)

    Morscher, Gregory N.; Yun, Hee Mann; DiCarlo, James A.

    2007-01-01

    The tensile mechanical properties of ceramic matrix composites (CMC) in directions off the primary axes of the reinforcing fibers are important for architectural design of CMC components that are subjected to multi-axial stress states. In this study, 2D-woven melt-infiltrated (MI) SiC/SiC composite panels with balanced fiber content in the 0 degree and 90 degree directions were tensile loaded in-plane in the 0 degree direction and at 45 degree to this direction. In addition, a 2D triaxially-braided MI composite panel with balanced fiber content in the plus or minus 67 degree bias directions and reduced fiber content in the axial direction was tensile loaded perpendicular to the axial direction tows (i.e., 23 degrees from the bias fibers). Stress-strain behavior, acoustic emission, and optical microscopy were used to quantify stress-dependent matrix cracking and ultimate strength in the panels. It was observed that both off-axis loaded panels displayed higher composite onset stresses for through-thickness matrix cracking than the 2D-woven 0/90 panels loaded in the primary 0 degree direction. These improvements for off-axis cracking strength can in part be attributed to higher effective fiber fractions in the loading direction, which in turn reduces internal stresses on critical matrix flaws for a given composite stress. Also for the 0/90 panel loaded in the 45 degree direction, an improved distribution of matrix flaws existed due to the absence of fiber tows perpendicular to the loading direction. In addition, for the +67/0/-67 braided panel, the axial tows perpendicular to the loading direction were not only low in volume fraction, but were also were well separated from one another. Both off-axis oriented panels also showed relatively good ultimate tensile strength when compared to other off-axis oriented composites in the literature, both on an absolute strength basis as well as when normalized by the average fiber strength within the composites. Initial implications are discussed for constituent and architecture design to improve the directional cracking of SiC/SiC CMC components with MI matrices.

  9. The effect of bone ingrowth depth on the tensile and shear strength of the implant-bone e-beam produced interface.

    PubMed

    Tarala, M; Waanders, D; Biemond, J E; Hannink, G; Janssen, D; Buma, P; Verdonschot, N

    2011-10-01

    New technologies, such as selective electron beam melting, allow to create complex interface structures to enhance bone ingrowth in cementless implants. The efficacy of such structures can be tested in animal experiments. Although animal studies provide insight into the biological response of new structures, it remains unclear how ingrowth depth is related to interface strength. Theoretically, there could be a threshold of ingrowth, above which the interface strength does not further increase. To test the relationship between depth and strength we performed a finite element study on micro models with simulated uncoated and hydroxyapatite (HA) coated surfaces. We examined whether complete ingrowth is necessary to obtain a maximal interface strength. An increase in bone ingrowth depth did not always enhance the bone-implant interface strength. For the uncoated specimens a plateau was reached at 1,500?m of ingrowth depth. For the specimens with a simulated HA coating, a bone ingrowth depth of 500?m already yielded a substantial interface strength, and deeper ingrowth did not enhance the interface strength considerably. These findings may assist in optimizing interface morphology (its depth) and in judging the effect of bone ingrowth depth on interface strength. PMID:21858722

  10. Revisiting the Recommended Geometry for the Diametrally Compressed Ceramic C-Ring Specimen

    SciTech Connect

    Jadaan, Osama M.; Wereszczak, Andrew A

    2009-04-01

    A study conducted several years ago found that a stated allowable width/thickness (b/t) ratio in ASTM C1323 (Standard Test Method for Ultimate Strength of Advanced Ceramics with Diametrally Compressed C-Ring Specimens at Ambient Temperature) could ultimately cause the prediction of a non-conservative probability of survival when the measured C-ring strength was scaled to a different size. Because of that problem, this study sought to reevaluate the stress state and geometry of the C-ring specimen and suggest changes to ASTM C1323 that would resolve that issue. Elasticity, mechanics of materials, and finite element solutions were revisited with the C ring geometry. To avoid the introduction of more than 2% error, it was determined that the C ring width/thickness (b/t) ratio should range between 1-3 and that its inner radius/outer radius (ri/ro) ratio should range between 0.50-0.95. ASTM C1323 presently allows for b/t to be as large as 4 so that ratio should be reduced to 3.

  11. STRENGTH OF A C-SPHERE FLEXURE SPECIMEN

    SciTech Connect

    Wereszczak, Andrew A; Wang, Wei; Jadaan, Osama M.; Lance, Michael J; Lin, Hua-Tay

    2007-01-01

    A 'C-Sphere' flexure strength specimen geometry was conceived and developed to measure a relevant strength of bearing-grade Si{sub 3}N{sub 4} balls and to relate that to surface-located strength-limiting flaws and to ultimately link those flaw populations to rolling contact fatigue performance. A slot was machined into the balls to a set depth to produce the C-sphere geometry. C-sphere specimens were then diametrally compressed to produce a monotonically increasing flexure or hoop tensile stress at their surface that caused their fracture. The strength was determined using the combination of failure load, C-sphere geometry, and FEA, and the stress field was used to determine C-sphere effective areas and effective volumes as a function of Weibull modulus. A description of the specimen and the aforementioned analysis are provided and a comparison of C-sphere flexure strength distributions of two bearing grade Si{sub 3}N{sub 4} materials (NBD200 and SN101C) is given.

  12. Tensile Test For Arboform Samples

    NASA Astrophysics Data System (ADS)

    Plavanescu (Mazurchevici), Simona; Quadrini, Fabrizio; Nedelcu, Dumitru

    2015-07-01

    Petroleum-based plastic materials constitute a major environmental problem due to their low biodegradability and accumulation in various environments. Therefore, searching for novel biodegradable plastics is received particular attention. Our studied material, "Liquid wood" produced from lignin, natural fibres and natural additives, is completely biodegradable in natural environment, in normal conditions. This paper presents the behaviour of Arboform and Arboform reinforced with Aramidic Fibers tensile test analysis. Experimental data show that the tensile strength reached an average value of 15.8 MPa, the modulus of elasticity after tests is 3513.3MPA for Arboform and for the reinforcement the tensile strength is 23.625MPa, the modulus of elasticity after tests is 3411.5MPA, the materials present a brittle behaviour. The high mechanical properties of newly developed material, better than of other ordinary plastics, recommend it as a potential environment-friendly substituent for synthetic plastics, which are present in all fields of activity.

  13. Isoclinic Ambiguity Unwrapping of Circular Ring under Diametric Compression

    NASA Astrophysics Data System (ADS)

    Huang, M.-J.

    2010-06-01

    Isoclinic and isochromatic parameters in photoelastic analysis are formulated by arc tangent function of several phase shifting frames but for isochromatic calculation it is, in addition, in terms of isoclinic data also. Thus, any isoclinic phase ambiguity would also result in the phase inconsistencies of isochromatic calculation and cause unwrapping problems and difficulties. Many methods had been proposed to treat these kinds of isochromatic fringes but lots of treatments were needed for the correct retrieval. In this work, the isoclinic ambiguity problem is investigated and solved directly by a novel regional phase unwrapping technique. Once the isoclinic phase ambiguity problems are solved, a correct isoclinic result can be obtained. Then, substituting this result into the isochromatic formation yields an ambiguity free isochromatic phase map, which can be easily restored by any phase unwrapping algorithm. A stress frozen sample - circular ring under diametric compression verifies its effectiveness. Usually happened is that this kind of sample is with ambiguous isoclinic data which would cause phase ambiguities of the isochromatic formulation if not treated well first.

  14. Investigation of strength of a hybrid adhesive anchor system used in precast concrete welded repair applications subjected to tensile and eccentric shear loading

    NASA Astrophysics Data System (ADS)

    Eilers, Michael Glenn

    A common precast industry repair for missing or misplaced connection plates is the use of an adhesive anchor system to fasten repair plates to precast members. Typically, the repair plate will experience elevated temperatures during the welding of the loose erection plate to the repair plate. Limited testing and theoretical data are currently available to provide design guidelines on how the elevated temperatures induced by welding affect the behavior and capacity of the adhesive anchoring systems. This dissertation outlines bond tests, eccentric shear tests, and a temperature investigation performed using a hybrid adhesive system in precast concrete repair applications. In addition, limited bond strength testing data using a high strength two-part epoxy adhesive is also included. The overall aim of this work is to provide test data and guidance to the industry and design professionals when designing adhesive anchoring systems for repair applications exposed to welding.

  15. Cassini First Diametric Radio Occultation of Saturn's Rings

    NASA Astrophysics Data System (ADS)

    Marouf, E.; French, R.; Rappaport, N.; Kliore, A.; Flasar, M.; Nagy, A.; Ambrosini, R.; McGhee, C.; Schinder, P.; Anabtawi, A.; Barbinis, E.; Goltz, G.; Thomson, F.; Wong, K.

    2005-05-01

    We present preliminary results expected from the first planned Cassini radio occultation observation of Saturn's rings, to be conducted on May 3rd, 2005. The path of Cassini as seen from Earth (the occultation track) has been designed to cross the rings from the west to the east ansa almost diametrically, allowing for occultation of all major ring features at two widely separated longitudes (about 180 deg apart). The duration of the geometric occultation is about 1.5 hours on each side. During the occultation, Cassini transmits through the rings three coherent monochromatic radio signals of wavelength 0.94, 3.6, and 13 cm (Ka-, X-, and S-band respectively), a capability unique to Cassini. The perturbed signals received at the Earth are recorded at the NASA DSN complexes at Goldstone and Canberra. Both direct and forward-scattered components of the signal may be identified in spectrograms of the received signals. The time history of the extinction of the direct signal is expected to yield high-spatial-resolution optical depth and phase shift profiles of ring structure. The timing of the occultation was optimized to allow probing the rings when the ring-opening-angle B (the angle between the line-of-sight and the ring plane) is relatively large (B = 23 deg), hence maximizing chances of measuring for the first time the structure of the relatively optically thick Ring B. In a similar experiment by Voyager in 1980, excessive signal attenuation along the long path within the nearly closed rings (B = 5.9 deg) limited the utility of the observations in relatively thick ring regions, in particular the main Ring B. For the Cassini optimized occultation geometry, a large B, slow radial velocity along the occultation track, and much improved phase stability of the reference ultrastable oscillator (USO) on board Cassini combine to promise achievable radial resolution approaching 100 m over a good fraction of the rings. Measurement of the amplitude and phase of the diffracted signal enables reconstruction of the observations to remove diffraction effects. Reliable high resolution profiling of ring structure at multiple ring longitudes is at the heart of investigating ring kinematics and dynamics, a major scientific objective of this experiment. In addition, observations of the scattered signal combined with measurements of the differential extinction of the three radio signals are expected to yield complementary information about ring physical properties, including particle size distribution and thickness, another major scientific objective.

  16. Effects of retained austenite on the tensile properties and toughness of ultra-high strength martensitic precipitation hardened stainless steels. Final technical report, 1 April 1997--31 March 1998

    SciTech Connect

    Garrison, W.M.

    1998-12-14

    The purpose of this work was to assess the effects of the amount of retained austenite content on the ductile-to-brittle transition temperature of martensitic precipitation strengthened stainless steels for four different precipitation strengthening systems, one utilizing NiTi strengthening and three utilizing R-phase strengthening. The retained austenite contents in the four systems were varied by varying composition. The austenite content in the NiTi strengthened system was varied by varying the chromium content and the austenite content in the R-phase strengthened Systems was varied by varying the nickel content. The room temperature toughness levels of the NiTi strengthened system were quite low and it was decided not to pursue this system further. The three R-phase strengthened systems had sufficient room temperature toughness and strength to be of further interest. Of these three systems the primary focus was on the 12Cr/12Co/5Mo system. In this system four alloys, identical except for variations in nickel content, were the primary focus of the work. These alloys achieved, on tempering at 5250 C for 3.16 hours, yield strengths on the order of 210 ksi and ultimate tensile strengths of 235 ksi. The effect of test temperature on the Charpy impact energy was investigated for two tempering temperatures for these four alloys. It was found for both tempering conditions that lower ductile-to-brittle transition temperatures were favored by increasing amounts of austenite in the structure. In fact, the ductile-to-brittle transition temperature was quite low, about -750 C, for the tempered at 5250 C for 3.16 hours microstructure of the alloy in this series which contained the highest nickel and the highest amount of retained austenite after quenching. At this point it is believed the austenite content is an important contributor to the low ductile-to-brittle transition temperature of this microstructure.

  17. Experimental Analysis of Work-piece's Diametrical Error in Ultrasonic-Vibration-Assisted Turning

    NASA Astrophysics Data System (ADS)

    Soleimanimehr, H.; Nategh, M. J.; Gholamzadeh, B.

    2011-01-01

    Vibration at an ultrasonic frequency is superimposed on the ordinary cutting motion in ultrasonic-vibration-assisted turning (UAT). This combinatory cutting motion results in reduction of the cutting force and surface roughness, and improvement of the dimensional tolerances compared with conventional turning (CT). The advantages obtainable from UAT has made this process suitable for machining hard-to-cut and brittle materials such as super-alloys and ceramics, as well as ordinary materials. The elastic deflection of work-pieces is primarily responsible for the diametrical errors of the machined parts. This is of course more obvious for slender work-pieces. The influence of UAT process on the diametrical error has not yet been investigated. This has been partly undertaken by the authors of the present paper. It has been experimentally illustrated in this paper that ultrasonic vibration superimposed on the tool tip can result in reduction of the diametrical error and thus reduced scrap rate is ensued.

  18. Experimental Analysis of Work-piece's Diametrical Error in Ultrasonic-Vibration-Assisted Turning

    SciTech Connect

    Soleimanimehr, H.; Nategh, M. J.; Gholamzadeh, B.

    2011-01-17

    Vibration at an ultrasonic frequency is superimposed on the ordinary cutting motion in ultrasonic-vibration-assisted turning (UAT). This combinatory cutting motion results in reduction of the cutting force and surface roughness, and improvement of the dimensional tolerances compared with conventional turning (CT). The advantages obtainable from UAT has made this process suitable for machining hard-to-cut and brittle materials such as super-alloys and ceramics, as well as ordinary materials. The elastic deflection of work-pieces is primarily responsible for the diametrical errors of the machined parts. This is of course more obvious for slender work-pieces. The influence of UAT process on the diametrical error has not yet been investigated. This has been partly undertaken by the authors of the present paper. It has been experimentally illustrated in this paper that ultrasonic vibration superimposed on the tool tip can result in reduction of the diametrical error and thus reduced scrap rate is ensued.

  19. Do Diametric Measurements Provide Sufficient and Reliable Tumor Assessment? An Evaluation of Diametric, Areametric, and Volumetric Variability of Lung Lesion Measurements on Computerized Tomography Scans

    PubMed Central

    Fogarty, Edward; Beal, James; Chaudhary, Vijay

    2015-01-01

    Diametric analysis is the standard approach utilized for tumor measurement on medical imaging. However, the availability of newer more sophisticated techniques may prove advantageous. An evaluation of diameter, area, and volume was performed on 64 different lung lesions by three trained users. These calculations were obtained using a free DICOM viewer and standardized measuring procedures. Measurement variability was then studied using relative standard deviation (RSD) and intraclass correlation. Volumetric measurements were shown to be more precise than diametric. With minimal RSD and variance between different users, volumetric analysis was demonstrated as a reliable measurement technique. Additionally, the diameters were used to calculate an estimated area and volume; thereafter the estimated area and volume were compared against the actual measured values. The results in this study showed independence of the estimated and actual values. Estimated area deviated an average of 43.5% from the actual measured, and volume deviated 88.03%. The range of this variance was widely scattered and without trend. These results suggest that diametric measurements cannot be reliably correlated to actual tumor size. Access to appropriate software capable of producing volume measurements has improved drastically and shows great potential in the clinical assessment of tumors. Its applicability merits further consideration. PMID:26064117

  20. Effect of the strain-induced melt activation (SIMA) process on the tensile properties of a new developed super high strength aluminum alloy modified by Al-5Ti-1B grain refiner

    SciTech Connect

    Haghparast, Amin; Nourimotlagh, Masoud; Alipour, Mohammad

    2012-09-15

    In this study, the effect of Al-5Ti-1B grain refiners and modified strain-induced melt activation process on an Al-Zn-Mg-Cu alloy was studied. The optimum level of Ti was found to be 0.1 wt.%. The specimens subjected to deformation ratio of 40% (at 300 Degree-Sign C) and various heat treatment times (10-40 min) and temperature (550-600 Degree-Sign C) regimes were characterized in this study. Reheating condition to obtain a fine globular microstructure was optimized. Microstructural examinations were conducted by optical and scanning electron microscopy coupled with an energy dispersive spectrometry. The optimum temperature and time in strain-induced melt activation process are 575 Degree-Sign C and 20 min, respectively. T6 heat treatment including quenching to room temperature and aging at 120 Degree-Sign C for 24 h was employed to reach to the maximum strength. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the T6 heat treatment, the average tensile strength increased from 283 MPa to 587 and 332 MPa to 617 for samples refined with 2 wt.% Al-5Ti-1B before and after strain-induced melt activation process and extrusion process, respectively. Ultimate strength of Ti-refined specimens without SIMA process has a lower value than globular microstructure specimens after SIMA and extrusion process. - Highlights: Black-Right-Pointing-Pointer The effect of Al-5Ti-1B on the aluminum alloy produced by SIMA process was studied. Black-Right-Pointing-Pointer Al-5Ti-1B is an effective in reducing the grain and reagent fine microstructure. Black-Right-Pointing-Pointer Reheating condition to obtain a fine globular microstructure was optimized. Black-Right-Pointing-Pointer The optimum temperature and time in SIMA process are 575 Degree-Sign C and 20 min respectively. Black-Right-Pointing-Pointer UTS of globular structure specimens have a more value than Ti-refined specimens.

  1. Are the Autism and Positive Schizotypy Spectra Diametrically Opposed in Empathizing and Systemizing?

    ERIC Educational Resources Information Center

    Russell-Smith, Suzanna N.; Bayliss, Donna M.; Maybery, Murray T.; Tomkinson, Rosy L.

    2013-01-01

    Crespi and Badcock's (Behaviour Brain Sci 31: 241-261, 2008) novel theory, which presents autism and positive schizophrenia as diametrical opposites on a cognitive continuum, has received mixed support in the literature to date. The current study aimed to further assess the validity of this theory by investigating predictions in relation to…

  2. Are the Autism and Positive Schizotypy Spectra Diametrically Opposed in Empathizing and Systemizing?

    ERIC Educational Resources Information Center

    Russell-Smith, Suzanna N.; Bayliss, Donna M.; Maybery, Murray T.; Tomkinson, Rosy L.

    2013-01-01

    Crespi and Badcock's (Behaviour Brain Sci 31: 241-261, 2008) novel theory, which presents autism and positive schizophrenia as diametrical opposites on a cognitive continuum, has received mixed support in the literature to date. The current study aimed to further assess the validity of this theory by investigating predictions in relation to

  3. An open-end burst test method to obtain uniaxial hoop tensile properties of fuel cladding in a hot cell

    NASA Astrophysics Data System (ADS)

    Nakatsuka, Masafumi; Aita, Makoto; Sakamoto, Kan; Higuchi, Toru

    2013-03-01

    The hoop stress-hoop strain relationship of fuel cladding is one of the essential input parameters for safety analysis of fuel rods. The three objectives of this paper were: to propose a burst test method for open-end tube specimens with the uniaxial hoop stress condition; to develop the necessary in-cell high temperature open-end burst (OEB) techniques to implement the method; and to determine the optimum specimen length for the proposed OEB test method. Silicone oil was selected as the pressurization medium, and it was sealed inside the specimens not by welding but by O-rings so that no axial tensile stress was induced in the specimens. The specimens with combined end plugs and O-rings were successfully assembled by manipulators in a hot cell, and a high temperature (⩽350 °C), high pressure (⩽100 MPa) seal was achieved. The optimum specimen length was determined by using ductile and embrittled tubes with various lengths of 30-60 mm and was found to be around 45 mm for typical BWR fuel rods. During the OEB test, internal pressure and diametral expansion were monitored to obtain the basic mechanical performance properties of the fuel cladding such as yield stress, ultimate strength, as well as the true hoop stress-hoop strain curve.

  4. Tensile Properties of GRCop-84

    NASA Technical Reports Server (NTRS)

    Ellis, David L.; Loewenthal, William S.; Yun, Hee-Man

    2012-01-01

    This is a chapter in the final report on GRCop-84 for the Reusable Launch Vehicle (RLV) Second Generation/Project Constellation Program. It contains information on the tensile properties of GRCop-84. GRCop-84 (Cu-8 at.% Cr-4 at.% Nb) was produced by extrusion and Hot Isostatic Pressing (HIPing). Some of the extrusions were rolled to plate and sheet while other extrusions were drawn into tubing. The material was further subjected to various heat treatments corresponding to annealing, anticipated typical brazing conditions, an end-of-life condition and various elevated temperature exposures to attempt to improve creep resistance. As anticipated, cold work increased strength while decreasing ductility. Annealing at 600 C (1112 F) and higher temperatures was effective. An exposure for 100 h at 500 C (932 F) resulted in an increase in strength rather than the anticipated decrease. High temperature simulated-braze cycles and thermal exposures lowered the strength of GRCop-84, but the deceases were small compared to precipitation strengthened copper alloys. It was observed that the excess Cr could form large precipitates that lower the reduction in area though it appears a minimum amount is required. Overall, GRCop-84 exhibits good stability of its tensile properties, which makes it an excellent candidate for rocket engine liners and many other high temperature applications.

  5. Tensile-property characterization of thermally aged cast stainless steels.

    SciTech Connect

    Michaud, W. F.; Toben, P. T.; Soppet, W. K.; Chopra, O. K.; Energy Technology

    1994-03-03

    The effect of thermal aging on tensile properties of cast stainless steels during service in light water reactors has been evaluated. Tensile data for several experimental and commercial heats of cast stainless steels are presented. Thermal aging increases the tensile strength of these steels. The high-C Mo-bearing CF-8M steels are more susceptible to thermal aging than the Mo-free CF-3 or CF-8 steels. A procedure and correlations are presented for predicting the change in tensile flow and yield stresses and engineering stress-vs.-strain curve of cast stainless steel as a function of time and temperature of service. The tensile properties of aged cast stainless steel are estimated from known material information, i.e., chemical composition and the initial tensile strength of the steel. The correlations described in this report may be used for assessing thermal embrittlement of cast stainless steel components.

  6. Tensile-property characterization of thermally aged cast stainless steels

    SciTech Connect

    Michaud, W.F.; Toben, P.T.; Soppet, W.K.; Chopra, O.K.

    1994-02-01

    The effect of thermal aging on tensile properties of cast stainless steels during service in light water reactors has been evaluated. Tensile data for several experimental and commercial heats of cast stainless steels are presented. Thermal aging increases the tensile strength of these steels. The high-C Mo-bearing CF-8M steels are more susceptible to thermal aging than the Mo-free CF-3 or CF-8 steels. A procedure and correlations are presented for predicting the change in tensile flow and yield stresses and engineering stress-vs.-strain curve of cast stainless steel as a function of time and temperature of service. The tensile properties of aged cast stainless steel are estimated from known material information, i.e., chemical composition and the initial tensile strength of the steel. The correlations described in this report may be used for assessing thermal embrittlement of cast stainless steel components.

  7. Performance of end-face seals with diametral tilt and coning - Hydrodynamic effects

    NASA Technical Reports Server (NTRS)

    Sharoni, A.; Etsion, I.

    1979-01-01

    Hydrodynamic effects in end-face seals with diametral tilt and coning are analyzed. A closed-form solution for the axial separating force and the restoring and transverse moments is presented that covers the whole range from zero to full angular misalignment at various degrees of coning. Both low-pressure seals with cavitating flow and high-pressure seals with full fluid film are considered. The effect of coning is to reduce the axial force and the restoring and transverse moments compared to their magnitude in flat-face seals. Strong coupling between diametral tilt and transverse moment is demonstrated. This transverse moment which is entirely due to hydrodynamic effects can be the source of dynamic instability in the form of seal wobble.

  8. Fatigue and tensile properties of radicular dentin substrate.

    PubMed

    Inoue, Toshiko; Nishimura, Fumio; Debari, Kazuhiro; Kou, Keitatsu; Miyazaki, Takashi

    2011-02-24

    The purpose of this study was to compare the fatigue and tensile strengths of radicular dentin. Forty bovine lower central incisors were used, twenty teeth for the fatigue test and twenty teeth for the tensile test. Bovine teeth were each sectioned into coronal and radicular portions. Dentin slabs of 1mm thickness were prepared along the radicular tooth using a low-speed cutting machine and trimmed into dumbbell-shaped specimens. A dentin slab was harvested from each tooth. Subsequently, fatigue and tensile tests were performed in Hank's balanced saline solution at 37 C. The staircase method was employed to determine fatigue strength and its standard deviation. Fracture surfaces were observed by scanning electron microscopy. Mean fatigue strength and tensile strength were 44.35.0 and 84.48.3 MPa, respectively. The fatigue strength of radicular dentin was significantly lower than the tensile strength. The fatigue strength of radicular dentin was only approximately one half of the tensile strength. PMID:21146824

  9. Numerical evaluation of the capping tendency of microcrystalline cellulose tablets during a diametrical compression test.

    PubMed

    Furukawa, Ryoichi; Chen, Yuan; Horiguchi, Akio; Takagaki, Keisuke; Nishi, Junichi; Konishi, Akira; Shirakawa, Yoshiyuki; Sugimoto, Masaaki; Narisawa, Shinji

    2015-09-30

    Capping is one of the major problems that occur during the tabletting process in the pharmaceutical industry. This study provided an effective method for evaluating the capping tendency during diametrical compression test using the finite element method (FEM). In experiments, tablets of microcrystalline cellulose (MCC) were compacted with a single tabletting machine, and the capping tendency was determined by visual inspection of the tablet after a diametrical compression test. By comparing the effects of double-radius and single-radius concave punch shapes on the capping tendency, it was observed that the capping tendency of double-radius tablets occurred at a lower compaction force compared with single-radius tablets. Using FEM, we investigated the variation in plastic strain within tablets during the diametrical compression test and visualised it using the output variable actively yielding (AC YIELD) of ABAQUS. For both single-radius and double-radius tablets, a capping tendency is indicated if the variation in plastic strain was initiated from the centre of tablets, while capping does not occur if the variation began from the periphery of tablets. The compaction force estimated by the FEM analysis at which the capping tendency was observed was in reasonable agreement with the experimental results. PMID:26188313

  10. Tensile properties of sand-reinforced low density polyethylene

    SciTech Connect

    Kandeil, A.Y.; Zahran, R.R.

    1995-10-01

    Sand-reinforced low density polyethylene samples were prepared using injection molding. The effect of some processing and structural parameters on the tensile properties of the prepared samples was investigated. The processing parameters were the melt and the die temperatures. The investigated structural parameters were sand content and sand particle size. The studied tensile properties were modulus of elasticity, tensile strength, ductility and toughness. The obtained results are thoroughly analyzed and interpreted as structure-property relationships.

  11. A comparative study of tensile fracture mechanisms.

    NASA Technical Reports Server (NTRS)

    Mullin, J. V.; Mazzio, V. F.

    1972-01-01

    Identification of the failure mechanism characteristic for the more widely used carbon fibers in epoxy matrices under tensile loads as an aid toward improvements and more reliable predictions of the performance of these composites. The presented results pertain to high-strength, high-modulus, and low-modulus fibers in unmodified and modified epoxy novolac matrices.

  12. Tensile Mechanical Properties of Swine Cortical Mandibular Bone

    PubMed Central

    Brosh, Tamar; Rozitsky, Doron; Geron, Silvia; Pilo, Raphael

    2014-01-01

    Temporary orthodontic mini implants serve as anchorage devices in orthodontic treatments. Often, they are inserted in the jaw bones, between the roots of the teeth. The stability of the mini implants within the bone is one of the major factors affecting their success and, consequently, that of the orthodontic treatment. Bone mechanical properties are important for implant stability. The aim of this study was to determine the tensile properties of the alveolar and basal mandible bones in a swine model. The diametral compression test was employed to study the properties in two orthogonal directions: mesio-distal and occluso-gingival. Small cylindrical cortical bone specimens (2.6 mm diameter, 1.5 mm thickness) were obtained from 7 mandibles using a trephine drill. The sites included different locations (anterior and posterior) and aspects (buccal and lingual) for a total of 16 specimens from each mandible. The load-displacement curves were continuously monitored while loading half of the specimens in the oclluso-gingival direction and half in the mesio-distal direction. The stiffness was calculated from the linear portion of the curve. The mesio-distal direction was 31% stiffer than the occluso-gingival direction. The basal bone was 40% stiffer than the alveolar bone. The posterior zone was 46% stiffer than the anterior zone. The lingual aspect was stiffer than the buccal aspect. Although bone specimens do not behave as brittle materials, the diametral compression test can be adequately used for determining tensile behavior when only small bone specimens can be obtained. In conclusion, to obtain maximal orthodontic mini implant stability, the force components on the implants should be oriented mostly in the mesio-distal direction. PMID:25463971

  13. Approaches for Tensile Testing of Braided Composites

    NASA Technical Reports Server (NTRS)

    Roberts, Gary D.; Salem, Jonathan A.; Bail, Justin L.; Kohlman, Lee W.; Binienda, Wieslaw K.; Martin, Richard E.

    2011-01-01

    For angleply composites, lamina tension and compression strengths are commonly determined by applying classical lamination theory to test data obtained from testing of angleply composite specimens. For textile composites such as 2D triaxial braids, analysis is more complex and standard test methods do not always yield reliable strength measurements. This paper describes recent research focused on development of more reliable tensile test methods for braided composites and presents preliminary data for various approaches. The materials investigated in this work have 0deg+/-60 2D triaxial braid architecture with nearly equal fiber volume fraction in each of the three fiber directions. Flat composite panels are fabricated by resin transfer molding (RTM) using six layers of the braided preform aligned along the 0deg fiber direction. Various epoxy resins are used as matrix materials. Single layer panels are also fabricated in order to examine local variations in deformation related to the braid architecture. Specimens are cut from these panels in the shape of standard straight-sided coupons, an alternative bowtie geometry, and an alternative notched geometry. Axial tensile properties are measured using specimens loaded along the 0deg fiber direction. Transverse tensile properties are measured using specimens loaded perpendicular to the 0deg fibers. Composite tubes are also fabricated by RTM. These tubes are tested by internal pressurization using a soft rubbery material sealed between the inside diameter of the tube and the load fixtures. The ends of the tube are unconstrained, so the primary load is in the hoop direction. Tubes are fabricated with the 0deg fibers aligned along the tube axis by overbraiding the preform on a mandrel. Since the loading is in the hoop direction, testing of the overbraided tube provides a measure of transverse tensile strength. Previous work has indicated that straight-sided coupons yield a transverse tensile strength that is much lower than the expected material strength because of premature edge-initiated failure. Full-field strain measured during transverse tensile tests clearly showed accumulation of edge damage prior to failure. In the current work, high speed video and testing of single layer specimens are used to investigate potential failure mechanisms in more detail. High speed video clearly shows the edge initiation in six layer transverse tensile test coupons. Specimens with the bowtie geometry and the notched geometry minimize this edge effect and yield significantly higher transverse tensile strength values compared to the straight-sided coupons. However, bowtie and notched specimens geometries are not ideal because of the non-uniform stress and strain fields in the region of failure. Testing of tubes using internal pressurization eliminates edge-initiated failure and provides a more uniform state of stress and strain. Preliminary results indicate that bowtie, notched, and tube specimens yield comparable values for transverse tensile strength and that these values are much higher than the strength measured using a straight-sided coupon.

  14. High strength, superplastic superalloy

    NASA Technical Reports Server (NTRS)

    Ashbrook, R. L.; Freche, J. C.; Waters, W. J.

    1969-01-01

    High strength superplastic superalloys are produced by extruding a pre-alloyed powder. The cast nickel base superalloy was remelted and converted to pre-alloyed powder by inert gas atomization. The superalloy shows high tensile strength and superplasticity and finds use in hot working and casting.

  15. Tensile properties of textile composites

    NASA Technical Reports Server (NTRS)

    Avva, V. Sarma; Sadler, Robert L.; Lyon, Malcolm

    1992-01-01

    The importance of textile composite materials in aerospace structural applications has been gaining momentum in recent years. With a view to better understand the suitability of these materials in aerospace applications, an experimental program was undertaken to assess the mechanical properties of these materials. Specifically, the braided textile preforms were infiltrated with suitable polymeric matrices leading to the fabrication of composite test coupons. Evaluation of the tensile properties and the analyses of the results in the form of strength moduli, Poisson's ratio, etc., for the braided composites are presented. Based on our past experience with the textile coupons, the fabrication techniques have been modified (by incorporating glass microballoons in the matrix and/or by stabilizing the braid angle along the length of the specimen with axial fibers) to achieve enhanced mechanical properties of the textile composites. This paper outlines the preliminary experimental results obtained from testing these composites.

  16. Tensile behavior of nanocrystalline copper

    SciTech Connect

    Sanders, P.G.; Weertman, J.R.; Eastman, J.A. |

    1995-11-01

    High density nanocrystalline copper produced by inert gas condensation was tested in tension. Displacements were measured using foil strain gauges, which greatly improved the accuracy of the strain data. The Young`s modulus of nanocrystalline copper was found to be consistent with that of coarse-grained copper. Total elongations of {approx} 1% were observed in samples with grain sizes less than 50 nm, while a sample with a grain size of 110 nm exhibited more than 10% elongation, perhaps signifying a change to a dislocation-based deformation mechanism in the larger-grained material. In addition, tensile tests were performed as a function of strain rate, with a possible trend of decreased strength and increased elongation as the strain rate was decreased.

  17. Assessing the Strength Enhancement of Heterogeneous Networks of Miscible Polymer Blends

    NASA Astrophysics Data System (ADS)

    Giller, Carl; Roland, Mike

    2013-03-01

    At the typical crosslink densities of elastomers, the failure properties vary inversely with mechanical stiffness, so that compounding entails a compromise between stiffness and strength. Our approach to circumvent this conventional limitation is by forming networks of two polymers that: (i) are thermodynamically miscible, whereby the chemical composition is uniform on the segmental level; and (ii) have markedly different reactivities for network formation. The resulting elastomer consists of one highly crosslinked component and one that is lightly or uncrosslinked. This disparity in crosslinking causes their respective contributions to the network mechanical response to differ diametrically. Earlier results showed some success with this approach for thermally crosslinked blends of 1,2-polybutadiene (PVE) and polyisoprene (PI), as well as ethylene-propylene copolymer (EPM) and ethylene-propylene-diene random terpolymer (EPDM), taking advantage of their differing reactivities to sulfur. In this work we demonstrate the miscibility of polyisobutylene (PIB) with butyl rubber (BR) (a copolymer of PIB and polyisoprene) and show that networks in which only the BR is crosslinked possess greater tensile strengths than neat BR over the same range of moduli. Office of Naval Research

  18. Effect of Strain Rate on Tensile Properties of Carbon Fiber Epoxy-Impregnated Bundle Composite

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi

    2014-03-01

    The tensile tests for high tensile strength polyacrylonitrile (PAN)-based (T1000GB) carbon fiber epoxy-impregnated bundle composite at various strain rates ranging from 3.33 × 10-5 to 6.0 × 102 s-1 (various crosshead speeds ranging from 8.33 × 10-7 to 1.5 × 101 m/s) were investigated. The statistical distributions of the tensile strength were also evaluated. The results clearly demonstrated that the tensile strength of bundle composite slightly increased with an increase in the strain rate (crosshead speed) and the Weibull modulus of tensile strength for the bundle composite decreased with an increase in the strain rate (crosshead speed), there is a linear relation between the Weibull modulus and the average tensile strength on log-log scale.

  19. Tensile properties of austempered ductile iron under thermomechanical treatment

    NASA Astrophysics Data System (ADS)

    Achary, J.

    2000-02-01

    A new processing method was investigated for improving the strength and elongation of austempered ductile iron (ADI) by grain refinement of parent austenite using thermomechanical treatment. The material was deformed at the austenitization temperature by single and multipass rolling before the austempering treatment. The effects of the amount of deformation, austenitization temperature, austempering temperatures, reaustenitization, and secondary deformation on the tensile properties were studied. The properties obtained using the method were compared with those of the ASTM standards. The effect of deformation on the graphite shape was also studied. Tensile strength/yield strength/elongation values were found to increase with increasing austenite deformation up to 40% and then to start decreasing. Tensile strength/yield strength and elongation values of 1700 MPa/1300 MPa/5% and 1350 MPa/920 MPa/15% can be achieved with this method in the ranges of variables studied.

  20. Tensile properties of austempered ductile iron under thermomechanical treatment

    SciTech Connect

    Achary, J.

    2000-02-01

    A new processing method was investigated for improving the strength and elongation of austempered ductile iron (ADI) by grain refinement of parent austenite using thermomechanical treatment. The material was deformed at the austenitization temperature by single and multipass rolling before the austempering treatment. The effects of the amount of deformation, austenitization temperature, austempering temperatures, reaustenitization, and secondary deformation on the tensile properties were studied. The properties obtained using the method were compared with those of the ASTM standards. The effect of deformation on the graphite shape was also studied. Tensile strength/yield strength/elongation values were found to increase with increasing austenite deformation up to 40% and then to start decreasing. Tensile strength/yield strength and elongation values of 1,700 MPa/1,300 MPa/5% and 1,350 MPa/920 MPa/15% can be achieved with this method in the ranges of variables studied.

  1. Strength properties of separators in alkaline solutions

    SciTech Connect

    Danko, T.

    1996-11-01

    Battery separator non-wovens that were coated with regenerated cellulose via the viscose process were subjected to storage in 40% potassium hydroxide (KOH) over a two month period. Samples were periodically checked for wet MD tensile strength. The test showed that among the non-wovens, the polyamide retained about 93% of its initial tensile strength whereas polyvinyl alcohol and cellulosic non-wovens retained only 55% and 35%, respectively. Adding a viscose coating to the non-wovens improved tensile strength retention by 20--25% for the polyvinyl alcohol and cellulosic materials. The viscose-coated polyamide retained more than 98% of its initial tensile strength.

  2. Quest for the Vulnerable Atheroma: Carotid Stenosis and Diametric Strain-A Feasibility Study.

    PubMed

    Xu, Canxing; Yuan, Chun; Stutzman, Edward; Canton, Gador; Comess, Keith A; Beach, Kirk W

    2016-03-01

    The Bernoulli effect may result in eruption of a vulnerable carotid atheroma, causing a stroke. We measured electrocardiography (ECG)-registered QRS intra-stenotic blood velocity and atheroma strain dynamics in carotid artery walls using ultrasonic tissue Doppler methods, providing displacement and time resolutions of 0.1 ?m and 3.7 ms. Of 22 arteries, 1 had a peak systolic velocity (PSV) >280 cm/s, 4 had PSVs between 165 and 280 cm/s and 17 had PSVs <165 cm/s. Eight arteries with PSVs <65 cm/s and 4 of 9 with PSVs between 65 and 165 cm/s had normal systolic diametric expansion (0% and 7%) and corresponding systolic wall thinning. The remaining 10 arteries had abnormal systolic strain dynamics, 2 with diametric reduction (>-0.05 mm), 2 with extreme wall expansion (>0.1 mm), 2 with extreme wall thinning (>-0.1 mm) and 4 with combinations. Decreases in systolic diameter and/or extreme systolic arterial wall thickening may indicate imminent atheroma rupture. PMID:26705891

  3. Effects of Coating and Diametric Load on Fiber Bragg Gratings as Cryogenic Temperature Sensors

    NASA Technical Reports Server (NTRS)

    Wu, meng-Chou; Pater, Ruth H.; DeHaven, Stanton L.

    2008-01-01

    Cryogenic temperature sensing was demonstrated using pressurized fiber Bragg gratings (PFBGs) with polymer coating of various thicknesses. The PFBG was obtained by applying a small diametric load to a regular fiber Bragg grating (FBG). The Bragg wavelengths of FBGs and PFBG were measured at temperatures from 295 K to 4.2 K. The temperature sensitivities of the FBGs were increased by the polymer coating. A physical model was developed to relate the Bragg wavelength shifts to the thermal expansion coefficients, Young's moduli, and thicknesses of the coating polymers. When a diametric load of no more than 15 N was applied to a FBG, a pressure-induced transition occurred at 200 K during the cooling cycle. The pressure induced transition yielded PFBG temperature sensitivities three times greater than conventional FBGs for temperatures ranging from 80 to 200 K, and ten times greater than conventional fibers for temperatures below 80 K. PFBGs were found to produce an increased Bragg wavelength shift of 2.2 nm compared to conventional FBGs over the temperature range of 4.2 to 300 K. This effect was independent of coating thickness and attributed to the change of the fiber thermo-optic coefficient.

  4. Effect of temperature on tensile and creep characteristics of PRD49 fiber/epoxy composites

    NASA Technical Reports Server (NTRS)

    Hanson, M. P.

    1972-01-01

    Tensile and creep data of PRD49-1 and 3 fiber/epoxy-resin composites are presented. Tensile data were obtained from 20 to 477 K (-423 to 400 F). Tensile strengths and moduli were determined at selected temperatures. Creep data are presented for fiber composites at 297, 422 and 450 K (75, 300, and 350 F) for as long as 1000 hours at stress levels of approximately 50 and 80 percent of the ultimate tensile strength at 297 K (75 F). Details of tensile specimens and test procedures used in the investigation are presented.

  5. Furnace for Tensile Testing of Flexible Ceramics

    NASA Technical Reports Server (NTRS)

    Smith, M.; Estrella, C. A.; Katvala, V. W.

    1986-01-01

    Ceramic cloth and thread tested quickly at temperatures up to 1,250 degree C. Tensile strengths of ceramic cloths and threads measured conveniently in new furnace at specified temperatures up to 1,250 degree C, using ordinary mechanical tester. Samples heated along part of their lengths in furnace slots. Interchangeable furnace chambers and matching heating elements sized to match size of tested ceramic material.

  6. Alumina fiber strength improvement

    NASA Technical Reports Server (NTRS)

    Pepper, R. T.; Nelson, D. C.

    1982-01-01

    The effective fiber strength of alumina fibers in an aluminum composite was increased to 173,000 psi. A high temperature heat treatment, combined with a glassy carbon surface coating, was used to prevent degradation and improve fiber tensile strength. Attempts to achieve chemical strengthening of the alumina fiber by chromium oxide and boron oxide coatings proved unsuccessful. A major problem encountered on the program was the low and inconsistent strength of the Dupont Fiber FP used for the investigation.

  7. Tensile properties of titanium electrolytically charged with hydrogen

    NASA Technical Reports Server (NTRS)

    Smith, R. J.; Otterson, D. A.

    1971-01-01

    Yield strength, ultimate tensile strength, and elongation were studied for annealed titanium electrolytically charged with hydrogen. The hydrogen was present as a surface hydride layer. These tensile properties were generally lower for uncharged titanium than for titanium with a continuous surface hydride; they were greater for uncharged titanium than for titanium with an assumed discontinuous surface hydride. We suggest that the interface between titanium and titanium hydride is weak. And the hydride does not necessarily impair strength and ductility of annealed titanium. The possibility that oxygen and/or nitrogen can embrittle titanium hydride is discussed.

  8. Tensile Properties of Under-Matched Weld Joints for 950 MPa Steel.

    NASA Astrophysics Data System (ADS)

    Yamamoto, Kouji; Arakawa, Toshiaki; Akazawa, Nobuki; Yamamoto, Kousei; Matsuo, Hiroki; Nakagara, Kiyoyuki; Suita, Yoshikazu

    In welding of 950 MPa-class high tensile strength steel, preheating is crucial in order to avoid cold cracks, which, however, eventually increases welding deformations. One way to decrease welding deformations is lowering preheating temperature by using under-matched weld metal. Toyota and others clarify that although breaking elongation can decrease due to plastic constraint effect under certain conditions, static tensile of under-matched weld joints is comparable to that of base metal. However, there has still been no report about joint static tensile of under-matched weld joints applied to 950 MPa-class high tensile strength steel. In this study, we aim to research tensile strength and fatigue strength of under-matched weld joints applied to 950 MPa-class high tensile steel.

  9. Effect of Electron Beam Irradiation on the Tensile Properties of Carbon Nanotubes Sheets and Yarns

    NASA Technical Reports Server (NTRS)

    Williams, Tiffany S.; Miller, Sandi G.; Baker, James S.; McCorkle, Linda S.; Meador, Michael A.

    2013-01-01

    Carbon nanotube sheets and yarns were irradiated using electron beam (e-beam) energy to determine the effect of irradiation dose on the tensile properties. Results showed that a slight change in tensile strength occurred after irradiating as-received CNT sheets for 20 minutes, and a slight decrease in tensile strength as the irradiation time approached 90 minutes. On the other hand, the addition of small molecules to the CNT sheet surface had a greater effect on the tensile properties of e-beam irradiated CNT sheets. Some functionalized CNT sheets displayed up to a 57% increase in tensile strength following 90 minutes of e-beam exposure. In addition, as-received CNT yarns showed a significant increase in tensile strength as the irradiation time increased.

  10. Development of Manila Hemp Fiber Epoxy Composite with High Tensile Properties Through Handpicking Fiber Fragments

    NASA Astrophysics Data System (ADS)

    Liu, Ke; Takagi, Hitoshi; Yang, Zhimao

    Manila hemp fibers are separated to several sequent fragments from single fiber. The tensile strength of each fiber fragments and their epoxy composite are measured, followed by scanning electronic microscopic (SEM) analysis. The results show that the tensile strength of fiber fragments is almost constant along fiber. For composite, the tensile strength first increases and then decreases at the position near to root. The Young's modulus presents increasing with location from root to top for fiber and composite. Microstructure analysis indicates that the difference of tensile properties between fiber fragments derive from the difference of fiber diameter.

  11. Tree Diametric Increment and Litterfall Production in an Eastern Amazonian Forest: the Role of Functional Groups

    NASA Astrophysics Data System (ADS)

    Camargo, P. B. D.; Ferreira, M. L.; Oliveira Junior, R. C.; Saleska, S. R.

    2014-12-01

    Tree growth is a biotic variable of great importance in understanding the dynamics of tree communities and may be used as a tool in studies of biological or climate modeling. Some climate models predict more recurrent climate anomalies in this century, which may alter the functioning of tropical forests with serious structural and demographic implications. The present study aimed to evaluate the profile of tree growth and litterfall production in an eastern Amazon forest, which has suffered recent climatic disturbances. We contrasted different functional groups based on wood density (stem with 0.55; 0.56-0.7; >0.7 g cm-3), light availability (crown illumination index; high illuminated crown - IIC1 until shaded crown - IIC5), and, size class (trees 10-22.5; 22.6-35; 35.1-55; 55,1-90; >90 cm dbh). Tree diameter increment was monthly measured from November 2011 to September 2013 by using dendrometer bands installed on 850 individuals from different families. Litterfall was collected in 64 circular traps, oven dried and weighed, separated into leaves, twigs, reproductive parts and miscellaneous. During the rainy season the sampled trees had the highest rates of tree diametric increment. When analyzing the data by functional groups, large trees had faster growth, but when grouped by wood density, trees with wood density up to 0.55 and between 0.56 and 0.7 g cm-3 had the fastest rates of growth. When grouped by crown illumination index, trees exposed to higher levels of light grew more in comparison to partially shaded trees. Maximum daily air temperature and precipitation were the most important environmental variables in determining the diametric increment profile of the trees. Litterfall production was estimated to be 7.1 Mg ha-1.year-1 and showed a strong seasonal pattern, with dry season production being higher than in the rainy season. Leaves formed the largest fraction of the litterfall, followed by twigs, reproductive parts, and finally miscellaneous. These results show that the profile of tree diametric growth and litterfall production are recorded at close intervals in the preterit analyzes in the same study area and highlights the efficiency of functional groups in determining the tree growth profile.

  12. Strength of Rewelded Inconel 718

    NASA Technical Reports Server (NTRS)

    Bayless, E.; Lovoy, C. V.; Mcllwain, M. C.; Munafo, P.

    1982-01-01

    Inconel 718, nickel-based alloy used extensively for high-temperature structural service, welded repeatedly without detriment to its strength. According to NASA report, tests show 12 repairs on same weld joint do not adversely affect ultimate tensile strenth, yield strength, fatigue strength, metallurgical grain structures, or ability of weld joint to respond to post weld heat treatments.

  13. Controlling factors in tensile deformation of nanocrystalline cobalt and nickel

    NASA Astrophysics Data System (ADS)

    Wang, Y. M.; Ott, R. T.; van Buuren, T.; Willey, T. M.; Biener, M. M.; Hamza, A. V.

    2012-01-01

    In an effort to understand and enhance the tensile ductility of truly nanocrystalline metals, we have investigated and compared the mechanical behavior, especially the tensile behavior, of hexagonal close-packed (hcp) nanocrystalline cobalt (20 nm) and face-centered cubic (fcc) nanocrystalline nickel (28 nm). Although both materials exhibit obvious plasticity in tension, their uniform tensile ductility, tensile elongation-to-failure, and fracture behavior are drastically different. In-situ synchrotron x-ray diffraction and ultra-small angle x-ray scattering reveal distinct deformation disparity in terms of residual strain development, texture evolution, nanovoid formation, and subsequent strain-hardening and strain-rate-hardening behavior. The dependence of tensile property on the strain rate and temperature is examined and discussed. Factors that influence the strength and ductility of nanocrystalline metals are considered and prioritized according to the current findings. A new Hall-petch relationship is proposed for nanocrystalline nickel.

  14. Improve the Strength of PLA/HA Composite Through the Use of Surface Initiated Polymerization and Phosphonic Acid Coupling Agent

    PubMed Central

    Wang, Tongxin; Chow, Laurence C.; Frukhtbeyn, Stanislav A.; Ting, Andy Hai; Dong, Quanxiao; Yang, Mingshu; Mitchell, James W.

    2012-01-01

    Bioresorbable composite made from degradable polymers, e.g., polylactide (PLA), and bioactive calcium phosphates, e.g., hydroxyapatite (HA), are clinically desirable for bone fixation, repair and tissue engineering because they do not need to be removed by surgery after the bone heals. However, preparation of PLA/HA composite from non-modified HA usually results in mechanical strength reductions due to a weak interface between PLA and HA. In this study, a calcium-phosphate/phosphonate hybrid shell was developed to introduce a greater amount of reactive hydroxyl groups onto the HA particles. Then, PLA was successfully grafted on HA by surface-initiated polymerization through the non-ionic surface hydroxyl groups. Thermogravimetric analysis indiated that the amount of grafted PLA on HA can be up to 7 %, which is about 50 % greater than that from the literature. PLA grafted HA shows significantly different pH dependent ?-potential and particle size profiles from those of uncoated HA. By combining the phosphonic acid coupling agent and surface initiated polymerization, PLA could directly link to HA through covalent bond so that the interfacial interaction in the PLA/HA composite can be significantly improved. The diametral tensile strength of PLA/HA composite prepared from PLA-grafted HA was found to be over twice that of the composite prepared from the non-modified HA. Moreover, the tensile strength of the improved composite was 23 % higher than that of PLA alone. By varying additional variables, this approach has the potential to produce bioresorbable composites with improved mechanical properties that are in the range of natural bones, and can have wide applications for bone fixation and repair in load-bearing areas. PMID:22399838

  15. Tensile testing apparatus

    NASA Technical Reports Server (NTRS)

    Blackburn, L. B.; Ellingsworth, J. R. (inventors)

    1985-01-01

    An improved mechanical extensometer is described for use with a constant load creep test machine. The dead weight of the extensometer is counterbalanced by two pairs of weights connected through a pulley system and to rod extension and leading into the furnace where the test sample is undergoing elevated temperature (above 500 F.) tensile testing. Novel gripper surfaces, conical tip and flat surface are provided in each sampling engaging platens to reduce the grip pressure normally required for attachment of the extensometer to the specimen and reduce initial specimen bending normally associated with foil-gage metal testing.

  16. Strength enhancement process for prealloyed powder superalloys

    NASA Technical Reports Server (NTRS)

    Waters, W. J.; Freche, J. C.

    1977-01-01

    A technique involving superplastic processing and high pressure autoclaving was applied to a nickel base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m at 480 C were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high temperature tensile and stress rupture strengths were also devised.

  17. Laser-induced generation of pure tensile stresses

    SciTech Connect

    Niemz, M.H.; Lin, C.P.; Pitsillides, C.; Cui, J.; Doukas, A.G.; Deutsch, T.F.

    1997-05-01

    While short compressive stresses can readily be produced by laser ablation, the generation of pure tensile stresses is more difficult. We demonstrate that a 90{degree} prism made of polyethylene can serve to produce short and pure tensile stresses. A compressive wave is generated by ablating a thin layer of strongly absorbing ink on one surface of the prism with a Q-switched frequency-doubled Nd:YAG laser. The compressive wave driven into the prism is reflected as a tensile wave by the polyethylene-air interface at its long surface. The low acoustic impedance of polyethylene makes it ideal for coupling tensile stresses into liquids. In water, tensile stresses up to {minus}200bars with a rise time of the order of 20 ns and a duration of 100 ns are achieved. The tensile strength of water is determined for pure tensile stresses lasting for 100 ns only. The technique has potential application in studying the initiation of cavitation in liquids and in comparing the effect of compressive and tensile stress transients on biological media. {copyright} {ital 1997 American Institute of Physics.}

  18. PBX 9502 TENSILE ANALYSIS

    SciTech Connect

    Idar, D.J.; Larson, S.A.

    2000-10-01

    With the recent creation of the PX HE Core Surveillance Database, individual specimen surveillance values can be easily compared to the corresponding individual qualification values to evaluate for trends. A review of the data shows a broad scatter in measured stress-strain values. Using the available HE surveillance database, it is clear that the surveillance measurements from the two Cycle 15 charges fall within the range of qualification stress and strain values recorded previously for PBX 9502 lots and that no apparent stockpile-age related trends are evident in the tensile stress-strain data. As a result of this investigation, some changes are being made to the core surveillance specifications to minimize the effects on tensile data scatter due to temperature and humidity differences and method to method changes. These data analyses do point out the need for a comprehensive understanding of the effect of a number of variables, i.e. formulation and pressing method, density, stockpile age, lot-to-lot variations, temperature, and humidity on the mechanical property behavior of HE composite materials. Too often data have been compared without the relevant details made available to determine if the test conditions were nominally the same or different. These results also point out the critical need to establish useful stress-strain limits for qualification and surveillance testing of HEs.

  19. Treatment of High Temperature Tensile Data for Alloy 617 and Alloy 230

    SciTech Connect

    Sham, Sam; Eno, Daniel R.; Jensen, Krista P.

    2008-01-01

    Yield strength and tensile strength at temperature are used to set time independent primary stress limits for structural materials in various high temperature design codes. For the Ni-based Alloy 617 and Alloy 230, the temperature trends for the yield strength and tensile strength change significantly above around 1100K and 1025K, respectively, from the lower temperature trends. It is shown that standard methods in obtaining design values for these parameters for Very High Temperature Reactor applications are not satisfactory. Improved methods for the treatment of tensile data are proposed, resulting in more consistent and quantifiable design margin over the full range of low to high temperatures.

  20. The Effect of Reprocessing on the Tensile Properties of Composites

    NASA Astrophysics Data System (ADS)

    Bodur, Mehmet Safa; Bakkal, Mustafa; Berkalp, Omer Berk; Sadikoglu, Telem Gok

    2011-01-01

    In this study, waste cotton fabric reinforced polymer matrix composite material has been manufactured by a custom made recycling extruder. Composites with different reinforcement ratios as 12,5%wt ( 12,5%wtRPE ) and 25%wt ( 25%wtRPE ) were tested for their mechanical properties such as tensile strength and young's modulus. The material was then granulated down to the size enough to be used in the extrusion process in order to observe the effects of reprocessing. Reprocessing leads to improve Tensile Strength of composite materials and slows down the reduction of tensile strength of polyethylene. It was observed that composite materials were highly affected by the fiber orientation and acts as anisotropic material under the load.

  1. Tensile properties of a thermomechanically processed ductile iron

    SciTech Connect

    Syn, C.K.; Lesuer, D.R.; Sherby, O.D.

    1997-05-01

    A ductile cast iron was continuously hot-and-warm-rolled or one-step-forged from a temperature in the austenite range (900 C to 1,100 C) to a temperature below the A{sub 1} temperature. Various amounts of reduction were used (from 60 to more than 90 pct). Tensile properties including tensile strength and total elongation were measured along the directions parallel and transverse to the rolling direction and along the direction transverse to the forging direction. The tensile ductility and strength both increase with a decrease in the amount of hot-and-warm working (HWW). Compared with the results obtained by other investigators, the present results showed higher strengths and ductilities over the same range of reduction in thickness. The improvement in properties is related to the lower temperature of the postprocessing heat treatment given in this study (600 C) compared to other studies (900 C). The low temperature of heat treatment leads to a structure of fine graphite in a matrix of ferrite and carbides, whereas the high temperature of heat treatment leads to coarse graphite in a matrix of carbide-free ferrite. The delay in failure from the presence of the small graphite constituent results in an increase in tensile ductility with an accompanying increase in tensile strength.

  2. Velocity anti-correlation of diametrically opposed galaxy satellites in the low-redshift Universe

    NASA Astrophysics Data System (ADS)

    Ibata, Neil G.; Ibata, Rodrigo A.; Famaey, Benoit; Lewis, Geraint F.

    2014-07-01

    Recent work has shown that the Milky Way and the Andromeda galaxies both possess the unexpected property that their dwarf satellite galaxies are aligned in thin and kinematically coherent planar structures. It is interesting to evaluate the incidence of such planar structures in the larger galactic population, because the Local Group may not be a representative environment. Here we report measurements of the velocities of pairs of diametrically opposed satellite galaxies. In the local Universe (redshift z < 0.05), we find that satellite pairs out to a distance of 150 kiloparsecs from the galactic centre are preferentially anti-correlated in their velocities (99.994 per cent confidence level), and that the distribution of galaxies in the larger-scale environment (out to distances of about 2 megaparsecs) is strongly clumped along the axis joining the inner satellite pair (>7? confidence). This may indicate that planes of co-rotating satellites, similar to those seen around the Andromeda galaxy, are ubiquitous, and their coherent motion suggests that they represent a substantial repository of angular momentum on scales of about 100 kiloparsecs.

  3. Velocity anti-correlation of diametrically opposed galaxy satellites in the low-redshift Universe.

    PubMed

    Ibata, Neil G; Ibata, Rodrigo A; Famaey, Benoit; Lewis, Geraint F

    2014-07-31

    Recent work has shown that the Milky Way and the Andromeda galaxies both possess the unexpected property that their dwarf satellite galaxies are aligned in thin and kinematically coherent planar structures. It is interesting to evaluate the incidence of such planar structures in the larger galactic population, because the Local Group may not be a representative environment. Here we report measurements of the velocities of pairs of diametrically opposed satellite galaxies. In the local Universe (redshift z<0.05), we find that satellite pairs out to a distance of 150kiloparsecs from the galactic centre are preferentially anti-correlated in their velocities (99.994 per cent confidence level), and that the distribution of galaxies in the larger-scale environment (out to distances of about 2megaparsecs) is strongly clumped along the axis joining the inner satellite pair (>7? confidence). This may indicate that planes of co-rotating satellites, similar to those seen around the Andromeda galaxy, are ubiquitous, and their coherent motion suggests that they represent a substantial repository of angular momentum on scales of about 100kiloparsecs. PMID:25043008

  4. Tensile Fracture of Ductile Materials. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Pai, D. M.

    1984-01-01

    For brittle materials, circular voids play an important role relative to fracture, intensifing both tensile and compressive stresses. A maximum intensified tensile stress failure criterion applies quite well to brittle materials. An attempt was made to explore the possibility of extending the approach to the tensile fracture of ductile materials. The three dimensional voids that exist in reality are modelled by circular holes in sheet metal. Mathematical relationships are sought between the shape and size of the hole, after the material is plastically deformed, and the amount of deformation induced. Then, the effect of hole shape, size and orientation on the mechanical properties is considered experimentally. The presence of the voids does not affect the ultimate tensile strength of the ductile materials because plastic flow wipes out the stress intensification caused by them. However, the shape and orientation of the defect is found to play an important role in affecting the strain at fracture.

  5. Tunable Tensile Ductility in Metallic Glasses

    PubMed Central

    Magagnosc, D. J.; Ehrbar, R.; Kumar, G.; He, M. R.; Schroers, J.; Gianola, D. S.

    2013-01-01

    Widespread adoption of metallic glasses (MGs) in applications motivated by high strength and elasticity combined with plastic-like processing has been stymied by their lack of tensile ductility. One emerging strategy to couple the attractive properties of MGs with resistance to failure by shear localization is to employ sub-micron sample or feature length scales, although conflicting results shroud an atomistic understanding of the responsible mechanisms in uncertainty. Here, we report in situ deformation experiments of directly moulded Pt57.5Cu14.7Ni5.3P22.5 MG nanowires, which show tunable tensile ductility. Initially brittle as-moulded nanowires can be coerced to a distinct glassy state upon irradiation with Ga+ ions, leading to tensile ductility and quasi-homogeneous plastic flow. This behaviour is reversible and the glass returns to a brittle state upon subsequent annealing. Our results suggest a novel mechanism for homogenous plastic flow in nano-scaled MGs and strategies for circumventing the poor damage tolerance that has long plagued MGs.

  6. Tensile and creep properties of titanium-vanadium, titanium-molybdenum, and titanium-niobium alloys

    NASA Technical Reports Server (NTRS)

    Gray, H. R.

    1975-01-01

    Tensile and creep properties of experimental beta-titanium alloys were determined. Titanium-vanadium alloys had substantially greater tensile and creep strength than the titanium-niobium and titanium-molybdenum alloys tested. Specific tensile strengths of several titanium-vanadium-aluminum-silicon alloys were equivalent or superior to those of commercial titanium alloys to temperatures of 650 C. The Ti-50V-3Al-1Si alloy had the best balance of tensile strength, creep strength, and metallurgical stability. Its 500 C creep strength was far superior to that of a widely used commercial titanium alloy, Ti-6Al-4V, and almost equivalent to that of newly developed commercial titanium alloys.

  7. Tensile Tests of NACA and Conventional Machine-countersunk Flush Rivets

    NASA Technical Reports Server (NTRS)

    Bartone, Leonard M.; Mandel, Merven W.

    1944-01-01

    An investigation was conducted to determine and compare the tensile strength of NACA and conventional machine-countersunk flush rivets of several rivet-head angles and varying countersunk depth. The results of the investigation are presented in the form of curves that show the variation of the tensile strength of the rivet with the ratio of the sheet thickness to the rivet diameter. For the same rivet-head angle and for a given angle of c/d, the NACA rivets developed higher tensile strength than the conventional rivets.

  8. Fabrication of Poly-l-lactic Acid/Dicalcium Phosphate Dihydrate Composite Scaffolds with High Mechanical Strength-Implications for Bone Tissue Engineering.

    PubMed

    Tanataweethum, Nida; Liu, Wai Ching; Goebel, W Scott; Li, Ding; Chu, Tien Min

    2015-01-01

    Scaffolds were fabricated from poly-l-lactic acid (PLLA)/dicalcium phosphate dihydrate (DCPD) composite by indirect casting. Sodium citrate and PLLA were used to improve the mechanical properties of the DCPD scaffolds. The resulting PLLA/DCPD composite scaffold had increased diametral tensile strength and fracture energy when compared to DCPD only scaffolds (1.05 vs. 2.70 MPa and 2.53 vs. 12.67 N-mm, respectively). Sodium citrate alone accelerated the degradation rate by 1.5 times independent of PLLA. Cytocompatibility of all samples were evaluated using proliferation and differentiation parameters of dog-bone marrow stromal cells (dog-BMSCs). The results showed that viable dog-BMSCs attached well on both DCPD and PLLA/DCPD composite surfaces. In both DCPD and PLLA/DCPD conditioned medium, dog-BMSCs proliferated well and expressed alkaline phosphatase (ALP) activity indicating cell differentiation. These findings indicate that incorporating both sodium citrate and PLLA could effectively improve mechanical strength and biocompatibility without increasing the degradation time of calcium phosphate cement scaffolds for bone tissue engineering purposes. PMID:26556380

  9. The effect of potential investment expansion and hot strength on the fit of full crown castings made with phosphate-bonded investment.

    PubMed

    Earnshaw, R; Morey, E F; Edelman, D C

    1997-07-01

    In an earlier investigation, it was shown that when full crowns are cast in gypsum-bonded investments, their relative inaccuracy is affected by both the investment's potential expansion and its hot strength. This study repeated the earlier one, but used a high-melting gold alloy and two phosphate-bonded investments. The investments were used under conditions which gave a range of potential expansions and hot strengths. Casting inaccuracies were determined both diametrally and axially. All castings showed distortion, which varied under the different conditions. All were oversized axially, by amounts varying from + 0.8% to +2.3%. Diametral inaccuracies ranged from -0.2% to +0.7%. Investment expansion had a strong effect on axial inaccuracy, but a negligible effect on diametral inaccuracy. Conversely, hot strength had a strong effect on diametral inaccuracy, but only a very weak effect on axial inaccuracy. With phosphate-bonded investments, both potential expansion and hot strength are important parameters of relative casting inaccuracy. In combination, these properties showed very strong correlations with both diametral and axial inaccuracies. The observed distortions were the result of anisotropic mould expansion and anisotropic alloy shrinkage. The best fit, and least distortion, occurred with an investment setting under dry conditions. PMID:9250842

  10. Tensile and fatigue properties of Inconel 718 at cryogenic temperatures

    NASA Technical Reports Server (NTRS)

    Malin, C. O.; Schmidt, E. H.

    1969-01-01

    Tests to determine the tensile and fatigue properties of Inconel 718 at cryogenic temperatures show that the alloy increases in strength at low temperatures, with very little change in toughness. The effect of surface finish and grain size on the fatigue properties was also determined.

  11. Effects of Effective Dendrite Size on Dynamic Tensile Properties of Ti-Based Amorphous Matrix Composites

    NASA Astrophysics Data System (ADS)

    Jeon, Changwoo; Park, Jaeyeong; Kim, Choongnyun Paul; Kim, Hyoung Seop; Lee, Sunghak

    2016-04-01

    In this study, dynamic tensile properties of dendrite-containing Ti-based amorphous matrix composites were examined, and effects of dendrite size on dynamic deformation were investigated. The composites contained 73 to 76 vol pct of dendrites whose effective sizes were varied from 63 to 103 μm. The dynamic tensile test results indicated that the ultimate tensile strength increased up to 1.25 GPa, whereas the elongation decreased to 1 pct, although the overall strength and elongation trends followed those of the quasi-static tensile test. According to the observation of dynamic tensile deformation behavior, very few deformation bands were observed beneath the fracture surface in the composite containing large dendrites. In the composite containing small dendrites, deformation bands initiated inside small dendrites propagated into adjacent dendrites through the amorphous matrix, and were crossly intersect perpendicularly in widely deformed areas, which beneficially worked for elongation as well as strength.

  12. Tensile and Adhesion Properties of Metal Thin Films Deposited onto Polyester Film Substrate Prepared by a Conventional Vacuum Evaporator

    NASA Astrophysics Data System (ADS)

    Kita, Takuya; Saitoh, Shou; Iwamori, Satoru

    Four kinds of metal, such as aluminum, copper, indium and tin, thin films were deposited onto polyester (PET) substrate by a conventional vacuum evaporator and evaluated their tensile and adhesion properties. The tensile property was estimated by observations of micro-cracks of the thin films due to the tensile test at 150C. The tensile property of the metal thin films seems to relate with Brinell hardness and thickness of the thin film. The adhesion property of these metal thin films was estimated by measuring the pull strength. Aluminum thin film showed highest pull strength of all the thin films, and the pull strength increased with increase of the thickness.

  13. Column strength of magnesium alloy AM-57S

    NASA Technical Reports Server (NTRS)

    Holt, M

    1942-01-01

    Tests were made to determine the column strength of extruded magnesium alloy AM-57S. Column specimens were tested with round ends and with flat ends. It was found that the compressive properties should be used in computations for column strengths rather than the tensile properties because the compressive yield strength was approximately one-half the tensile yield strength. A formula for the column strength of magnesium alloy AM-57S is given.

  14. Biaxial and uniaxial data for statistical comparisons of a ceramic's strength

    NASA Technical Reports Server (NTRS)

    Giovan, M. N.; Sines, G.

    1979-01-01

    The uniaxial and equibiaxial tensile strengths of a brittle material were measured in bending. Equibiaxial tension was attained by concentric ring loading of disks and uniaxial tension by four-point line loading of plates. The two specimen designs give equal volumes, surface areas, and stress gradients. Ground surfaces and lapped surfaces were tested. The equibiaxial tensile strength of a dense alumina was lower than the uniaxial tensile strengths for both ground and lapped surfaces, 8.5 and 8.1%, respectively. The Batdorf theory of flaw statistics, in which biaxial tensile strengths can be predicted from the statistical distribution of uniaxial tensile strength measurements, agreed with the data.

  15. Effect of Root Moisture Content and Diameter on Root Tensile Properties

    PubMed Central

    Yang, Yuanjun; Chen, Lihua; Li, Ning; Zhang, Qiufen

    2016-01-01

    The stabilization of slopes by vegetation has been a topical issue for many years. Root mechanical characteristics significantly influence soil reinforcement; therefore it is necessary to research into the indicators of root tensile properties. In this study, we explored the influence of root moisture content on tensile resistance and strength with different root diameters and for different tree species. Betula platyphylla, Quercus mongolica, Pinus tabulaeformis, and Larix gmelinii, the most popular tree species used for slope stabilization in the rocky mountainous areas of northern China, were used in this study. A tensile test was conducted after root samples were grouped by diameter and moisture content. The results showedthat:1) root moisture content had a significant influence on tensile properties; 2) slightly loss of root moisture content could enhance tensile strength, but too much loss of water resulted in weaker capacity for root elongation, and consequently reduced tensile strength; 3) root diameter had a strong positive correlation with tensile resistance; and4) the roots of Betula platyphylla had the best tensile properties when both diameter and moisture content being controlled. These findings improve our understanding of root tensile properties with root size and moisture, and could be useful for slope stabilization using vegetation. PMID:27003872

  16. Tensile testing of nylon and Kevlar parachute materials under Federal specified temperature and relative humidity conditions

    SciTech Connect

    Botner, W.T.

    1980-01-01

    A small 10-ft x 12-ft temperature and relative humidity controlled room for tensile testing of parachute materials is presented. Tensile tests of nylon and Kevlar parachute materials indicate there is a negligible change in break strength of test samples soaked in the controlled environment vs samples soaked in ambient conditions.

  17. Tensile shock waves in rubber

    NASA Astrophysics Data System (ADS)

    Ravi-Chandar, Krishnaswamy; Niemczura, Johnathan

    2011-03-01

    We examine the propagation of waves of finite deformation in rubbers through experiments and analysis; in particular attention is focused on the propagation of one-dimensional tensile shock waves in strips of latex and nitrile rubber. Tensile wave propagation experiments were conducted at high strain-rates by holding one end fixed and displacing the other end at a constant velocity. A high-speed video camera was used to monitor the motion and to determine the evolution of strain and particle velocity in rubber strips. Shock waves have been generated under tensile impact in pre-stretched rubber strips; analysis of the response yields the tensile shock adiabat for rubbers. The propagation of shocks is analyzed by developing an analogy with the theory of detonation; it is shown that the condition for shock propagation can be determined using the Chapman-Jouguet shock condition.

  18. Tensile Testing: A Simple Introduction

    ERIC Educational Resources Information Center

    Carr, Martin

    2006-01-01

    Tensile testing may be used to decide, say, which steel to use in various constructions. Analogous testing can be done simply in the classroom using plasticine and helps to introduce pupils to the various properties studied in materials science.

  19. Manufacturing of Plutonium Tensile Specimens

    SciTech Connect

    Knapp, Cameron M

    2012-08-01

    Details workflow conducted to manufacture high density alpha Plutonium tensile specimens to support Los Alamos National Laboratory's science campaigns. Introduces topics including the metallurgical challenge of Plutonium and the use of high performance super-computing to drive design. Addresses the utilization of Abaqus finite element analysis, programmable computer numerical controlled (CNC) machining, as well as glove box ergonomics and safety in order to design a process that will yield high quality Plutonium tensile specimens.

  20. Contact hardening of Al interlayer in laminated Mg/Al composites during compressive and tensile loading

    NASA Astrophysics Data System (ADS)

    Gurevich, L.; Pronichev, D.; Trunov, M.

    2016-02-01

    The study presents result of the FEM simulation of Mg alloy/Al/Ti alloy composite under tensile and compression loads. The simulation revealed the strength of Al interlayer at its various thickness values.

  1. Fluid dynamic lateral slicing of high tensile strength carbon nanotubes.

    PubMed

    Vimalanathan, Kasturi; Gascooke, Jason R; Suarez-Martinez, Irene; Marks, Nigel A; Kumari, Harshita; Garvey, Christopher J; Atwood, Jerry L; Lawrance, Warren D; Raston, Colin L

    2016-01-01

    Lateral slicing of micron length carbon nanotubes (CNTs) is effective on laser irradiation of the materials suspended within dynamic liquid thin films in a microfluidic vortex fluidic device (VFD). The method produces sliced CNTs with minimal defects in the absence of any chemical stabilizers, having broad length distributions centred at ca 190, 160 nm and 171 nm for single, double and multi walled CNTs respectively, as established using atomic force microscopy and supported by small angle neutron scattering solution data. Molecular dynamics simulations on a bent single walled carbon nanotube (SWCNT) with a radius of curvature of order 10 nm results in tearing across the tube upon heating, highlighting the role of shear forces which bend the tube forming strained bonds which are ruptured by the laser irradiation. CNT slicing occurs with the VFD operating in both the confined mode for a finite volume of liquid and continuous flow for scalability purposes. PMID:26965728

  2. Fluid dynamic lateral slicing of high tensile strength carbon nanotubes

    PubMed Central

    Vimalanathan, Kasturi; Gascooke, Jason R.; Suarez-Martinez, Irene; Marks, Nigel A.; Kumari, Harshita; Garvey, Christopher J.; Atwood, Jerry L.; Lawrance, Warren D.; Raston, Colin L.

    2016-01-01

    Lateral slicing of micron length carbon nanotubes (CNTs) is effective on laser irradiation of the materials suspended within dynamic liquid thin films in a microfluidic vortex fluidic device (VFD). The method produces sliced CNTs with minimal defects in the absence of any chemical stabilizers, having broad length distributions centred at ca 190, 160 nm and 171 nm for single, double and multi walled CNTs respectively, as established using atomic force microscopy and supported by small angle neutron scattering solution data. Molecular dynamics simulations on a bent single walled carbon nanotube (SWCNT) with a radius of curvature of order 10 nm results in tearing across the tube upon heating, highlighting the role of shear forces which bend the tube forming strained bonds which are ruptured by the laser irradiation. CNT slicing occurs with the VFD operating in both the confined mode for a finite volume of liquid and continuous flow for scalability purposes. PMID:26965728

  3. Tensile strengths of problem shales and clays. Master's thesis

    SciTech Connect

    Rechner, F.J.

    1990-01-01

    The greatest single expense faced by oil companies involved in the exploration for crude oil is that of drilling wells. The most abundant rock drilled is shale. Some of these shales cause wellbore stability problems during the drilling process. These can range from slow rate of penetration and high torque up to stuck pipe and hole abandonment. The mechanical integrity of the shale must be known when the shalers are subjected to drilling fluids to develop an effective drilling plan.

  4. Strength enhancement process for prealloyed powder superalloys

    NASA Technical Reports Server (NTRS)

    Waters, W. J.; Freche, J. C.

    1977-01-01

    A technique involving superplastic processing and high-pressure autoclaving was applied to a nickel-base prealloyed powder alloy. Tensile strengths as high as 2865 MN/sq m (415 ksi) at 480 C (900 F) were obtained with as-superplastically deformed material. Appropriate treatments yielding materials with high-temperature tensile and stress-rupture strengths (980 C (1800 F)) were also devised.

  5. Collagen network strengthening following cyclic tensile loading.

    PubMed

    Susilo, Monica E; Paten, Jeffrey A; Sander, Edward A; Nguyen, Thao D; Ruberti, Jeffrey W

    2016-02-01

    The bulk mechanical properties of tissues are highly tuned to the physiological loads they experience and reflect the hierarchical structure and mechanical properties of their constituent parts. A thorough understanding of the processes involved in tissue adaptation is required to develop multi-scale computational models of tissue remodelling. While extracellular matrix (ECM) remodelling is partly due to the changing cellular metabolic activity, there may also be mechanically directed changes in ECM nano/microscale organization which lead to mechanical tuning. The thermal and enzymatic stability of collagen, which is the principal load-bearing biopolymer in vertebrates, have been shown to be enhanced by force suggesting that collagen has an active role in ECM mechanical properties. Here, we ask how changes in the mechanical properties of a collagen-based material are reflected by alterations in the micro/nanoscale collagen network following cyclic loading. Surprisingly, we observed significantly higher tensile stiffness and ultimate tensile strength, roughly analogous to the effect of work hardening, in the absence of network realignment and alterations to the fibril area fraction. The data suggest that mechanical loading induces stabilizing changes internal to the fibrils themselves or in the fibril-fibril interactions. If such a cell-independent strengthening effect is operational in vivo, then it would be an important consideration in any multiscale computational approach to ECM growth and remodelling. PMID:26855760

  6. Evaluation of Transverse Tensile Stress Characteristics of GdBCO Coated Conductors

    NASA Astrophysics Data System (ADS)

    Sato, H.; Nakamura, N.; Fujita, S.; Daibo, M.; Iijima, Y.

    Recently, GdBCO coated conductor (CC) coils for high field magnets are investigated for practical use. GdBCO CC coils are subjected to longitudinal and transverse tensile stresses in their operation, so there is some research for mechanical properties of the GdBCO CCs in the recent years. Fujikura has also researched mechanical properties, for example, tensile or delamination strength, of the GdBCO CCs. In this report, we investigated pin-pull delamination test in Liquid nitrogen (LN2) to research mechanical delamination and critical current (Ic) degradation strength. We found out mechanical delamination strength is corresponding to Ic degradation strength. In addition, we experiment repeated transverse tensile stress on GdBCO CCs in LN2, most of the samples have more than 50 times at 50 MPa, which corresponds to single delamination strength, and there is no Ic degradation before mechanical delamination.

  7. Cryogenic Temperature-Gradient Foam/Substrate Tensile Tester

    NASA Technical Reports Server (NTRS)

    Vailhe, Christophe

    2003-01-01

    The figure shows a fixture for measuring the tensile strength of the bond between an aluminum substrate and a thermally insulating polymeric foam. The specimen is meant to be representative of insulating foam on an aluminum tank that holds a cryogenic liquid. Prior to the development of this fixture, tensile tests of this type were performed on foam/substrate specimens immersed in cryogenic fluids. Because the specimens were cooled to cryogenic temperatures throughout their thicknesses, they tended to become brittle and to fracture at loads below true bond tensile strengths. The present fixture is equipped to provide a thermal gradient from cryogenic temperature at the foam/substrate interface to room temperature on the opposite foam surface. The fixture includes an upper aluminum block at room temperature and a lower aluminum block cooled to -423 F (approx. -253 C) by use of liquid helium. In preparation for a test, the metal outer surface (the lower surface) of a foam/substrate specimen is bonded to the lower block and the foam outer surface (the upper surface) of the specimen is bonded to the upper block. In comparison with the through-the-thickness cooling of immersion testing, the cryogenic-to-room-temperature thermal gradient that exists during testing on this fixture is a more realistic approximation of the operational thermal condition of sprayed insulating foam on a tank of cryogenic liquid. Hence, tensile tests performed on this fixture provide more accurate indications of operational bond tensile strengths. In addition, the introduction of the present fixture reduces the cost of testing by reducing the amount of cryogenic liquid consumed and the time needed to cool a specimen.

  8. Tensile Properties of Electrodeposited Nanocrystalline Ni-Cu Alloys

    NASA Astrophysics Data System (ADS)

    Dai, P. Q.; Zhang, C.; Wen, J. C.; Rao, H. C.; Wang, Q. T.

    2016-01-01

    Nanocrystalline Ni-Cu alloys with a Cu content of 6, 10, 19, and 32 wt.% were prepared by pulse electrodeposition. The microstructure and tensile properties of the nanocrystalline Ni-Cu alloys were characterized by x-ray diffraction, transmission electron microscopy, and tensile testing. The x-ray diffraction analysis indicates that the structure of the nanocrystalline Ni-Cu alloys is a face-centered cubic, single-phase solid solution with an average grain size of 18 to 24 nm, and that the average grain size decreased with increasing Cu content. The ultimate tensile strength (~1265 to 1640 MPa) and elongation to failure (~5.8 to 8.9%) of the Ni-Cu alloys increased with increasing Cu content. The increase in tensile strength results from the solid solution and fine-grain strengthening. Elemental Cu addition results in a decrease in stacking fault energy, an increase in work hardening rate, a delay in plasticity instability, and consequently, a higher plasticity.

  9. Tensile and creep data on type 316 stainless steel

    SciTech Connect

    Sikka, V. K.; Booker, B. L.P.; Booker, M. K.; McEnerney, J. W.

    1980-01-01

    This report summarizes tensile and creep data on 13 heats of type 316 stainless steel. It includes ten different product forms (three plates, four pipes, and three bars) of the reference heat tested at ORNL. Tensile data are presented in tabular form and analyzed as a function of temperature by the heat centering method. This method yielded a measure of variations within a single heat as well as among different heats. The upper and lower scatter bands developed by this method were wider at the lower temperatures than at the high temperatures (for strength properties), a trend reflected by the experimental data. The creep data on both unaged and aged specimens are presented in tabular form along with creep curves for each test. The rupture time data are compared with the ASME Code Case minimum curve at each test temperature in the range from 538 to 704{sup 0}C. The experimental rupture time data are also compared with the values predicted by using the rupture model based on elevated-temperature ultimate tensile strength. A creep ductility trend curve was developed on the basis of the reference heat data and those published in the literature on nitrogen effects. To characterize the data fully, information was also supplied on vendor, product form, fabrication method, material condition (mill-annealed vs laboratory annealed and aged), grain size, and chemical composition for various heats. Test procedures used for tensile and creep results are also discussed.

  10. Tensile Behavior of Al2o3/feal + B and Al2o3/fecraly Composites

    NASA Technical Reports Server (NTRS)

    Draper, S. L.; Eldridge, J. I.; Aiken, B. J. M.

    1995-01-01

    The feasibility of Al2O3/FeAl + B and Al2O3/FeCrAlY composites for high-temperature applications was assessed. The major emphasis was on tensile behavior of both the monolithics and composites from 298 to 1100 K. However, the study also included determining the chemical compatibility of the composites, measuring the interfacial shear strengths, and investigating the effect of processing on the strength of the single-crystal Al2O3 fibers. The interfacial shear strengths were low for Al203/FeAl + B and moderate to high for Al203/FeCrAlY. The difference in interfacial bond strengths between the two systems affected the tensile behavior of the composites. The strength of the Al203 fiber was significantly degraded after composite processing for both composite systems and resulted in poor composite tensile properties. The ultimate tensile strength (UTS) values of the composites could generally be predicted with either rule of mixtures (ROM) calculations or existing models when using the strength of the etched-out fiber. The Al2O3/FeAl + B composite system was determined to be unfeasible due to poor interfacial shear strengths and a large mismatch in coefficient of thermal expansion (CTE). Development of the Al2O3/FeCrAlY system would require an effective diffusion barrier to minimize the fiber strength degradation during processing and elevated temperature service.

  11. Extreme strength observed in limpet teeth

    PubMed Central

    Barber, Asa H.; Lu, Dun; Pugno, Nicola M.

    2015-01-01

    The teeth of limpets exploit distinctive composite nanostructures consisting of high volume fractions of reinforcing goethite nanofibres within a softer protein phase to provide mechanical integrity when rasping over rock surfaces during feeding. The tensile strength of discrete volumes of limpet tooth material measured using in situ atomic force microscopy was found to range from 3.0 to 6.5 GPa and was independent of sample size. These observations highlight an absolute material tensile strength that is the highest recorded for a biological material, outperforming the high strength of spider silk currently considered to be the strongest natural material, and approaching values comparable to those of the strongest man-made fibres. This considerable tensile strength of limpet teeth is attributed to a high mineral volume fraction of reinforcing goethite nanofibres with diameters below a defect-controlled critical size, suggesting that natural design in limpet teeth is optimized towards theoretical strength limits. PMID:25694539

  12. Extreme strength observed in limpet teeth.

    PubMed

    Barber, Asa H; Lu, Dun; Pugno, Nicola M

    2015-04-01

    The teeth of limpets exploit distinctive composite nanostructures consisting of high volume fractions of reinforcing goethite nanofibres within a softer protein phase to provide mechanical integrity when rasping over rock surfaces during feeding. The tensile strength of discrete volumes of limpet tooth material measured using in situ atomic force microscopy was found to range from 3.0 to 6.5 GPa and was independent of sample size. These observations highlight an absolute material tensile strength that is the highest recorded for a biological material, outperforming the high strength of spider silk currently considered to be the strongest natural material, and approaching values comparable to those of the strongest man-made fibres. This considerable tensile strength of limpet teeth is attributed to a high mineral volume fraction of reinforcing goethite nanofibres with diameters below a defect-controlled critical size, suggesting that natural design in limpet teeth is optimized towards theoretical strength limits. PMID:25694539

  13. Weld width indicates weld strength

    NASA Technical Reports Server (NTRS)

    Nunes, A. C. J.; Novak, H. L.; Mcllwain, M. C.

    1982-01-01

    Width of butt weld in 2219-T87 aluminum has been found to be more reliable indicator of weld strength than more traditional parameters of power input and cooling rate. Yield stress and ultimate tensile strength tend to decrease with weld size. This conclusion supports view of many professional welders who give priority to weld geometry over welding energy or cooling rate as indicator of weld quality.

  14. The Cryogenic Tensile Properties of an Extruded Aluminum-Beryllium Alloy

    NASA Technical Reports Server (NTRS)

    Gamwell, W. R.

    2002-01-01

    Basic mechanical properties; i.e., ultimate tensile strength, yield strength, percent elongation, and elastic modulus, were obtained for the aluminum-beryllium alloy, AlBeMet162, at cryogenic (-195.5 C (-320 F) and -252.8 C (-423 F)) temperatures. The material evaluated was purchased to the requirements of SAE-AMS7912, "Aluminum-Beryllium Alloy, Extrusions."

  15. Mechanical tensile testing of titanium 15-3-3-3 and Kevlar 49 at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    James, B. L.; Martinez, R. M.; Shirron, P.; Tuttle, J.; Galassi, N. M.; McGuinness, D. S.; Puckett, D.; Francis, J. J.; Flom, Y.

    2012-06-01

    Titanium 15-3-3-3 and Kevlar 49 are highly desired materials for structural components in cryogenic applications due to their low thermal conductivity at low temperatures. Previous tests have indicated that titanium 15-3-3-3 becomes increasingly brittle as the temperature decreases. Furthermore, little is known regarding the mechanical properties of Kevlar 49 at low temperatures, most specifically its Young's modulus. This testing investigates the mechanical properties of both materials at cryogenic temperatures through cryogenic mechanical tensile testing to failure. The elongation, ultimate tensile strength, yield strength, and break strength of both materials are provided and analyzed here.

  16. Manual for LDEF tensile tests

    NASA Technical Reports Server (NTRS)

    Witte, W. G., Jr.

    1985-01-01

    One of the experiments aboard the NASA Long Duration Exposure Facility (LDEF) consists of a tray of approximately one hundred tensile specimens of several candidate space structure composite materials. During the LDEF flight the materials will be subjected to the space environment and to possible contamination during launch and recovery. Tensile tests of representative samples were made before the LDEF flight to obtain baseline data. Similar tests will be made on control specimens stored on earth for the length of the LDEF flight and on recovered flight specimens. This manual codifies the details of testing, data acquisition, and handling used in obtaining the baseline data so that the same procedures and equipment will be used on the subsequent tests.

  17. Distributed measurements of fiber birefringence and diametric load using optical low-coherence reflectometry and fiber gratings.

    PubMed

    Coric, Dragan; Limberger, Hans G; Salathé, René P

    2006-11-27

    Polarization sensitive optical low-coherence reflectometry (OLCR) is used for measuring the complex fiber Bragg gratings (FBG) reflection coefficient. We determine the beat length directly from oscillations in the OLCR amplitude with a resolution of 10(-6) and a spatial resolution only limited by the minimum beat length or the coherence length of the light source. Using the OLCR amplitude and phase in combination with an inverse scattering algorithm the birefringence is retrieved with a resolution of 2x10(-5) while the spatial resolution is 25 mum. The two developed techniques are applied for measuring position, magnitude and footprint of induced birefringence of an FBG under uniform and non-uniform diametric loading. PMID:19529603

  18. The connection between load distribution and fracture load in the diametral compression test. An experimental study.

    PubMed

    Ehrnford, L

    1980-01-01

    Dental stone specimens (diameter 41,5 mm, length 14,0 mm) manufactured with water/powder ratios 0.22 (unimpregnated and polymethylmethacrylate-impregnated specimens) and 0.30 were loaded by direct contact with the platens of the testing device and with interposed soft paddings of varying thickness and width. To ensure an even load distribution, in some experiments, inserts of aluminium with one side vaulted were inserted next to the platens. The experiments showed that: - if strip shaped paddings were inserted which were as wide as the contact surface formed on direct contact, the load required for fracture did not change; - if the contact surfaces were reduced by means of strip-shaped paddings, fracture load was considerably reduced even for small changes in the load bearing area; - if the contact surface was increased, by means of wide paddings or vaulted inserts, the fracture load also increased. The results could not be explained on the basis of statistical fracture theories. This conclusion was supported by some experiments with miniature specimens. A probabel explantation would, however, be that below a critical load distribution parasitic stresses are generated which entail fractures with fracture patterns which do not distinctively deviate from what previously has been considered as typical for valid tensile fractures. PMID:6940252

  19. Study on strength, elastic modulus of artifical lightweight aggregate concrete

    NASA Astrophysics Data System (ADS)

    Kakizaki, M.

    1982-04-01

    Aggregate strength of artificial lightweight concrete and concrete used with this artificial lightweight aggregate can be expected to have nearly the same strength as normal weight concrete. An experimental study of properties of concrete strength and correlation between compressive and tensile and flexural strengths and elastic modulus of its concrete was made.

  20. Tensile Properties of Boronized N80 Steel Tube Cooled by Different Methods

    NASA Astrophysics Data System (ADS)

    Tian, X.; Yang, Y. L.; Sun, S. J.; An, J.; Lu, Y.; Wang, Z. G.

    2009-03-01

    The microstructures and tensile properties of boronized N80 steel pipes by pack boriding under four different cooling conditions were investigated. The boride layer was composed of FeB and Fe2B phases with a hardness range of 1200-1600 HV. Fan cooling and fan cooling with a graphite bar in the center of the boriding agent were employed to improve the tensile properties. As cooling velocity was increased, the thickness of boride layer and grain size of the steel substrate were consequently reduced, whereas the pearlite volume in steel substrate was increased, resulting in improvement of tensile properties. Boronized N80 steel pipe which was fan cooled with a graphite bar inside possessed the highest ultimate tensile strength and yield strength, in accordance with the mechanical properties required by API SPEC 5L. Fracture surface analysis revealed that the boronized N80 steel showed ductile fracture at room temperature.

  1. Insights into the effects of tensile and compressive loadings on human femur bone

    PubMed Central

    Havaldar, Raviraj; Pilli, S. C.; Putti, B. B.

    2014-01-01

    Background: Fragile fractures are most likely manifestations of fatigue damage that develop under repetitive loading conditions. Numerous microcracks disperse throughout the bone with the tensile and compressive loads. In this study, tensile and compressive load tests are performed on specimens of both the genders within 19 to 83 years of age and the failure strength is estimated. Materials and Methods: Fifty five human femur cortical samples are tested. They are divided into various age groups ranging from 19-83 years. Mechanical tests are performed on an Instron 3366 universal testing machine, according to American Society for Testing and Materials International (ASTM) standards. Results: The results show that stress induced in the bone tissue depends on age and gender. It is observed that both tensile and compression strengths reduces as age advances. Compressive strength is more than tensile strength in both the genders. Conclusion: The compression and tensile strength of human femur cortical bone is estimated for both male and female subjecting in the age group of 19-83 years. The fracture toughness increases till 35 years in male and 30 years in female and reduces there after. Mechanical properties of bone are age and gender dependent. PMID:24800190

  2. Probabilistic Modeling of Ceramic Matrix Composite Strength

    NASA Technical Reports Server (NTRS)

    Shan, Ashwin R.; Murthy, Pappu L. N.; Mital, Subodh K.; Bhatt, Ramakrishna T.

    1998-01-01

    Uncertainties associated with the primitive random variables such as manufacturing process (processing temperature, fiber volume ratio, void volume ratio), constituent properties (fiber, matrix and interface), and geometric parameters (ply thickness, interphase thickness) have been simulated to quantify the scatter in the first matrix cracking strength (FMCS) and the ultimate tensile strength of SCS-6/RBSN (SiC fiber (SCS-6) reinforced reaction-bonded silicon nitride composite) ceramic matrix composite laminate at room temperature. Cumulative probability distribution function for the FMCS and ultimate tensile strength at room temperature (RT) of (0)(sub 8), (0(sub 2)/90(sub 2), and (+/-45(sub 2))(sub S) laminates have been simulated and the sensitivity of primitive variables to the respective strengths have been quantified. Computationally predicted scatter of the strengths for a uniaxial laminate have been compared with those from limited experimental data. Also the experimental procedure used in the tests has been described briefly. Results show a very good agreement between the computational simulation and the experimental data. Dominating failure modes in (0)(sub 8), (0/90)(sub s) and (+/-45)(sub S) laminates have been identified. Results indicate that the first matrix cracking strength for the (0)(sub S), and (0/90)(sub S) laminates is sensitive to the thermal properties, modulus and strengths of both the fiber and matrix whereas the ultimate tensile strength is sensitive to the fiber strength and the fiber volume ratio. In the case of a (+/-45)(sub S), laminate, both the FMCS and the ultimate tensile strengths have a small scatter range and are sensitive to the fiber tensile strength as well as the fiber volume ratio.

  3. Development of High Specific Strength Envelope Materials

    NASA Astrophysics Data System (ADS)

    Komatsu, Keiji; Sano, Masa-Aki; Kakuta, Yoshiaki

    Progress in materials technology has produced a much more durable synthetic fabric envelope for the non-rigid airship. Flexible materials are required to form airship envelopes, ballonets, load curtains, gas bags and covering rigid structures. Polybenzoxazole fiber (Zylon) and polyalirate fiber (Vectran) show high specific tensile strength, so that we developed membrane using these high specific tensile strength fibers as a load carrier. The main material developed is a Zylon or Vectran load carrier sealed internally with a polyurethane bonded inner gas retention film (EVOH). The external surface provides weather protecting with, for instance, a titanium oxide integrated polyurethane or Tedlar film. The mechanical test results show that tensile strength 1,000 N/cm is attained with weight less than 230g/m2. In addition to the mechanical properties, temperature dependence of the joint strength and solar absorptivity and emissivity of the surface are measured. 

  4. Inert strength of pristine silica glass fibers

    SciTech Connect

    Smith, W.L.; Michalske, T.A.

    1993-11-01

    Silica glass fibers have been produced and tested under ultra high vacuum (UHV) conditions to investigate the inert strength of pristine fibers in absence of reactive agents. Analysis of the coefficient of variation in diameter ({upsilon}{sub d}) vs the coefficient of variation of breaking strength ({upsilon}{sub {sigma}}) does not adequately explain the variation of breaking stress. Distribution of fiber tensile strength data suggests that the inert strength of such fibers is not single valued and that the intrinsic strength is controlled by defects in the glass. Furthermore, comparison of room temperature UHV data with LN{sub 2} data indicates that these intrinsic strengths are not temperature dependent.

  5. The tensile behavior of porous metals made by GASAR process

    SciTech Connect

    Kovacik, J.

    1998-09-18

    The tensile behavior of porous metals (Cu, Ni) made by the solid-gas eutectic solidification (GASAR) process was studied with respect to the macro- and microscopic point of view. In the macroscopic approach, the percolation power-law dependence of the tensile properties on porosity was observed. Obtained characteristic exponents of 0.2% yield stress, ultimate tensile strength and strain at peak stress were related to the value of the critical exponent of the modulus of elasticity predicted by percolation theory. The ductility of solid copper can explain the variations in the values of the obtained characteristic exponents for porous copper. In the microscopic approach, the modified model for out-of-plane tension of regular honeycombs was used to relate tensile behavior of porous metals with microstructure. The model failed at high porosity due to the irregular structure of the porous metals. This indicates that any model based on the regular structure is not valid and supports the validity of the percolation model.

  6. High-temperature tensile properties of fiber reinforced reaction bonded silicon nitride

    NASA Technical Reports Server (NTRS)

    Jablonski, David A.; Bhatt, Ramakrishna T.

    1990-01-01

    Measurements of tensile properties of unidirectional silicon carbide fiber-reinforced reaction-bonded silicon nitride (SiC/RBSN) composite specimens were carried out in air at 25, 1300, and 1500 C, using a new testing technique and a specially designed gripping system that minimizes bending moment and assures that failure always occurred in the gage section. The material was found to display metallike stress-strain behavior at all temperatures tested, and a noncatastrophic failure beyond the matrix fracture. The tensile properties were found to be temperature dependent, with the values of the ultimate tensile strength decreasing with temperature, from 543 MPa at 25 C to 169 at 1500 C.

  7. Microstructure and tensile properties of thixoformed A356 alloy

    SciTech Connect

    Tahamtan, S.; Golozar, M.A. Karimzadeh, F.; Niroumand, B.

    2008-03-15

    In the research work presented here, mechanical properties of a thixoformed A356 alloy were measured and compared with the mechanical properties of rheocast and gravity-cast alloy with the same composition. In the thixoforming process, a 60% solid fraction rheocast alloy was reheated to 600 deg. C or 610 deg. C, held about 10 min, and then reduced by 30% or 50% reduction of cross section. Microstructural and mechanical properties of the alloys were investigated. The results obtained show that the tensile strength, yield strength and elongation-to-failure of the alloy thixoformed at 600 deg. C was greater than that thixoformed at 610 deg. C. Moreover, the tensile strength, yield strength and elongation-to-failure of the thixoformed alloy were higher than those of the rheocast and gravity-cast samples. The improvement in the mechanical properties due to thixoforming is attributed to morphological aspects of the silicon phase, as well as to the non-dendritic structure produced.

  8. Tensile Hoop Behavior of Irradiated Zircaloy-4 Nuclear Fuel Cladding

    SciTech Connect

    Jaramillo, Roger A; Hendrich, WILLIAM R; Packan, Nicolas H

    2007-03-01

    A method for evaluating the room temperature ductility behavior of irradiated Zircaloy-4 nuclear fuel cladding has been developed and applied to evaluate tensile hoop strength of material irradiated to different levels. The test utilizes a polyurethane plug fitted within a tubular cladding specimen. A cylindrical punch is used to compress the plug axially, which generates a radial displacement that acts upon the inner diameter of the specimen. Position sensors track the radial displacement of the specimen outer diameter as the compression proceeds. These measurements coupled with ram force data provide a load-displacement characterization of the cladding response to internal pressurization. The development of this simple, cost-effective, highly reproducible test for evaluating tensile hoop strain as a function of internal pressure for irradiated specimens represents a significant advance in the mechanical characterization of irradiated cladding. In this project, nuclear fuel rod assemblies using Zircaloy-4 cladding and two types of mixed uranium-plutonium oxide (MOX) fuel pellets were irradiated to varying levels of burnup. Fuel pellets were manufactured with and without thermally induced gallium removal (TIGR) processing. Fuel pellets manufactured by both methods were contained in fuel rod assemblies and irradiated to burnup levels of 9, 21, 30, 40, and 50 GWd/MT. These levels of fuel burnup correspond to fast (E > 1 MeV) fluences of 0.27, 0.68, 0.98, 1.4 and 1.7 1021 neutrons/cm2, respectively. Following irradiation, fuel rod assemblies were disassembled; fuel pellets were removed from the cladding; and the inner diameter of cladding was cleaned to remove residue materials. Tensile hoop strength of this cladding material was tested using the newly developed method. Unirradiated Zircaloy-4 cladding was also tested. With the goal of determining the effect of the two fuel types and different neutron fluences on clad ductility, tensile hoop strength tests were performed on cladding for these varying conditions. Experimental data revealed negligible performance differences for cladding containing TIGR vs non-TIGR processed fuel pellets. Irradiation hardening was observed in tensile hoop data as the strength of the cladding increased with increasing neutron dose and appeared to saturate for a fast fluence of 1.7 1021 neutrons/cm2.

  9. Changes in boron fiber strength due to surface removal by chemical etching

    NASA Technical Reports Server (NTRS)

    Smith, R. J.

    1976-01-01

    The effects of chemical etching on the tensile strength of commercial boron/tungsten fibers were investigated. Fibers with as-received diameters of 203, 143, and 100 micrometers were etched to diameters as small as 43 micrometers. The etching generally resulted in increasing fiber tensile strength with decreasing fiber diameter. And for the 203 micrometer fibers there was an accompanying significant decrease in the coefficient of variation of the tensile strength for diameters down to 89 micrometers. Heat treating these fibers above 1,173 K in a vacuum caused a marked decrease in the average tensile strength of at least 80 percent. But after the fibers were etched, their strengths exceeded the as-received strengths. The tensile strength behavior is explained in terms of etching effects on surface flaws and the residual stress pattern of the as-received fibers.

  10. Tensile behavior of the L(1)2 compound Al67Ti25Cr8

    NASA Technical Reports Server (NTRS)

    Kumar, K. S.; Brown, S. A.

    1992-01-01

    Temperature-related variations in tensile yield strength and ductility were studied on cast, homogenized and isothermally forged Al67Ti25Cr8. Yield strength dropped discontinuously between 623 K and 773 K and then decreased gradually with increasing temperature. Below 623 K, fracture occurred prior to macroscopic yielding. Ductility decreased from 0.2 percent at 623 K to zero at 773 K, but increased again at higher temperatures. At 1073 K, an elongation of 19 percent was obtainable, and ultimate tensile strength and localized necking were observed. Fracture surfaces and deformed microstructures were examined. The 1073 K tensile specimen that exhibited 19 percent elongation showed grain boundary serrations and some evidence of recrystallization (likely dynamic) although fracture occurred predominantly via an intergranular mode.

  11. Study on ARALL failure behavior under tensile loading

    SciTech Connect

    Yan Hai; Ren Rongzhen; Tao Chunhu; Li Hongyun

    1996-12-15

    This paper studies the failure behavior of ARALL (Aramid Aluminum Laminate) under tensile loading by means of acoustic emission (AE), optical metallography (OM) and scanning electronic microscope (SEM), and analyzes the fracture appearance of ARALL and its fracture characteristics. The damage models of ARALL are concluded in this paper. The results show that ARALL will yield under tensile loading, and its strength will decrease as the content of resin increases. During fracture process, AE amplitude distribution curves show that there are three obvious peaks, which respectively correspond to separation of the interface between fibers and resin, local delamination damage and fracture of a small quantity of fibers, and delamination damage of large area and final fracture of a large numbers of fibers. Dynamic damage and fracture process of ARALL can be detected by AE.

  12. Tensile Properties and Fracture Behavior of Different Carbon Nanotube-Grafted Polyacrylonitrile-Based Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi

    2014-11-01

    The tensile properties and fracture behavior of different carbon nanotube (CNT)-grafted polyacrylonitrile-based (T1000GB) single carbon fibers were investigated. Grafting of CNTs was achieved via chemical vapor deposition (CVD). When Fe(C5H5)2 (also applied via CVD) was used as the catalyst, the tensile strength and Weibull modulus of the carbon fibers were improved, possibly due to the growth of dense CNT networks on the carbon fibers, which may have led to a reduction in the number of strength-limiting defects. Separately, at lower concentrations of an Fe(NO3)3·9H2O catalyst in ethanol, which was applied via dipping, the tensile strength of CNT-grafted fibers was nearly identical to that of the as-received fibers, although the Weibull modulus was higher. For higher concentrations of the Fe(NO3)3·9H2O catalyst, however, the tensile strength and the Weibull modulus were lower than those for the as-received material. Although the density of the CNT network increased with the concentration of the Fe(NO3)3·9H2O catalyst in the ethanol solution, heating of the ethanolic Fe(NO3)3·9H2O catalyst solution generated nitric acid (HNO3) due to decomposition, which damaged the fiber surfaces, resulting in an increase in the number of flaws and consequently a reduction in the tensile strength. Therefore, the tensile strength and Weibull modulus of CNT-grafted carbon fibers vary due to the combination of these effects and as a function of the catalyst concentration.

  13. An Assessment of Variability in the Average Tensile Properties of a Melt-Infiltrated SiC/SiC Composite

    NASA Technical Reports Server (NTRS)

    Kalluri, Sreeramesh; Brewer, David N.; Calomino, Anthony M.

    2004-01-01

    Woven SiC/SiC Ceramic Matrix Composites (CMCs), manufactured by the slurry-cast, melt-infiltration process are under consideration as combustor liner materials in aircraft gas turbine engines. Tensile properties (elastic modulus, proportional limit strength, in-plane tensile strength and strain to failure) of the CMC, manufactured during two separate time periods (9/99 and 1/01) were determined at 816 and 1024 C by conducting tensile tests on specimens machined from the CMC plates. A total of 24 tensile tests were conducted for each temperature and CMC variant combination. In this study average tensile properties of the two cMC variants were statistically compared to evaluate significant differences, if any, within the CMC's properties.

  14. A cryo-jaw designed for in vitro tensile testing of the healing Achilles tendons in rats.

    PubMed

    Wieloch, Peter; Buchmann, Gerhard; Roth, Wolfgang; Rickert, Markus

    2004-11-01

    We present a simple but very secure non-compressive clamping device for in vitro tensile testing of the Achilles tendon in rats. Biomechanical studies were performed on 178 native and injured specimens without any registration of slippage out of the clamp. The average tensile strength of the native rat Achilles tendon was determined to be 48 N (+/-11 N) and its displacement to failure averaged 0.8 mm (+/-0.2 mm). The mean values for tensile strength within the injured tendons increased with time and were above the native tendon values from week 2 and later. Correspondingly, the displacement to failure decreased with time. PMID:15388314

  15. Tensile Properties of Hydrogels and of Snake Skin

    NASA Technical Reports Server (NTRS)

    Hinkley, Jeffrey A.; Savitzky, Alan H.; Rivera, Gabriel; Gehrke, Stevin H.

    2002-01-01

    Stimulus-responsive or 'smart' gels are of potential interest as sensors and actuators, in industrial separations, and as permeable delivery systems. In most applications, a certain degree of mechanical strength and toughness will be required, yet the large-strain behavior of gels has not been widely reported. Some exceptions include work on gelatin and other food gels, some characterization of soft gels applicable for in-vitro cell growth studies, and toughness determinations on commercial contact lens materials. In general, it can be anticipated that the gel stiffness will increase with increasing degree of crosslinking, but the tensile strength may go through a maximum. Gel properties can be tailored by varying not only the degree of crosslinking, but also the polymer concentration and the nature of the polymer backbone (e.g. its stiffness or solubility). Polypeptides provide an especially interesting case, where secondary structure affects trends in moduli and conformational transitions may accompany phase changes. A few papers on the tensile properties of responsive gels have begun to appear. The responsive hydrogel chosen for the present study, crosslinked hydroxypropylcellulose, shrinks over a rather narrow temperature range near 44 C. Some vertebrate skin is also subject to substantial strain. Among reptiles, the morphologies of the skin and scales show wide variations. Bauer et al. described the mechanical properties and histology of gecko skin; longitudinal tensile properties of snake skin were examined by Jayne with reference to locomotion. The present measurements focus on adaptations related to feeding, including the response of the skin to circumferential tension. Tensile properties will be related to interspecific and regional variation in skin structure and folding.

  16. Tensile test of pressureless-sintered silicon nitride at elevated temperature

    NASA Technical Reports Server (NTRS)

    Matsusue, K.; Fujisawa, Y.; Takahara, K.

    1985-01-01

    Uniaxial tensile strength tests of pressureless sintered silicon nitride were carried out in air at temperatures ranging from room temperature up to 1600 C. Silicon nitrides containing Y2O3, Al2O3, Al2O3-MgO, or MgO-CeO2 additives were tested. The results show that the composition of the additive used influences the strength characteristics of the silicon nitride. The tensile strength rapidly decreased at temperatures above 1000 C for the materials containing MgO as the additive and above 1000 C for the material with Y2O3. When the temperature increased to as high as 1300 C, the strength decreased to about 10 percent of the room temperature strength in each case. Observations of the fracture origin and of the crack propagation on the fracture surfaces are discussed.

  17. Probabilistic simulation of uncertainties in composite uniaxial strengths

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.; Stock, T. A.

    1990-01-01

    Probabilistic composite micromechanics methods are developed that simulate uncertainties in unidirectional fiber composite strengths. These methods are in the form of computational procedures using composite mechanics with Monte Carlo simulation. The variables for which uncertainties are accounted include constituent strengths and their respective scatter. A graphite/epoxy unidirectional composite (ply) is studied to illustrate the procedure and its effectiveness to formally estimate the probable scatter in the composite uniaxial strengths. The results show that ply longitudinal tensile and compressive, transverse compressive and intralaminar shear strengths are not sensitive to single fiber anomalies (breaks, intergacial disbonds, matrix microcracks); however, the ply transverse tensile strength is.

  18. Micro-tensile testing system

    DOEpatents

    Wenski, Edward G. (Lenexa, KS)

    2007-08-21

    A micro-tensile testing system providing a stand-alone test platform for testing and reporting physical or engineering properties of test samples of materials having thicknesses of approximately between 0.002 inch and 0.030 inch, including, for example, LiGA engineered materials. The testing system is able to perform a variety of static, dynamic, and cyclic tests. The testing system includes a rigid frame and adjustable gripping supports to minimize measurement errors due to deflection or bending under load; serrated grips for securing the extremely small test sample; high-speed laser scan micrometers for obtaining accurate results; and test software for controlling the testing procedure and reporting results.

  19. Micro-tensile testing system

    DOEpatents

    Wenski, Edward G. (Lenexa, KS)

    2007-07-17

    A micro-tensile testing system providing a stand-alone test platform for testing and reporting physical or engineering properties of test samples of materials having thicknesses of approximately between 0.002 inch and 0.030 inch, including, for example, LiGA engineered materials. The testing system is able to perform a variety of static, dynamic, and cyclic tests. The testing system includes a rigid frame and adjustable gripping supports to minimize measurement errors due to deflection or bending under load; serrated grips for securing the extremely small test sample; high-speed laser scan micrometers for obtaining accurate results; and test software for controlling the testing procedure and reporting results.

  20. Micro-tensile testing system

    DOEpatents

    Wenski, Edward G.

    2006-01-10

    A micro-tensile testing system providing a stand-alone test platform for testing and reporting physical or engineering properties of test samples of materials having thicknesses of approximately between 0.002 inch and 0.030 inch, including, for example, LiGA engineered materials. The testing system is able to perform a variety of static, dynamic, and cyclic tests. The testing system includes a rigid frame and adjustable gripping supports to minimize measurement errors due to deflection or bending under load; serrated grips for securing the extremely small test sample; high-speed laser scan micrometers for obtaining accurate results; and test software for controlling the testing procedure and reporting results.

  1. Effects of strain rate on tensile properties of TZM and Mo-5%Re

    NASA Astrophysics Data System (ADS)

    Filacchioni, G.; Casagrande, E.; De Angelis, U.; De Santis, G.; Ferrara, D.

    2002-12-01

    In the present work, we have studied the strain rate sensitivity of tensile properties of TZM and Mo-5%Re alloys. Tests were performed at room temperature and around the transition temperature of each alloy, at strain rates varying over five decades. Ductility appeared insensitive to strain rate, whereas the strength is found to be strain rate dependent. Both proof stress and ultimate tensile strength are affected by strain rate and the Mo-5%Re alloy is more sensitive than TZM. As expected, the hardening decreases with temperature; in TZM alloy the strain rate sensitivity was apparent only at room temperature.

  2. Galvanic corrosion induced degredation of tensile properties in micromachined polycrystalline silicon

    NASA Astrophysics Data System (ADS)

    Miller, David C.; Boyce, Brad L.; Gall, Ken; Stoldt, Conrad R.

    2007-05-01

    Immersion of polycrystalline silicon in hydrofluoric acid-based solutions is often utilized in microsystem fabrication to liberate mechanical structures. The authors demonstrate, using microfabricated tensile specimens, that such etching can cause a catastrophic reduction in tensile strength and elastic modulus in silicon galvanically coupled to a metallic layer, such as commonly used gold. Galvanically corroded silicon exhibits grain-boundary attack leading to intergranular fracture and/or generalized material removal. The severity of damage and corresponding losses in strength and modulus depend on etch duration and etch chemistry. In contrast, without a metallic layer, uncorroded silicon fails transgranularly and independent of etch duration or chemistry.

  3. Apple Strength Issues

    SciTech Connect

    Syn, C

    2009-12-22

    Strength of the apple parts has been noticed to decrease, especially those installed by the new induction heating system since the LEP campaign started. Fig. 1 shows the ultimate tensile strength (UTS), yield strength (YS), and elongation of the installed or installation-simulated apples on various systems. One can clearly see the mean values of UTS and YS of the post-LEP parts decreased by about 8 ksi and 6 ksi respectively from those of the pre-LEP parts. The slight increase in elongation seen in Fig.1 can be understood from the weak inverse relationship between the strength and elongation in metals. Fig.2 shows the weak correlation between the YS and elongation of the parts listed in Fig. 1. Strength data listed in Figure 1 were re-plotted as histograms in Figs. 3 and 4. Figs. 3a and 4a show histograms of all UTS and YS data. Figs. 3b and 4b shows histograms of pre-LEP data and Figs. 3c and 4c of post-LEP data. Data on statistical scatter of tensile strengths have been rarely published by material suppliers. Instead, only the minimum 'guaranteed' strength data are typically presented. An example of strength distribution of aluminum 7075-T6 sheet material, listed in Fig. 5, show that its scatter width of both UTS and YS for a single sheet can be about 6 ksi and for multi-lot scatter can be as large as 11 ksi even though the sheets have been produced through well-controlled manufacturing process. By approximating the histograms shown in Figs. 3 and 4 by a Gaussian or similar type of distribution curves, one can plausibly see the strength reductions in the later or more recent apples. The pre-LEP data in Figs. 3b and 4b show wider scatter than the post-LEP data in Figs. 3c and 4c and seem to follow the binomial distribution of strength indicating that the apples might have been made from two different lots of material, either from two different vendors or from two different melts of perhaps slightly different chemical composition by a single vendor. The post-LEP apples seem to have been from a single batch of material. The pre-LEP apples of the weak strength and the post-LEP apples with even weaker strength could have been made of the same batch of material, and the small strength differential might be due to the difference in the induction heating system. If the pre-LEP apples with the lower strength and the post LEP apples are made from the same batch of material, their combined scatter of strength data would be wider and can be understood as a result of the additional processing steps of stress relief and induction heating as discussed.

  4. Microstructure-Tensile Properties Correlation for the Ti-6Al-4V Titanium Alloy

    NASA Astrophysics Data System (ADS)

    Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing; Guo, Ping

    2015-04-01

    Finding the quantitative microstructure-tensile properties correlations is the key to achieve performance optimization for various materials. However, it is extremely difficult due to their non-linear and highly interactive interrelations. In the present investigation, the lamellar microstructure features-tensile properties correlations of the Ti-6Al-4V alloy are studied using an error back-propagation artificial neural network (ANN-BP) model. Forty-eight thermomechanical treatments were conducted to prepare the Ti-6Al-4V alloy with different lamellar microstructure features. In the proposed model, the input variables are microstructure features including the ? platelet thickness, colony size, and ? grain size, which were extracted using Image Pro Plus software. The output variables are the tensile properties, including ultimate tensile strength, yield strength, elongation, and reduction of area. Fourteen hidden-layer neurons which can make ANN-BP model present the most excellent performance were applied. The training results show that all the relative errors between the predicted and experimental values are within 6%, which means that the trained ANN-BP model is capable of providing precise prediction of the tensile properties for Ti-6Al-4V alloy. Based on the corresponding relations between the tensile properties predicted by ANN-BP model and the lamellar microstructure features, it can be found that the yield strength decreases with increasing ? platelet thickness continuously. However, the ? platelet thickness exerts influence on the elongation in a more complicated way. In addition, for a given ? platelet thickness, the yield strength and the elongation both increase with decreasing ? grain size and colony size. In general, the ? grain size and colony size play a more important role in affecting the tensile properties of Ti-6Al-4V alloy than the ? platelet thickness.

  5. Rating Coal Mine Roof strength from expoloratory drill core

    SciTech Connect

    Mark, C.; Molinda, G.M.

    1996-12-01

    Characterizing coal mine roof rock is extremely important for hazard assessment, reinforcement, and entry design. The Coal Mine Roof Rating (CMRR) is an innovative rock mass classification that has found acceptance in the coal mining industry. A disadvantage of the original CMRR is that it cannot be determined in advance of mining, because it requires underground observations. An entirely new set of procedures have now been developed to determine the CMRR from exploratory drill core, as described in this paper. The new procedures employ Point Load Tests (PLT) to determine strength parameters that account for approximately 60% of the rating. Both diametral (parallel to bedding) and axial (perpendicular to bedding) PLT are conducted. The diametral tests allow estimates of bedding plane cohesion and rock anisotropy, both of which are critical to estimating susceptibility to horizontal stress. Traditional core logging procedures are used to determine discontinuity spacing and roughness. To ensure compatibility with the original CMRR, the new rating scales were verified by comparing drill core results with nearby underground exposures. To assist mine planners in using the new CMRR procedures, a large database of strength ratings of roof rocks was assembled through extensive point load testing and logging. Over 2000 point load tests (both axial and diametral) have been made on 30 common coal measure rock types from mines representing most U.S. coalfields. This database has been merged with the popular core rating system of J.C. Ferm. into a field guide for geologists and engineers. By using the pictorial classification system of Ferm to identify the rock, typical CMRR can be compared with values calculated using the new CMRR procedures.

  6. Effects of Aluminum Addition on Tensile and Cup Forming Properties of Three Twinning Induced Plasticity Steels

    NASA Astrophysics Data System (ADS)

    Hong, Seokmin; Shin, Sang Yong; Kim, Hyoung Seop; Lee, Sunghak; Kim, Sung-Kyu; Chin, Kwang-Geun; Kim, Nack J.

    2012-06-01

    In the present study, a high Mn twinning induced plasticity (TWIP) steel and two Al-added TWIP steels were fabricated, and their microstructures, tensile properties, and cup formability were analyzed to investigate the effects of Al addition on deformation mechanisms in tensile and cup forming tests. In the high Mn steel, the twin formation was activated to increase the strain hardening rate and ultimate tensile strength, which needed the high punch load during the cup forming test. In the Al-added TWIP steels, the twin formation was reduced, while the slip activation increased, thereby leading to the decrease in strain hardening rate and ultimate tensile strength. As twins and slips were homogeneously formed during the tensile or cup forming test, the punch load required for the cup forming and residual stresses were relatively low, and the tensile ductility was sufficiently high even after the cup forming test. This indicated that making use of twins and slips simultaneously in TWIP steels by the Al addition was an effective way to improve overall properties including cup formability.

  7. A Weibull characterization for tensile fracture of multicomponent brittle fibers

    NASA Technical Reports Server (NTRS)

    Barrows, R. G.

    1977-01-01

    Necessary to the development and understanding of brittle fiber reinforced composites is a means to statistically describe fiber strength and strain-to-failure behavior. A statistical characterization for multicomponent brittle fibers is presented. The method, which is an extension of usual Weibull distribution procedures, statistically considers the components making up a fiber (e.g., substrate, sheath, and surface) as separate entities and taken together as in a fiber. Tensile data for silicon carbide fiber and for an experimental carbon-boron alloy fiber are evaluated in terms of the proposed multicomponent Weibull characterization.

  8. In-situ rock strength determination for blasting purposes

    SciTech Connect

    Soni, D.K.; Jain, A.

    1994-12-31

    Compressive strength of rocks is often required by mining engineers and quarrying authorities for blasting operations. Uniaxial compressive strength of rocks can be predicted with reasonable accuracy with the help of point load strength tests which can be easily conducted at site by the field staff, simultaneously as the cores are recovered from drilling operations. A number of diametral point load tests and uniaxial compressive strength tests have been conducted on the specimens of different rock types under air dried, and saturated condition as well to study the effect of ground water saturation on strength. It has been observed that due to saturation uniaxial compressive strength and point load strength get reduced to a maximum of 32 and 29 percent respectively. It has also been observed that uniaxial strength is sixteen times the point load strength in air dried as well as saturated condition. However, this factor used for calculating uniaxial compressive strength may be reduced to a lower value for the safety of miners in field blasting operations.

  9. A Novel Ni-Containing Powder Metallurgy Steel with Ultrahigh Impact, Fatigue, and Tensile Properties

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Wei; Shu, Guo-Jiun; Chang, Shih-Ying; Lin, Bing-Hao

    2014-08-01

    The impact toughness of powder metallurgy (PM) steel is typically inferior, and it is further impaired when the microstructure is strengthened. To formulate a versatile PM steel with superior impact, fatigue, and tensile properties, the influences of various microstructures, including ferrite, pearlite, bainite, and Ni-rich areas, were identified. The correlations between impact toughness with other mechanical properties were also studied. The results demonstrated that ferrite provides more resistance to impact loading than Ni-rich martensite, followed by bainite and pearlite. However, Ni-rich martensite presents the highest transverse rupture strength (TRS), fatigue strength, tensile strength, and hardness, followed by bainite, pearlite, and ferrite. With 74 pct Ni-rich martensite and 14 pct bainite, Fe-3Cr-0.5Mo-4Ni-0.5C steel achieves the optimal combination of impact energy (39 J), TRS (2170 MPa), bending fatigue strength at 2 106 cycles (770 MPa), tensile strength (1323 MPa), and apparent hardness (38 HRC). The impact energy of Fe-3Cr-0.5Mo-4Ni-0.5C steel is twice as high as those of the ordinary high-strength PM steels. These findings demonstrate that a high-strength PM steel with high-toughness can be produced by optimized alloy design and microstructure.

  10. An improved tensile deformation model for in-situ dendrite/metallic glass matrix composites

    PubMed Central

    Sun, X. H.; Qiao, J. W.; Jiao, Z. M.; Wang, Z. H.; Yang, H. J.; Xu, B. S.

    2015-01-01

    With regard to previous tensile deformation models simulating the tensile behavior of in-situ dendrite-reinforced metallic glass matrix composites (MGMCs) [Qiao et al., Acta Mater. 59 (2011) 4126; Sci. Rep. 3 (2013) 2816], some parameters, such as yielding strength of the dendrites and glass matrix, and the strain-hardening exponent of the dendrites, are estimated based on literatures. Here, Ti48Zr18V12Cu5Be17 MGMCs are investigated in order to improve the tensile deformation model and reveal the tensile deformation mechanisms. The tensile behavior of dendrites is obtained experimentally combining nano-indentation measurements and finite-element-method analysis for the first time, and those of the glass matrix and composites are obtained by tension. Besides, the tensile behavior of the MGMCs is divided into four stages: (1) elastic-elastic, (2) elastic-plastic, (3) plastic-plastic (work-hardening), and (4) plastic-plastic (softening). The respective constitutive relationships at different deformation stages are quantified. The calculated results coincide well with the experimental results. Thus, the improved model can be applied to clarify and predict the tensile behavior of the MGMCs. PMID:26354724

  11. An improved tensile deformation model for in-situ dendrite/metallic glass matrix composites.

    PubMed

    Sun, X H; Qiao, J W; Jiao, Z M; Wang, Z H; Yang, H J; Xu, B S

    2015-01-01

    With regard to previous tensile deformation models simulating the tensile behavior of in-situ dendrite-reinforced metallic glass matrix composites (MGMCs) [Qiao et al., Acta Mater. 59 (2011) 4126; Sci. Rep. 3 (2013) 2816], some parameters, such as yielding strength of the dendrites and glass matrix, and the strain-hardening exponent of the dendrites, are estimated based on literatures. Here, Ti48Zr18V12Cu5Be17 MGMCs are investigated in order to improve the tensile deformation model and reveal the tensile deformation mechanisms. The tensile behavior of dendrites is obtained experimentally combining nano-indentation measurements and finite-element-method analysis for the first time, and those of the glass matrix and composites are obtained by tension. Besides, the tensile behavior of the MGMCs is divided into four stages: (1) elastic-elastic, (2) elastic-plastic, (3) plastic-plastic (work-hardening), and (4) plastic-plastic (softening). The respective constitutive relationships at different deformation stages are quantified. The calculated results coincide well with the experimental results. Thus, the improved model can be applied to clarify and predict the tensile behavior of the MGMCs. PMID:26354724

  12. An improved tensile deformation model for in-situ dendrite/metallic glass matrix composites

    NASA Astrophysics Data System (ADS)

    Sun, X. H.; Qiao, J. W.; Jiao, Z. M.; Wang, Z. H.; Yang, H. J.; Xu, B. S.

    2015-09-01

    With regard to previous tensile deformation models simulating the tensile behavior of in-situ dendrite-reinforced metallic glass matrix composites (MGMCs) [Qiao et al., Acta Mater. 59 (2011) 4126; Sci. Rep. 3 (2013) 2816], some parameters, such as yielding strength of the dendrites and glass matrix, and the strain-hardening exponent of the dendrites, are estimated based on literatures. Here, Ti48Zr18V12Cu5Be17 MGMCs are investigated in order to improve the tensile deformation model and reveal the tensile deformation mechanisms. The tensile behavior of dendrites is obtained experimentally combining nano-indentation measurements and finite-element-method analysis for the first time, and those of the glass matrix and composites are obtained by tension. Besides, the tensile behavior of the MGMCs is divided into four stages: (1) elastic-elastic, (2) elastic-plastic, (3) plastic-plastic (work-hardening), and (4) plastic-plastic (softening). The respective constitutive relationships at different deformation stages are quantified. The calculated results coincide well with the experimental results. Thus, the improved model can be applied to clarify and predict the tensile behavior of the MGMCs.

  13. Tensile Properties of Al-Cu 206 Cast Alloys with Various Iron Contents

    NASA Astrophysics Data System (ADS)

    Liu, K.; Cao, X.; Chen, X.-G.

    2014-05-01

    The Al-Cu 206 cast alloys with varying alloy compositions ( i.e., different levels of Fe, Mn, and Si) were investigated to evaluate the effect of the iron-rich intermetallics on the tensile properties. It is found that the tensile strength decreases with increasing iron content, but its overall loss is less than 10 pct over the range of 0.15 to 0.5 pct Fe at 0.3 pct Mn and 0.3 pct Si. At similar iron contents, the tensile properties of the alloys with dominant Chinese script iron-rich intermetallics are generally higher than those with the dominant platelet phase. In the solution and artificial overaging condition (T7), the tensile strength of the 206 cast alloys with more than 0.15 pct Fe is satisfactory, but the elongation does not sufficiently meet the minimum requirement of ductility (>7 pct) for critical automotive applications. However, it was found that both the required ductility and tensile strength can be reached at high Fe levels of 0.3 to 0.5 pct for the alloys with well-controlled alloy chemistry and microstructure in the solution and natural aging condition (T4), reinforcing the motivation for developing recyclable high-iron Al-Cu 206 cast alloys.

  14. Tensile Properties, Ferrite Contents, and Specimen Heating of Stainless Steels in Cryogenic Gas Tests

    NASA Astrophysics Data System (ADS)

    Ogata, T.; Yuri, T.; Ono, Y.

    2006-03-01

    We performed tensile tests at cryogenic temperatures below 77 K and in helium gas environment for SUS 304L and SUS 316L in order to obtain basic data of mechanical properties of the materials for liquid hydrogen tank service. We evaluate tensile curves, tensile properties, ferrite contents, mode of deformation and/or fracture, and specimen heating during the testing at 4 to 77 K. For both SUS 304L and 316L, tensile strength shows a small peak around 10 K, and specimen heating decreases above 30 K. The volume fraction of α-phase increases continuously up to 70 % with plastic strain, at approximately 15 % plastic strain for 304L and up to 35 % for 316L. There was almost no clear influence of testing temperature on strain-induced martensitic transformation at the cryogenic temperatures.

  15. Notched Strength Allowables and Inplane Shear Strength of AS4/VRM-34 Textile Laminates

    NASA Technical Reports Server (NTRS)

    Grenoble, Ray W.; Johnston, William M.

    2013-01-01

    Notched and unnotched strength allowables were developed for a textile composite to provide input data to analytical structural models based on the Pultruded Rod Stiffened Efficient Unitized Structure (PRSEUS) concept. Filled-hole tensile strength, filled-hole compressive strength, and inplane shear strength along stitch lines have been measured. The material system evaluated in this study is based on warp-knitted preforms of AS4 carbon fibers and VRM-34 epoxy resin, which have been processed via resin infusion and oven curing. All specimens were tested in as-fabricated (dry) condition. Filled-hole strengths were evaluated with and without through-thickness stitching. The effects of scaling on filled-hole tensile strength were evaluated by testing specimens in two widths, but with identical width / hole-diameter ratios. Inplane shear specimens were stitched in two configurations, and two specimen thicknesses were tested for each stitch configuration.

  16. The Effects of Defects on Tensile Properties of Cast ADC12 Aluminum Alloy

    NASA Astrophysics Data System (ADS)

    Okayasu, Mitsuhiro; Sakai, Hikoyuki

    2015-11-01

    To better understand the effects of cast defects on mechanical properties, cast aluminum alloys with various porosities were used. Porosity in the cast samples was created during the casting process, and to clearly identify the porosity effects on the mechanical properties, artificial defects (porosity-like tiny holes) were created mechanically. The tensile properties for the cast aluminum alloys appear to be attributed to the area fraction of the porosity on the fracture surface (namely, the defect rate, DR), although there were different trends because of the different stress concentrations: the ultimate tensile strength and 0.2 pct proof strength were linearly related to DR, while a non-linear correlation was detected for fracture strain. Even in Al alloys with small amounts of defects, significant reductions in the fracture strain were observed. These results were verified using tensile tests on specimens containing artificial defects. The effects of artificial defects on the tensile properties were further investigated using numerous tiny holes, created in several formations. The artificial defects (several small holes), lined up at perpendicular (90 deg) and 45 deg directions against the loading direction, made significant reductions in the tensile properties, even though only weak defect effects were observed for the 90 deg loading direction. No severe defect effects were obvious for the specimen with a tiny defect of ?0.1 mm, because of the lower stress concentration, compared to the microstructural effects in the cast Al alloys: the grain boundaries and the second phases. Such phenomena were clarified using tensile tests on cast samples with differently sized microstructures. There were no clear defect effects on the yield strength as the defect amount was less than 10 pct, and microstructural effects were not detected either in this case. Failure characteristics during tensile loading were revealed directly by in-situ strain observations using high-speed cameras.

  17. Tensile properties of SiC/aluminum filamentary composites - Thermal degradation effects

    NASA Technical Reports Server (NTRS)

    Skinner, A.; Koczak, M. J.; Lawley, A.

    1982-01-01

    Aluminium metal matrix composites with a low cost fiber, e.g. SiC, provide for an attractive combination of high elastic modulus and longitudinal strengths coupled with a low density. SiC (volume fraction 0.55)-aluminum (6061) systems have been studied in order to optimize fiber composite strength and processing parameters. A comparison of two SiC/aluminum composites produced by AVCO and DWA is provided. Fiber properties are shown to alter composite tensile properties and fracture morphology. The room temperature tensile strengths appear to be insensitive to thermal exposures at 500 C up to 150 h. The elastic modulus of the composites also appears to be stable up to 400 C, however variations in the loss modulus are apparent. The fracture morphology reflects the quality of the interfacial bond, fiber strengths and fiber processing.

  18. Correlating macrohardness and tensile behavior in discontinuously reinforced metal matrix composites

    SciTech Connect

    Shen, Y.L.; Fishencord, E.; Chawla, N.

    2000-02-14

    hardness tests are routinely used as a simple and effective means of quantifying the tensile strength of metallic materials. The correlation between various hardness scales and tensile t=strength has been compiled for a variety of metals and alloys. When a metal is reinforced with ceramic particles or short fibers, higher stiffness, higher strength and lower ductility for the composite can be observed. The composite, when viewed as a continuum, displays a stronger strain hardening behavior in a tensile test. The overall elastic-plastic nature of the composite, however, bears a qualitative resemblance to that of monolithic metals. This implies that traditional macrohardness may be useful in characterizing the mechanical properties of the composite, as in the case of many engineering alloys. As metal matrix composites are generating increased interest for applications where quality control may be important, the need for understanding the relationship between hardness and tensile strength becomes essential. In a recent study of a 6061 Al/SiC particulate composite with various aging treatments, a linear relationship between the Rockwell superficial-scale hardness and the ultimate tensile strength of the composite was reported. In the present study, the authors seek to explore this correlation in greater detail, in a 2080/SiC{sub p} composite, by taking into account different reinforcement volume fraction, particle size, and matrix microstructure. It will be shown that the hardness-strength correlation in discontinuously reinforced metal matrix composites is not as straightforward as what has been reported for conventional monolithic materials, due to the different micromechanisms of deformation and damage.

  19. The tensile properties of polyimide film at cryogenic temperatures and radiation effects on polyimide films

    SciTech Connect

    Tanaka, T.; Hosoyama, K.; Hara, K.

    1997-06-01

    Polyimide films has been used as insulating component in superconducting machinery. A full understanding of the property at low temperatures and the radiation effect is very important for stabilization of superconducting coils. The tensile properties of polyimide films have been measured at 4.2 K {approximately} 473 K. Stress-Strain curve profiles vary as a function of temperature. At cryogenic temperature, the elongation is much lower but the tensile strength is higher than that at room temperature. Also, polyimide film degradation performances after exposure of to an electron beam at very high dose level are examined. The test device for irradiation has a cooling system for preventing polyimide film from heating by electron absorption. The tests are performed at room temperature in He gas. After 80 MGy absorption, the elongation maintains about 60% level of the non irradiated film, and the tensile strength maintains about 85%.

  20. Fundamental mechanisms of tensile fracture in aluminum sheet undirectionally reinforced with boron filament

    NASA Technical Reports Server (NTRS)

    Herring, H. W.

    1972-01-01

    Results are presented from an experimental study of the tensile-fracture process in aluminum sheet unidirectionally reinforced with boron filament. The tensile strength of the material is severely limited by a noncumulative fracture mechanism which involves the initiation and sustenance of a chain reaction of filament fractures at a relatively low stress level. Matrix fracture follows in a completely ductile manner. The minimum filament stress for initiation of the fracture mechanism is shown to be approximately 1.17 GN/sq m (170 ksi), and appears to be independent of filament diameter, number of filament layers, and the strength of the filament-matrix bond. All the commonly observed features of tensile fracture surfaces are explained in terms of the observed noncumulative fracture mechanism.

  1. Tensile and transient burst properties of advanced ferritic/martensitic steel claddings after neutron irradiation

    NASA Astrophysics Data System (ADS)

    Yano, Y.; Yoshitake, T.; Yamashita, S.; Akasaka, N.; Onose, S.; Takahashi, H.

    2007-08-01

    The effects of fast neutron irradiation on tensile and transient burst properties of advanced ferritic/martensitic steel claddings for fast breeder reactors were investigated. Specimens were irradiated in the experimental fast reactor JOYO using the material irradiation rig at temperatures between 773 and 1013 K to fast neutron doses ranging from 11 to 102 dpa. The post-irradiation tensile and temperature-transient-to-burst tests were carried out. The results of mechanical tests showed that there was no significant degradation in tensile and transient burst strengths after neutron irradiation below 873 K. This was attributed to grain boundary strengthening caused by precipitates that preferentially formed on prior-austenite grain boundaries. Both strengths at neutron irradiation above about 903 K up to 102 dpa decreased due to radiation enhanced recovery of lath martensite structures and recrystallization.

  2. Tensile fracture dynamics and intrinsic plasticity of metallic glasses

    NASA Astrophysics Data System (ADS)

    Cui, J. W.; Calin, M.; Eckert, J.; Zhang, Z. F.

    2013-01-01

    Under tensile tests of metallic glasses (MGs) subjected to annealing below glass transition temperature Tg, ductile-to-brittle transition (DBT) occurs due to structural relaxation, which results in more ordered atomic packing and decrease of glass fraction ?. DBT is observed simultaneously with fracture mechanism transition: shear banding to cracking. All MG samples annealed under different temperature were also restricted to shear banding and cracking separately under small-aspect-ratio compression and compact tension avoiding DBT. Experimental results prove that as annealing temperature increases (or glass fraction ? decreases), strength for shear banding increases, while strength for cracking decreases; as ? becomes less than critical state ?DBT, MG samples tend to cracking instead of shear banding. So, ?DBT is proposed as an important parameter to characterize the intrinsic plasticity of various MGs and to conform to the previous factors soundly.

  3. Tensile stress-strain behavior of boron/aluminum laminates

    NASA Technical Reports Server (NTRS)

    Sova, J. A.; Poe, C. C., Jr.

    1978-01-01

    The tensile stress-strain behavior of five types of boron/aluminum laminates was investigated. Longitudinal and transverse stress-strain curves were obtained for monotonic loading to failure and for three cycles of loading to successively higher load levels. The laminate strengths predicted by assuming that the zero deg plies failed first correlated well with the experimental results. The stress-strain curves for all the boron/aluminum laminates were nonlinear except at very small strains. Within the small linear regions, elastic constants calculated from laminate theory corresponded to those obtained experimentally to within 10 to 20 percent. A limited amount of cyclic loading did not affect the ultimate strength and strain for the boron/aluminum laminates. The laminates, however, exhibited a permanent strain on unloading. The Ramberg-Osgood equation was fitted to the stress-strain curves to obtain average curves for the various laminates.

  4. High temperature tensile properties and fracture characteristics of bimodal 12Cr-ODS steel

    NASA Astrophysics Data System (ADS)

    Chauhan, Ankur; Litvinov, Dimitri; Aktaa, Jarir

    2016-01-01

    This article describes the tensile properties and fracture characteristics of a 12Cr oxide dispersion strengthened (ODS) ferritic steel with unique elongated bimodal grain size distribution. The tensile tests were carried out at four different temperatures, ranging from room temperature to 700C, at a nominal strain rate of 10-3s-1. At room temperature the material exhibits a high tensile strength of 1294MPa and high yield strength of 1200MPa. At 700C, the material still exhibits relatively high tensile strength of 300MPa. The total elongation-to-failure exceeds 18% over the whole temperature range and has a maximum value of 29% at 600C. This superior ductility is attributed to the material's bimodal grain size distribution. In comparison to other commercial, as well as experimental, ODS steels, the material shows an excellent compromise between strength and ductility. The fracture surface studies reveal a change in fracture behavior from a mixed mode fracture at room temperature to fully ductile fracture at 600C. At 700C, the fracture path changes from intragranular to intergranular fracture, which is associated with a reduced ductility.

  5. Postoperative irradiation impairs or enhances wound strength depending on time of administration

    SciTech Connect

    Vegesna, V.; McBride, W.H.; Withers, H.R.

    1995-08-01

    Irradiation can complicate surgical wound healing, yet little is known of the importance of the time between surgery and irradiation on this process. This study investigated the impact of post-operative irradiation on gain in wound tensile strength in a murine skin model. Irradiation on the same day as wounding or to 2-day-old wounds reduced wound tensile strength. In contrast, postoperative irradiation delivered at 7, 9 and 14 days transiently enhanced wound tensile strength, as measure d 3 but not 4 or 5 weeks later. This effect was independent of the inclusion (hemi-body) or exclusion (skin alone) of the hematopoietic system in the field of irradiation. Radiation-enhanced wound tensile strength was greater and occurred earlier after higher radiation doses. Even though the effect of irradiation in enhancing wound tensile strength is transitory, it could be important in assisting early wound healing. 14 refs., 3 figs., 1 tab.

  6. In situ tensile and creep testing of lithiated silicon nanowires

    SciTech Connect

    Boles, Steven T.; Kraft, Oliver; Thompson, Carl V.; Mönig, Reiner; Helmholtz Institute Ulm for Electrochemical Energy Storage , 89069 Ulm

    2013-12-23

    We present experimental results for uniaxial tensile and creep testing of fully lithiated silicon nanowires. A reduction in the elastic modulus is observed when silicon nanowires are alloyed with lithium and plastic deformation becomes possible when the wires are saturated with lithium. Creep testing was performed at fixed force levels above and below the tensile strength of the material. A linear dependence of the strain-rate on the applied stress was evident below the yield stress of the alloy, indicating viscous deformation behavior. The observed inverse exponential relationship between wire radius and strain rate below the yield stress indicates that material transport was controlled by diffusion. At stress levels approaching the yield strength of fully lithiated silicon, power-law creep appears to govern the strain-rate dependence on stress. These results have direct implications on the cycling conditions, rate-capabilities, and charge capacity of silicon and should prove useful for the design and construction of future silicon-based electrodes.

  7. Intrinsic tensile properties of cocoon silk fibres can be estimated by removing flaws through repeated tensile tests.

    PubMed

    Rajkhowa, Rangam; Kaur, Jasjeet; Wang, Xungai; Batchelor, Warren

    2015-06-01

    Silk fibres from silkworm cocoons have lower strength than spider silk and have received less attention as a source of high-performance fibres. In this work, we have used an innovative procedure to eliminate the flaws gradually of a single fibre specimen by retesting the unbroken portion of the fibre, after each fracture test. This was done multiple times so that the final test may provide the intrinsic fibre strength. During each retest, the fibre specimen began to yield once the failure load of the preceding test was exceeded. For each fibre specimen, a composite curve was constructed from multiple tests. The composite curves and analysis show that strengths of mass-produced Muga and Eri cocoon silk fibres increased from 446 to 618 MPa and from 337 to 452 MPa, respectively. Similarly, their toughness increased from 84 to 136 MJ m(-3) and from 61 to 104 MJ m(-3), respectively. Composite plots produced significantly less inter-specimen variations compared to values from single tests. The fibres with reduced flaws as a result of retests in the tested section have a tensile strength and toughness comparable to naturally spun dragline spider silk with a reported strength of 574 MPa and toughness of 91-158 MJ m(-3), which is used as a benchmark for developing high-performance fibres. This retesting approach is likely to provide useful insights into discrete flaw distributions and intrinsic mechanical properties of other fatigue-resistant materials. PMID:25948613

  8. Effect of Thermal Exposure on the Tensile Properties of Aluminum Alloys for Elevated Temperature Service

    NASA Technical Reports Server (NTRS)

    Edahl, Robert A., Jr.; Domack, Marcia

    2004-01-01

    Tensile properties were evaluated for four aluminum alloys that are candidates for airframe applications on high speed transport aircraft. These alloys included the Al-Cu-Mg-Ag alloys C415 and C416 and the Al-Cu-Li-Mg-Ag alloys RX818 and ML377. The Al-Cu-Mg alloys CM001, which was used on the Concorde SST, and 1143, which was modified from the alloy used on the TU144 Russian supersonic aircraft, were tested for comparison. The alloys were subjected to thermal exposure at 200 F, 225 F and 275 F for times up to 30,000 hours. Tensile tests were performed on thermally-exposed and as-received material at -65 F, room temperature, 200 F, 225 F and 275 F. All four candidate alloys showed significant tensile property improvements over CM001 and 1143. Room temperature yield strengths of the candidate alloys were at least 20% greater than for CM001 and 1143, for both the as-received and thermally-exposed conditions. The strength levels of alloy RX818 were the highest of all materials investigated, and were 5-10% higher than for ML377, C415 and C416 for the as-received condition and after 5,000 hours thermal exposure. RX818 was removed from this study after 5,000 hours exposure due to poor fracture toughness performance observed in a parallel study. After 30,000 hours exposure at 200 F and 225 F, the alloys C415, C416 and ML377 showed minor decreases in yield strength, tensile strength and elongation when compared to the as-received properties. Reductions in tensile strength from the as-received values were up to 25% for alloys C415, C416 and ML377 after 15,000 hours exposure at 275 F.

  9. Influences of post-weld heat treatment on tensile properties of friction stir-welded AA6061 aluminum alloy joints

    SciTech Connect

    Elangovan, K.; Balasubramanian, V.

    2008-09-15

    This paper reports on studies of the influences of various post-weld heat treatment procedures on tensile properties of friction stir-welded AA6061 aluminum alloy joints. Rolled plates of 6-mm thick AA6061 aluminum alloy were used to fabricate the joints. Solution treatment, an artificial aging treatment and a combination of both were given to the welded joints. Tensile properties such as yield strength, tensile strength, elongation and joint efficiency were evaluated. Microstructures of the welded joints were analyzed using optical microscopy and transmission electron microscopy. A simple artificial aging treatment was found to be more beneficial than other treatment methods to enhance the tensile properties of the friction stir-welded AA6061 aluminum alloy joints.

  10. Application of GursonTvergaardNeedleman Constitutive Model to the Tensile Behavior of Reinforcing Bars with Corrosion Pits

    PubMed Central

    Xu, Yidong; Qian, Chunxiang

    2013-01-01

    Based on meso-damage mechanics and finite element analysis, the aim of this paper is to describe the feasibility of the GursonTvergaardNeedleman (GTN) constitutive model in describing the tensile behavior of corroded reinforcing bars. The orthogonal test results showed that different fracture pattern and the related damage evolution process can be simulated by choosing different material parameters of GTN constitutive model. Compared with failure parameters, the two constitutive parameters are significant factors affecting the tensile strength. Both the nominal yield and ultimate tensile strength decrease markedly with the increase of constitutive parameters. Combining with the latest data and trial-and-error method, the suitable material parameters of GTN constitutive model were adopted to simulate the tensile behavior of corroded reinforcing bars in concrete under carbonation environment attack. The numerical predictions can not only agree very well with experimental measurements, but also simplify the finite element modeling process. PMID:23342140

  11. Preparation and tensile properties of linear low density polyethylene/rambutan peels (Nephelium chryseum Blum.) flour blends

    NASA Astrophysics Data System (ADS)

    Nadhirah, A. Ainatun.; Sam, S. T.; Noriman, N. Z.; Voon, C. H.; Samera, S. S.

    2015-05-01

    The effect of rambutan peels flour (RPF) content on the tensile properties of linear low density polyethylene filled with rambutan peel flour was studied. RPF was melt blended with linear low-density polyethylene (LLDPE). LLDPE/RPF blends were prepared by using internal mixer (brabender) at 160 C with the flour content ranged from 0 to 15 wt%. The tensile properties were tested by using a universal testing machine (UTM) according to ASTM D638. The highest tensile strength was observed for pure LLDPE while the tensile strength LLDPE/RPF decreased gradually with the addition of rambutan peels flour content from 0% to 15%. Young's modulus of 63 m to 250 m rambutan peels blends with LLDPE with the fiber loading of 0 - 15 wt% increased with increasing fiber loading.

  12. Application of Gurson-Tvergaard-Needleman constitutive model to the tensile behavior of reinforcing bars with corrosion pits.

    PubMed

    Xu, Yidong; Qian, Chunxiang

    2013-01-01

    Based on meso-damage mechanics and finite element analysis, the aim of this paper is to describe the feasibility of the Gurson-Tvergaard-Needleman (GTN) constitutive model in describing the tensile behavior of corroded reinforcing bars. The orthogonal test results showed that different fracture pattern and the related damage evolution process can be simulated by choosing different material parameters of GTN constitutive model. Compared with failure parameters, the two constitutive parameters are significant factors affecting the tensile strength. Both the nominal yield and ultimate tensile strength decrease markedly with the increase of constitutive parameters. Combining with the latest data and trial-and-error method, the suitable material parameters of GTN constitutive model were adopted to simulate the tensile behavior of corroded reinforcing bars in concrete under carbonation environment attack. The numerical predictions can not only agree very well with experimental measurements, but also simplify the finite element modeling process. PMID:23342140

  13. IMPACT STRENGTH OF GLASS AND GLASS CERAMIC

    SciTech Connect

    Bless, S.; Tolman, J.

    2009-12-28

    Strength of glass and glass ceramic was measured with a bar impact technique. High-speed movies show regions of tensile and compressive failure. The borosilicate glass had a compressive strength of at least 2.2 GPa, and the glass ceramic at least 4 GPa. However, the BSG was much stronger in tension than GC. In ballistic tests, the BSG was the superior armor.

  14. High-Hot-Strength Ceramic Fibers

    NASA Technical Reports Server (NTRS)

    Sayir, Ali; Matson, Lawrence E.

    1994-01-01

    Continuous fibers consisting of laminae of alumina and yttrium aluminum garnet offer exceptionally high strength, resistance to creep, and chemical stability at high temperatures. These fibers exceed tensile strength of sapphire fibers. Leading candidates for reinforcement of intermetallic-matrix composites in exhaust nozzles of developmental high-speed civil transport aircraft engines. Other applications are in aerospace, automotive, chemical-process, and power-generation industries.

  15. Understanding the strength of hot-pressed nanostructured powder compacts

    SciTech Connect

    Rawers, J.C.; Harlow, D.G.

    1999-02-01

    Attrition-milled nanostructured powders were hot pressed, and macroscopic properties of density, hardness, grain size, and strength were measured. No correlation was found between processing conditions (temperature and time) used in this study and compact properties, nor was a correlation found between the tensile (or failure) stress and density, hardness, or grain size. Variations of compact properties of unmilled powder were similar to that of milled powders. Tensile data were not well fitted to a Gaussian distribution but were well fitted to a two-parameter Weibull distribution. Thus, although the milled powder compacts had an average tensile strength greater than the unmilled powder compacts, all sample compositions fit a distribution with zero as a possible minimal stress level. Weibull analysis suggests that the tensile and compression strength is controlled by the presence of fine cracks, which may limit future engineering applications. Efforts to eliminate these cracks during hot pressing were unsuccessful.

  16. Suture anchor strength revisited.

    PubMed

    Barber, F A; Herbert, M A; Click, J N

    1996-02-01

    The rapid proliferation of suture anchors continues. Our prior report on the pullout strength of 14 different anchors is supplemented by a similar test conducted on 8 additional anchors. Comparative data on modes of failure and failure strengths (ultimate loads to failure) for these new devices are compared statistically with the previously tested anchors. In a fresh never-frozen porcine femur model, 10 samples of each of the additional anchors tested were threaded with stainless steel sutures and inserted into three different test areas (diaphyseal cortex, metaphyseal cortex, and a cancellous trough). Tensile stress parallel to the axis of insertion was applied at a rate of 12.5 mm/s by an Instron 1321 testing machine (Instron Corp, Canton, MA) until failure and mean anchor failure strengths calculated. The anchors tested were the Mitek G2 as a control, miniMitek, Mitek Superanchor, Mitek Rotator Cuff anchor (Mitek Products, Westwood, MA), Innovasive Devices Radial Osteal Compression device (Innovasive Devices, Hopkinton, MA), Arthrex Fastak (Arthrex Inc, Naples, FL), Arthrotek miniHarpoon (Arthrotek, Warsaw, IN), Orthopedic Biosystems PeBA 3 and PeBA 5 (Orthopedic Biosystems, Scottsdale, AZ), and AME 5.5 screw (American Medical Electronics, Richardson, TX). Failure mode (anchor pullout, suture eyelet cut out, or wire breakage) was generally consistent for each anchor type. The size of insertion hole is clinically important and each anchor's performance was evaluated as a function of its minor diameter or drill hole. For screw anchors, the larger the minor diameter of the screw, the higher the mean failure strengths in all three test areas (P = .001). However, larger drill holes for non-screw anchors resulted in lower mean failure strengths in cancellous bone (P = .03) and diaphyseal cortex (P < .005). PMID:8838726

  17. Influence of Width of Specimen on Tensile Properties of NiCo Thin Film

    NASA Astrophysics Data System (ADS)

    Park, Jun-Hyub; An, Joong-Hyok; Jeon, Yun-Bae; Kim, Yun-Jae; Huh, Yong-Hak

    This paper represents the results of tensile test for NiCo thin films, to investigate the size effect on tensile properties. An axial loading tensile tester developed by authors was used to measure the mechanical characteristics of thin film materials. The tester has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle of capacitance micrometry. The dog-bone type specimen was designed and fabricated by electroplating process. The 50 and 150?m width of reduced section respectively were designed on 6 in. wafer. The length of reduced section is 1,000?m and the radius of the blending fillet is 1,000?m to minimize a stress concentration of the specimen. The thickness is 10?m. The elastic moduli of NiCo thin film were about 18 4.1GPa for 50?m width and about 148 8.4GPa for 150?m width. The ultimate tensile strength for the width of 50 and 150?m were 2,43187.8 and 2,34893.3MPa, respectively. However, the difference between tensile strengths is a little, as 3.3%.

  18. Effect of cryogenic treatment on tensile behavior of case carburized steel-815M17

    SciTech Connect

    Bensely, A. . E-mail: benzlee@annauniv.edu; Senthilkumar, D.; Mohan Lal, D.; Nagarajan, G.; Rajadurai, A.

    2007-05-15

    The crown wheel and pinion represent the most highly stressed parts of a heavy vehicle; these are typically made of 815M17 steel. The reasons for the frequent failure of these components are due to tooth bending impact, wear and fatigue. The modern processes employed to produce these as high, durable components include cryogenic treatment as well as conventional heat treatment. It helps to convert retained austenite into martensite as well as promote carbide precipitation. This paper deals with the influence of cryogenic treatment on the tensile behavior of case carburized steel 815M17. The impetus for studying the tensile properties of gear steels is to ensure that steels used in gears have sufficient tensile strength to prevent failure when gears are subjected to tensile or fatigue loads, and to provide basic design information on the strength of 815M17 steel. A comparative study on the effects of deep cryogenic treatment (DCT), shallow cryogenic treatment (SCT) and conventional heat treatment (CHT) was made by means of tension testing. This test was conducted as per ASTM standard designation E 8M. The present results confirm that the tensile behavior is marginally reduced after cryogenic treatment (i.e. both shallow and deep cryogenic treatment) for 815M17 when compared with conventional heat treatment. Scanning electron microscopic (SEM) analysis of the fracture surface indicates the presence of dimples and flat fracture regions are more common in SCT specimens than for CHT and DCT-processed material.

  19. Ball Indentation Studies on the Effect of Nitrogen on the Tensile Properties of 316LN SS

    NASA Astrophysics Data System (ADS)

    Mathew, M. D.; Ganesh Kumar, J.; Ganesan, V.; Laha, K.

    2015-12-01

    Type 316L(N) stainless steel (SS) containing 0.02-0.03 wt% carbon and 0.06-0.08 wt% nitrogen is used as the major structural material for the components of fast reactors. Research is underway to improve the high-temperature mechanical properties of 316LN SS by increasing the nitrogen content in the steel above the level of 0.08 wt%. In this investigation, ball indentation (BI) technique was used to evaluate the effect of nitrogen content on the tensile properties of 316LN SS. BI tests were conducted on four different heats of 316LN SS containing 0.07, 0.11, 0.14 and 0.22 wt% nitrogen in the temperature range 300-923 K. The tensile properties such as yield strength and ultimate tensile strength increased with increase in nitrogen content at all the investigated temperatures. These results were consistent with the corresponding uniaxial tensile test results. These studies showed that BI technique can be used to optimize the chemical composition during alloy development by evaluating tensile properties with minimum volume of material.

  20. High temperature tensile testing of ceramic composites

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John Z.; Hemann, John H.

    1988-01-01

    The various components of a high temperature tensile testing system are evaluated. The objective is the high temperature tensile testing of SiC fiber reinforced reaction bonded Si3N4 specimens at test temperatures up to 1650 C (3000 F). Testing is to be conducted in inert gases and air. Gripping fixtures, specimen configurations, furnaces, optical strain measuring systems, and temperature measurement techniques are reviewed. Advantages and disadvantages of the various techniques are also noted.

  1. Strength Testing.

    ERIC Educational Resources Information Center

    Londeree, Ben R.

    1981-01-01

    Postural deviations resulting from strength and flexibility imbalances include swayback, scoliosis, and rounded shoulders. Screening tests are one method for identifying strength problems. Tests for the evaluation of postural problems are described, and exercises are presented for the strengthening of muscles. (JN)

  2. Static and dynamic tensile behaviour of aluminium processed by high pressure torsion

    NASA Astrophysics Data System (ADS)

    Verleysen, Patricia; Oelbrandt, Wouter; Naghdy, Soroosh; Kestens, Leo

    2015-09-01

    High pressure torsion (HPT) is a severe plastic deformation technique in which a small, disk-like sample is subjected to a torsional deformation under a high hydrostatic pressure. In present study, the static and dynamic tensile behaviour of commercially pure aluminium (99.6 wt%) processed by HPT is studied. The high strain rate tensile behaviour is characterized using a purpose-developed miniature split Hopkinson tensile bar setup by which strain rates up to 5 103 s-1 can be reached. During the tests, the deformation of a speckle pattern applied to the samples is recorded, by which local information on the strain is obtained using a digital image correlation technique. Electron back scatter diffraction images are used to investigate the microstructural evolution, more specifically the grain refinement obtained by HPT. The fracture surfaces of the tensile samples are studied by scanning electron microscopy. Results show that the imposed severe plastic deformation significantly increases the tensile strength, however, at the expense of ductility. The strain rate only has a minor influence on the materials tensile behaviour.

  3. Enhancing tensile ductility of a particulate-reinforced aluminum MMC by lamination with Mg-9% Li alloy

    SciTech Connect

    Syn, C.K.; Lesuer, D.R.; Sherby, O.D.

    1995-05-01

    A laminated metal composite has been made by press bonding alternating layers of a particulate-reinforced aluminum MMC, 6090/SiC/25p, and a Mg-9%Li alloy. The mechanical properties including tensile ductility were evaluated. The tensile ductility of the Al MMC was found to increase from 3.5% to 11.5%. In contrast to other laminates based on ultrahigh carbon, steel, the laminate of this study and other Al MMC laminates exhibited tensile yield strengths that did not follow the rule of averages. This is attributed to interlayer reaction products developed during processing of the Al MMC laminates.

  4. Influence of temperature, composition, and grain size on the tensile failure of water ice: Implications for erosion on Titan

    NASA Astrophysics Data System (ADS)

    Litwin, Kimberly L.; Zygielbaum, Beth R.; Polito, Peter J.; Sklar, Leonard S.; Collins, Geoffrey C.

    2012-08-01

    Ice resistance to tensile fracture influences surface morphodynamics on outer planetary satellites such as Titan, yet measurements of tensile strength and fracture toughness of polycrystalline water ice at temperatures below terrestrial conditions (<220 K) have not been previously reported. We investigated these parameters from 260 K to 110 K using a walk-in freezer, and chilling by dry ice and liquid nitrogen. We also investigated the influence of solid impurity concentration and the spread in crystal grain size distribution. Although fracture toughness showed no sensitivity to temperature, we find that tensile strength increases with decreasing temperature at 7 kPa K-1 for all ice types tested. For pure water ice, samples made from uniform-sized seed crystals were stronger than mixed-grain-size ice, suggesting that strength is limited by the coarse tail of the size distribution. Samples tested submerged in liquid ethanol were 0.45 MPa weaker than in air; increasing porosity reduced tensile strength. Tensile strength increased linearly with concentration of urea, basalt and ammonium sulfate. These results suggest that on Titan and other icy satellites, the tensile strength of fine-grained polycrystalline water ice containing solid impurities may be several times greater than the 1 MPa value commonly used in modeling. For low strain rate processes where fracture propagation rather than fracture initiation limits strength, a temperature invariant fracture toughness of 0.15 MPa m1/2 is appropriate. Understanding ice diagenesis on Titan, and the resulting composition, grain size distribution, and porosity, is needed to accurately model surface processes that are limited by ice resistance to fracture.

  5. Size Scaling of Tensile Failure Stress in a Soda-Lime-Silicate Float Glass

    SciTech Connect

    Wereszczak, Andrew A; Kirkland, Timothy Philip; Ragan, Meredith E; Strong, Kevin T; Lin, Hua-Tay; Patel, P

    2010-01-01

    The (tensile) strength-size scaling of a float soda-lime silicate glass was studied using biaxial flexure and Hertzian ring crack initiation testing. The examined Weibull effective areas spanned ~ 0.4 to 48,000 mm2. Both the air- and tin-sides were tested. The air side was stronger than the tin side as others have observed; however, the differences in their characteristic strengths decreased with decreasing effective area, and their strengths converged for effective areas smaller than ~ 100 mm2. The failure stress at the smallest effective area examined for the tin-side was ~ 500% greater than that at the largest effective area while that difference was ~ 250% for the air- side. A Weibull modulus change at ~ 100 mm2 suggests different strength-limiting flaw types were dominant below and above that effective area. These results reinforce the importance to interpret and use tensile strength of glass in context to how much of its area is being tensile stressed.

  6. Modified ring stretch tensile testing of Zr-1Nb cladding.

    SciTech Connect

    Billone, M. C.; Chung, H. M.; Cohen, A. B.; Majumdar, S.; Neimark, L. A.; Ruther, W. E.

    1997-12-05

    In a round robin effort between the US Nuclear Regulatory Commission, Institut de Protection et de Surete Nucleaire in France, and the Russian Research Centre-Kurchatov Institute, Argonne National Laboratory conducted 16 modified ring stretch tensile tests on unirradiated samples of Zr-1Nb cladding, which is used in Russian VVER reactors. Tests were conducted at two temperatures (25 and 400 C) and two strain rates (0.001 and 1 s{sup {minus}1}). At 25 C and 0.001 s{sup {minus}1}, the yield strength (YS), ultimate tensile strength (UTS), uniform elongation (UE), and total elongation (TE) were 201 MPa, 331 MPa, 18.2%, and 57.6%, respectively. At 400 C and 0.001 s{sup {minus}1}, the YS, UTS, UE, and TE were 109 MPa, 185 MPa, 15.4%, and 67.7%, respectively. Finally, at 400 C and 1 s{sup {minus}1}, the YS, UTS, UE, and TE were 134 MPa, 189 MPa, 18.9%, and 53.4%, respectively. The high strain rate tests at room temperature were not successful. Test results proved to be very sensitive to the amount of lubrication used on the inserts; because of the large contact area between the inserts and specimen, too little lubrication leads to significantly higher strengths and lower elongations being reported. It is also important to note that only 70 to 80% of the elongation takes place in the gauge section, depending on specimen geomeq. The appropriate percentage can be estimated from a simple model or can be calculated from finite-element analysis.

  7. Tensile testing method for rare earth based bulk superconductors at liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Kasaba, K.; Katagiri, K.; Murakami, A.; Sato, G.; Sato, T.; Murakami, M.; Sakai, N.; Teshima, H.; Sawamura, M.

    2005-10-01

    Bending tests have been commonly carried out to investigate the mechanical properties of melt-processed rare earth based bulk superconductors. Tensile tests by using small specimen, however, are preferable to evaluate the detailed distribution of the mechanical properties and the intrinsic elastic modulus because no stress distributions exist in the cross-section. In this study, the tensile test method at low temperature by using specimens with the dimensions of 3 × 3 × 4 mm from Y123 and Gd123 bulks was examined. They were glued to Al alloy rods at 400 K by using epoxy resin. Tests were carried out at liquid nitrogen temperature (LNT) by using the immersion type jig. Although the bending strength in the direction perpendicular to the c-axis of the bulks at LNT is higher than that at room temperature (RT), the tensile strength at LNT was lower than that at RT. Many of specimens fractured near the interface between the specimen and the Al alloy rod at LNT. According to the finite element method analysis, it was shown that there was a peak thermal stress in the loading direction near the interface and it was significantly higher at LNT than that at RT. It was also shown that the replacement of the Al alloy rod to Ti rod of which the coefficient of thermal expansion is close to that of bulks significantly increased the tensile strength.

  8. Elevated-temperature tensile and creep properties of several ferritic stainless steels

    NASA Technical Reports Server (NTRS)

    Whittenberger, J. D.

    1977-01-01

    The elevated-temperature mechanical properties of several ferritic stainless steels were determined. The alloys evaluated included Armco 18SR, GE 1541, and NASA-18T-A. Tensile and creep strength properties at 1073 and 1273 K and residual room temperature tensile properties after creep testing were measured. In addition, 1273 K tensile and creep tests and residual property testing were conducted with Armco 18SR and GE 1541 which were exposed for 200 hours to a severe oxidizing environment in automotive thermal reactors. Aside from the residual tensile properties for Armco 18SR, prior exposure did not affect the mechanical properties of either alloy. The 1273 K creep strength parallel to the sheet-rolling direction was similar for all three alloys. At 1073 K, NASA-18T-A had better creep strength than either Armco 18SR or GE 1541. NASA-18T-A possesses better residual properties after creep testing than either Armco 18SR or Ge 1541.

  9. Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers

    NASA Astrophysics Data System (ADS)

    Naito, Kimiyoshi

    2014-09-01

    The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4'-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.

  10. Tensile and compressive behavior of Ti-based bulk metallic glass composites

    NASA Astrophysics Data System (ADS)

    Wang, Yong-sheng; Hao, Guo-jian; Lin, Jun-pin

    2013-06-01

    This article focuses on the tensile and compressive characteristics of a Ti-based bulk metallic glass composite (BMGC). It is found that the yield stress, maximum strength, and fracture strain are 1380 MPa, 1516 MPa, and 4.3% for uniaxial tension, but 1580 MPa, 4010 MPa, and 29% for uniaxial compression, respectively. The composite displays a linear "work hardening" capacity under compression; however, the "work softening" behavior is observed in the true engineering stress-strain curve upon tensile loading. The fracture surfaces of specimens also exhibit dissimilar properties under the different loadings.

  11. Tensile Behavior of Tungsten/Niobium Composites at 1300 to 1600 K

    NASA Technical Reports Server (NTRS)

    Yun, Hee Mann; Titran, Robert H.

    1989-01-01

    The tensile behavior of continuous tungsten fiber reinforced niobium composites (W/Nb), fabricated by an arc-spray process, was studied in the 1300 to 1600 K temperature range. The tensile properties of the fiber and matrix components as well as of the composites were measured and were compared to rule of mixtures (ROM) predictions. The deviation from the ROM was found to depend upon the chemistry of the tungsten alloy fibers, with positive deviations for ST300/Nb (i.e., stronger composite strength than the ROM) and negative or zero deviations for 218/Nb.

  12. Tensile strain-rate sensitivity of tungsten/niobium composites at 1300 to 1600 K

    NASA Technical Reports Server (NTRS)

    Yun, H. M.; Titran, R. H.

    1992-01-01

    The tensile behavior of continuous tungsten fiber reinforced niobium composites (W/Nb), fabricated by an arc-spray process, was studied in the 1300 to 1600 K temperature range. The tensile properties of the fiber and matrix components as well as of the composites were measured and were compared to rule of mixtures (ROM) predictions. The deviation from the ROM was found to depend upon the chemistry of the tungsten alloy fibers, with positive deviations for ST300/Nb (i.e., stronger composite strength than the ROM) and negative or zero deviations for 218/Nb.

  13. Tensile Properties of Some Structural Sheet Materials Under Rapid-Heating Conditions

    NASA Technical Reports Server (NTRS)

    Heimerl, George J.

    1957-01-01

    The results of the NACA tests to determine the tensile strength of some structural sheet materials heated to failure at temperature rates from 0.2 deg. F to 100 deg F per second under constant load conditions are reviewed . Yield and rupture stresses obtained under rapid-heating conditions are compared with the results of conventional elevated-temperature tensile tests. The relation between rapid-heating tests, short-time creep tests, and conventional creep tests is discussed . The application of a phenomenological theory for calculating rapid-heating curves is shown. Methods are given for predicting yield and rupture stresses and temperatures from master curves and temperature-rate parameters

  14. Multi-scale investigation of tensile creep of ultra-high performance concrete for bridge applications

    NASA Astrophysics Data System (ADS)

    Garas Yanni, Victor Youssef

    Ultra-high performance concrete (UHPC) is relatively a new generation of concretes optimized at the nano and micro-scales to provide superior mechanical and durability properties compared to conventional and high performance concretes. Improvements in UHPC are achieved through: limiting the water-to-cementitious materials ratio (i.e., w/cm ≤ 0.20), optimizing particle packing, eliminating coarse aggregate, using specialized materials, and implementing high temperature and high pressure curing regimes. In addition, and randomly dispersed and short fibers are typically added to enhance the material's tensile and flexural strength, ductility, and toughness. There is a specific interest in using UHPC for precast prestressed bridge girders because it has the potential to reduce maintenance costs associated with steel and conventional concrete girders, replace functionally obsolete or structurally deficient steel girders without increasing the weight or the depth of the girder, and increase bridge durability to between 75 and 100 years. UHPC girder construction differs from that of conventional reinforced concrete in that UHPC may not need transverse reinforcement due to the high tensile and shear strengths of the material. Before bridge designers specify such girders without using shear reinforcement, the long-term tensile performance of the material must be characterized. This multi-scale study provided new data and understanding of the long-term tensile performance of UHPC by assessing the effect of thermal treatment, fiber content, and stress level on the tensile creep in a large-scale study, and by characterizing the fiber-cementitious matrix interface at different curing regimes through nanoindentation and scanning electron microscopy (SEM) in a nano/micro-scale study. Tensile creep of UHPC was more sensitive to investigated parameters than tensile strength. Thermal treatment decreased tensile creep by about 60% after 1 year. Results suggested the possibility of achieving satisfactory microstructural refinement at the same temperature input despite the maximum temperature applied. For the first time, the presence of a 10 microm (394 micro inch) wide porous fiber-cementitious matrix interface was demonstrated by nanoindentation and SEM for non-thermally treated UHPC only. Tensile creep at 90 days increased by 64% and 46% upon eliminating fibers for thermally and non-thermally treated UHPC, respectively. Increases in creep upon reducing the fiber content suggested that fibers carry part of the sustained load and thus reduce creep. Tensile creep strain was proportional to the stress applied up to 60% of the ultimate strength. No tensile creep failure occurred for a period of 1 year for pre-cracked UHPC under stress level of 40%. Also, no tensile creep failure occurred for a period of 90 days under stress level of 60%. Tensile creep failure occurred at stress levels of 70% and 80%. This study showed that fibers cannot be accounted for as shear reinforcement in lieu of stirrups unless micro-defect-free fiber-matrix interface is achieved.

  15. Interfacial Shear Strength Evaluation of Jute/Poly(Lactic Acid)

    NASA Astrophysics Data System (ADS)

    Kobayashi, Satoshi; Yamamoto, Tatsuro; Nakai, Asami

    In order to evaluate the interfacial shear strength between fiber bundle and matrix of jute/poly(lactic acid) (PLA), a fiber bundle pull-out test method is proposed. Shear stress distribution was calculated based on the parabolic shear-lag analysis. Fiber bundle pull-out tests were conducted to evaluate the effects of molding condition on the interfacial shear strength. The interfacial shear strength increased with increasing molding temperature up to 185C. Then gradual decrease in the interfacial shear strength with molding temperature was observed. Similar tendency was also observed in the effect of molding time, whereas the interfacial shear strength decreased with increasing molding pressure. Comparing the result of the tensile tests in the previous study, interfacial shear strength has corelations with tensile strength.

  16. Increase vs. decrease in the strength of granitic rocks subjected to heat

    NASA Astrophysics Data System (ADS)

    Trk, Anita; Trk, kos

    2015-04-01

    Accidental fire generally causes catastrophic loss in granitic structures or tunnels excavated in granitic rocks. It is necessary to measure strength of materials at various degrees to understand the mechanical behaviour of such stone structures or tunnels. Our laboratory experiments were aimed to detect indirect tensile strength and uniaxial compressive strength of granitic rocks that were subjected to temperatures of up to 600C. For control measurements ultrasonic pulse velocity was also recorded. The studied rocks included three granites: a Hungarian dark pink granite (Mrgy), an Austrian greyish granite (Mauthausen) and a common pinkish Spanish granite (Rosa Beta). Cylindrical tests specimens of the three granites were subjected to 300C and 600C, respectively. Compressive strength test and tensile strength test results were compared to strength values obtained at room temperature. Our test results show that two of the studied granites (Hungarian and the Spanish one) have higher strength at 300C that at room temperature. To the contrary ultrasonic pulse velocity decreased for all the three granites from room temperature to 300C. The tensile strength of the granites did not show such a clear trend, however Hungarian granite has a slightly increased tensile strength at 300C than at room temperature. At 600C the compressive strength, tensile strength and ultrasonic pulse velocity dropped but not at the same rate. Our experiments showed that a given and limited temperature increase can have a positive effect on strength of granites rather than an adverse effect on a short-term.

  17. Opposite risk patterns for autism and schizophrenia are associated with normal variation in birth size: phenotypic support for hypothesized diametric gene-dosage effects.

    PubMed

    Byars, Sean G; Stearns, Stephen C; Boomsma, Jacobus J

    2014-11-01

    Opposite phenotypic and behavioural traits associated with copy number variation and disruptions to imprinted genes with parent-of-origin effects have led to the hypothesis that autism and schizophrenia share molecular risk factors and pathogenic mechanisms, but a direct phenotypic comparison of how their risks covary has not been attempted. Here, we use health registry data collected on Denmark's roughly 5 million residents between 1978 and 2009 to detect opposing risks of autism and schizophrenia depending on normal variation (mean 1 s.d.) in adjusted birth size, which we use as a proxy for diametric gene-dosage variation in utero. Above-average-sized babies (weight, 3691-4090 g; length, 52.8-54.3 cm) had significantly higher risk for autism spectrum (AS) and significantly lower risk for schizophrenia spectrum (SS) disorders. By contrast, below-average-sized babies (2891-3290 g; 49.7-51.2 cm) had significantly lower risk for AS and significantly higher risk for SS disorders. This is the first study directly comparing autism and schizophrenia risks in the same population, and provides the first large-scale empirical support for the hypothesis that diametric gene-dosage effects contribute to these disorders. Only the kinship theory of genomic imprinting predicts the opposing risk patterns that we discovered, suggesting that molecular research on mental disease risk would benefit from considering evolutionary theory. PMID:25232142

  18. Opposite risk patterns for autism and schizophrenia are associated with normal variation in birth size: phenotypic support for hypothesized diametric gene-dosage effects

    PubMed Central

    Byars, Sean G.; Stearns, Stephen C.; Boomsma, Jacobus J.

    2014-01-01

    Opposite phenotypic and behavioural traits associated with copy number variation and disruptions to imprinted genes with parent-of-origin effects have led to the hypothesis that autism and schizophrenia share molecular risk factors and pathogenic mechanisms, but a direct phenotypic comparison of how their risks covary has not been attempted. Here, we use health registry data collected on Denmark's roughly 5 million residents between 1978 and 2009 to detect opposing risks of autism and schizophrenia depending on normal variation (mean 1 s.d.) in adjusted birth size, which we use as a proxy for diametric gene-dosage variation in utero. Above-average-sized babies (weight, 36914090 g; length, 52.854.3 cm) had significantly higher risk for autism spectrum (AS) and significantly lower risk for schizophrenia spectrum (SS) disorders. By contrast, below-average-sized babies (28913290 g; 49.751.2 cm) had significantly lower risk for AS and significantly higher risk for SS disorders. This is the first study directly comparing autism and schizophrenia risks in the same population, and provides the first large-scale empirical support for the hypothesis that diametric gene-dosage effects contribute to these disorders. Only the kinship theory of genomic imprinting predicts the opposing risk patterns that we discovered, suggesting that molecular research on mental disease risk would benefit from considering evolutionary theory. PMID:25232142

  19. Effect of boron on post irradiation tensile properties of reduced activation ferritic steel (F-82H) irradiated in HFIR

    SciTech Connect

    Shiba, Kiyoyuki; Suzuki, Masahide; Hishinuma, Akimichi; Pawel, J.E.

    1994-12-31

    Reduced activation ferritic/martensitic steel, F-82H (Fe-8Cr-2W-V-Ta), was irradiated in the High Flux Isotope Reactor (HFIR) to doses between 11 and 34 dpa at 400 and 500 C. Post irradiation tensile tests were performed at the nominal irradiation temperature in vacuum. Some specimens included {sup 10}B or natural boron (nB) to estimate the helium effect on tensile properties. Tensile properties including the 0.2% offset yield stress, the ultimate tensile strength, the uniform elongation and the total elongation were measured. The tensile properties were not dependent on helium content in specimens irradiated to 34 dpa, however {sup 10}B-doped specimens with the highest levels of helium showed slightly higher yield strength and less ductility than boron-free specimens. Strength appears to go through a peak, and ductility through a trough at about 11 dpa. The irradiation to more than 21 dpa reduced the strength and increased the elongation to the unirradiated levels. Ferritic steels are one of the candidate alloys for nuclear fusion reactors because of their good thermophysical properties, their superior swelling resistance, and the low corrosion rate in contact with potential breeder and coolant materials.

  20. The Effect of Thermomechanical Processing on the Tensile, Fatigue, and Creep Behavior of Magnesium Alloy AM60

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Huang, J.; Decker, R. F.; Lebeau, S. E.; Walker, L. R.; Cavin, O. B.; Watkins, T. R.; Boehlert, C. J.

    2011-05-01

    Tensile, fatigue, fracture toughness, and creep experiments were performed on a commercially available magnesium-aluminum alloy (AM60) after three processing treatments: (1) as-THIXOMOLDED (as-molded), (2) THIXOMOLDED then thermomechanically processed (TTMP), and (3) THIXOMOLDED then TTMP then annealed (annealed). The TTMP procedure resulted in a significantly reduced grain size and a tensile yield strength greater than twice that of the as-molded material without a debit in elongation to failure ( ? f ). The as-molded material exhibited the lowest strength, while the annealed material exhibited an intermediate strength but the highest ? f (>1 pct). The TTMP and annealed materials exhibited fracture toughness values almost twice that of the as-molded material. The as-molded material exhibited the lowest fatigue threshold values and the lowest fatigue resistance. The annealed material exhibited the greatest fatigue resistance, and this was suggested to be related to its balance of tensile strength and ductility. The fatigue lives of each material were similar at both room temperature (RT) and 423 K (150 C). The tensile-creep behavior was evaluated for applied stresses ranging between 20 and 75 MPa and temperatures between 373 and 473 K (100 and 200 C). During both the fatigue and creep experiments, cracking preferentially occurred at grain boundaries. Overall, the results indicate that thermomechanical processing of AM60 dramatically improves the tensile, fracture toughness, and fatigue behavior, making this alloy attractive for structural applications. The reduced creep resistance after thermomechanical processing offers an opportunity for further research and development.

  1. Micro-mechanical studies on graphite strength prediction models

    NASA Astrophysics Data System (ADS)

    Kanse, Deepak; Khan, I. A.; Bhasin, V.; Vaze, K. K.

    2013-06-01

    The influence of type of loading and size-effects on the failure strength of graphite were studied using Weibull model. It was observed that this model over-predicts size effect in tension. However, incorporation of grain size effect in Weibull model, allows a more realistic simulation of size effects. Numerical prediction of strength of four-point bend specimen was made using the Weibull parameters obtained from tensile test data. Effective volume calculations were carried out and subsequently predicted strength was compared with experimental data. It was found that Weibull model can predict mean flexural strength with reasonable accuracy even when grain size effect was not incorporated. In addition, the effects of microstructural parameters on failure strength were analyzed using Rose and Tucker model. Uni-axial tensile, three-point bend and four-point bend strengths were predicted using this model and compared with the experimental data. It was found that this model predicts flexural strength within 10%. For uni-axial tensile strength, difference was 22% which can be attributed to less number of tests on tensile specimens. In order to develop failure surface of graphite under multi-axial state of stress, an open ended hollow tube of graphite was subjected to internal pressure and axial load and Batdorf model was employed to calculate failure probability of the tube. Bi-axial failure surface was generated in the first and fourth quadrant for 50% failure probability by varying both internal pressure and axial load.

  2. Microstructure and tensile properties of tungsten at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Shen, Tielong; Dai, Yong; Lee, Yongjoong

    2016-01-01

    In order to support the development of the 5 MW spallation target for the European Spallation Source, the effect of fabrication process on microstructure, ductile-to-brittle transition temperature (DBTT), tensile and fracture behaviour of powder-metallurgy pure tungsten materials has been investigated. A hot-rolled (HR) tungsten piece of 12 mm thickness and a hot-forged (HF) piece of about 80 mm thickness were used to simulate the thin and thick blocks in the target. The two tungsten pieces were characterized with metallography analysis, hardness measurement and tensile testing. The HR piece exhibits an anisotropic grain structure with an average size of about 330 × 140 × 40 μm in rolling, long transverse and short transverse (thickness) directions. The HF piece possesses a bimodal grain structure with about 310 × 170 × 70 μm grain size in deformed part and about 25 μm sized grains remained from sintering process. Hardness (HV0.2) of the HR piece is slightly greater than that of the HF one. The ductility of the HR tungsten specimens is greater than that of the HF tungsten. For the HF tungsten piece, specimens with small grains in gauge section manifest lower ductility but higher strength. The DBTT evaluated from the tensile results is 250-300 °C for the HR tungsten and about 350 °C for the HF tungsten.

  3. Leached components from dental composites in oral simulating fluids and the resultant composite strengths.

    PubMed

    Lee, S Y; Huang, H M; Lin, C Y; Shih, Y H

    1998-08-01

    The aim of this study was to analyse the leached moieties of dental composites after storage in ethanol and organic acids of plaque and further evaluate the resultant effect on the diametral tensile strength (DTS) of the composites. Three commercial composites were used: Bis-GMA-based Z100, Bis-GMA/UDMA-based Heliomolar, and Bis-MPEPP-based Marathon One. The solutions used were: 99.9% acetic acid, 99% propionic acid and 75% ethanol. Specimens (4 mm diam. x 2 mm thick) were stored at 37 degrees C in 3 mL of solution for up to 30 days. Gas chromatography/mass spectrometry was used to characterize the leached moieties and DTS of the specimens after immersion was evaluated. Data were analysed using ANOVA and Tukey LSD test. The eluted substances were not all the same in different solutions and composites but mostly increased with immersion time, and included diluents (TEGDMA and decamethacrylate) and some additives, such as an ultra-violet stabilizer (TINUVINP), plasticizers (dicyclohexyl phthalate and bis(2-ethylhexyl) phthalate), initiator (triphenyl stibine), coupling agent (gamma-methacryloxypropyl trimethoxysilane), and phenyl benzoate. The chief polymerizing monomers were not found. More kinds of components were found in the acetic acid and ethanol groups studied. The fewest kinds and quantities of leached moieties were found for Bis-GMA specimens and then Bis-GMA/UDMA ones, most of which are diluent agents. Bis-MPEPP specimens leached the most substances, which were composed mostly of a short phenyl group chain structure. The BisGMA composite showed the highest DTS (54.8 +/- 5.7 MPa), which was not greatly affected by the length of storage. Bis-GMA/UDMA (36.2 +/- 6.8 MPa) and Bis-MPEPP (26.1 +/- 4.5 MPa) composites were significantly reduced (P < 0.05) after 30 days storage in the ethanol (35-50%), in the propionic acid (25-30%), and in the acetic acid (40-60%). Irreversible processes such as the leaching of components occur in fluids simulating an oral environment, which may contribute to irreversible material degradation, especially for non-Bis-GMA-based composites. PMID:9781860

  4. In Situ Radiography During Tensile Tests

    NASA Technical Reports Server (NTRS)

    Baaklini, George Y.; Bhatt, Ramakrishna T.

    1994-01-01

    Laboratory system for testing specimens of metal-, ceramic-, and intermetallic-matrix composite materials incorporates both electromechanical tensile-testing subsystem and either of two imaging subsystems that take x-ray photographs of specimens before, during, and after tensile tests. Used to test specimens of reaction-bonded silicon nitride reinforced with silicon carbide fibers (SiC/RBSN) considered for high-temperature service in advanced aircraft turbine engines. Provides data on effects of preexisting flaws (e.g., high-density impurities and local variations of density) on fracture behavior. Accumulated internal damage monitored during loading. X-ray source illuminates specimen in load frame while specimen is pulled. X-ray images on film correlated with stress-vs.-strain data from tensile test.

  5. Pressure reversal study through tensile tests

    SciTech Connect

    Swinson, W.F.; Battiste, R.L.; Wright, A.L.; Yahr, G.T.; Robertson, J.P.

    1997-12-31

    This paper is a summary of the results from a study of the variables related to pressure reversal and was sponsored by the US Department of Transportation, Office of Pipeline Safety. The circumferential pipe stress, which is the most significant variable in pressure reversal, was examined by using tensile specimens and then relating the results to pressurized pipe. A model is proposed that gives some insight into how pressure reversal can be minimized when a section of pipe is being hydrotested. Twenty tensile specimens from X-42 electric resistance welded (ERW) pipe and twenty specimens from X-52 ERW pipe were tested. Each specimen had a machined flaw. The flaw regions were monitored using strain gages and photoelasticity. These tensile tests represent the first phase of a research effort to examine and understand the variables related to pressure reversal. The second phase of this effort will be with pipe specimens and presently is in progress.

  6. Distinct Tensile Response of Model Semi-flexible Elastomer Networks

    NASA Astrophysics Data System (ADS)

    Aguilera-Mercado, Bernardo M.; Cohen, Claude; Escobedo, Fernando A.

    2011-03-01

    Through coarse-grained molecular modeling, we study how the elastic response strongly depends upon nanostructural heterogeneities in model networks made of semi-flexible chains exhibiting both regular and realistic connectivity. Idealized regular polymer networks have been shown to display a peculiar elastic response similar to that of super-tough natural materials (e.g., organic adhesives inside abalone shells). We investigate the impact of chain stiffness, and the effect of including tri-block copolymer chains, on the network's topology and elastic response. We find in some systems a dual tensile response: a liquid-like behavior at small deformations, and a distinct saw-tooth shaped stress-strain curve at moderate to large deformations. Additionally, stiffer regular networks exhibit a marked hysteresis over loading-unloading cycles that can be deleted by heating-cooling cycles or by performing deformations along different axes. Furthermore, small variations of chain stiffness may entirely change the nature of the network's tensile response from an entropic to an enthalpic elastic regime, and micro-phase separation of different blocks within elastomer networks may significantly enhance their mechanical strength. This work was supported by the American Chemical Society.

  7. Lifetimes of fiber composites under sustained tensile loading

    NASA Technical Reports Server (NTRS)

    Chiao, T. T.; Sherry, R. J.; Chiao, C. C.

    1977-01-01

    Results are presented for a study intended to summarize lifetime data on several fiber/epoxy composite materials subjected to sustained uniaxial tensile loading, to report preliminary results of an accelerated test method for predicting the life of simple composites, and to describe related work in progress on pressure vessels and other filament-wound structures. The lifetime performance of the tested composites was compared by plotting the percent of ultimate strength (applied fiber stress normalized with respect to fiber failure stress in a composite) versus lifetime. In terms of performance in long-term tensile applications, the tested composites are ranked in the following order: graphite/epoxy, Be wire/epoxy, Aramid/epoxy, and S-glass/epoxy. The accelerated test using temperature and stress to simulate the passage of time proves to be encouraging, at least in the case of the Aramid/epoxy composite. The potential of a statistical analysis based on Weibull distribution analyses or a power law relationship is demonstrated.

  8. High temperature tensile deformation behavior of Grade 92 steel

    NASA Astrophysics Data System (ADS)

    Alsagabi, Sultan; Shrestha, Triratna; Charit, Indrajit

    2014-10-01

    Candidate structural materials for advanced reactors need to have superior high temperature strength and creep-rupture properties among other characteristics. The ferritic-martensitic Grade 92 steel (Fe-9Cr-2W-0.5Mo, wt.%) is considered such a candidate structural material. Tensile tests were performed at temperatures of 600, 650 and 700 C in the strain rate range of 10-5-10-3 s-1. After analyzing the tensile results using the Bird-Mukherjee-Dorn (BMD) equation, a stress exponent of about 9.5 and an activation energy of about 646 kJ/mol were obtained. In the light of high values of the stress exponent and activation energy, the threshold stress concept was used to elucidate the operating high temperature deformation mechanism. As a result of this modification, the true activation energy and stress exponent of the high temperature deformation in Grade 92 steel were found to be about 245 kJ/mol and 5, respectively. Thus, the dominant high temperature deformation mechanism was identified as the high temperature climb of edge dislocations and the appropriate constitutive equation was developed.

  9. Tensile properties of copper alloyed austempered ductile iron: Effect of austempering parameters

    NASA Astrophysics Data System (ADS)

    Batra, U.; Ray, S.; Prabhakar, S. R.

    2004-10-01

    A ductile iron containing 0.6% copper as the main alloying element was austenitized at 850 C for 120 min and was subsequently austempered for 60 min at austempering temperatures of 270, 330, and 380 C. The samples were also austempered at 330 C for austempering times of 30 150 min. The structural parameters for the austempered alloy austenite (X ? ), average carbon content (C ? ), the product X ? C ? , and the size of the bainitic ferrite needle (d ? ) were determined using x-ray diffraction. The effect of austempering temperature and time has been studied with respect to tensile properties such as 0.2% proof stress, ultimate tensile strength (UTS), percentage of elongation, and quality index. These properties have been correlated with the structural parameters of the austempered ductile iron microstructure. Fracture studies have been carried out on the tensile fracture surfaces of the austempered ductile iron (ADI).

  10. Tensile behavior of laser treated Fe-Si-B metallic glass

    NASA Astrophysics Data System (ADS)

    Joshi, Sameehan S.; Samimi, Peyman; Ghamarian, Iman; Katakam, Shravana; Collins, Peter C.; Dahotre, Narendra B.

    2015-10-01

    Fe-Si-B metallic glass foils were treated with a linear laser track using a continuous wave Nd-YAG laser and its effect on the overall tensile behavior was investigated. Microstructure and phase evolutions were evaluated using X-ray diffraction, resistivity measurements, and transmission electron microscopy. Crystallization fraction was estimated via the differential scanning calorimetry technique. Metallic glass foils treated with the lower laser fluences (<0.49 J/mm2) experienced structural relaxation, whereas higher laser fluences led to crystallization within the laser treated region. The overall tensile behavior was least impacted by structural relaxation, whereas crystallization severely reduced the ultimate tensile strength of the laser treated metallic glass foils.

  11. Superior Tensile Ductility in Bulk Metallic Glass with Gradient Amorphous Structure

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Yang, Y.; Jiang, H.; Liu, C. T.; Ruan, H. H.; Lu, J.

    2014-04-01

    Over centuries, structural glasses have been deemed as a strong yet inherently `brittle' material due to their lack of tensile ductility. However, here we report bulk metallic glasses exhibiting both a high strength of ~2 GPa and an unprecedented tensile elongation of 2-4% at room temperature. Our experiments have demonstrated that intense structural evolution can be triggered in theses glasses by the carefully controlled surface mechanical attrition treatment, leading to the formation of gradient amorphous microstructures across the sample thickness. As a result, the engineered amorphous microstructures effectively promote multiple shear banding while delay cavitation in the bulk metallic glass, thus resulting in superior tensile ductility. The outcome of our research uncovers an unusual work-hardening mechanism in monolithic bulk metallic glasses and demonstrates a promising yet low-cost strategy suitable for producing large-sized, ultra-strong and stretchable structural glasses.

  12. Effects of annealing on tensile property and corrosion behavior of Ti-Al-Zr alloy

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Kyu; Choi, Byung-Seon; Jeong, Yong-Hwan; Lee, Doo-Jeong; Chang, Moon-Hee

    2002-03-01

    The effects of annealing on the tensile property and corrosion behavior of Ti-Al-Zr alloy were evaluated. The annealing in the temperature range from 500 to 800 C for 1 h induced the growth of the grain and the precipitate sizes. The results of tensile tests at room temperature showed that the strengths and the ductility were almost independent of the annealing temperature. However, the results of corrosion test in an ammonia aqueous solution of pH 9.98 at 360 C showed that the corrosion resistance depended on the annealing temperature, and the corrosion rate was accelerated with increasing annealing temperature. Hydrogen contents absorbed during the corrosion test of 220 days also increased with the annealing temperature. It could be attributed to the growth of Fe-rich precipitates by annealing. It is thus suggested that the lower annealing temperatures provide the better corrosion properties without degrading the tensile properties.

  13. Superior Tensile Ductility in Bulk Metallic Glass with Gradient Amorphous Structure

    PubMed Central

    Wang, Q.; Yang, Y.; Jiang, H.; Liu, C. T.; Ruan, H. H.; Lu, J.

    2014-01-01

    Over centuries, structural glasses have been deemed as a strong yet inherently brittle material due to their lack of tensile ductility. However, here we report bulk metallic glasses exhibiting both a high strength of ~2?GPa and an unprecedented tensile elongation of 24% at room temperature. Our experiments have demonstrated that intense structural evolution can be triggered in theses glasses by the carefully controlled surface mechanical attrition treatment, leading to the formation of gradient amorphous microstructures across the sample thickness. As a result, the engineered amorphous microstructures effectively promote multiple shear banding while delay cavitation in the bulk metallic glass, thus resulting in superior tensile ductility. The outcome of our research uncovers an unusual work-hardening mechanism in monolithic bulk metallic glasses and demonstrates a promising yet low-cost strategy suitable for producing large-sized, ultra-strong and stretchable structural glasses. PMID:24755683

  14. Effect of loading rate on tensile properties and failure behavior of glass fibre/epoxy composite

    NASA Astrophysics Data System (ADS)

    Mahato, K. K.; Biswal, M.; Rathore, D. K.; Prusty, R. K.; Dutta, K.; Ray, B. C.

    2016-02-01

    Fibre reinforced polymeric (FRP) composite materials are subjected to different range of loading rates during their service life. Present investigation is focused on to study the effects of variation of loading rates on mechanical behavior and various dominating failure modes of these potential materials when subjected to tensile loading. The results revealed that on the variation of loading rates the ultimate tensile strength varies but the tensile modulus is mostly unaffected. Furthermore, the strain to failure is also increasing with increase in loading rates. Different failure patterns of glass/epoxy composite tested at 1, 10,100, 500 and 1000 mm/min loading rates are identified. Scanning electron micrographs shows various dominating failures modes in the glass/epoxy composite.

  15. Tensile strain-induced softening of iron at high temperature

    PubMed Central

    Li, Xiaoqing; Schönecker, Stephan; Simon, Eszter; Bergqvist, Lars; Zhang, Hualei; Szunyogh, László; Zhao, Jijun; Johansson, Börje; Vitos, Levente

    2015-01-01

    In weakly ferromagnetic materials, already small changes in the atomic configuration triggered by temperature or chemistry can alter the magnetic interactions responsible for the non-random atomic-spin orientation. Different magnetic states, in turn, can give rise to substantially different macroscopic properties. A classical example is iron, which exhibits a great variety of properties as one gradually removes the magnetic long-range order by raising the temperature towards its Curie point of  = 1043 K. Using first-principles theory, here we demonstrate that uniaxial tensile strain can also destabilise the magnetic order in iron and eventually lead to a ferromagnetic to paramagnetic transition at temperatures far below . In consequence, the intrinsic strength of the ideal single-crystal body-centred cubic iron dramatically weakens above a critical temperature of ~500 K. The discovered strain-induced magneto-mechanical softening provides a plausible atomic-level mechanism behind the observed drop of the measured strength of Fe whiskers around 300–500 K. Alloying additions which have the capability to partially restore the magnetic order in the strained Fe lattice, push the critical temperature for the strength-softening scenario towards the magnetic transition temperature of the undeformed lattice. This can result in a surprisingly large alloying-driven strengthening effect at high temperature as illustrated here in the case of Fe-Co alloy. PMID:26556127

  16. Tensile strain-induced softening of iron at high temperature

    NASA Astrophysics Data System (ADS)

    Li, Xiaoqing; Schnecker, Stephan; Simon, Eszter; Bergqvist, Lars; Zhang, Hualei; Szunyogh, Lszl; Zhao, Jijun; Johansson, Brje; Vitos, Levente

    2015-11-01

    In weakly ferromagnetic materials, already small changes in the atomic configuration triggered by temperature or chemistry can alter the magnetic interactions responsible for the non-random atomic-spin orientation. Different magnetic states, in turn, can give rise to substantially different macroscopic properties. A classical example is iron, which exhibits a great variety of properties as one gradually removes the magnetic long-range order by raising the temperature towards its Curie point of ?=?1043?K. Using first-principles theory, here we demonstrate that uniaxial tensile strain can also destabilise the magnetic order in iron and eventually lead to a ferromagnetic to paramagnetic transition at temperatures far below . In consequence, the intrinsic strength of the ideal single-crystal body-centred cubic iron dramatically weakens above a critical temperature of ~500?K. The discovered strain-induced magneto-mechanical softening provides a plausible atomic-level mechanism behind the observed drop of the measured strength of Fe whiskers around 300500?K. Alloying additions which have the capability to partially restore the magnetic order in the strained Fe lattice, push the critical temperature for the strength-softening scenario towards the magnetic transition temperature of the undeformed lattice. This can result in a surprisingly large alloying-driven strengthening effect at high temperature as illustrated here in the case of Fe-Co alloy.

  17. Tensile strain-induced softening of iron at high temperature.

    PubMed

    Li, Xiaoqing; Schönecker, Stephan; Simon, Eszter; Bergqvist, Lars; Zhang, Hualei; Szunyogh, László; Zhao, Jijun; Johansson, Börje; Vitos, Levente

    2015-01-01

    In weakly ferromagnetic materials, already small changes in the atomic configuration triggered by temperature or chemistry can alter the magnetic interactions responsible for the non-random atomic-spin orientation. Different magnetic states, in turn, can give rise to substantially different macroscopic properties. A classical example is iron, which exhibits a great variety of properties as one gradually removes the magnetic long-range order by raising the temperature towards its Curie point of  TC°= 1043 K. Using first-principles theory, here we demonstrate that uniaxial tensile strain can also destabilise the magnetic order in iron and eventually lead to a ferromagnetic to paramagnetic transition at temperatures far below TC°. In consequence, the intrinsic strength of the ideal single-crystal body-centred cubic iron dramatically weakens above a critical temperature of ~500 K. The discovered strain-induced magneto-mechanical softening provides a plausible atomic-level mechanism behind the observed drop of the measured strength of Fe whiskers around 300-500 K. Alloying additions which have the capability to partially restore the magnetic order in the strained Fe lattice, push the critical temperature for the strength-softening scenario towards the magnetic transition temperature of the undeformed lattice. This can result in a surprisingly large alloying-driven strengthening effect at high temperature as illustrated here in the case of Fe-Co alloy. PMID:26556127

  18. Geometrically controlled tensile response of braided sutures.

    PubMed

    Rawal, Amit; Sibal, Apurv; Saraswat, Harshvardhan; Kumar, Vijay

    2015-03-01

    Sutures are the materials used for wound closure that are caused by surgery or trauma. The main pre-requisite to the success of the suture is to obtain ultimate level of tensile properties with defined geometrical constraints. In this communication, the model for tensile properties of braided sutures has been proposed by elucidating the most important geometrical and material parameters. The model has accounted for the kinematical changes occurring in the braid and constituent strand geometries under defined level of strain. A comparison has been made between the theoretical and experimental results of stress-strain characteristics of braided sutures. PMID:25579946

  19. Tensile and stress-rupture behavior of hafnium carbide dispersed molybdenum and tungsten base alloy wires

    NASA Technical Reports Server (NTRS)

    Yun, Hee Mann; Titran, Robert H.

    1993-01-01

    The tensile strain rate sensitivity and the stress-rupture strength of Mo-base and W-base alloy wires, 380 microns in diameter, were determined over the temperature range from 1200 K to 1600 K. Three molybdenum alloy wires; Mo + 1.1w/o hafnium carbide (MoHfC), Mo + 25w/o W + 1.1w/o hafnium carbide (MoHfC+25W) and Mo + 45w/o W + 1.1w/o hafnium carbide (MoHfC+45W), and a W + 0.4w/o hafnium carbide (WHfC) tungsten alloy wire were evaluated. The tensile strength of all wires studied was found to have a positive strain rate sensitivity. The strain rate dependency increased with increasing temperature and is associated with grain broadening of the initial fibrous structures. The hafnium carbide dispersed W-base and Mo-base alloys have superior tensile and stress-rupture properties than those without HfC. On a density compensated basis the MoHfC wires exhibit superior tensile and stress-rupture strengths to the WHfC wires up to approximately 1400 K. Addition of tungsten in the Mo-alloy wires was found to increase the long-term stress rupture strength at temperatures above 1400 K. Theoretical calculations indicate that the strength and ductility advantage of the HfC dispersed alloy wires is due to the resistance to recrystallization imparted by the dispersoid.

  20. Lifetimes of fiber composites under sustained tensile loading

    NASA Technical Reports Server (NTRS)

    Chiao, T. T.; Sherry, R. J.; Chiao, C. C.

    1977-01-01

    A description is presented of the test techniques which have been used to apply sustained uniaxial tensile loading to fiber/epoxy composites. The fiber types used include S-glass, aramid, graphite, and beryllium wire. The applied load vs lifetime data for four composite materials are presented in graphs. Attention is given to a statistical analysis of data, a performance comparison of various composites, the age effect on the strength of composites, the applicability of the lifetime data to complex composites, and aspects of accelerated test method development. It is found that the lifetime of a composite under a sustained load varies widely. Depending on the composite system, the minimum life typically differs from the maximum life by a factor of 100 to 1000. It is in this connection recommended that a use of average life data should be avoided in serious design calculations.

  1. Fracture strength of hydride precipitates in Zr-2.5Nb alloys

    NASA Astrophysics Data System (ADS)

    Shi, S.-Q.; Puls, M. P.

    1999-11-01

    The hydride precipitate fracture strength as a function of precipitate size and temperature (23-250C) in smooth tensile specimens of Zr-2.5Nb pressure tube material (nominal hydrogen content 100 ppm by weight) was studied using the acoustic emission technique. At room temperature, this strength is sensitive to hydride length when the average hydride length is short, and is insensitive to the hydride length when the average hydride length is longer than 25 ?m. The hydride fracture strength decreases slightly with temperature, but a more rapid decrease in the yield strength offsets this decrease, resulting in a brittle-to-ductile transition at 120C to 140C in smooth tensile tests. The presence of hydrides causes a decrease in the ultimate tensile strength of the material at low temperatures, and has no effect at high temperatures for these smooth tensile specimens.

  2. Dry Bag Isostatic Pressing for Improved Green Strength of Nuclear Fuel Pellets

    SciTech Connect

    G. W. Egeland; L. D. Zuck; W. R. Cannon; P. A. Lessing; P. G. Medvedev

    2010-11-01

    Dry bag isostatic pressing is proposed for mass production of nuclear fuel pellets. Dry bag isostatically pressed rods of a fuel surrogate (95% CeO2-5% HfO2) 200 mm long by 8 mm diameter were cut into pellets using a wire saw. Four different binder and two different CeO2 powder sources were investigated. The strength of the isostatically pressed pellets for all binder systems measured by diametral compression was about 50% higher than pellets produced by uniaxial dry pressing at the same pressure. It was proposed that the less uniform density of uniaxially pressed pellets accounted for the lower strength. The strength of pellets containing CeO2 powder with significantly higher moisture content was five times higher than pellets containing CeO2 powder with a low moisture content. Capillary pressure of the moisture was thought to supply the added binding strength.

  3. Hydrogen-involved tensile and cyclic deformation behavior of low-alloy pressure vessel steel

    NASA Astrophysics Data System (ADS)

    Wu, Xinqiang; Katada, Yasuyuki; Kim, In S.; Lee, Sang G.

    2004-05-01

    The temperature- and strain-rate-dependent tensile behavior of hydrogen-charged low-alloy pressure vessel steel ASTM A508 C1.3 has been investigated. The fatigue crack initiation and propagation behavior of the steel in high-temperature water environments has also been evaluated. It was found that hydrogen played significant roles in both tensile and cyclic deformation processes, especially in the temperature and strain-rate region of dynamic strain aging (DSA). The presence of hydrogen resulted in a distinct softening in tensile strength and a certain loss in tensile ductility in the DSA region. Remarkable degradation in fatigue crack initiation and propagation resistance in high-temperature water environments was observed in the DSA strain-rate region. Typical hydrogen-induced cracking features also appeared on the corresponding fatigue fracture surfaces. The interactions between hydrogen and DSA in tensile and cyclic deformation processes are discussed as well as their combined effects on the environmentally assisted cracking (EAC) mechanism of pressure vessel steels in high-temperature water environments.

  4. A Tensile Deformation Model for In-situ Dendrite/Metallic Glass Matrix Composites

    PubMed Central

    Qiao, J. W.; Zhang, T.; Yang, F. Q.; Liaw, P. K.; Pauly, S.; Xu, B. S.

    2013-01-01

    In-situ dendrite/metallic glass matrix composites (MGMCs) with a composition of Ti46Zr20V12Cu5Be17 exhibit ultimate tensile strength of 1510 MPa and fracture strain of about 7.6%. A tensile deformation model is established, based on the five-stage classification: (1) elastic-elastic, (2) elastic-plastic, (3) plastic-plastic (yield platform), (4) plastic-plastic (work hardening), and (5) plastic-plastic (softening) stages, analogous to the tensile behavior of common carbon steels. The constitutive relations strongly elucidate the tensile deformation mechanism. In parallel, the simulation results by a finite-element method (FEM) are in good agreement with the experimental findings and theoretical calculations. The present study gives a mathematical model to clarify the work-hardening behavior of dendrites and softening of the amorphous matrix. Furthermore, the model can be employed to simulate the tensile behavior of in-situ dendrite/MGMCs. PMID:24085187

  5. Mechanical Testing of TR-55 Rubber Thermally Aged Under Tensile Strain

    SciTech Connect

    Small IV, W; Alviso, C T; Wilson, T S; Chinn, S C; Maxwell, R S

    2009-03-10

    TR-55 rubber specimens were previously subjected to an aging process consisting of the application of a tensile strain of approximately 67%, 100%, 133%, or 167% elongation for 4, 8, 12, or 16 h at either 250 C or room temperature. Control specimens at the same temperatures/durations were not subjected to tensile strain. The specimens were allowed to recover at room temperature without external stimuli for over 100 days before tensile testing. A single dog bone was cut from each specimen and a stress-strain curve was obtained. The elastic modulus of each specimen was calculated. Specimens aged under tensile strain exhibited rubber-like behavior dependent on the aging elongation and duration. This behavior was not evident in the unstrained controls. For the unstrained controls, exposure to 250 C resulted in an increase in modulus relative to the unheated material independent of the heating duration. The tensile strain applied during the aging process caused a reduction in modulus relative to the controls; lower moduli were observed for the shorter aging durations. Slippage of the specimens in the grips prevented determination of ultimate strength, as all specimens either slipped completely out of the grip before failure or failed at the original grip edge after slipping.

  6. Additive decomposition of shear strength in cohesive granular media from grain-scale interactions.

    PubMed

    Taboada, Alfredo; Estrada, Nicolas; Radja, Farhang

    2006-09-01

    We study cemented granular media by introducing cohesive bonding (sliding or rolling friction and tensile strength) between grains in the framework of the contact dynamics method. We find that, for a wide range of bond parameters, the macroscopic angle of friction at the peak state can be split into three distinct terms of collisional, frictional and dilational origins. Remarkably, the macroscopic tensile strength depends only on the bond tensile strength, and the friction angle at the peak state is proportional to the dilatancy angle which varies linearly with sliding friction. PMID:17026408

  7. Weldability evaluation of high tensile plates using GMAW process

    NASA Astrophysics Data System (ADS)

    Datta, R.; Mukerjee, D.; Rohira, K. L.; Veeraraghavan, R.

    1999-08-01

    High tensile plates, SAILMA-450 high impact (HI) (yield strength, 45 kg/mm2 minimum; ultimate tensile strength, 57 kg/mm2 minimum; elongation, 19% minimum; Charpy impact energy 2.0 kg.m at -20 C minimum) were successfully developed at the Steel Authority of India Ltd., up to 32 mm plate thickness. Since then the steel has been extensively used for the fabrication of impellers, bridges, excavators, and mining machineries, where welding is an important processing step. The present study deals with the weldability properties of SAILMA-450 HI plates employing the gas metal arc welding process and carbon dioxide gas. Implant and elastic restraint cracking tests were conducted to assess the cold cracking resistance of the weld joint under different welding conditions. The static fatigue limit values were found to be in excess of minimum specified yield strength at higher heat input levels (9.4 and 13.0 kJ/cm), indicating adequate cold cracking resistance. The critical restraint intensities, K cr, were found to vary between 720 and 1280 kg/mm2, indicating that the process can be utilized for fabrication of structures involving moderate to low restraint intensities (200 to 1000 kg/mm2). Lamellar tear tests conducted using full thickness plates at heat input levels ranging from 10 to 27 kJ/cm showed no incidence of lamellar tear upon visual, ultrasonic, and four-section macroexamination. These tests were repeated using machined plates, such that the midthickness of the plates (segregated zone) corresponded to the heat affected zone of the weld. No cracks were observed, indicating good lamellar tear resistance of the weld joint. Optimized welding conditions were formulated based on these tests. The weld joint was subjected to extensive tests to assess the physical properties and soundness of the weld joint. The weld joint exhibited good strength (64.7 kg/mm2) and impact toughness (5.7 and 3.5 kg.m at -20 C for weld metal and heat affected zone properties. Crack tip opening displacement (CTOD) tests carried out for parent metal, heat-affected zone, and weld metal resulted in ?m values of 0.41, 0.40, and 0.34 mm, respectively, which indicates adequate resistance to cleavage fracture. It was concluded that the weld joint conforms to the requirements of SAILMA-450 HI specification and ensures a high integrity of the fabricated products.

  8. Tensile and Charpy impact properties of irradiated reduced-activation ferritic steels

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.

    1996-10-01

    Tensile tests were conducted on 8 reduced-activation Cr-W steels after irradiation to 15-17 and 26-29 dpa, and Charpy impact tests were conducted on steels irradiated to 26-29 dpa. Irradiation was in Fast Flux Test Facility at 365 C on steels containing 2.25-12% Cr, varying amounts of W, V, and Ta, and 0.1%C. Previously, tensile specimens were irradiated to 6-8 dpa and Charpy specimens to 6-8, 15- 17, and 20-24 dpa. Tensile and Charpy specimens were also thermally aged to 20,000 h at 365 C. Thermal aging had little effect on tensile properties or ductile-brittle transition temperature (DBTT), but several steels showed a slight increase in upper-shelf energy (USE). After 7 dpa, strength increased (hardened) and then remained relatively unchanged through 26-29 dpa (ie, strength saturated with fluence). Post-irradiation Charpy impact tests after 26-29 dpa showed that the loss of impact toughness (increased DBTT, decreased USE) remained relatively unchanged from the values after 20-24 dpa, which had been relatively unchanged from the earlier irradiations. As before, the two 9Cr steels had the most irradiation resistance.

  9. Tensile behavior of tungsten and tungsten-alloy wires from 1300 to 1600 K

    NASA Technical Reports Server (NTRS)

    Hee, Man Yun

    1988-01-01

    The tensile behavior of a 200-micrometer-diameter tungsten lamp (218CS-W), tungsten + 1.0 atomic percent (a/o) thoria (ST300-W), and tungsten + 0.4 a/o hafnium carbide (WHfC) wires was determined over the temperature range 1300 t0 1600 K at strain rates of 3.3 X 10 to the -2 to 3.3 X 10 to the -5/sec. Although most tests were conducted on as-drawn materials, one series of tests was undertaken on ST300-W wires in four different conditions: as-drawn and vacuum-annealed at 1535 K for 1 hr, with and without electroplating. Whereas heat treatment had no effect on tensile properties, electropolishing significantly increased both the proportional limit and ductility, but not the ultimate tensile strength. Comparison of the behavior of the three alloys indicates that the HfC-dispersed material possesses superior tensile properties. Theoretical calculations indicate that the strength/ductility advantage of WHfC is due to the resistance to recrystallization imparted by the dispersoid.

  10. Tensile and charpy impact properties of irradiated reduced-activation ferritic steels

    SciTech Connect

    Klueh, R.L.; Alexander, D.J.

    1996-10-01

    Tensile tests were conducted on eight reduced-activation Cr-W steels after irradiation to 15-17 and 26-29 dpa, and Charpy impact tests were conducted on the steels irradiated to 26-29 dpa. Irradiation was in the Fast Flux Test Facility at 365{degrees}C on steels containing 2.25-12% Cr, varying amounts of W, V, and Ta, and 0.1%C. Previously, tensile specimens were irradiated to 6-8 dpa and Charpy specimens to 6-8, 15-17, and 20-24 dpa. Tensile and Charpy specimens were also thermally aged to 20000 h at 365{degrees}C. Thermal aging had little effect on the tensile behavior or the ductile-brittle transition temperature (DBTT), but several steels showed a slight increase in the upper-shelf energy (USE). After {approx}7 dpa, the strength of the steels increased and then remained relatively unchanged through 26-29 dpa (i.e., the strength saturated with fluence). Post-irradiation Charpy impact tests after 26-29 dpa showed that the loss of impact toughness, as measured by an increase in DBTT and a decrease in the USE, remained relatively unchanged from the values after 20-24 dpa, which had been relatively unchanged from the earlier irradiations. As before, the two 9Cr steels were the most irradiation resistant.

  11. Effects of Sample Geometry and Loading Rate onTensile Ductility of TRIP800 Steel

    SciTech Connect

    Sun, Xin; Soulami, Ayoub; Choi, Kyoo Sil; Guzman, O.; Chen, Weinong W.

    2012-04-15

    The effects of sample geometry and loading rate on the tensile ductility of a commercial grade Transformation Induced Plasticity (TRIP) steel are examined in this paper. Quasistatic tensile tests were performed for the 1.2mm gauge TRIP800 steel sheets with two geometries: sub-sized ASTM E-8 and a custom designed miniature tensile sample. Sample geometry effects on post-uniform elongation are discussed together with other experimental data reported in the open literature. Further discussions on the effects of sample geometry are cast in the context of mesh-size dependent ductility in finite element-based engineering simulations. The quasi-static tensile curve for the miniature sample is then compared with the split Hopkinson bar results at the loading rates of 1700-S-1 and 2650-S-1 with the same sample design. In contrary to the typical strain rate sensitivity results for mild steel where the dynamic strength increase at high strain rate usually occurs at the price of ductility reduction, our results show that the TRIP800 under examination has positive strain rate sensitivity on both strength and ductility. Images of the deformation process captured by high speed camera together with scanning electron microscopy (SEM) near the fracture zone are also used to elucidate the different deformation modes at different loading rates.

  12. Effects of lamination and coating with drying oils on tensile and barrier properties of zein films.

    PubMed

    Rakotonirainy, A M; Padua, G W

    2001-06-01

    Zein films plasticized with oleic acid have been considered potentially useful for biodegradable packaging applications. However, moisture was found to affect their tensile and gas barrier properties. We investigated the effects of two converting processes, fusion lamination and coating with drying oils, on tensile properties and gas permeability of zein films. Zein films were laminated to 4-ply sheets in a Carver press and coated with tung oil, linseed oil, or a mixture of tung and soybean oils. Tensile properties and permeability to water vapor, oxygen, and carbon dioxide were measured according to ASTM methods. Laminated films were clearer, tougher, and more flexible, and had a smoother finish than nontreated sheets. Lamination decreased O(2) and CO(2) permeability by filling in voids and pinholes in the film structure. Coating increased tensile strength and elongation and decreased water vapor permeability. Coatings acted as a composite layer preventing crack propagation and increasing film strength. They also formed a highly hydrophobic surface that prevented film wetting. PMID:11409979

  13. Tensile Properties of Ni-Based Superalloy 720Li: Temperature and Strain Rate Effects

    NASA Astrophysics Data System (ADS)

    Gopinath, K.; Gogia, A. K.; Kamat, S. V.; Balamuralikrishnan, R.; Ramamurty, U.

    2008-10-01

    Tensile properties, deformation, and fracture behavior of a wrought nickel-base superalloy 720Li have been studied in standard solutionized and two-stage-aged condition in the temperature range of 25 C to 750 C. Effect of strain rate on tensile behavior was assessed at 25 C, 400 C, and 750 C at five strain rates that range between 10-5 s-1 and 10-1 s-1. The yield strength and ultimate tensile strength of the alloy remained unaffected by temperature until about 600 C and 500 C, respectively, typical of superalloys strengthened by fine and coherent intermetallic Ni3Al-based precipitates. The flow stress of the alloy was found to be insensitive to the strain rates studied at 25 C and 400 C. However, at 750 C, the flow stresses showed strain rate sensitivity at strain rates <10-3 s-1. The strain hardening behavior at 25 C and 400 C were similar. At 750 C, stain hardening was observed only at strain rates >10-3 s-1, and at lower strain rates, tensile instability was seen to set in immediately after yielding. The alloy exhibited ductile dimple fracture at all the temperatures and strain rates studied. Microstructural investigations indicate that in regimes where flow stresses are insensitive to strain rate, deformation occurs through heterogeneous planar slip, whereas in strain rate sensitive regimes, thermally activated diffusion processes promote homogeneous deformation.

  14. Tensile properties of glass/natural jute fibre-reinforced polymer bars for concrete reinforcement

    NASA Astrophysics Data System (ADS)

    Han, J. W.; Lee, S. K.; Kim, K. W.; Park, C. G.

    2015-12-01

    The tensile performance of glass/natural jute fibre-reinforced polymer (FRP) bar, intended for concrete reinforcement was evaluated as a function of volume fraction of natural jute fibre. Natural jute fibre, mixed at a ratio of 7:3 with vinyl ester, was surface-treated with a silane coupling agent and used to replaced glass fibre in the composite in volume fractions of 0%, 30%, 50%, 70%, and 100%. The tensile load-displacement curve showed nearly linear elastic behaviour up to 50% natural jute fibre, but was partially nonlinear at a proportion of 70%. However, the glass/natural jute FRP bars prepared using 100% natural jute fibre showed linear elastic behaviour. Tensile strength decreased as the natural jute fibre volume fraction increased because the tensile strength of natural jute fibre is much lower than that of glass fibre (about 1:8.65). The degree of reduction was not proportional to the natural jute fibre volume fraction due to the low density of natural jute fibre (1/2 that of glass fibre). Thus, as the mix proportion of natural jute fibre increased, the amount (wt%) and number of fibres used also increased.

  15. Static tensile and tensile creep testing of four boron nitride coated ceramic fibers at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Coguill, Scott L.; Adams, Donald F.; Zimmerman, Richard S.

    1989-01-01

    Six types of uncoated ceramic fibers were static tensile and tensile creep tested at various elevated temperatures. Three types of boron nitride coated fibers were also tested. Room temperature static tensile tests were initially performed on all fibers, at gage lengths of 1, 2, and 4 inches, to determine the magnitude of end effects from the gripping system used. Tests at one elevated temperature, at gage lengths of 8 and 10 inches, were also conducted, to determine end effects at elevated temperatures. Fiber cross sectional shapes and areas were determined using scanning electron microscopy. Creep testing was typically performed for 4 hours, in an air atmosphere.

  16. Study on the Microstructures and Tensile Behaviors of Friction Stir Welded T-joints for AA6061-T4 Alloys

    NASA Astrophysics Data System (ADS)

    Zhou, G.; Yang, X. Q.; Cui, L.; Zhang, Z. H.; Xu, X. D.

    2012-10-01

    Friction stir welding (FSW) of T-joints with 3 mm thickness for AA6061-T4 sheets has been performed, and the influences of process parameters on the microstructures, defects, hardness profiles, and tensile strength were discussed specifically. It is found that the macrostructures and microstructures are similar in different process parameters, and the microstructure features in the skin welds have the same patterns as that of butt-joints. The unique microstructures of T-joints are the two fillet zones. Two lower hardness zones in the skin and one lower hardness zone in the stringer are found. Additionally, the tensile properties of T-welded joints are examined along the skin and the stringer plane directions. Results show that the tensile strength is in the range of 170-180 MPa for all the specimens along the skin direction, and the specimens fail in the heat affected zone (HAZ). In the stringer direction, the larger tunnel defects (DA) (the DA is greater than 0.1 mm2) would reduce the ultimate tensile strength of the T-joints and cause the joints to fracture at the bonding interface. The smaller tunnel defects (the DA is less than 0.015 mm2) and the zigzag lines have no pronounced effect on the failed location. In the stringer direction, tensile efficiencies of T-joints could be 83% of the base material (BM) when ω/v = 1541/218 r/mm is applied.

  17. A new tensile stage for in situ electron microscopy examination of the mechanical properties of 'superelastic' specimens

    SciTech Connect

    Dragnevski, Kalin I.; Fairhead, Trevor W.; Balsod, Rik; Donald, Athene M.

    2008-12-15

    We have developed a novel tensile stage that can be used for in situ electron microscopy examination of the mechanical properties of ''superelastic'' materials. In our stage, one of the specimen clamps is replaced by a cylindrical roller, which when driven by a motor can easily stretch (''roll on'') any specimen irrespective of its plastic properties. We have used the so-called Roll-o-meter in the study of the tensile behavior of two different film formed latex formulations, here referred to as standard and novel. We find that the values of the tensile strength and extension to break of the studied systems, measured by using the Roll-o-meter, are similar to those measured by a Hounsfield tensile testing machine outside the microscope chamber. Further, in situ environmental scanning electron microscopy examination of the deformation and failure of the lattices revealed that the standard specimens exhibit a more ductile behavior, compared to the novel ones.

  18. Evaluation of Tensile Deformation Properties of Friction Stir Processed Pure Copper: Effect of Processing Parameters and Pass Number

    NASA Astrophysics Data System (ADS)

    Barmouz, Mohsen; Besharati Givi, Mohammad Kazem; Jafari, Jalal

    2014-01-01

    In this work, the tensile behavior of pure copper including ultimate tensile stress, yield stress, and elongation in the specimens friction stir processed under different processing parameters and pass adding was investigated in detail. The effect of strain hardening, grain refinement, and heat input on the tensile properties of these specimens was explained as well. It was observed that, regarding the aforementioned factors, the processing parameters and pass number could have considerable effects on the tensile deformation properties of the pure copper such as 300 and 47% enhancements in elongation and ultimate strength, respectively. It was demonstrated that higher passes resulted in the development of ultrafine grains (up to 700-800 nm) in the specimens. The fracture surface morphology was also used to further support the elongation results.

  19. The elevated temperature tensile properties of S-200E commercially pure beryllium

    SciTech Connect

    Henshall, G.A.; Torres, S.G.; Hanafee, J.E.

    1995-03-01

    Experiments were performed at 300-100 C in longitudinal and transverse orientations at quasi-static strain rate 5.5 {times} 10{sup {minus}4}s{sup {minus}1}. Results show that the stress-strain curve is smooth, without yield points or serrations. Yield stress and ultimate tensile stress decrease monotonically with temperature. Similar strengths were measured for both orientations. Failure elongation vs temperature is complex.

  20. Tensile and creep rupture properties of (16) uncoated and (2) coated engineering alloys at elevated temperatures

    NASA Technical Reports Server (NTRS)

    Fritz, L. J.; Koster, W. P.

    1977-01-01

    Sixteen test materials were supplied by NASA-Lewis Research Center as wrought bar or cast remelt stock. The cast remelt stock was cast into test blanks with two such materials being also evaluated after Jocoat coating was applied. Mechanical properties evaluated included tensile, modulus of elasticity, Poisson's Ratio, creep properties and creep rupture strength. Tests were conducted at temperatures applicable to the service temperature of the various alloys. This range extended from room temperature to 1000 C.