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1

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

PubMed Central

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 (ø 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.

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

2010-01-01

2

Diametral tensile strength and water sorption of glass-ionomer cements used in Atraumatic Restorative Treatment.  

PubMed

The purposes of this study were to evaluate the diametral tensile strength and the water sorption of restorative (Fuji IX and Ketac Molar) and resin-modified glass-ionomer luting cements (ProTec Cem, Fuji Plus and Vitremer) mixed at both manufacturer and increased powder: liquid ratio, for their use in the Atraumatic Restorative Treatment. A conventional restorative glass-ionomer (Ketac Fil) was used as control. Specimens (6.0 mm in diameter x 3.0 mm in height) were prepared and stored (1 hour, 1 day and 1 week) for a diametral tensile strength test. Data were subjected to two-way ANOVA and Tukey tests (p<0.05). For the water sorption test, specimens of 15.0 mm in diameter x 0.5 mm in height were prepared and transfered to desiccators until a constant mass was obtained. Then the specimens were immersed in deionized water for 7 days, weighed and reconditioned to a constant mass in desiccators. Data were subjected to one-way ANOVA and Tukey tests (p<0.05). Five specimens of each studied material and consistency were prepared for each test. The resin-modified glass-ionomer cements showed significantly higher strength than the conventional materials. Except for ProTec Cem, the diametral tensile strength of the resin-modified materials significantly increased from luting to restorative consistency. Except for ProTec Cem, the water sorption of the resin-modified glass ionomers was higher than the others. The water sorption of resin-modified materials at restorative consistency was significantly lower than at luting consistency. Resin-modified glass-ionomer luting cements mixed at increased powder: liquid ratio showed better properties than at luting consistency. PMID:21409320

Cefaly, Daniela Francisca Gigo; Franco, Eduardo Batista; Mondelli, Rafael Francisco Lia; Francisconi, Paulo Afonso Silveira; Navarro, Maria Fidela de Lima

2003-06-01

3

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

PubMed Central

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- 10.94±1.30; COP 10%- 30.06±0.64; COP 50%- 29.87±0.27; zinc phosphate- 4.88±0.96. The values of FT (µm) were: Pure COP- 31.09±3.16; COP 10%- 17.05±4.83; COP 50%- 13.03±4.83; Zinc Phosphate- 20.00±0.12. 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.

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

2012-01-01

4

The diametral tensile strength and hydrostability of polymer-ceramic nano-composite (pcnc) material prototypes  

NASA Astrophysics Data System (ADS)

Statement of the problem: There is a weak connection between the filler and the resin matrix of dental composites caused primarily by hydrolysis of silane coupling agent, therefore, jeopardizing the mechanical properties of the dental restorations. Purpose: The purpose of this study was to compare the diametral tensile strength (DTS) of a nano-mechanically bonded polymer ceramic nano composite (pcnc) versus the chemically bonding prototype polymer ceramic nano composite (pcnc) fabricated by using hydrolytically stable interphase. Materials and Methods: Composites were made with 60wt % filler, 38% triethyleneglycol dimethacrylate (TEDGMA), 1% camphorquinone (CQ) and 1% 2-(dimethylamino) ethyl methacrylate (DMAEMA). Tests for DTS were performed using a universal testing machine. The disk-shaped specimens were loaded in compression between two supporting plates at a crosshead speed of 0.5 mm/min until fracture. The samples, measuring 3 mm in height and 6 mm in diameter, were produced in a round stainless steel (SS) mold. A total of 144 samples were created. Groups of 48 samples were made for each of three different fillers. Specimens were soaked in artificial saliva at 37° for four time periods, dry(t=0), 1 day, 7 days, 28 days). At the end of each soaking time DTS tests were performed. Results: There where statistically significant differences in the DTS between the filler groups and the soaking times (p=<0.001) as well as for the pairwise comparison between the different filler group values and between the different soaking times as an individual treatment. Overall, longer soaking times resulted in lower mean DTS values. The DTS of the PCNC for filler #1 decreased to 82.4% of the original value after 1 day of soaking, 67.2% after 7 days and 27.2 % after 28 days. For filler #2 decreased to 54.8% of the original value after 1 day of soaking, 62.3% after 7 days and 61.2% after 28 days. For filler #3 decreased to 71.2% of the original value, 67.3% after 7 days and 51.4% after 28 days (Fig 8). Conclusions: Within the limitation of this study it can be concluded that the use of coupling agent will significantly influence the degradation of the material under wet environment. Clinical Implication: Changes within matrix composition and bonding interphase of resin base composites promise improvements of mechanical properties, decreasing the incidence of clinical failure of posterior composite restorations, hence resulting in a more ideal restorative material for use in posterior segment. The results of this investigation showed that the deficiency of hydrostability in dental composites is a detrimental factor in the mechanical behavior. The silanation of the filler particles have a positive influence on the mechanical properties of dental composites but the hydrolysis of the silane coupling agent can dramatically reduce the average lifetime of dental composites.

Yepez, Johanna

5

Effect of time on the diametral tensile strength of resin-modified restorative glass ionomer cements and compomer.  

PubMed

The aim of this study was to analyze the diametral tensile strengths of three resin-modified restorative glass ionomer cements--Vitremer, Fuji II LC and Photac Fil and one compomer--Dyract. They were tested at 1 hour, 1 day and 1 week. Kratos testing machine was used to load the specimens at a cross-head speed of 0.5 mm/min. The data were analyzed by two-way ANOVA and Tukey's test that showed statistically significant differences among the materials. The tested materials presented an increase in strength from 1 hour to 1 week and were as follows for each material respectively: Vitremer (19.22-27.29), Fuji II LC (23.91-28.67), Photac Fil (19.35-22.86), Dyract (28.83-46.95). Dyract presented the highest strengths. PMID:11696919

Cefaly, D F; Valarelli, F P; Seabra, B G; Mondelli, R F; Navarro, M F

2001-01-01

6

Tensile strength of dried gelcast green bodies  

SciTech Connect

Ceramic green bodies were prepared by three different techniques, dry pressing, slip casting, and gelcasting. The tensile strength of the green bodies was measured using a diametral compression test. It was found that the gelcast samples were from 2 to 20 times stronger than the conventionally formed green bodies. SEM examination of the gelcast samples revealed a homogeneous, brittle fracture surface indicating a very uniform distribution of the binder and excellent dispersion of the ceramic powder.

Nunn, S.D.; Omatete, O.O.; Walls, C.A.; Barker, D.L.

1994-04-01

7

Measurement of the tensile strength of brittle materials  

Microsoft Academic Search

Three alternative methods for measuring the tensile strengths of brittle materials are investigated and compared with the conventional pull method. These are a bending test, an indentation test and a test in which disks are compressed diametrally. Experiments on plaster of Paris, coal and cement show that, apart from the bending test, the methods give results in reasonable agreement. The

R. Berenbaum; I. Brodie

1959-01-01

8

Effects of temperature on the tensile strength of pharmaceutical powders.  

PubMed

Measurements have been made of the tensile strengths of fatty acids, lactose and of an oxtetracycline and a paracetamol tablet formulation at temperatures between -20 and +90 degrees. The measurements were made on compressed tablets and on consolidated beds of powders, using a diametral compression tester and a split plate tensile tester which had been designed to operate over this range of temperature. The tensile strengths of all the materials increase with temperature and values are given for the activation energies of bonding between particles. PMID:31427

Britten, J R; Pilpel, N

1978-11-01

9

Evaluation of Tensile Strength Testing.  

National Technical Information Service (NTIS)

The report contains a summary of the activities related to the development, application and use of the splitting tensile test and of the flexure beam test to estimate the tensile strength of portland cement concrete pavement. Information related to the de...

A. H. Meyer D. W. Fowler L. M. Melis

1985-01-01

10

7 CFR 29.3061 - Strength (tensile).  

Code of Federal Regulations, 2010 CFR

... 2009-01-01 false Strength (tensile). 29.3061 Section 29...Foreign Type 93) § 29.3061 Strength (tensile). The stress a tobacco leaf can bear without tearing. Tensile strength is not an important...

2009-01-01

11

7 CFR 29.3061 - Strength (tensile).  

Code of Federal Regulations, 2010 CFR

... 2010-01-01 false Strength (tensile). 29.3061 Section 29...Foreign Type 93) § 29.3061 Strength (tensile). The stress a tobacco leaf can bear without tearing. Tensile strength is not an important...

2010-01-01

12

Hydrate adhesive and tensile strengths  

NASA Astrophysics Data System (ADS)

The physical properties of hydrate-bearing sediments depend on the interaction between hydrates and minerals. In particular, hydrates prefer to nucleate on mineral surfaces, therefore, the hydrate-mineral adhesive strength and the tensile strength of the hydrate mass itself affect the mechanical response of hydrate-bearing sediments. In this study, ice and hydrates made with various guest molecules (CO2, CH4, and THF) are formed between mica and calcite substrates. Adhesive and tensile strengths are measured by applying an external pull-out force. Results show that tensile failure occurs in CO2 and CH4 hydrates when calcite is the substrate, while ice and all hydrates exhibit adhesive failure on mica. The debonding strength is higher when calcite substrates are involved rather than mica substrates. A nominal pull-out strength of 0.15 ± 0.03 MPa can be adopted for mechanical analyses of hydrate-bearing sediments.

Jung, J. W.; Santamarina, J. Carlos

2011-08-01

13

Tensile strength of hybrid composites  

Microsoft Academic Search

This paper presents an approximate, statistical analysis for the tensile strength of unidirectional hybrid composite materials consisting of two-dimensional arrays of alternating low elongation and high elongation fibres in a common matrix. Expressions for ineffective length and fibre strain concentration factor in hybrid composites are developed. The analysis identifies a number of important material properties that affect the failure process

Carl Zweben; E. L du Pont de Nemours

1977-01-01

14

Investigations into the tensile failure of doubly-convex cylindrical tablets under diametral loading using finite element methodology.  

PubMed

In the literature various solutions exist for the calculation of the diametral compression tensile strength of doubly-convex tablets and each approach is based on experimental data obtained from single materials (gypsum, microcrystalline cellulose) only. The solutions are represented by complex equations and further differ for elastic and elasto-plastic behaviour of the compacts. The aim of this work was to develop a general equation that is applicable independently of deformation behaviour and which is based on simple tablet dimensions such as diameter and total tablet thickness only. With the help of 3D-FEM analysis the tensile failure stress of doubly-convex tables with central cylinder to total tablet thickness ratios W/D between 0.06 and 0.50 and face-curvature ratios D/R between 0.25 and 1.85 were evaluated. Both elastic and elasto-plastic deformation behaviour were considered. The results of 80 individual simulations were combined and showed that the tensile failure stress ?t of doubly-convex tablets can be calculated from ?t=(2P/?DW)(W/T)=2P/?DT with P being the failure load, D the diameter, W the central cylinder thickness, and T the total thickness of the tablet. This equation converts into the standard Brazilian equation (?t=2P/?DW) when W equals T, i.e. is equally valid for flat cylindrical tablets. In practice, the use of this new equation removes the need for complex measurements of tablet dimensions, because it only requires values for diameter and total tablet thickness. It also allows setting of standards for the mechanical strength of doubly-convex tablets. The new equation holds both for elastic and elasto-plastic deformation behaviour of the tablets under load. It is valid for all combinations of W/D-ratios between 0.06 and 0.50 with D/R-ratios between 0.00 and 1.85 except for W/D=0.50 in combination with D/R-ratios of 1.85 and 1.43 and for W/D-ratios of 0.40 and 0.30 in combination with D/R=1.85. FEM-analysis indicated a tendency to failure by capping or even more complex failure patterns in these exceptional cases. The FEM-results further indicated that in general W/D-ratios between 0.15 and 0.20 are favourable when the overall size and shape of the tablets is modified to give maximum tablet tensile strength. However, the maximum tensile stress of doubly-convex tablets will never exceed that of a flat-face cylindrical tablet of similar W/D-ratio. The lowest tensile stress depends on the W/D-ratio. For the thinnest central cylinder thickness, this minimum stress occurs at D/R=0.50; for W/D-ratios between 0.10 and 0.20 the D/R-ratio for the minimum tensile stress increases to 0.67, and for all other central cylinder thicknesses the minimum tensile stress is found at D/R=1.00. PMID:23834836

Podczeck, Fridrun; Drake, Kevin R; Newton, J Michael

2013-09-15

15

A new analytic solution for the diametral point load strength test on finite solid circular cylinders  

Microsoft Academic Search

This paper presents an exact analytic solution for a finite isotropic circular cylinder of diameter D and length 2L subjected to the diametral point load strength test (PLST). Two displacement functions are introduced to uncouple the equations of equilibrium, and two new series expressions for these functions are proposed in terms of the Bessel and modified Bessel functions of the

K. T. Chau; X. X. Wei

2001-01-01

16

Tensile strength testing of Topopah Spring tuff.  

National Technical Information Service (NTIS)

Laboratory experiments were conducted to compare two techniques for determining the tensile strength of nonlithophysal, welded tuff of the Topopah Spring Member and determine which technique should be used for site characterization. Tensile strengths were...

L. W. Teufel M. J. McNamee

1991-01-01

17

An Interlaminar Tensile Strength Specimen  

NASA Technical Reports Server (NTRS)

This paper describes a technique to determine interlaminar tensile strength, sigma(sub 3c), of a fiber reinforced composite material using a curved beam. The specimen was a unidirectional curved beam, bent 90 deg, with straight arms. Attached to each arm was a hinged loading mechanism that was held by the grips of a tension testing machine. Geometry effects of the specimen, including the effects of loading arm length, inner radius, thickness, and width, were studied. The data sets fell into two categories: low strength corresponding to a macroscopic flaw related failure and high strength corresponding to a microscopic flaw related failure. From the data available, the specimen width and loading arm length had little effect on sigma(sub 3c). The inner radius was not expected to have a significant effect on sigma(sub 3c), but this conclusion could not be confirmed because of differences in laminate quality for each curve geometry. The thicker specimens had the lowest value of sigma(sub 3c) because of poor laminate quality.

Martin, Roderick H.; Jackson, Wade C.

1993-01-01

18

Experimental and Numerical Studies on Determination of Indirect Tensile Strength of Rocks  

NASA Astrophysics Data System (ADS)

Indirect tension tests using Brisbane tuff Brazilian disc specimens under standard Brazilian jaws and various loading arcs were performed. The standard Brazilian indirect tensile tests caused catastrophic, crushing failure of the disc specimens, rather than the expected tensile splitting failure initiated by a central crack. This led to an investigation of the fracturing of Brazilian disc specimens and the existing indirect tensile Brazilian test using steel loading arcs with different angles. The results showed that the ultimate failure load increased with increasing loading arc angles. With no international standard for determining indirect tensile strength of rocks under diametral load, numerical modelling and analytical solutions were undertaken. Numerical simulations using RFPA2D software were conducted with a heterogeneous material model. The results predicted tensile stress in the discs and visually reproduced the progressive fracture process. It was concluded that standard Brazilian jaws cause catastrophic, crushing failure of the disc specimens instead of producing a central splitting crack. The experimental and numerical results showed that 20° and 30° loading arcs result in diametral splitting fractures starting at the disc centre. Moreover, intrinsic material properties (e.g. fracture toughness) may be used to propose the best loading configuration to determine the indirect tensile strength of rocks. Here, by using numerical outcomes and empirical relationships between fracture toughness and tensile strength, the best loading geometry to obtain the most accurate indirect tensile strength of rocks was the 2? = 30° loading arc.

Erarslan, Nazife; Liang, Zheng Zhao; Williams, David John

2012-09-01

19

Determination of tensile strength of paraffin waxes  

Microsoft Academic Search

The tensile strength of paraffin wax is considered to be one of the important property indices that are used to characterize the service properties of this material. Methods used to determine the tensile strength of waxes are based on the use of Perkins and Tinius-Olsen testers [1]. Essentially, these methods consist of determinations of the force required to break a

O. G. Asadchii; B. Z. Votlokhin; N. F. Bogdanov; V. P. Gladyshev

1979-01-01

20

Method and apparatus for determining tensile strength  

DOEpatents

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.

Ratigan, J.L.

1982-05-28

21

Method and apparatus for determining tensile strength  

DOEpatents

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.

Ratigan, Joe L. (Rapid City, SD)

1984-01-01

22

Tear Strength and Tensile Strength of Model Filled Elastomers.  

National Technical Information Service (NTIS)

Measurements have been made of the tear strength, tensile strength, and energy dissipated during stretching for model filled elastomers consisting of polybutadiene with glass beads incorporated. The glass beads were pretreated with various silanes, some o...

P. Dreyfuss A. N. Gent J. R. Williams

1980-01-01

23

Tensile Strength of Notched Composites  

Microsoft Academic Search

Two postulates on the strength of notched laminated composites are compared to experimental data. The first concerns the use of the fracture strength of angle ply composites to estimate the fracture strength of lami nates of several angle plys. The second concerns a macromechanics ex planation of the notch size effect on static strength for circular notches. The results of

Thomas A. Cruse

1973-01-01

24

Tensile strength of wet granula materials  

Microsoft Academic Search

The dimensionless tensile strength ?d\\/? of wet granular materials with saturation levels in the plateau region of the pendular state was correlated with the void fraction of the agglomerate. The correlation fitted well with experimental measurements carried out on glass beads of diameter 93 ?m and with literature data, and was an improvement over the traditional Rumpf model. The tensile

Patrice Pierrat; Hugo S. Caram

1997-01-01

25

Measurement of Indirect Tensile Strength of Anisotropic Rocks by the Ring Test  

Microsoft Academic Search

Summary  \\u000a This paper presents a new approach, combined with the Boundary Element Method (BEM) analysis and the diametrical compression\\u000a on a thin disc with a small central hole, referred to as the ring test, for determining the indirect tensile strength of anisotropic\\u000a rocks. The stress distribution around the hole can be successfully obtained by the proposed single-domain BEM. The complex

C. S. Chen; S. C. Hsu

2001-01-01

26

Dynamic tensile strength of lunar rock types  

NASA Technical Reports Server (NTRS)

The dynamic tensile strength of four rocks are determined. A flat plate impact experiment is employed to generate approximately one-microsecond-duration tensile stress pulses in rock samples by superposing rarefaction waves to induce fracture. It is noted that the effect of chemical weathering and other factors has not been explicitly studied. The given tensile strengths are based on a series of experiments on each rock where determination of incipient spallation is made by terminal microscopic examination. The data are generally consistent with previous determinations, at least one of which was for a significantly chemically altered but physically coherent rock.

Cohn, S. N.; Ahrens, T. J.

1981-01-01

27

Dynamic tensile strength of lunar rock types  

NASA Astrophysics Data System (ADS)

The dynamic tensile strength of four rocks are determined. A flat plate impact experiment is employed to generate approximately one-microsecond-duration tensile stress pulses in rock samples by superposing rarefaction waves to induce fracture. It is noted that the effect of chemical weathering and other factors has not been explicitly studied. The given tensile strengths are based on a series of experiments on each rock where determination of incipient spallation is made by terminal microscopic examination. The data are generally consistent with previous determinations, at least one of which was for a significantly chemically altered but physically coherent rock.

Cohn, S. N.; Ahrens, T. J.

1981-03-01

28

Making High-Tensile-Strength Amalgam Components  

NASA Technical Reports Server (NTRS)

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.

Grugel, Richard

2008-01-01

29

49 CFR 230.26 - Tensile strength of shell plates.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 2013-10-01 false Tensile strength of shell plates. 230.26 Section... Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of steel or wrought-iron shell...

2013-10-01

30

49 CFR 230.26 - Tensile strength of shell plates.  

Code of Federal Regulations, 2010 CFR

...2009-10-01 2009-10-01 false Tensile strength of shell plates. 230.26 Section... Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of steel or wrought-iron shell...

2009-10-01

31

49 CFR 230.26 - Tensile strength of shell plates.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 2010-10-01 false Tensile strength of shell plates. 230.26 Section... Strength of Materials § 230.26 Tensile strength of shell plates. When the tensile strength of steel or wrought-iron shell...

2010-10-01

32

Inherent tensile strength of molybdenum nanocrystals  

NASA Astrophysics Data System (ADS)

The strength of Mo nanorods was measured under uniaxial tension. Tensile tests of lang 110rang-oriented single-crystalline molybdenum rod-shaped specimens with diameters from 25 to 90 nm at the apex were conducted inside a field-ion microscope (FIM). The nanocrystals were free from dislocations, planar defects and microcracks, and exhibited the plastic mode of failure under uniaxial tension with the formation of a chisel-edge tip by multiple gliding in the (11\\bar{2})[111] and (112)[11\\bar{1}] deformation systems. The experimental values of tensile strength vary between 6.3 and 19.8 GPa and show a decrease with increasing nanorod diameter. A molecular dynamic simulation of Mo nanorod tension also suggests that the strength decreases from 28.8 to 21.0 GPa when the rod diameter increases from 3.1 to 15.7 nm. The maximum values of experimental strength are thought to correspond to the inherent strength of Mo nanocrystals under uniaxial tension (19.8 GPa, or 7.5% of Young's modulus).

Shpak, Anatoly P.; Kotrechko, Sergiy O.; Mazilova, Tatjana I.; Mikhailovskij, Igor M.

2009-08-01

33

Structure and tensile strength of LaS(1.4)  

NASA Technical Reports Server (NTRS)

The tensile strength of LaS(1.4) has been estimated by diametral stress testing at room temperature, 800 and 1300 K. Brittle, tensile-type failures were obtained at all temperatures when the crosshead speed was 0.0021 mm/s; however, a 1300 K test at 0.00085 mm/s produced plastic flow. The microstructure of LaS(1.4) consisted of two phases with beta-La2S3 comprising about 15 vol percent of the structure and gamma-La2S3 the remainder. Because of the limited amount of material available for testing, no correlation between microstructure and mechanical strength could be drawn.

Whittenberger, J. Daniel; Smoak, Richard H.

1987-01-01

34

Stochastic models for the tensile strength, fatigue  

NASA Technical Reports Server (NTRS)

The time-to-failure of a single fiber is modeled as a functional of the fiber load history and reasonable forms for this functional are proposed. Earlier models by Daniels and Coleman are shown to be special cases of the proposed model and apparent disparities in their behavior are discussed. Techniques are presented for determining analytically the asymptotic distributions of the tensile strength and time-to-failure for bundles of a large number of fibers. For smaller bundles, exact results are far too cumbersome to be of use so that efficient Monte Carlo simulation procedures are proposed.

Phoenix, S. L.

1976-01-01

35

Measuring the Tensile Strength of B/AL Composites  

NASA Technical Reports Server (NTRS)

Proposed nondestructive technique correlates damping measurements with material strength. Increasing axial damping and decreasing axial tensile strength are observed after 1-hour treatment of B/AL composites containing about 50 percent fiber. Damping was measured in vacuum at frequencies near 2,000 Hz, and tensile strength was normalized by maximum strength observed before thermally induced degradation.

Dicarlo, J. A.

1983-01-01

36

The tensile strength of liquid helium four  

SciTech Connect

In this study, a piezoelectric transducer in the form of a hemispherical shell was used to focus high-intensity ultrasound into a small volume of {sup 4}He. The transducer was gated at its resonant frequency of 566 kHz with gate widths of less than 1 msec in order to minimize the effects of transducer heating and acoustic streaming. The onset of the nucleation was detected from the absorption of acoustic energy and the scattering of laser light from microscopic bubbles. A new theory for the diffraction of light from the focal zone of a spherical converging sound wave was developed to confirm calculations of the acoustic pressure amplitude at the focus of the piezoelectric transducer, calculations which were based on the acoustic power radiated into the liquid and the nonlinear absorption of sound. The experimental results were in agreement with homogeneous nucleation theory for a nucleation rate of approximately 10{sup 15} critical size bubbles/sec-cm{sup 3}. This is only the third liquid for which the theoretical tensile strength has been reached and it confirms homogeneous nucleation theory over a range three times greater than any other experiment. A noticeable decrease in the magnitude of the tensile strength was noted at temperatures near the lambda transition and a hypothesis that bubbles are being nucleated heterogeneously on quantitized vortices is presented.

Nissen, J.A.

1988-01-01

37

The relationship between tensile strength and flexure strength in fiber-reinforced composites  

Microsoft Academic Search

Tensile data on unidirectional composites generated from a flexure test usually yield a higher strength than observed from a standard tensile coupon. According to a statistical-strength theory based on a Weibull distribution, the presence of a stress gradient in the flexure-test results in an apparent increase in tensile strength as compared to the tensile test under uniform stress. In the

J. M. Whitney; M. Knight

1980-01-01

38

Silphenylene elastomers have high thermal stability and tensile strength  

NASA Technical Reports Server (NTRS)

Two polymeric silphenylene ethers, when cured by reactions with ethyl silicates and metal salts at room temperature, form elastomers having excellent thermal stability and tensile properties. The highest tensile strength obtained in a reinforced elastomer was 2800 psi.

1969-01-01

39

Tensile bond strength of maxillofacial adhesives.  

PubMed

A common technique for fixation of facial prostheses is the use of skin adhesives. The present study compared the tensile bond strength of five RTV-silicone elastomers used with four different skin adhesives to human skin. The elastomers were: Silskin II, MDX4-4210, Cosmesil, Cosmesil HC2, and RS 330 T-RTV. The adhesives were: Dow Corning 355 medical adhesive, PSA 1, Daro, and 9874 3M double-coated medical tape. The RTV silicones were cured as described by the manufacturer, fixed in circular metal holders, and glued to the skin (inner aspect of forearm) with the various adhesives. The specimens were pulled off 20 seconds after fixation by use of a universal testing machine with a crosshead speed of 1 mm/minute. Eight specimens of each silicone and adhesive combination were tested, and a mean bond strength was calculated for each combination and compared by Duncan's multiple range test on a personal computer. Significant differences were observed among the various combinations of silicones and adhesives. Dow Corning 355 adhesive showed the highest bond strength with all materials, and the medical tape had the lowest. Differences between the RTV silicones were also significant. The strongest bond with all adhesives was MDX4-4210 elastomer and the weakest for RS 330 T-RTV elastomer. PMID:8463965

Polyzois, G L; Oilo, G; Dahl, J E

1993-04-01

40

Neutron irradiated beryllium: tensile strength and swelling  

NASA Astrophysics Data System (ADS)

Four different species of beryllium: S-200F (vacuum hot pressed, 1.2 wt% BeO), S-200FH (hot isostatic pressed, 0.9 wt% BeO); S-65 (vacuum hot pressed, 0.6 wt% BeO) and S-65H (hot isostatic pressed, 0.5 wt% BeO) are fabricated by Brush Wellman. Three batches of the berylliums are investigated, a neutron irradiated batch, a thermal control batch and a reference batch. Neutron irradiation is performed at nominal temperature conditions of 200, 400 and 600°C up to a fluence of 1.5 × 10 25 n m -2 ( En ? 1 MeV). Based on the tensile tests results, the S-65 VHP and the S-200 HIP show slightly higher elongation and strength after irradiation. Based on the swelling determination, S-200 swells less than S-65. In conclusion, the S-200 HIP might tentatively be selected.

Moons, Frans; Sannen, Leo; Rahn, August; Van De Velde, José

1996-10-01

41

A Method for Testing Dynamic Tensile Strength and Elastic Modulus of Rock Materials Using SHPB  

NASA Astrophysics Data System (ADS)

An experimental procedure for testing dynamic tensile strength and elastic modulus of rock materials at high strain rate loading is presented in this paper. In our test the split Hopkinson pressure bar (SHPB) was used to diametrally impact the Brazilian disc (BD) and flattened Brazilian disc (FBD) specimens of marble. A tensile strain rate of about 45 1/s was achieved at the center of the specimen. In order to improve the accuracy of the analysis, the initiation time difference between the strain waves acting on the two flat ends of the FBD specimen was treated properly. Typical failure modes corresponding to different loading conditions were observed. It was verified with a finite-element simulation that the equilibrium condition was established in the specimen before its failure. This numerical simulation validates the experimental procedure and also proves the suitability of formulation for the basic equations.

Wang, Q. Z.; Li, W.; Song, X. L.

2006-06-01

42

The relationship between tensile strength and shear strength in composite materials subjected to high strain rates  

Microsoft Academic Search

The dynamic behavior of a woven carbon\\/epoxy composite subjected to tensile and shear impact loading in the orthogonal direction (using the tensile and torsional split-Hopkinson bars, respectively) is studied. The influences of the equivalent strain rates on the tensile and shear yield stress and strength are found. The yield stress ratio and strength ratio between tensile and shear loading on

Chi-Yuen Chiem; Zeng-Gang Liu

1988-01-01

43

Aluminum/steel wire composite plates exhibit high tensile strength  

NASA Technical Reports Server (NTRS)

Composite plate of fine steel wires imbedded in an aluminum alloy matrix results in a lightweight material with high tensile strength. Plates have been prepared having the strength of titanium with only 85 percent of its density.

1966-01-01

44

An experimental evaluation of the tensile strength of impact ice  

NASA Technical Reports Server (NTRS)

The evaluation of the tensile strength of impact built-up ice on structural components has been prompted by such problems as electrical transmission line losses and catastrophic failures in Arctic regions, deicing problems with fixed-wing and rotary-wing aircraft, etc. It is demonstrated that the conventional tensile-testing technique furnishes adequate data on artificially refrigerated ice, and helps establish the influence of extrinsic factors on ice tensile strength.

Xian, X.; Chu, M. L.; Scavuzzo, R. J.; Srivatsan, T. S.

1989-01-01

45

The Hen's egg: Variation in tensile strength of shell material and its relationship with shearing strength  

Microsoft Academic Search

The tensile strength of egg?shell material is believed to play an important role in determining whether or not a shell will crack when exposed to an environmental insult. Experiments are described in which shell tensile strength was measured. It is concluded that: i. the force required to produce tensile failure did not vary linearly with the width of the piece

T. C. Carter

1971-01-01

46

Numerical simulation of microstructural damage and tensile strength of snow  

NASA Astrophysics Data System (ADS)

This contribution uses finite-element analysis to simulate microstructural failure processes and the tensile strength of snow. The 3-D structure of snow was imaged by microtomography. Modeling procedures used the elastic properties of ice with bond fracture assumptions as inputs. The microstructure experiences combined tensile and compressive stresses in response to macroscopic tensile stress. The simulated nonlocalized failure of ice lattice bonds before or after reaching peak stress creates a pseudo-plastic yield curve. This explains the occurrence of acoustic events observed in advance of global failure. The measured and simulated average tensile strengths differed by 35%, a typical range for strength measurements in snow given its low Weibull modulus. The simulation successfully explains damage, fracture nucleation, and strength according to the geometry of the microstructure of snow and the mechanical properties of ice. This novel method can be applied to more complex snow structures including the weak layers that cause avalanches.

Hagenmuller, Pascal; Theile, Thiemo C.; Schneebeli, Martin

2014-01-01

47

Enhanced tensile strength for electrodeposited nickel-copper multilayer composites  

NASA Astrophysics Data System (ADS)

The tensile strength of electrodeposited layered composites of the nominal overall composition 90 pct Ni-10 pct Cu is shown to increase sharply to the 1300 MPa range as the thickness of the Cu layers is decreased below ~0.4 ?m. This tensile strength value is almost a factor of three greater than that measured for Ni itself, and more than a factor of two greater than the handbook value for Monel 400.

Tench, Dennis; White, John

1984-11-01

48

Tensile and shear strength of adhesives  

NASA Technical Reports Server (NTRS)

This experiment is conducted in a freshman-level course: Introduction to Engineering Materials. There are no prerequisites for the course although students should have some knowledge of basic algebra. The objectives are to tension and shear test adhesives and to determine the tensile and shear properties of adhesives. Details of equipment of procedure are given.

Stibolt, Kenneth A.

1990-01-01

49

Correlation of Yield Strength and Tensile Strength with Hardness for Steels  

NASA Astrophysics Data System (ADS)

Hardness values as well as yield and tensile strength values were compiled for over 150 nonaustenitic, hypoeutectoid steels having a wide range of compositions and a variety of microstructures. The microstructures include ferrite, pearlite, martensite, bainite, and complex multiphase structures. The yield strength of the steels ranged from approximately 300 MPa to over 1700 MPa. Tensile strength varied over the range of 450-2350 MPa. Regression analysis was used to determine the correlation of the yield strength and the tensile strength to the diamond pyramid hardness values for these steels. Both the yield strength and tensile strength of the steels exhibited a linear correlation with the hardness over the entire range of strength values. Empirical relationships are provided that enable the estimation of strength from a bulk hardness measurement. A weak effect of strain-hardening potential on the hardness-yield strength relationship was also observed.

Pavlina, E. J.; van Tyne, C. J.

2008-12-01

50

Hoop Tensile Strength Testing of Small Diameter Ceramic Particles  

SciTech Connect

A method to measure hoop tensile strength of 1-mm-diameter brittle ceramic spheres was demonstrated through the use of a "C-sphere" flexure strength specimen. This innovative specimen geometry was chosen because a simple, monotonically increasing uniaxial compressive force produces a hoop tensile stress at the C-sphere's outer surface that ultimately initiates fracture. This enables strength quantification and strength-limiting flaw identification of the sphere itself. Such strength information is relevant to design optimization and durability assessments of ceramic fuel particles and breeder/multiplier pebbles for fusion whose surfaces are subjected to tensile stresses caused by thermal gradients, thermal transients, swelling, etc., during their manufacturing or service.

Wereszczak, Andrew A [ORNL; Jadaan, Osama M. [University of Wisconsin, Platteville; Lin, Hua-Tay [ORNL; Champoux, Gregory J [ORNL; Ryan, David P [ORNL

2007-01-01

51

The tensile strength and ductility of continuous fibre composites  

Microsoft Academic Search

The plastic instability approach has been applied to the tensile behaviour of a continuous fibre composite. It is shown that the combination of two components with different strengths and degrees of work-hardening produces a new material with a new degree of work-hardening, which may be determined by the present analysis. Expressions for the elongation at rupture and the strength of

S. T. Mileiko

1969-01-01

52

On the dynamic tensile strength of Zirconium  

NASA Astrophysics Data System (ADS)

Despite its fundamental nature, the process of dynamic tensile failure (spall) is poorly understood. Spall initiation via cracks, voids, etc, before subsequent coalesce, is known to be highly microstructure-dependant. In particular, the availability of slip planes and other methods of plastic deformation controls the onset (or lack thereof) of spall. While studies have been undertaken into the spall response of BCC and FCC materials, less attention has paid to the spall response of highly anisotropic HCP materials. Here the dynamic behaviour of zirconium is investigated via plate-impact experiments, with the aim of building on an ongoing in-house body of work investigating these highly complex materials. In particular, in this paper the effect of impact stress on spall in a commercially sourced Zr rod is considered, with apparent strain-rate softening highlighted.

Appleby-Thomas, G. J.; Hameed, A.; Vignjevic, R.; Hazell, P. J.; Painter, J.; Cademartori, S.

2014-05-01

53

Silicon nitride having a high tensile strength  

DOEpatents

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.

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

54

Silicon nitride having a high tensile strength  

DOEpatents

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.

Pujari, Vimal K. (Northboro, MA); Tracey, Dennis M. (Medfield, MA); Foley, Michael R. (Oxford, MA); Paille, Norman I. (Oxford, MA); Pelletier, Paul J. (Millbury, MA); Sales, Lenny C. (Grafton, MA); Willkens, Craig A. (Sterling, MA); Yeckley, Russell L. (Oakham, MA)

1996-01-01

55

Collagen cross-linking and ultimate tensile strength in dentin.  

PubMed

Several studies have indicated differences in bond strength of dental materials to crown and root dentin. To investigate the potential differences in matrix properties between these locations, we analyzed upper root and crown dentin in human third molars for ultimate tensile strength and collagen biochemistry. In both locations, tensile strength tested perpendicular to the direction of dentinal tubules (undemineralized crown = 140.4 +/- 48.6/root = 95.9 +/- 26.1; demineralized crown = 16.6 +/- 6.3/root = 29.0 +/- 12.4) was greater than that tested parallel to the tubular direction (undemineralized crown = 73.1 +/- 21.2/root = 63.2 +/- 22.6; demineralized crown = 9.0 +/- 3.9/root = 16.2 +/- 8.0). The demineralized specimens showed significantly greater tensile strength in root than in crown. Although the collagen content was comparable in both locations, two major collagen cross-links, dehydrodihydroxylysinonorleucine/its ketoamine and pyridinoline, were significantly higher in the root (by ~ 30 and ~ 55%, respectively) when compared with those in the crown. These results indicate that the profile of collagen cross-linking varies as a function of anatomical location in dentin and that the difference may partly explain the site-specific tensile strength. PMID:15381724

Miguez, P A; Pereira, P N R; Atsawasuwan, P; Yamauchi, M

2004-10-01

56

On the Tensile Strength of a Solid Nanowire  

Microsoft Academic Search

The present paper is concerned with the mechanical characterization of the measured tensile strength of a solid nanowire.\\u000a As miniaturization is a general trend in nanotechnology, a variety of nanowires have been successfully fabricated\\/synthesized,\\u000a including but not limited to Si, C, polymer DNA, MoSe, Au, Cu, TiC, Fe, Mo, NiAl and W. Mechanical strength is essential to\\u000a maintaining the structural

Tze-jer Chuang

57

Improved molding process ensures plastic parts of higher tensile strength  

NASA Technical Reports Server (NTRS)

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.

Heier, W. C.

1968-01-01

58

Through-the-Thickness Tensile Strength of Textile Composites.  

National Technical Information Service (NTIS)

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-t...

W. C. Jackson P. G. Ifju

1994-01-01

59

Importance of Tensile Strength on the Shear Behavior of Discontinuities  

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

60

The theoretical tensile strength of fcc crystals predicted from shear strength calculations.  

PubMed

This work presents a simple way of estimating uniaxial tensile strength on the basis of theoretical shear strength calculations, taking into account its dependence on a superimposed normal stress. The presented procedure enables us to avoid complicated and time-consuming analyses of elastic stability of crystals under tensile loading. The atomistic simulations of coupled shear and tensile deformations in cubic crystals are performed using first principles computational code based on pseudo-potentials and the plane wave basis set. Six fcc crystals are subjected to shear deformations in convenient slip systems and a special relaxation procedure controls the stress tensor. The obtained dependence of the ideal shear strength on the normal tensile stress seems to be almost linearly decreasing for all investigated crystals. Taking these results into account, the uniaxial tensile strength values in three crystallographic directions were evaluated by assuming a collapse of the weakest shear system. Calculated strengths for [Formula: see text] and [Formula: see text] loading were found to be mostly lower than previously calculated stresses related to tensile instability but rather close to those obtained by means of the shear instability analysis. On the other hand, the strengths for [Formula: see text] loading almost match the stresses related to tensile instability. PMID:21825337

Cerný, M; Pokluda, J

2009-04-01

61

Tensile Strength of Natural Fiber Reinforced Polyester Composite  

NASA Astrophysics Data System (ADS)

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.

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

2007-05-01

62

Strength and modulus of carbon nanotubes under a tensile load  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNTs) were fabricated using low-pressure chemical vapor deposition and then embedded in epoxy polymer at several weight ratios, 0, 0.75, 1.5, and 3 wt%, for tensile testing and Young's modulus determination using an Instron machine. The tensile strength and Young's modulus of the epoxy resin were increased with the addition of CNTs to a certain extent, and then decreased with the increase in the weight fraction of CNTs. The best properties occurred at 1.5 wt% of CNTs. Scanning electron microscopy was used to reveal the dispersion status of CNTs in the nanocomposites.

Alnefaie, Khaled A.

2014-05-01

63

Study of the theoretical tensile strength of Fe by a first-principles computational tensile test  

NASA Astrophysics Data System (ADS)

This paper employs a first-principles total-energy method to investigate the theoretical tensile strengths of bcc and fcc Fe systemically. It indicates that the theoretical tensile strengths are shown to be 12.4, 32.7, 27.5 GPa for bcc Fe, and 48.1, 34.6, 51.2 GPa for fcc Fe in the [001], [110] and [111] directions, respectively. For bcc Fe, the [001] direction is shown to be the weakest direction due to the occurrence of a phase transition from ferromagnetic bcc Fe to high spin ferromagnetic fcc Fe. For fcc Fe, the [110] direction is the weakest direction due to the formation of an instable saddle-point 'bct structure' in the tensile process. Furthermore, it demonstrates that a magnetic instability will occur under a tensile strain of 14%, characterized by the transition of ferromagnetic bcc Fe to paramagnetic fcc Fe. The results provide a good reference to understand the intrinsic mechanical properties of Fe as a potential structural material in the nuclear fusion Tokamak.

Liu, Yue-Lin; Zhang, Ying; Hong, Rong-Jie; Lu, Guang-Hong

2009-05-01

64

[Tensile strength of short-fiber-reinforced temporary plastics].  

PubMed

Glass fibers added to temporary crown and bridge material (Proviso-Blend, Blendax) by 5% to the weight increased the tensile strength of the acrylic resin by 38%. The increase was even greater when carbon fibers were added (50%), but the resin discoloured to a greyish shade. The results were less spectacular with Dentalon Plus (Kulzer), and the experiment did not work with Protemp (Espe). The amount of improvement in tensile strength depended on the type and geometry of the fiber and of the fiber concentration. Neither the properties of the polished surface of a fiber-reinforced acrylic nor adverse effects of such fibers possibly swallowed by the patient are investigated as yet. PMID:2772590

Setz, J; Lin, W

1989-01-01

65

Tensile properties of short fiber composites with fiber strength distribution  

Microsoft Academic Search

The influence of fiber rupture, fiber pull-out and fiber tensile strength distribution on the post-cracking behavior of short-randomly-distributed fiber reinforced brittle-matrix composites has been analyzed using an approach based on the Weibull weakest-link statistics. The analysis led to the development of a predicting model for the composite bridging stress-crack opening displacement (sc - d) law—a fundamental material property necessary for

M. Maalej

2001-01-01

66

Morphogenesis of Plasmodium zoites is uncoupled from tensile strength  

PubMed Central

A shared feature of the motile stages (zoites) of malaria parasites is a cortical cytoskeletal structure termed subpellicular network (SPN), thought to define and maintain cell shape. Plasmodium alveolins comprise structural components of the SPN, and alveolin gene knockout causes morphological abnormalities that coincide with markedly reduced tensile strength of the affected zoites, indicating the alveolins are prime cell shape determinants. Here, we characterize a novel SPN protein of Plasmodium berghei ookinetes and sporozoites named G2 (glycine at position 2), which is structurally unrelated to alveolins. G2 knockout abolishes parasite transmission and causes zoite malformations and motility defects similar to those observed in alveolin null mutants. Unlike alveolins, however, G2 contributes little to tensile strength, arguing against a cause-effect relationship between tensile strength and cell shape. We also show that G2 null mutant sporozoites display an abnormal arrangement of their subpellicular microtubules. These results provide important new understanding of the factors that determine zoite morphogenesis, as well as the potential roles of the cortical cytoskeleton in gliding motility.

Tremp, Annie Z; Carter, Victoria; Saeed, Sadia; Dessens, Johannes T

2013-01-01

67

Experimental Study on Tensile Strength of Composite Repair  

NASA Astrophysics Data System (ADS)

In this research, CFRP scarf repair panels were tested to evaluate the tensile mechanical properties and impact characteristics. CFRP scarf repair panels were prepared to simulate the assumed three different situations. These situations consist of two different scarf repair methods and impact damage case which are autoclave repair, heat blanket repair, and impact damage case. As the result, these strengths are not recovered in all situations, however, stiffness was recovered in all situations. Moreover, the strength of heat blanket repair and impact damage case were reduced compared with autoclave repair.

Hoshi, Hikaru; Iwahori, Yutaka; Yajima, Hiroshi

68

Tensile strength of bilayered ceramics and corresponding glass veneers  

PubMed Central

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.

Champirat, Tharee; Jirajariyavej, Bundhit

2014-01-01

69

[The compressive strength, tensile strength, flexural strength and micro-hardness of Plat-II Castable Ceramics].  

PubMed

In preparation for the clinical use of Plat-II Castable Ceramics (PCC-II), we tested its compressive strength, tensile strength, flexural strength and microhardness. The flexural strength was tested by the three-point bending test. The result showed that the compressive strength was 541.7 MPa; the tensile strength 42.5 MPa; the flexural strength 142.0 MPa; the modulus of elasticity 61.4 GPa; and the micro-hardness 499.6 kg/mm3. The strength anol micro-hardness of PCC-II materials were better than those of human enamel. So PCC-II is applicable to restorations in dentistry. PMID:10683943

Wang, H; Zhao, Y; Fan, Y; Chen, Y

1997-12-01

70

Through-the-thickness tensile strength of textile composites  

NASA Technical Reports Server (NTRS)

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.

Jackson, Wade C.; Ifju, Peter G.

1994-01-01

71

Predicting Tensile Strengths of Boron/Aluminum Composites  

NASA Technical Reports Server (NTRS)

To develop predictive theory to account for time/temperature effect of B/A1 composites, series of deformation and fracture studies was performed on commercial boron fibers over wide ranges of stress, stress application time, and temperature. By combining these single fiber results with fracture theory for metal matrix composites, design formulas were derived that describe B/A1 composite tensile and stress rupture strengths as function of time and temperature. Using derived formulas, calculated and experimental results agree to within 3 percent.

Decarlo, J. A.

1982-01-01

72

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

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

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

2012-06-01

73

Dynamic yield and tensile strengths of spark plasma sintered alumina  

NASA Astrophysics Data System (ADS)

Fully dense alumina samples with 0.6 ?m grain size were produced from alumina powder using Spark Plasma Sintering and tested in two types of VISAR-instrumented planar impact tests. In the tests of the first type the samples of 0.28 to 6-mm thickness were loaded by 1-mm tungsten impactors accelerated up to a velocity of about 1 km/s. These tests were aimed to study the Hugoniot elastic limit (HEL) of the SPS-processed alumina and the decay of the elastic precursor wave with propagation distance. In the second type of test the samples of ~3-mm thickness were loaded by 1-mm copper impactors accelerated up to velocities 100-1000 m/s. These tests were aimed to study the dynamic tensile (spall) strength of the alumina. The data on tensile fracture of the alumina demonstrate a monotonic decline of the spall strength with the amplitude of the loading stress pulse. The data on the decay of the elastic precursor wave allows for determining the rates of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of shock-induced inelastic deformation and, thus, to derive some conclusions concerning the mechanisms responsible of the deformation.

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

2014-05-01

74

Experimental and numerical investigation on the dynamic tensile strength of concrete  

Microsoft Academic Search

A new experimental method for testing the dynamic tensile behavior of concrete at high strain rates was designed and established. By using this method, the dynamic tensile strength of concrete and its dependence on strain rates were measured and investigated. The experimental results indicate that the dynamic tensile strength of concrete is rate sensitive. The numerical simulation results have a

Haijun Wu; Qingming Zhang; Fenglei Huang; Qiankun Jin

2005-01-01

75

Some investigations about the tensile strength and the desiccation process of unsaturated clay  

NASA Astrophysics Data System (ADS)

The current paper presents an investigation on the tensile strength of unsaturated clay, and a discussion about the significant differences between the behaviours of compacted soils and those of the completely remoulded soils. The adapted experimental device based on the shear box for the measurement of the tensile strength is also presented. In the tensile tests, stress-strain characteristics are measured using high precision transducers and electronic data acquisition. The equipment is capable of measuring tensile strengths of soil (about 10 MPa). Moreover, a new model to predict cracks is presented in 3D. This analytical model for the prediction of tensile strength, as a function of suction and porosity, is given.

Trabelsi, H.; Jamei, M.; Guiras, H.; Hatem, Z.; Romero, E.; Sebastia, O.

2010-06-01

76

Tensile strength of single-walled carbon nanotubes directly measured from their macroscopic ropes  

Microsoft Academic Search

20 mm long ropes consisting of soundly aligned single-walled carbon nanotube (SWNT) ropes, synthesized by the catalytic decomposition of hydrocarbons, were employed for direct tensile strength measurements. The average tensile strength of SWNT rope composites is as high as 3.6+\\/-0.4 GPa, similar to that of carbon fibers. The tensile strength of SWNT bundles was extrapolated from the strength of the

F. Li; H. M. Cheng; S. Bai; G. Su; M. S. Dresselhaus

2000-01-01

77

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

SciTech Connect

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.

Levy, B.S.

1984-01-01

78

Prediction of residual tensile strength of transversely impacted composite laminates  

NASA Technical Reports Server (NTRS)

The response to low velocity impact of graphite-epoxy T300/5208 composite laminates is discussed. Steel balls of 3/8 inch, 5/8 inch, and 1 inch diameter were the projectiles. Impact energy was limited to 1.2 joules. Impacted specimens were ultrasonically C scanned to determine the impact damaged region. The threshold value of impact energy for impact damage was found to be approximately 0.3 joules. A model was developed to predict the tensile residual strength of impact damaged specimens from fracture mechanics concepts. Impacted specimens were tested in tension to provide a fracture data base. The experimental results agreed well with the predictions from fracture mechanics. In this study, the maximum impact velocity used to simulate the low velocity transverse impact from common objects like tool drops was 10 m/s.

Lal, K. M.

1982-01-01

79

Tensile Strength and the Mining of Black Holes  

NASA Astrophysics Data System (ADS)

There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This Letter looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta, and puts a severe constraint on the operation of “space elevators” near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation, and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed. As a consequence of this limitation, the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings.

Brown, Adam R.

2013-11-01

80

The relation between the tensile strength and the hardness of metals  

NASA Technical Reports Server (NTRS)

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.

Schwarz, O

1930-01-01

81

ZERODUR: bending strength data for tensile stress loaded support structures  

NASA Astrophysics Data System (ADS)

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.

Bizjak, Tanja; Hartmann, Peter; Westerhoff, Thomas

2012-03-01

82

Evaluation of tensile strength of surgical synthetic absorbable suture materials: an in vitro study  

PubMed Central

Purpose The purpose of this study was to evaluate the tensile strength of surgical synthetic absorbable sutures over a period of 14 days under simulated oral conditions. Methods Three suture materials (polyglycolic acid [PGA], polyglactin [PG] 910, and poly (glycolide-co-?-caprolactone) [PGC]) were used in 4-0 and 5-0 gauges. 210 suture samples (35 of each material and gauge) were used. All of the samples were tested preimmersion and 1 hour and 1, 3, 7, 10, and 14 days postimmersion. The tensile strength of each suture material and gauge was assessed. The point of breakage and the resorption pattern of the sutures were also assessed. Results During the first 24 hours of immersion, all 4-0 and 5-0 samples of PGA, PG 910, and PGC maintained their initial tensile strength. At baseline (preimmersion), there was a statistically significant (P<0.001) difference in the tensile strengths between the 4-0 and 5-0 gauge of PGA, PG 910, and PGC. PGA 4-0 showed the highest tensile strength until day 10. At 7 days, all the 4-0 sutures of the three materials had maintained their tensile strength with PGA 4-0 having significantly greater (P=0.003) tensile strength compared to PG. Conclusions 4-0 sutures are stronger and have greater tensile strength than 5-0 sutures. The PGA 4-0 suture showed the highest tensile strength at the end of day 10.

Ranganath, V.; Nichani, Ashish Sham

2013-01-01

83

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengths  

NASA Astrophysics Data System (ADS)

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes were experimentally studied by rotating bending tests, to investigate the effects of the tensile strength obtained by different heat treatment processes on very high cycle fatigue failure mechanisms. The material with higher tensile strength of 1 710MPa exhibited typical gigacycle fatigue failure characteristics, whereas one with lower tensile strength of 1 010MPa showed only traditional fatigue limit during the tests and no gigacycle failure could be found even when the specimen ran up to more than 108 cycles. Metallographic and fractographic analysis were carried out by an optical microscope (OM) and scanning electron microscope (SEM). It showed two different crack initiation mechanisms that for the specimen with lower tensile strength the crack prefers surface initiation and for that with higher strength the crack initiates from subsurface inclusions revealed by a fish-eye like microstructure.

Duan, Zheng; Ma, Xian-Feng; Shi, Hui-Ji; Murai, Ryosuke; Yanagisawa, Eiichi

2011-10-01

84

Strength and Breaking Mechanism of Multiwalled Carbon Nanotubes Under Tensile Load  

Microsoft Academic Search

The tensile strengths of individual multiwalled carbon nanotubes (MWCNTs) were measured with a ``nanostressing stage'' located within a scanning electron microscope. The tensile-loading experiment was prepared and observed entirely within the microscope and was recorded on video. The MWCNTs broke in the outermost layer (``sword-in-sheath'' failure), and the tensile strength of this layer ranged from 11 to 63 gigapascals for

Min-Feng Yu; Oleg Lourie; Mark J. Dyer; Katerina Moloni; Thomas F. Kelly; Rodney S. Ruoff

2000-01-01

85

THE DYNAMIC TENSILE STRENGTH OF ICE AND ICE-SILICATE MIXTURES  

Microsoft Academic Search

We determined the dynamic tensile of fracturing and fragmentation properties of icy strength of ice and ice silicate mixtures at substances. Our goal in previous studies has been strain rates of 104 s -1. At these strain rates, to establish some data and scaling laws related to ice has a tensile strength of ~17 MPa, and impact crater formation and

Manfred A. Lange; Thomas J. Ahrens

1983-01-01

86

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

NASA Technical Reports Server (NTRS)

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.

Miyoshi, K.; Buckley, D. H.

1982-01-01

87

The dynamic tensile strength of ice and ice-silicate mixtures  

NASA Technical Reports Server (NTRS)

The dynamic tensile strength of icy media is measured at strain rates on the order of 10,000/sec to aid in the understanding of impact and cratering phenomena. Compressed samples consisting of ice and ice-silicate mixtures with 5 and 30 wt % sand were impacted at temperatures between 230 and 250 K by projectile plexiglas plates imparting the required strain rates in less than 0.75 microsec. Taking the tensile stress corresponding to the transition from intact to spalled or fragmented samples as the dynamic tensile strength, strengths of 17, 20 and 22 MPa were obtained for the pure ice, 5 wt % sand, and 30 wt % sand specimens, respectively. The values lie considerably above those observed in static testing. A continuum fracturing model is used to obtain relations between tensile strength and stress rate as well as to derive stress and damage histories during tensile loading and the size distribution of icy fragments as a function of strain rate.

Lange, M. A.; Ahrens, T. J.

1983-01-01

88

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

PubMed

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

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

2014-05-14

89

Relationships between tensile strength, morphology and crystallinity of treated kenaf bast fibers  

NASA Astrophysics Data System (ADS)

Surface treatments on kenaf bast fibers were carried out with steam, alkali and a combination of steam-alkali. To verify and gain an understanding of their inter-relationship, tensile strength, surface morphology and crystallinity of treated and raw fibers were characterized. Tensile strength of fibers was measured with a universal tensile machine (UTM), crystallinity was estimated using X-ray diffraction (XRD) and Fourier transformation infrared (FTIR) spectroscopy, and surface morphology was examined by scanning electron microscopy (SEM). Tensile strength of the treated fibers was higher than that of the raw fiber. Tensile strength increased after steam treatment and was further improved by alkali treatment, but slightly reduced after steam treatment followed by alkalization. Increase of concentration of alkali tended to increase tensile strength. Differences in tensile strength of the treated fibers are discussed in relation to the changes in surface morphology and crystallinity. Understanding of these relationships may provide direction towards the goal of producing better performance of natural fiber composites.

Sosiati, H.; Rohim, Ar; Ma`arif; Triyana, K.; Harsojo

2013-09-01

90

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

NASA Astrophysics Data System (ADS)

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.

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

2010-11-01

91

Specimen size effect on tensile strength of surface-micromachined polycrystalline silicon thin films  

Microsoft Academic Search

A new tensile tester using an electrostatic-force grip was developed to evaluate the tensile strength and the reliability of thin-film materials. The tester was constructed in a scanning electron microscope (SEM) chamber for in situ observation and was applied for tensile testing of polycrystalline silicon (poly-Si) thin films with dimensions of 30-300 ?m long, 2-5 ?m wide, and 2 ?m

Toshiyuki Tsuchiya; Osamu Tabata; Jiro Sakata; Yasunori Taga

1998-01-01

92

Evaluation of press-and-sinter parameters for tantalum pentoxide by the diametral compression test  

SciTech Connect

Submicron Ta{sub 2}O{sub 5} powder was consolidated by cold pressing using pressures between 24 MPa and 240 MPa followed by sintering at temperatures in the range 1300 degrees C to 1500 degrees C. The resulting disks were fractured in diametral compression tests (DCT) to determine the tensile strength. The strength, mode of fracture, and fracture surface were subsequently used to identify potential processing routes for high density, fine grained Ta{sub 2}O{sub 5} for the use as sputtering targets. Besides the conventional single or triple cleft fracture, two other modes of failure were observed in the diametrical compression test: delamination due to stratification flaws introduced by high pressure pre-pressing before sintering, and fragmentation caused by slow microcrack growth in the presence of phase transformation stresses arising in samples sintered above the transformation temperature of 1360 degrees C.

Livne, Z.; Fields, R.J.; Agulyansky, A.

1997-05-15

93

Effects of Porosity on Weld-Joint Tensile Strength of Aluminum Alloys.  

National Technical Information Service (NTIS)

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 ...

C. V. Lovoy

1974-01-01

94

Semicircular bend testing with split Hopkinson pressure bar for measuring dynamic tensile strength of brittle solids  

Microsoft Academic Search

We propose and validate an indirect tensile testing method to measure the dynamic tensile strength of rocks and other brittle solids: semicircular bend (SCB) testing with a modified split Hopkinson pressure bar (SHPB) system. A strain gauge is mounted near the failure spot on the specimen to determine the rupture time. The momentum trap technique is utilized to ensure single

F. Dai; K. Xia; S. N. Luo

2008-01-01

95

Tensile-strength apparatus applies high strain-rate loading with minimum shock  

NASA Technical Reports Server (NTRS)

Tensile-strength testing apparatus employs a capillary bundle through which a noncompressible fluid is extruded and a quick-release valve system. This apparatus applies the test loads at relatively constant very high strain rates with minimal shock and vibration to the tensile specimen and apparatus.

Cotrill, H. E., Jr.; Mac Glashan, W. F., Jr.

1966-01-01

96

Correlation between ultimate tensile strength and solidification microstructure for the sand cast A357 aluminium alloy  

Microsoft Academic Search

Many studies have demonstrated a relationship between secondary dendrite arm spacing (SDAS) and the mechanical behaviour of cast aluminium–silicon alloys, both for tensile and fatigue strength. SDAS is related to the solidification time and can be predicted, with a good approximation, by finite-element simulation. However, other microstructural features can affect the tensile behaviour of cast aluminium alloys such as size

L. Ceschini; Alessandro Morri; Andrea Morri; A. Gamberini; S. Messieri

2009-01-01

97

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

NASA Astrophysics Data System (ADS)

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.

Chang, Kyong-Ho; Jang, Gab-Chul

2011-06-01

98

Unbinding force of chemical bonds and tensile strength in strong crystals  

Microsoft Academic Search

A model of covalent and ionic bond strength is proposed in terms of the tensile unbinding force by introducing the concept of the effectively bonded valence electron (EBVE) number of a chemical bond. Bond strength proves to be exclusively dependent on two microscopic parameters: bond length and EBVE number. This model allows us to determine bond strength for a variety

Xiaoju Guo; Li-Min Wang; Bo Xu; Zhongyuan Liu; Dongli Yu; Julong He; Hui-Tian Wang; Yongjun Tian

2009-01-01

99

Micro-cantilever method for measuring the tensile strength of biofilms and microbial flocs  

Microsoft Academic Search

Cohesive strength is an important factor in determining the structure and function of biofilm systems, and cohesive strength plays a key role in our ability to remove or control biofilms in engineered systems. A micro-mechanical device has been developed to directly measure the tensile strength of biofilms and other microbial aggregates. An important feature of this method is the combination

Eric H Poppele; Raymond M Hozalski

2003-01-01

100

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

PubMed Central

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.

Min, Fanlu; Yao, Zhanhu; Jiang, Teng

2014-01-01

101

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

PubMed

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

Min, Fanlu; Yao, Zhanhu; Jiang, Teng

2014-01-01

102

Effect of Steam Oxidation on the Tensile Strength of HTGR Structural Graphites.  

National Technical Information Service (NTIS)

The core support system of the General Atomic Company design High Temperature Gas-Cooled Reactor (HTGR) contains type PGX graphite as core support blocks. The change in ultimate tensile strength of PGX graphite specimens with oxidation (burnoff) has been ...

A. J. Romano J. G. Y. Chow

1977-01-01

103

Effects of Strain Rate and Moisture on the Tensile Strength of Heterogeneous Materials.  

National Technical Information Service (NTIS)

Strain rate effects on tensile strength of concrete and mortar were investigated using three different size specimens, two different sized split Hopkinson pressure bars (SHPB) and a standard material test machine. All combinations of data show the same tr...

C. A. Ross

1998-01-01

104

Influence of Gold Plating of Stainless Steel Pins on the Tensile Strength of Dental Amalgam  

Microsoft Academic Search

Neither gold plating of stainless steel pins nor mercury wetting of gold-plated stainless steel pins caused an increase in tensile strength of amalgam that was significantly higher than that caused by plain stainless steel pins in amalgam.

M. S. Bapna; A. A. Lugassy

1971-01-01

105

Enhancement of hydrophobicity and tensile strength of muga silk fiber by radiofrequency Ar plasma discharge  

Microsoft Academic Search

The hydrophobicity and tensile strength of muga silk fiber are investigated using radiofrequency (RF) Ar plasma treatment at various RF powers (10–30W) and treatment times (5–20min). The Ar plasma is characterized using self-compensated Langmuir and emissive probe. The ion energy is observed to play an important role in determining the tensile strength and hydrophobicity of the plasma treated fibers. The

D. Gogoi; A. J. Choudhury; J. Chutia; A. R. Pal; N. N. Dass; D. Devi; D. S. Patil

2011-01-01

106

An Experimental Method to Determine the Tensile Strength of Concrete at High Rates of Strain  

Microsoft Academic Search

In the present work, dynamic tensile strength of concrete is experimentally investigated by means of spalling tests. Based\\u000a on extensive numerical simulations, the paper presents several advances to improve the processing of spalling tests. The striker\\u000a is designed to get a more uniform tensile stress field in the specimen. Three methods proposed in the literature to deduce\\u000a the dynamic strength

B. Erzar; P. Forquin

2010-01-01

107

Impact of a microwave curing process on tensile strength of selected carbon fiber composites  

NASA Astrophysics Data System (ADS)

The traditional process for curing carbon fiber (CF) composites has been the autoclave system. A review of recent research indicates curing CF composites in a microwave oven has the potential for reducing processing time. The problem statement of the experimental study was that the impact of a microwave curing process on tensile strength of selected CF composite specimens was unknown. The research study describes the statistical procedure and analysis of data to answer the specific question for the experimental trials: What is the effect on the tensile strength of cured CF composite samples due to the relationship of the autoclave and microwave curing process cycle time and temperature? ASTM International standard test method designation D 5083 - 02 was used for testing tensile strength of reinforced carbon fiber plastics using straight-sided specimens. Analytical data was obtained for evaluating the effects of process cycle time and temperature on tensile strength of the CF composite specimens. The result was that curing time of the autoclave system and microwave process had significant effects on the maximum tensile stress of CF composite specimen. Although 83% faster than the autoclave system, the microwave curing process had CF specimens with lower maximum tensile strength compared with the autoclave system results. The primary reason for the difference was that the microwave process did not use vacuum or pressure. Considering the cost/benefit ratio, the research study indicated that the microwave oven would be a viable and efficient process for curing CF composites.

Balzer, Brian B.

108

Further Studies of the Partial Gasification of Coke in Relation to the Coke Tensile Strength.  

National Technical Information Service (NTIS)

Previous reports have described studies of the partial gasification of coke and its influence on the coke tensile strength and of the quantification of the changes in the coke structure and strength brought about by reaction with carbon dioxide at 1000 Sq...

1980-01-01

109

Effect of abrasive wear on the tensile strength of steel wire rope  

Microsoft Academic Search

Known amounts of external abrasive wear were introduced into a new 6-strand steel wire rope and the effects of this wear on the tensile strength of the rope examined against the rope discard criteria for wear stated in ISO 4309: 1990 and other selected international standards. The variations of strength with degree of wear in the test rope were compared

A. R. T. de Silva; Long Woon Fong

2002-01-01

110

An experimental study on the tensile strength of steel fiber reinforced concrete  

Microsoft Academic Search

This paper deals with steel fiber reinforced concrete mechanical static behaviour and with its classification with respect to fibers content and mix-design variations. A number of experimental tests were conducted to investigate uniaxial compressive strength and tensile strength. Different mixtures were prepared varying both mix-design and fiber length. Fibers content in volume was of 1% and 2%. Mechanical characterization was

R. S. Olivito; F. A. Zuccarello

2010-01-01

111

Shear vs. Tensile Bond Strength of Resin Composite Bonded to Ceramic  

Microsoft Academic Search

Since the mode of failure of resin composites bonded to ceramics has frequently been reported to be cohesive fracture of either ceramic or resin composite rather than separation at the adhesive interface, this study was designed to question the validity of shear bond strength tests. The reasons for such a failure mode are identified and an alternative tensile bond strength

A. Della Bona; R. van Noort

1995-01-01

112

Tensile strength and creep resistance in nanocrystalline Cu, Pd and Ag.  

National Technical Information Service (NTIS)

Measurements of tensile strength and creep resistance have been made on bulk samples of nanocrystalline Cu, Pd and Ag consolidated from powders by cold compaction. Samples of Cu-Cu(sub 2)O have also been tested. Yield strength for samples with mean grains...

G. W. Nieman J. R. Weertman R. W. Siegel

1990-01-01

113

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

NASA Astrophysics Data System (ADS)

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.

Nagasako, Naoyuki; Asahi, Ryoji; Hafner, Jürgen

2012-01-01

114

Functional loading augments the initial tensile strength and energy absorption capacity of regenerating rabbit Achilles tendons.  

PubMed

The biomechanical effect of functional loading was studied in surgically tenotomized, repaired and immobilized right Achilles tendons of 34 rabbits. Beginning from the 5th day after surgery, loading was initiated by removing the immobilization casts of the animals to permit unrestricted weight-bearing to tolerance. At each of 12, 18 and 21 days after surgery, functionally loaded tendons and their corresponding nonloaded controls were excised and compared for differences in tensile strength, tensile stress and energy absorption capacity. Functional loading induced a twofold increase in the tensile strength (P less than 0.05) and energy absorption capacity (P less than 0.05) of the tendons, at both 12 and 18 days after surgery. No statistically significant differences were observed in the tensile strength and energy absorption capacity of the tendons at 21 days after surgery. Statistically significant differences in tensile stress were not observed at any time period throughout the study. These findings demonstrate that functional loading augments the tensile strength and energy absorption capacity of experimentally tenotomized tendons without promoting re-rupture, but only during the very early stages of healing. Even though the healing process of rabbit tendons may differ from healing of human tendons, these results suggest that similar beneficial effects may be attained if repaired human Achilles tendon ruptures are carefully loaded during the very early rather than later stages of healing. PMID:1739442

Enwemeka, C S

1992-02-01

115

Quantitative fracture strength and plasticity measurements of lithiated silicon nanowires by in situ TEM tensile experiments.  

PubMed

We report in situ tensile strength measurement of fully lithiated Si (Li-Si alloy) nanowires inside a transmission electron microscope. A specially designed dual probe with an atomic force microscopy cantilever and a scanning tunneling microscopy electrode was used to conduct lithiation of Si nanowires and then perform in situ tension of the lithiated nanowires. The axial tensile strength decreased from the initial value of 3.6 GPa for the pristine unlithiated Si nanowires to 0.72 GPa for the lithiated Li-Si alloy. We observed large fracture strain ranging from 8% to 16% for Li-Si alloy, 70% of which remained permanent after fracture. This indicates a certain degree of tensile plasticity in the lithiated silicon before fracture, important for constitutive modeling of the lithium-ion battery cyclability. We also compare the ab initio computed ideal strengths with our measured strengths and attribute the differences to the morphology and flaws in the lithiated nanowires. PMID:23025575

Kushima, Akihiro; Huang, Jian Yu; Li, Ju

2012-11-27

116

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

SciTech Connect

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.

P.E. Klingsporn

2011-08-01

117

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

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

118

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

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

119

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

NASA Technical Reports Server (NTRS)

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.

Gordon, Stephen S.

1992-01-01

120

A modified Johnson–Cook model for tensile behaviors of typical high-strength alloy steel  

Microsoft Academic Search

The uniaxial tensile tests were conducted with the initial strain rates range of (0.0001–0.01)s?1 and the temperature range of (1123–1373)K for typical high-strength alloy steel. Based on the experimental results, the modified Johnson–Cook model, which considers the coupled effects of strain, strain rate and deformation temperature, was proposed to describe the tensile behaviors of the studied alloy steel. Results show

Y. C. Lin; Xiao-Min Chen; Ge Liu

2010-01-01

121

Age-related changes in the density and tensile strength of human femoral cortical bone  

Microsoft Academic Search

Summary  In order to ascertain whether the intrinsic strength of human bone changes with age or not, we have determined the ultimate\\u000a tensile strength and density of strips of femoral cortical bone. These femora were collected from cadavers varying in age\\u000a from 13 to 97 years. The results show that both density and intrinsic strength of bone increase up to about

J. C. Wall; S. K. Chatterji; J. W. Jeffery

1979-01-01

122

Tensile Strength of Welded Steel Tubes : First Series of Experiments  

NASA Technical Reports Server (NTRS)

The purpose of the experiments was to determine the difference in the strength of steel tubes welded by different methods, as compared with one another and also with unwelded, unannealed tubes, including; moreover, a comparison of the results obtained by experienced and inexperienced welders.

Rechtlich, A

1928-01-01

123

Tensile strength of laser welded cobalt-chromium alloy with and without an argon atmosphere.  

PubMed

The tensile strength and depth of weld of two cobalt chromium alloys before and after laser welding with and without an argon gas atmosphere were investigated. Using two cobalt chromium alloys, rod shaped specimens (5 cm x 1.5 mm) were cast. Specimens were sand blasted, sectioned and welded with a pulsed Nd: YAG laser welding machine and tested in tension using an Instron universal testing machine. A statistically significant difference in tensile strength was observed between the two alloys. The tensile strength of specimens following laser welding was significantly less than the unwelded controls. Scanning electron microscopy showed that the micro-structure of the cast alloy was altered in the region of the weld. No statistically significant difference was found between specimens welded with or without an argon atmosphere. PMID:20698419

Tartari, Anna; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

2010-06-01

124

Development of a silicon carbide fibre with high tensile strength  

Microsoft Academic Search

MUCH work has been done on preparing heat-resistant silicon carbide materials in fibrous form, since plastics or metals can be reinforced with them to obtain very heat-resistant material of great mechanical strength. SiC whiskers1 are, however, impractical because of their shortness (several mm), their non-uniform diameter and high cost of production. SiC-on-W (ref. 2) and SiC-on-C (ref. 3) filaments have

S. Yajima; J. Hayashi; M. Omori; K. Okamura

1976-01-01

125

Establishing a Mathematical Model to Predict the Tensile Strength of Friction Stir Welded Pure Copper Joints  

NASA Astrophysics Data System (ADS)

This investigation was undertaken to predict the tensile strength of friction stir welded pure copper. Response surface methodology based on a central composite rotatable design with four welding parameters, five levels, and 31 runs was used to conduct the experiments and to develop the mathematical regression model by means of Design-Expert software. Four welding parameters considered were tool profile design, rotational speed, welding speed, and axial force. Analysis of variance was applied to validate the predicted model. Confirmation experiments including microstructural characterization and conducted tensile tests showed that developed models are reasonably accurate. The results showed that the joints welded using the square and triangular tools had higher tensile strength compared to the joints welded using other tools. The increase in tool rotational speed, welding speed, and axial force resulted in increasing the tensile strength of the joints up to a maximum value. Also, the developed model showed that the optimum parameters to get a maximum of tensile strength were rotational speed, welding speed, and axial force of 942 rpm, 84 mm/min, and 1.62 kN, respectively.

Heidarzadeh, A.; Saeid, T.; Khodaverdizadeh, H.; Mahmoudi, A.; Nazari, E.

2013-02-01

126

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

127

The effect of temperature on the tensile strength and disintegration of paracetamol and oxytetracycline tablets.  

PubMed

The tensile strengths and disintegration times of paracetamol and oxytetracycline tablets at room temperature are higher when they have been prepared at high temperatures, e.g. 85 degrees, than at room temperature or below, e.g.--20 degrees. The activation energies of the two materials, 3 and 1 k cal mol-1 (13 and 4kJmol-1) respectively, were derived from plots of log tensile strength and log disintegration time versus the reciprocal of the absolute temperature. The results have been explained in terms of sintering theory and the formation of welded bonds between particles. PMID:19574

Pilpel, N; Esezobo, S

1977-07-01

128

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

NASA Technical Reports Server (NTRS)

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.

Nettles, A. T.

1990-01-01

129

Scale effects on the transverse tensile strength of graphite epoxy composites  

NASA Technical Reports Server (NTRS)

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.

Obrien, T. Kevin; Salpekar, Satish A.

1992-01-01

130

Tensile Strength of Carbon Nanotubes Under Realistic Temperature and Strain Rate  

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

131

Determination of the High Temperature Strength of Ceramic. Discussion of Testing Techniques: Flexural and Tensile Tests, Creep Tests with Flexural and Tensile Load.  

National Technical Information Service (NTIS)

High temperature strength of ceramic materials was determined within the service temperature range of an automobile gas turbine. For the use of ceramics as construction materials in gas turbine assemblies, results for flexural and tensile behavior are of ...

W. Gebhard

1981-01-01

132

Tensile strengths and porosities of solar system primitive bodies  

NASA Astrophysics Data System (ADS)

Recent measurements of asteroid bulk densities suggest that rubble-pile asteroids with typical porosities of 30 to 50% may be common (Britt et al., 2006). However, the presence of such objects doesn't mean necessarily that the initial porosity had been preserved (Kerridge, 1993). In fact, the fluffy aggregates produced in laboratory experiments that we expect to be representative of the oldest protoplanetary disk materials, exhibit even higher porosities (Blum et al., 2006). Recent results confirm that primitive meteorites (like e.g. CM carbonaceous chondrites) are compacted samples of the nebula matter exhibiting different density and porosity that their precursors materials (Trigo-Rodríguez et al., 2006). Consequently, aqueous alteration, brecciation, and impact-induced metamorphism make very unlikely to find pristine bodies between the asteroidal population. However, there is clear evidence for the existence of high-porosity bodies between the C-type asteroids like e.g. Mathilde (Housen et al., 1999) or the Tagish Lake parent body (Brown et al., 2002). Although extensive post-accretionary processing of meteorite parent bodies can produce high degrees of porosity, only the most pristine ones seem to preserve more than 50% of porosity. Consequently, we should look for these low strength bodies among the C-type asteroids, or very especially in some unprocessed comets that continue being representative of the precursor materials. Recent suggestion that CI1 chondrites are originated from comets should be studied in this context (Gounelle et al., 2006). Particularly, we think that studies of the porosity and strength of primitive meteorites would provide valuable clues on the origin and nature of their parent bodies. REFERENCES Blum J., R. Schräpler, B.J.R. Davidson and J.M. Trigo-Rodríguez (2006) Astroph. J., submitted. Britt D.T., G.J. Consolmagno, and W.J. Merline (2006) Lunar Planet. Sci. Conf. Abstract #2214. Brown, P. G., D. O. Revelle, E. Tagliaferri, and A.R. Hildebrand (2002) Meteorit. & Planet. Sci. 37, 661-675. 1 Gounelle M., P. Spurny, and P. Bland (2006) Meteorit. & Planet. Sci. 41, 135-150. Housen K.R., K.A. Holsapple and M.E. Voss (1999) Nature 402, 155. Kerridge J.F. (2003) Icarus 106, 135-150. Trigo-Rodríguez J.M., Rubin A.E. and J.T. Wasson (2006) Geochim. et Cosmoch. Acta 70, 1271-1290. 2

Trigo-Rodriguez, J. M.; Llorca, J.; Blum, J.

133

Tensile properties of an ultrahigh-strength graphite fiber in an epoxy matrix  

NASA Technical Reports Server (NTRS)

The fiber performance and reinforcement potential for fiber composites of a special PAN-based graphite fiber were evaluated by testing the fiber's tensile properties in an epoxy matrix. Representative strand samples were taken from 30 spools of single-end, 1500-filament fiber to make over 5000 fiber/epoxy strand specimens using the filament-winding process. Characteristics studied were fiber uniformity, strength and modulus distributions at room and liquid-nitrogen temperatures, stress-strain behavior, the effect of strain rate on fiber strength, and acoustic emission during tensile loading to failure. The fiber was found to have a 3570-MPa failure stress, a 1.7% failure strain, a 206-GPa modulus, and a density of 1.77 Mg/cu m at 23 C. Liquid-nitrogen temperature and various strain rates had no significant effect on fiber tensile properties.

Chiao, T. T.; Hamstad, M. A.; Jessop, E. S.

1974-01-01

134

The native tensile strength of the supraspinatus tendon. A biomechanical study  

Microsoft Academic Search

Summary  \\u000a The traumatic tear of the rotator cuff has been discussed very intensively for a long time despite the fact that there do\\u000a not exist representative objective data about the native tensile strength of these tendons. The aim of this study was to evaluate\\u000a the age related native strength of the supraspinatus tendon. 25 fresh frozen cadaver specimen (age: 23–94,

M. Rickert; H. Georgousis; U. Witzel

1998-01-01

135

Effect of matrix texture on tensile strength and oxidation behavior of carbon fiber reinforced carbon composites  

Microsoft Academic Search

Unidirectional carbon fiber reinforced carbon composites (C?C composites) with different matrix textures were prepared from six matrix precursors. Two composites with an optically isotropic matrix showed tensile strength and modulus values that increased on heat treatment of the samples at a high temperature. Composites with an anisotropic matrix, having preferred orientation parallel to fiber surface, were deformed due to shrinkage

Norio Iwashita; Yoshihiro Sawada; Kazuyuki Shimizu; Shigekazu Shinke; Hiroshi Shioyama

1995-01-01

136

The tensile strength of bilayered tablets made from different grades of microcrystalline cellulose  

Microsoft Academic Search

The aim of this work was to determine the tensile strength of bilayered tablets made from different grades of microcrystalline cellulose. While these grades are chemically identical, they differ significantly in their particle size distribution and in their mechanical properties such as Young's modulus of elasticity. Tablets were produced in the shape of beams of similar dimensions using uniaxial compression,

Fridrun Podczeck; Emad Al-Muti

2010-01-01

137

Warm and Hot Stamping of Ultra High Tensile Strength Steel Sheets Using Resistance Heating  

Microsoft Academic Search

A warm and hot stamping process of ultra high tensile strength steel sheets using resistance heating was developed to improve springback and formability. In this process, the decrease in temperature of the sheet before the forming is prevented by directly heating the sheets set into the dies by means of the electrical resistance, the so-called Joule heat. Since the heating

K. Mori; S. Maki; Y. Tanaka

2005-01-01

138

Strength of Tensile Loaded Graphite\\/Epoxy Laminates Containing Cracks, Open and Filled Holes  

Microsoft Academic Search

Most methods currently used for predicting tensile strength of composite laminates containing holes and cracks adopt a characteristic distance approach such as the Point Stress Criterion (PSC) or the Average Stress Criterion (ASC). These and similar ap proaches are attractive to designers since they are simple to apply. The limitation of such approaches, however, is that the characteristic distance is

Ingvar Eriksson; Carl-Gustaf Aronsson

1990-01-01

139

Effects of Moisture and Temperature on the Tensile Strength of Composite Materials  

Microsoft Academic Search

The ultimate tensile strengths of Thornel 300\\/Fiberite 1034 graphite epoxy composites were measured with material temperatures ranging from 200 K to 422 K and moisture contents from 0% (dry) to 1.5% (fully saturated). All measurements were performed using 0°, 90° and ?\\/4 laminates. A survey was also made of the existing data showing the effects of temperature and moisture content

Chi-Hung Shen; George S. Springer

1977-01-01

140

Comparison of Tensile Strength of Wounds Closed by Sutures and Cyanoacrylates.  

National Technical Information Service (NTIS)

Skin incisions closed by 3 homologous alpha-alkyl cyanoacrylates were compared with sutured control wounds in rat skin with respect to tensile strength at 6 different times (postoperation days 1, 4, and 7 and postoperation weeks 4,8, and 16). The data ind...

P. B. Lamborn H. B. Solouay T. Matsumoto G. V. Aaby

1969-01-01

141

Dynamic split tensile test of Flattened Brazilian Disc of rock with SHPB setup  

Microsoft Academic Search

The Flattened Brazilian Disc (FBD) specimens were impacted diametrically by a pulse shaping split Hopkinson pressure bar to measure dynamic tensile strength of a brittle rock. With application of strain gauge technique, the stress waves traveling through the incident bar, the transmission bar as well as the FBD specimen were recorded and analyzed. The loading history was determined based on

Q. Z. Wang; W. Li; H. P. Xie

2009-01-01

142

Qualitative femur bone tensile strength analysis in radiographic images using wavelets - biomed 2011.  

PubMed

In this work, the tensile strength of femur bone is qualitatively analyzed using radiographic images. The sub anatomic tensile regions were delineated from conventional planar radiographic femur images using digital image processing algorithms. The normal and abnormal images are then subjected to Daubechies5, coiflet5 and Haar wavelets decomposed at three levels to derive approximation and detail coefficients. The qualitative analyses were also performed on the delineated images to derive apparent mineralization and total area. The values of higher order energy parameter are derived for both approximation and detail coefficients in each level of decomposition and are correlated with apparent mineralization for analysis. Results show that the low values of energy correlates well with abnormalities in all levels of decomposition for all the three wavelets. Among all, the values of energy derived out of approximation coefficient using Haar wavelets show higher degrees of correlations in both primary tensile and secondary tensile regional strength. The variations between normal and abnormal were also found to be statistically significant. Poor correlation was observed in the case of detailed coefficients for all the wavelets irrespective of levels. Among all wavelets, the parameters decomposed at level one approximation coefficient of Haar wavelet appear to be a useful predictor for classifying normal and abnormal samples. This could be attributed to sensitivity of adopted wavelets to the architectural changes and discontinuities in regional distribution of trabecular pattern in tensile region. It appears that this methodology could be used for gross abnormality detection, micro-damage studies and modeling the mechanics of soft tissue in diseases. Thus wavelet extracted feature on tensile trabeculae regions of radiographic femur images could be a used as an index for automated screening of bone strength. PMID:21525609

Sangeetha, S; Sujatha, C M; Ramakrishnan, S

2011-01-01

143

The Effect of Thermocycling on Tensile Bond Strength of Two Soft Liners  

PubMed Central

Objective: Failure of soft liners depends mostly on separation from the denture base resin; therefore measurement of the bond strength is very important. The purpose of this study was to compare the tensile bond strength of two soft liners (Acropars, Molloplast-B) to denture base resin before and after thermocycling. Materials and Methods: Twenty specimens fromeach of the two different soft liners were processed according to the manufacturer’s instructions between two polymethyl methacrylate (PMMA) sheets. Ten specimens in each group were maintained in 37°C water for 24 hours and 10 were thermocycled (5000 cycles) among baths of 5° and 55°C. The tensile bond strength was measured using a universal testing machine at a crosshead speed of 5 mm/min. Mode of failure was determined with SEM (magnification ×30). Two-way ANOVA was used to analyze the data. Results: The mean and standard deviation of tensile bond strength of Acropars and Molloplast-B before thermocycling were 6.59±1.85 and1.51±0.22 MPa, respectively and 5.89±1.52 and1.37±0.18 MPa, respectively after thermocycling. There was no significant difference before and after thermocycling. Mode of failure in Acropars and Molloplast-B were adhesive and cohesive, respectivley. Conclusion: The bond strength of Acropars was significantly higher than Molloplast-B (P<0.05).

Geramipanah, Farideh; Ghandari, Masoumeh; Zeighami, Somayeh

2013-01-01

144

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

NASA Technical Reports Server (NTRS)

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.

Vary, A.; Lark, R. F.

1978-01-01

145

Correlation of fiber composite tensile strength with the ultrasonic stress wave factor  

NASA Technical Reports Server (NTRS)

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) 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.

Vary, A.; Lark, R. F.

1978-01-01

146

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

147

High Tensile Strength Amalgams for In-Space Repair and Fabrication  

NASA Technical Reports Server (NTRS)

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.

Grugel, R. N.

2005-01-01

148

Spall experiments for the measurement of the tensile strength and fracture energy of concrete at high strain rates  

Microsoft Academic Search

To study the behavior of concrete under dynamic loads, a Hopkinson-Bar was set up and used. Cylindrical concrete specimens were positioned at the end of the incident bar and the spall event was studied. The purpose of this contribution is to explain the measurement of the tensile strength and the specific fracture energy. To determine the tensile strength, the measured

Harald Schuler; Christoph Mayrhofer; Klaus Thoma

2006-01-01

149

Comparison of the Effect of two Denture Cleansers on Tensile bond Strength of a Denture Liner  

PubMed Central

Statement of Problem: One of the most clinical challenging issues in prosthodontics is debonding of soft liners from the denture base. Purpose: The aim of this study was to evaluate and compare tensile bond strength between soft liner and heat-cured acrylic resin when immersed in two different types of denture cleanser and distilled water, at different period of times. Materials and Method: In this experimental in vivo study, 238 heat-cured acrylic blocks were made. A soft liner was embedded between the acrylic blocks. Samples were divided into four groups: 17 samples were in the control group and were not soaked in any solution .The remaining samples were divided into 3 groups (Distilled water, Calgon and Fittydent). Each group was then subdivided into two subcategories, regarding the immersion time variable; 15 and 45 minutes. All samples were placed in tension force and tensile bond strength was recorded with the testing machine. One- way ANOVA and Tucky HSD post-hoc test were adopted to analyze the yielded data (?> 0.05). Results: Specimens which were immersed in two denture cleansers (Fittydent and Calgon) and in distilled water showed significant difference (p= 0.001) in bonding strength when compared to the control group. The subjects immersed in denture cleanser solutions and distilled water did not reveal any significant difference (p= 0.90). For all groups; most of the bonding failures (72%) were cohesive type. Conclusion: The effect of the denture cleansers and distilled water on the bond strength was not statistically different; however, the difference was significant between the immersed groups with the non-immersed group. Moreover, type of the denture cleanser did not show any effect on the tensile strength. The tensile strength increases with time of immersion.

Farzin, M; Bahrani, F; Adelpour, E

2013-01-01

150

Quantifying the tensile strength of microbial mats grown over noncohesive sediments.  

PubMed

Biofilms in marine and fluvial environments can comprise strong bacterial and diatom mats covering large areas of the bed and act to bind sediments. In this case the bed material becomes highly resistant to shear stresses applied by the overlying fluid motion and detachment, when it does occur, is manifest in patches of biofilm of the order cm(2) being entrained into the flow. This article is the first to report tensile test data specific to the centimeter scale using moist biofilm/sediment composite materials; the strain (?)-stress (?) relationships permit quantification of the elasticity (Young's modulus, E) and cohesive strength of each specimen. Specifically, we compare the mechanical strength of cyanobacterial biofilm-only samples to that of biofilm cultured over sediment samples (glass beads or natural sands of d ~ 1 mm) for up to 8 weeks. The range of tensile strength (1,288-3,283 Pa) for composite materials was up to three times higher than previous tensile tests conducted at smaller scale on mixed culture biofilm [Ohashi et al. (1999) Water Sci Technol 39:261-268], yet of similar range to cohesive strength values recorded on return activated sludge flocs [RAS; Poppele and Hozalski (2003) J Microbiol Methods 55:607-615]. Composite materials were 3-6 times weaker than biofilm-only samples, indicating that adhesion to sediment grains is weaker than cohesion within the biofilm. Furthermore, in order to relate the tensile test results to the more common in-situ failure of bio-mats due to shear flow, controlled erosion experiments were conducted in a hydraulic flume with live fluid flow. Here, the fluid shear stress causing erosion was 3 orders of magnitude lower than tensile stress; this highlights both the problem of interpreting material properties measured ex-situ and the need for a better mechanistic model of bio-mat detachment. PMID:22170239

Vignaga, E; Haynes, H; Sloan, W T

2012-05-01

151

Prediction of Uniaxial Compressive Strength, Tensile Strength and Porosity of Sedimentary Rocks Using Sound Level Produced During Rotary Drilling  

NASA Astrophysics Data System (ADS)

The main purpose of the study is to develop a general prediction model and to investigate the relationships between sound level produced during drilling and physical properties such as uniaxial compressive strength, tensile strength and percentage porosity of sedimentary rocks. The results were evaluated using the multiple regression analysis taking into account the interaction effects of various predictor variables. Predictor variables selected for the multiple regression model are drill bit diameter, drill bit speed, penetration rate and equivalent sound level produced during rotary drilling ( L eq). The constructed models were checked using various prediction performance indices. Consequently, it is possible to say that the constructed models can be used for practical purposes.

Rajesh Kumar, B.; Vardhan, Harsha; Govindaraj, M.

2011-09-01

152

Various conditioning methods for root canals influencing the tensile strength of titanium posts.  

PubMed

Conditioning the root canal is frequently advised to achieve high post-retention when resin composite luting cements are used. However, manufacturers' instructions for this purpose differ widely from one another. The aim of this study was to compare the tensile bond strengths of passive, tapered, titanium root posts that were luted with four different resin composite cements (Compolute Aplicap, Flexi-Flow cem, Panavia 21 EX, Twinlook) in the root canals at three conditions, namely (i) no conditioning, (ii) etching with 37% phosphoric acid, and (iii) etching + bonding agent application. Panavia 21 EX was further tested after using the primer for the post-surface according to the manufacturer's recommendations. The posts luted with zinc phosphate cement (Tenet) acted as the control group. Following endodontic preparation of 140 intact anterior teeth with hand instruments, the post-spaces were prepared using the opening drills of the corresponding size of the posts. The samples were first stored in water at 37 degrees C for 24 h and then thermocycled (5000 cycles, 5-55 degrees C, 30 s). The tensile strength values were measured with the universal testing machine at a crosshead speed of 0.5 mm min(-1). The data were analysed statistically using anova and corrected with Scheffé test due to the significance levels (P < 0.05). The tensile bond strengths of the titanium posts after luting with various cements and thermocycling were affected by the conditioning systems used for the root canals. Tensile bond strengths were the highest with Flexi-Flow (475 +/- 78 N) followed in descending order by Panavia 21 EX (442 +/- 97 N), Twinlook (430 +/- 78 N) and Compolute Aplicap (352 +/- 76 N) after conditioning the root canal. The use of primer on the post improved the tensile bond strength compared with the non-conditioned group for the Panavia 21 EX group (375 +/- 77 N) (P < 0.001). Tensile bond strengths obtained after luting the posts with zinc phosphate cement (414 +/- 102 N) were not significantly different (P < 0.05) than those of resin composite cements. Although the importance of conditioning the root canal was evident for Panavia 21 EX, it was not the case for the other luting cements tested. PMID:15369471

Schmage, P; Sohn, J; Nergiz, I; Ozcan, M

2004-09-01

153

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

NASA Technical Reports Server (NTRS)

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.

Lovoy, C. V.

1974-01-01

154

Casting behavior and tensile strength of cast BaTiO sub 3 tape  

SciTech Connect

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.

Karas, A.; Kumagai, Toshiya; Cannon, W.R. (Rutgers, The State Univ. of New Jersey, Piscataway (USA))

1988-07-01

155

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

NASA Technical Reports Server (NTRS)

The variation of ultimate tensile strength with thermal treatment of B-Al composite materials and of boron fibers chemically removed from these composites is studied systematically in an attempt to determine the mechanism of the resulting strength degradation. The results indicate that thermally cycling of B-Al represents a more severe condition than equivalent time at temperature. Degradation of composite tensile strength from about 1.3 GN/sq m to as low as 0.34 GN/sq m was observed after 3000 cycles to 420 C for 203-micron 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. On the basis of various thermal-cycling studies and electron diffraction analysis, a mechanism is favored in which B reacts with Al, freshly exposed by cold working during cycling, to form AlB2. The nonuniform interface reaction leads to a highly flawed and weakened B fiber.

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

1977-01-01

156

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

NASA Astrophysics Data System (ADS)

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.

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

1998-01-01

157

Effects of carbon percentage, Stelmor cooling rate and laying head temperature on tensile strength gain in low carbon steels  

NASA Astrophysics Data System (ADS)

Low carbon steel wire rods are used to produce finished products such as fine wire, coat hangers, staples, and roofing nails. These products are subjected to excessively high work hardening rates during wire drawing process resulting in a variation in wire tensile strength. This research analyzes the effects of carbon percentage, StelmorRTM cooling rate and laying head temperature on the tensile strength gain in wire drawn low carbon steels using design of experiments. The probable reasons for variations in tensile strength gain are analyzed by observing the microstructural changes during experiments. Microstructural analysis was done extensively using optical microscope and Transmission Electron Microscope (TEM) and it was found that the tensile strength gain variation is mainly caused by the increase in the dislocation density in wire rod and wire due to high cooling rate and high laying head temperature, within the range considered. This research concludes that a low carbon wire rod can be produced with minimum tensile strength gain, lower dislocation density and finer ferrite grain size by maintaining a low cooling rate in the StelmorRTM cooling zone and low laying head temperature, which is the temperature at which the wire rod coils are laid on the Stelmor RTM deck. It is also concluded from the results of the present study that: (1) The lowest tensile strength gain is for NS 1006T-3 (0.07 wt.% Carbon) with low cooling rate of 14°F/s and low laying head temperature of 1500°F. (2) The highest tensile strength gain is for NS 1006T-3 with high cooling rate of 26°F/s and high laying head temperature of 1650°F. (3) The effect of StelmorRTM cooling rate and laying head temperature and their interaction are found to be the significant factors causing the variation in wire tensile strength gain. The StelmorRTM cooling rate has the most significant effect on tensile strength gain among the three factors. (4) The effect of carbon percentage on wire tensile strength gain is very minimal. (5) With an increase in the StelmorRTM cooling rate from 14°F/s to 26°F/s, there is a substantial increase in the dislocation densities in the wire rods and wires, which is the primary cause of the increase in the tensile strength gain. (6) The effect of carbon percentage on wire tensile strength gain is very minimal. North Star Steel Texas would benefit substantially from this research by being able to produce better quality wire rods, through better understanding of the factors affecting the tensile strength gain variation. This is expected to lead to a reduction in customer complaints on failure of wire products.

Gade, Surya Prakash

158

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

PubMed

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

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

2010-05-01

159

Synthesis, characterization, and tensile strength of CVI SiC/BN/SiC composites  

SciTech Connect

Tows of Nicalon yarn were first precoated by CVD with amorphous BN, then infiltrated with SiC by CVD to form single strand composites. Two different methods for the preparation of BN were investigated. The first involved the formation of a BCl3-NH3 adduct; the second consisted of the direct reaction of the gases in hot zone. Tensile strength measurements made on the composites were about 277 MPa and displayed a considerable amount of fiber pull-out and crack bridging. In order to establish their thermal stability, the ends of the composites were cut, exposing the fiber and interface, and annealed in air to 1100 C for 70 h. This annealing process did not result in a decrease in tensile strength. The composites were characterized by AES, SEM, and X-ray diffraction analysis. 16 refs.

Kmetz, M.A.; Laliberte, J.M.; Willis, W.S.; Suib, S.L.; Galasso, F.S.

1991-10-01

160

Dust release and tensile strength of the non-volatile layer of cometary nuclei  

NASA Astrophysics Data System (ADS)

We developed a thermophysical model for cometary nuclei, which is based upon the assumption that comets form by the gravitational instability of an ensemble of dust and ice aggregates. Under this condition, the tensile strength of the ice-free outer layers of a cometary nucleus can be calculated, using the dust-aggregate collision and adhesion model of Weidling et al. (Weidling, R. et al. [2012]. Icarus, 218, 688-700). Based on available laboratory data on the gas permeability and thermal conductivity of ice-free dust layers, we derived the temperature and pressure at the dust-ice interface for pure water and pure carbon dioxide ice. Comparison of the vapor pressure below the dust crust with its tensile strength allows the prediction of dust release from cometary surfaces. Our model predicts dust activity for pure CO2 ice and for heliocentric distances of ?3 AU, whereas pure H2O ice cannot explain the dust emission.

Skorov, Yuri; Blum, Jürgen

2012-09-01

161

Effect of different surface treatments on tensile bond strength of silicone-based soft denture liner  

Microsoft Academic Search

Failure of the bond between the acrylic resin and resilient liner material is commonly encountered in clinical practice. The\\u000a purpose of this study was to investigate the effect of different surface treatments (sandblasting, Er:YAG, Nd:YAG, and KTP\\u000a lasers) on tensile bond strength of silicone-based soft denture liner. Polymethyl methacrylate test specimens were fabricated\\u000a and each received one of eight surface

Hakan Akin; Faik Tugut; Burcu Mutaf; Gulsah Akin; A. Kemal Ozdemir

162

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

NASA Technical Reports Server (NTRS)

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.

Moore, Thomas J.; Watson, Gordon K.

1994-01-01

163

Effect of steam oxidation on the tensile strength of HTGR structural graphites  

Microsoft Academic Search

The core support system of the General Atomic Company design High Temperature Gas-Cooled Reactor (HTGR) contains type PGX graphite as core support blocks. The change in ultimate tensile strength of PGX graphite specimens with oxidation (burnoff) has been determined in a safety-related experimental program at Brookhaven National Laboratory(BNL). It is shown that Fe, an impurity in PGX graphite, plays a

A. J. Romano; J. G. Y. Chow

1977-01-01

164

Direct mechanical measurement of the tensile strength and elastic modulus of multiwalled carbon nanotubes  

Microsoft Academic Search

We have conducted pulling and bending tests on individual carbon nanotubes in-situ in a transition electron microscope. Based on our observation of the force required to break the tube, a tensile strength of 0.15 TPa was computed. From corresponding bending studies on such nanotubes, the Young's modulus was estimated to be 0.9 TPa (0.8 TPa after ‘sub continuum’ corrections). These

B. G. Demczyk; Y. M. Wang; J. Cumings; M. Hetman; W. Han; A. Zettl; R. O. Ritchie

2002-01-01

165

Tensile Bond Strength and SEM Evaluation of Caries-affected Dentin Using Dentin Adhesives  

Microsoft Academic Search

Tensile bond strength measurements are commonly used for the evaluation of dentin adhesive systems. Most tests are performed using extracted non-carious human or bovine dentin. However, the adhesion of resins to caries-affected dentin is still unclear. The objectives of this study were to test the hypothesis that bonding to caries-affected dentin is inferior to bonding to normal dentin, and that

M. Nakajima; H. Sano; M. F. Burrow; J. Tagami; M. Yoshiyama; S. Ebisu; B. Ciucchi; C. M. Russell; D. H. Pashley

1995-01-01

166

Development of high tensile strength silicon carbide fibre using an organosilicon polymer precursor  

Microsoft Academic Search

THE high tensile strength SiC fibre developed in our laboratory1-5 is extremely heat-resistant and its wettability by metals is good. Metal-matrix composites reinforced with the SiC fibre should therefore be of practical use. Polycarbosilane, the precursor of the fibre, is synthesised by thermal decomposition under high pressure of poly dimethylsilane in an autoclave. To produce the SiC fibre on an

S. Yajima; Y. Hasegawa; K. Okamura; T. Matsuzawa

1978-01-01

167

Tensile strength of mesh fixation methods in laparoscopic incisional hernia repair  

Microsoft Academic Search

  Background: Fixation of the mesh is crucial for the successful laparoscopic repair of incisional hernias. In the present\\u000a experimental study, we used a pig model to compare the tensile strengths of mesh fixation with helical titanium coils (tackers)\\u000a and transabdominal wall sutures. Methods: Thirty-six full-thickness specimens (5 × 7 cm) of the anterior abdominal wall of\\u000a nine pig cadavers were

M. Riet; P. J. Steenwijk; G. J. Kleinrensink; E. W. Steyerberg; H. J. Bonjer

2002-01-01

168

Tensile and creep strengths of hot-pressed Si 3 N 4  

Microsoft Academic Search

Tensile, creep, and stress-rupture data for Norton HS-110 and HS-130 hot-pressed Si3N4 are presented. It is shown that the strength of the material is controlled by the grain-boundary glass phase. At elevated temperatures, >1000‡ C, deformation is controlled by grain-boundary sliding. A model based on the concept of geometrically necessary wedge cracks is then developed which accounts for the observed

Ram Kossowsky; D. G. Miller; E. S. Diaz

1975-01-01

169

Fast tablet tensile strength prediction based on non-invasive analytics.  

PubMed

In this paper, linkages between tablet surface roughness, tablet compression forces, material properties, and the tensile strength of tablets were studied. Pure sodium halides (NaF, NaBr, NaCl, and NaI) were chosen as model substances because of their simple and similar structure. Based on the data available in the literature and our own measurements, various models were made to predict the tensile strength of the tablets. It appeared that only three parameters-surface roughness, upper punch force, and the true density of material-were needed to predict the tensile strength of a tablet. Rather surprising was that the surface roughness alone was capable in the prediction. The used new 3D imaging method (Flash sizer) was roughly a thousand times quicker in determining tablet surface roughness than traditionally used laser profilometer. Both methods gave practically analogous results. It is finally suggested that the rapid 3D imaging can be a potential in-line PAT tool to predict mechanical properties of tablets in production. PMID:24638870

Halenius, Anna; Lakio, Satu; Antikainen, Osmo; Hatara, Juha; Yliruusi, Jouko

2014-06-01

170

Enhancement of hydrophobicity and tensile strength of muga silk fiber by radiofrequency Ar plasma discharge  

NASA Astrophysics Data System (ADS)

The hydrophobicity and tensile strength of muga silk fiber are investigated using radiofrequency (RF) Ar plasma treatment at various RF powers (10-30 W) and treatment times (5-20 min). The Ar plasma is characterized using self-compensated Langmuir and emissive probe. The ion energy is observed to play an important role in determining the tensile strength and hydrophobicity of the plasma treated fibers. The chemical compositions of the fibers are observed to be affected by the increase in RF power rather than treatment time. XPS study reveals that the ions that are impinging on the substrates are mainly responsible for the cleavage of peptide bond and side chain of amino acid groups at the surface of the fibers. The observed properties (tensile strength and hydrophobicity) of the treated fibers are found to be dependent on their variation in atomic concentration and functional composition at the surfaces. All the treated muga fibers exhibit almost similar thermal behavior as compared to the virgin one. At RF power of 10 W and treatment time range of 5-20 min, the treated fibers exhibit properties similar to that of the virgin one. Higher RF power (30 W) and the increase in treatment time deteriorate the properties of the fibers due to incorporation of more surface roughness caused by sufficiently high energetic ion bombardment. The properties of the plasma treated fibers are attempted to correlate with the XPS analysis and their surface morphologies.

Gogoi, D.; Choudhury, A. J.; Chutia, J.; Pal, A. R.; Dass, N. N.; Devi, D.; Patil, D. S.

2011-10-01

171

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

172

Simulation of tensile strength of anisotropic fibre-reinforced composites at low temperature  

NASA Astrophysics Data System (ADS)

This article presents a simulation scheme to predict the effect of fibre anisotropy on composite tensile failure strength at room and low temperatures. The simulation model combines the shear lag equation with the chain of bundles probability model to describe the composite failure behaviour. The effect of fibre anisotropy on thermal stresses developed in composite constituents due to cooling to low temperatures is considered. The failure strength of composites composed of fibres with different degrees of anisotropy is obtained and comparisons are made with experiments. Simulated results for E-glass-, graphite- and Kevlar-epoxy type composites showed close agreement with the experiments.

Abdelmohsen, H. H.

173

Parameters of tensile strength, elongation, and tenacity of 70mm IIaO spectroscopic film  

NASA Technical Reports Server (NTRS)

The 70mm IIaO spectroscopic film was tested to determine its tensile strength, elongation, and breaking strength, using an Instron (strength and compression) 4201 Test Instrument. These data provide information leading to the upper and lower limits of the above parameters for 70mm IIaO spectroscopic film. This film will be developed by a commercial developing machine after the Ultraviolet Telescope Space Shuttle Mission returns to the Earth in the early 1990's; thus, it is necessary to understand these force parameters. Several test strips of approximately 200mm in length were used. The results indicate that when a stress load of 100 kg was applied, the film elongated approximately 1.06mm and the break strength was 19.45 kilograms.

Hammond, Ernest C., Jr.; Peters, Kevin A.

1989-01-01

174

Dynamic Tensile Strength of Crustal Rocks and Application to Impact Cratering  

NASA Astrophysics Data System (ADS)

Dynamic tensile strengths of two crustal rocks, San Marcos gabbro and Coconino sandstone (Meteor Crater, Arizona), were determined by carrying out flat plate impact experiments. Porosity of San Marcos gabbro is very low, and the reported porosity for Coconino sandstone is approx. 25%. Aluminum flyer plates were used for gabbro with impact velocities of 13 to 50 m/s, which produce tensile stresses in the range of 120 to 450 MPa. PMMA flyer plates were used for sandstone with impact velocities of 5 to 25 m/s, resulting tensile stresses in the range of approx. 13 to 55 MPa. Impact was normal to the bedding of sandstone. Tensile duration times for two cases were approx. 1 and approx. 2.3 microns, respectively. Pre-shot and post-shot ultrasonic P and S wave velocities were measured for the targets. Velocity reduction for gabbro occurred at approx. 150 MPa, very close to the earlier result determined by microscopic examination. The reduction of S wave is slightly higher than that of P wave. This indicates that the impact-induced cracks were either aligned, or there were residual fluids within cracks, or both. Data for sandstone velocity reduction was few and scattered caused by its high porosity. The range of dynamic tensile strength of Coconino sandstone is within 25 and 30 MPa. Obvious radial cracks at certain stresses indicate that deformation was not restricted to one dimensional strain as being assumed. Spall fragmentation occurred above 40 MPa. The combination of impact velocities, U (km/s), and impactor radii, a0)(m, are constrained by Meteor Crater fracture depth, approx. 850 m, and the dynamic tensile fracture strength from our experiments, 40 MPa. Volume of the crater for each impact was calculated using V = 0.009mU1.65, where V is crater volume (cu m), m is the mass of the impactor (kg). Volume of impact with U = 28 km/s, a0 = 10 m is close to the real Meteor Crater volume, 7.6e7 cu m. Impact energy for this case is 3.08 Mt., which agrees well with theoretical calculation (3.3 to 7.4 Mt.).(1 Mt. = 4.18e 15J).

Ai, H.; Ahrens, T. J.

2003-01-01

175

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

SciTech Connect

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.

Humer, K.; Weber, H.W. [Atominstitut der Oesterreichischen Universitaeten, Vienna (Austria); Tschegg, E.K. [Technische Univ., Vienna (Austria). Inst. fuer Angewandte und Technische Physik; Egusa, S. [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; Birtcher, R.C. [Argonne National Lab., IL (United States); Gerstenberg, H. [Technische Univ. Muenchen, Garching (Germany). Physikdepartment

1993-08-01

176

Texture of parenchymatous plant tissue: a comparison between tensile and other instrumental and sensory measurements of tissue strength and juiciness  

Microsoft Academic Search

The cellular basis of textural diversity in selected fruit and root tissue has been investigated using tensile measurements of tissue strength. The mechanism of tissue failure, either cell rupture or cell-to-cell debonding, was determined by examining the fracture surface using Low Temperature Scanning Electron Microscopy (LTSEM). Information provided by tensile measurements was compared with that provided by sensory and other

F. Roger Harker; Margaret G. H. Stec; Ian C. Hallett; Carey L. Bennett

1997-01-01

177

Immediate and delayed micro-tensile bond strength of different luting resin cements to different regional dentin  

PubMed Central

We sought to evaluate immediate and delayed micro-tensile bond strength of Panavia F2.0 and Multilink Sprint resin cement to superficial, deep and cervical dentin. Thirty-six freshly extracted non-carious human molars were sectioned in the mesiodistal direction to expose three different dentin regions including superficial dentin (1 mm below the dentine-enamel junction), deep dentin (1 mm above the highest pulp horn) and cervical dentin (0.5 mm above the cemento-enamel junction and 0.5 mm below the dentine-enamel junction). Resin cements were applied on dentin surfaces and composite blocks were luted under constant seating pressure. Each group was divided into three subgroups according to time intervals. Specimens were sectioned to obtain sticks of 1 mm2 in diameter and subjected to microtensile bond strength testing at a cross head speed of 1 mm/min. Both resin cements showed higher micro-tensile bond strength to superficial dentin than that to deep or cervical dentin (P < 0.001). Micro-tensile bond strengths of Panavia F2.0 were higher than those of Multilink Sprint at different dentin regions (P < 0.001). Immediate micro-tensile bond strengths were higher than those of delayed micro-tensile bond strengths for both resin cements (P < 0.001). It was concluded that resin cements with different chemical formulations and applications yield significantly different micro-tensile bond strengths to different dentin regions.

Ali, Abdelraheem Mohamed; Hamouda, Ibrahim Mohamed; Ghazy, Mohamed Hamed; Abo-Madina, Manal Mohamed

2013-01-01

178

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

PubMed

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. PMID:24931632

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

2014-01-01

179

Tensile and flexural strength of non-graphitic superhybrid composites: Predictions and comparisons  

NASA Technical Reports Server (NTRS)

Equations are presented and described which can be used to predict bounds on the tensile and flexural strengths of nongraphitic superhybrid (NGSH) composites. These equations are derived by taking into account the measured stress-strain behavior, the lamination residual stresses and the sequence of events leading to fracture. The required input for using these equations includes constituents, properties (elastic and strength), NGSH elastic properties, cure temperature, and ply stress influence coefficients. Results predicted by these equations are in reasonably good agreement with measured data for strength and for the apparent knees in the nonlinear stress-strain curve. The lower bound values are conservative compared to measured data. These equations are relatively simple and are suitable for use in the preliminary design and initial sizing of structural components made from NGSH composites.

Chamis, C. C.; Sinclair, J. H.; Lark, R. F.

1979-01-01

180

Tensile and flexural strength of nongraphitic superhybrid composites - Predictions and comparisons  

NASA Technical Reports Server (NTRS)

Equations are presented and described which can be used to predict bounds on the tensile and flexural strengths of nongraphitic superhybrid (NGSH) composites. These equations are derived by taking into account the measured stress-strain behavior, the lamination residual stresses and the sequence of events leading to fracture. The required input for using these equations includes constituent composites, elastic and strength properties, NGSH elastic properties, cure temperature, and ply stress influence coefficients. Results predicted by these equations are in reasonably good agreement with measured data for strength and for the apparent 'knees' in the nonlinear stress-strain curve. The lower bound values are conservative compared to measured data. These equations are relatively simple and should be suitable for use in the preliminary design and initial sizing of structural components made from NGSH composites.

Chamis, C. C.; Sinclair, J. H.; Lark, R. F.

1979-01-01

181

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

PubMed Central

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.

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

2014-01-01

182

High Tensile Strength Amalgams for In-Space Fabrication and Repair  

NASA Technical Reports Server (NTRS)

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.

Grugel, Richard N.

2006-01-01

183

Effects of Mechanical and Environmental Factors on the Notch Tensile Strength of 1,300MPa Class SCM435 High-Strength Steel in Hydrogen Gas  

NASA Astrophysics Data System (ADS)

There are several factors that affect the strength of high-strength steel SCM435 as a sharp notched specimen in a hydrogen gas environment. In this paper, tensile tests were carried out in several hydrogen and helium gas environments. The examined factors were the gas pressure, the gas temperature, the cross-head speed and the notch root radius. The results of the tensile tests in the hydrogen gas environments showed a decrease in the tensile strengths for any given environmental factor. This was not observed in the helium gas environments. Additionally, by investigating the area of intergranular fracture, it was found that the tensile strength had a reciprocal relationship with the area of the intergranular fracture regardless of several environmental factors.

Suzuki, Yuichi; Itoga, Hisatake; Noguchi, Hiroshi

184

Low-velocity impact characteristics and residual tensile strength of carbon fiber composite lattice core sandwich structures  

Microsoft Academic Search

In this paper, low-velocity impact characteristics and residual tensile strength of carbon fiber composite lattice core sandwich structures are investigated by experimentally and numerically. Low-velocity impact tests and residual tensile strength tests are performed using an instrumented drop-weight machine (Instron 9250HV) and static test machine (Instron 5569), respectively. The FE (finite element) software, ABAQUS\\/Explicit is employed to simulate low-velocity impact

Bing Wang; Lin-Zhi Wu; Li Ma; Ji-Cai Feng

2011-01-01

185

Tensile strength of thermomechanically processed Cu-9Ni-6Sn alloys  

SciTech Connect

The tensile properties of Cu-9Ni-6Sn alloys with different swaging amounts of 64, 77, and 95 pct, either solutionized and aged (S/A), were examined as a function of aging time. It was found that the aging response of Cu-9Ni-6Sn alloys varied greatly depending on the prior solution heat treatment before aging and/or different swaging amounts. The swaged S/A Cu-9Ni-6Sn alloys showed a multistage increase in tensile strength with respect to aging time, probably due to the sequential occurrence of spinodal decomposition, formation of metastable {gamma}{center{underscore}dot} precipitates, and recrystallization. The effect of different swaging amounts, ranging from 64 to 95 pct, was minimal on the aging response of S/A specimens. The prior cold working, however, appeared to favor the spinodal strengthening, comparing unswaged and swaged S/A Cu-9Ni-6Sn alloys. In 95 pct swaged D/A Cu-9Ni-6Sn alloys, the level of hardening was much less sensitive to aging time. A complex interaction between the reduction in dislocation density, the formation of equilibrium precipitates, and the reduction of Sn content in the Sn-rich segregates during an aging process is believed to be responsible for such a lean sensitivity. The increases in tensile strength of 64 and 77 pct swaged D/A Cu-9Ni-6Sn alloys were found to be much steeper than that in the 95 pct counterparts in the early and intermediate stages of aging, which is believed to be related to the relative contribution from work hardening and precipitation hardening to the strength level of D/A specimens.

Rhu, J.C.; Kim, S.S.; Jung, Y.C.; Han, S.Z.; Kim, C.J.

1999-10-01

186

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

NASA Technical Reports Server (NTRS)

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.

Miyoshi, K.; Buckley, D. H.

1981-01-01

187

New enzyme-based process direction to prevent wool shrinking without substantial tensile strength loss.  

PubMed

In this paper a new enzymatic process direction is described for obtaining machine washable wool with acceptable quality. In general, application of protease enzyme technology in wool processing results in considerable loss of tensile strength by diffusion of the enzyme into the interior of wool fibers. To overcome this disadvantage enzymatic activity has been more targeted to the outer surface of the scales by improving the susceptibility of the outer surface scale protein for proteolytic degradation. This has been realized by a pretreatment of wool with hydrogen peroxide at alkaline pH in the presence of high concentrations of salt. PMID:16791725

Lenting, H B M; Schroeder, M; Guebitz, G M; Cavaco-Paulo, A; Shen, J

2006-05-01

188

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

NASA Technical Reports Server (NTRS)

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.

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

1996-01-01

189

Evaluation of Interfacial Tensile Strength in Glass Fiber/Epoxy Resin Interface using the Cruciform Specimen Method  

NASA Astrophysics Data System (ADS)

Glass/epoxy interfacial tensile strength is investigated by the cruciform specimen method. The conventional transverse tensile test for single fiber composite is one of methods for evaluating the interfacial tensile strength, but stress singularity at the specimen edge is a very complicated problem to be solved. A cruciform specimen which has large width only around fiber embedded in transverse direction can potentially prevent the stress singularity problem. The cruciform specimen geometry is first discussed by means of finite element analysis considering experimental conditions. Transverse tensile test is conducted and an interfacial debonding which initiates at the middle of specimen not at edge is observed using the cruciform specimens. The interfacial tensile strength can be obtained by the value of stress concentration factor at interface multiplied by specimen stress. The location which the debonding initiates from is discussed and the validity of the evaluation method in this study is verified when interfacial tensile strength is as high as or lower than interfacial shear strength.

Ogihara, Shinji; Sakamoto, Yoriaki; Koyanagi, Jun

190

An experimental investigation on the tensile moduli and strengths of graphite/epoxy laminates  

NASA Technical Reports Server (NTRS)

The results of a series of tensile tests on some graphite/epoxy laminates, at rates varying from 0.002 to 2 in./min are examined. The loads were applied at various angles to the fiber directions in each case. The rate-dependent behavior of the stress-strain response is assessed. Evidence is presented to indicate that failure first occurs on inner plies, and that, in some cases, moduli increase with increasing stress (or strain) level. Lamination theory is used to predict the moduli, and comparisons with experiment are given. This theory is also used in conjunction with three failure theories to predict ultimate strengths (with varying degrees of success). Further, two approaches to ply unloading after first-ply failure are used and discussed. One is a standard method found in the literature while the other is a proposed 'strength-of-materials' type of technique which is computationally much simpler.

Yeow, Y. T.; Brinson, H. F.

1977-01-01

191

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

PubMed Central

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.

Liu, Jie; Lu, Xiaolong; Wu, Chunrui

2013-01-01

192

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

PubMed

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

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

2013-01-01

193

Effect of the tensile strength on the stability against rotational breakup of icy bodies  

NASA Astrophysics Data System (ADS)

Focusing on primitive icy minor bodies in the solar system like cometary nuclei, centaurs, transneptunian objects (TNOs), and main-belt comets (MBCs) we investigate the stability of these objects against rotational breakup by comparing their location in (radius - rotational period) space with respect to separation lines of the stable and breakup zones in this plane. We estimate the bulk tensile strength according to new structural and elasto-mechanical models of grain-aggregates, using these tensile strengths to compute separation lines. We note that the process of grain coagulation and growth is highly uncertain in the field of solar system formation and we simply don't know how to grow interstellar grains to aggregates larger than about 1 mm but we apply in our calculations the recently available elasto-mechanical models of grain-aggregates. Accorging to this study most of the observed comets, centaurs, TNOs, and MBCs are stable against rotational breakup, with a few notable exceptions. E.g., we suggest that the rotational fission is a likely scenario for the Haumea-family in the Kuiper belt.

Toth, Imre; Lisse, Carey M.

194

Effects of fiber length and fiber orientation distributions on the tensile strength of short-fiber-reinforced polymers  

Microsoft Academic Search

This paper presents an analytical method considering the effects of fiber length and fiber orientation distributions for predicting the tensile strength (TS) of short-fiber-reinforced polymers (SFRP). Two probability density functions are used for modelling the distributions of fiber length and fiber orientation. The strength of SFRP is derived as a function of fiber length and fiber orientation distribution taking into

Shao-Yun Fu; Bernd Lauke

1996-01-01

195

Comparison of the flexural strength of six reinforced restorative materials.  

PubMed

This study calculated the flexural strength for six reinforced restorative materials and demonstrated that flexural strength values can be determined simply by using physical parameters (diametral tensile strength and Young's modulus values) that are easily determined experimentally. A one-way ANOVA analysis demonstrated a statistically significant difference between the two reinforced glass ionomers and the four composite resin materials, with the composite resin being stronger than the glass ionomers. PMID:12017792

Cohen, B I; Volovich, Y; Musikant, B L; Deutsch, A S

2001-01-01

196

Observed and simulated fracture pattern in diametrically loaded discs of rock material  

Microsoft Academic Search

To investigate the influence of a tensile stress gradient on fracture initiation and fracture growth in rock material, a configuration, consisting of a diametrically loaded disc with a hole on the diameter perpendicular to the loaded diameter, is used. The maximum local tensile stresses the material is able to withstand increase as the stress gradient increases. Depending on the diameter

B. Van De. Steen; A. Vervoort; J. A. L. Napier

2005-01-01

197

Back Propagation Neural Networks for Predicting Ultimate Strengths of Unidirectional Graphite/Epoxy Tensile Specimens  

NASA Technical Reports Server (NTRS)

The research presented herein demonstrates the feasibility of predicting ultimate strengths in simple composite structures through a neural network analysis of their acoustic emission (AE) amplitude distribution data. A series of eleven ASTM D-3039 unidirectional graphite/epoxy tensile samples were loaded to failure to generate the amplitude distributions for this analysis. A back propagation neural network was trained to correlate the AE amplitude distribution signatures generated during the first 25% of loading with the ultimate strengths of the samples. The network was trained using two sets of inputs: (1) the statistical parameters obtained from a Weibull distribution fit of the amplitude distribution data, and (2) the event frequency (amplitude) distribution itself. The neural networks were able to predict ultimate strengths with a worst case error of -8.99% for the Weibull modeled amplitude distribution data and 3.74% when the amplitude distribution itself was used to train the network. The principal reason for the improved prediction capability of the latter technique lies in the ability of the neural network to extract subtle features from within the amplitude distribution.

Walker, James L.; Hill, Eric v. K.

1993-01-01

198

Diametral Pairs of Linear Extensions  

Microsoft Academic Search

Given a finite poset P, we consider pairs of linear extensions of P with maximal distance, where the distance between two linear extensions L_1, L_2 is the number of pairs of elements of P appearing in different orders in L_1 and L_2. A diametral pair maximizes the distance among all pairs of linear extensions of P. Felsner and Reuter defined

Graham Brightwell; Mareike Massow

2008-01-01

199

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

NASA Technical Reports Server (NTRS)

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.

OBrien, T. Kevin; Krueger, Ronald

2001-01-01

200

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

NASA Technical Reports Server (NTRS)

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.

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

1977-01-01

201

Role of additives on tensile strength of wood-plastic composite  

NASA Astrophysics Data System (ADS)

Wood-plastic composite (WPC) formation has been studied with simul+styrene system at various compositions of styrene with methanol as the swelling solvent. Effect of additives, e.g. multifunctional monomers (MFM) and oligomers used in very low quantity (1% v/v) on the polymer loading (PL) and tensile strength (TS) of the WPC has been elaborately investigated. Enhanced PL and TS values are observed. Inorganic co-additives like Lithium (Li +), Copper (Cu 2+) and acid (H +) and urea (U) used in combinations with additives (MFM or oligomers) have influenced the results of PL and TS in these systems. Li + ion has been a good replacement for H + ion; U has substantially enhanced the PL values with retention of the TS values of WPC. Co-additive Cu 2+ used in these system can act as a preservative and protective agent for WPC.

Khan, Mubarak A.; Ali, K. M. Idriss

202

Discrete simulation of model, loose cohesive powders: plastic consolidation, fractal microstructure and tensile strength  

NASA Astrophysics Data System (ADS)

Isotropic packings of cohesive disks in 2D are studied by discrete, stress-controlled numerical simulations. Depending on the assembling process and on whether contacts possess rolling resistance (RR), configurations form under low pressure P with varying solid fraction ? and fractal dimension dF describing small scale correlations below some blob size ?. The gradual collapse observed under growing P is described as a linear relation between lnP and 1/? within some range, once the influence of initial conditions has faded out, and until a maximum density is approached. This corresponds to a decrease of ? that is compatible with the fractal blob model. The isotropic tensile strength is always considerably smaller than the naive Rumpf estimate, and grows with consolidation. Coordination numbers in systems with small RR change little while density increases by large amounts in consolidation.

Gilabert, Francisco; Roux, Jean-Noël; Castellanos, Antonio

2009-06-01

203

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

SciTech Connect

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.

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

1982-06-11

204

Dimensional stability and tensile strength of irradiated Nicalon-CG and Hi-Nicalon SiC fibers  

SciTech Connect

Nicalon-CG and Hi-Nicalon fibers were characterized by measuring their length, density, and tensile strength in the unirradiated, thermal annealed, and irradiated conditions. The irradiation was conducted in the EBR-II to a dose of 43 dpa-SiC at a nominal irradiation temperature of 1,000 C. The annealed specimens were held at 1,010 C for 165 days to approximately duplicate the thermal exposure of the irradiated specimens. The results indicate the fibers that perform best in an irradiation environment are those that approach stoichiometric and crystalline SiC. Hi-Nicalon exhibited negligible densification, accompanied by an increase in tensile strength after irradiation. Nicalon-CG possessed a higher tensile strength than hi-Nicalon in the unirradiated condition, but was significantly weakened in the annealed and irradiated conditions. In addition, Nicalon-CG exhibited unacceptable irradiation-induced shrinkage. Loss o fiber tensile strength after irradiation is shown to reduce the flexural strength of irradiated composites and Nicalon-CG fiber shrinkage observed in irradiated composites.

Youngblood, G.E.; Henager, C.H. Jr.; Senor, D.J. [Pacific Northwest National Lab., Richland, WA (United States); Newsome, G.A.; Woods, J.J. [Lockheed Martin, Schenectady, NY (United States)

1997-05-01

205

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

NASA Astrophysics Data System (ADS)

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).

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

2010-03-01

206

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

NASA Astrophysics Data System (ADS)

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.

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

2009-12-01

207

Influence of Welding Parameters on the Tensile Shear Strength of Aluminum Alloy Joint Welded by Resistance Spot Welding  

NASA Astrophysics Data System (ADS)

Aluminum alloy A5052 sheets were welded using the technique of resistance spot welding with cover plates. The effects of welding parameters on the tensile shear strength of the joints were investigated. The results reveal that the technique is feasible to weld aluminum alloy, and that the enhanced electrode force is more effective than the extended down-sloping time for inhibiting pores formation and increasing the strength of the joint.

Qiu, Ranfeng; Zhang, Zhanling; Zhang, Keke; Shi, Hongxin; Ding, Gaojian

2011-04-01

208

Size effects on nominal tensile strength of concrete structures: multifractality of material ligaments and dimensional transition from order to disorder  

Microsoft Academic Search

The nominal tensile strength of concrete structures is constant for relatively large sizes, whereas it decreases with the\\u000a size for relatively small sizes. When, as usually occurs, the experimental investigation does not exceed one order of magnitude\\u000a in the scale range, a unique tangential slope in the bilogarithmic strength versus size diagram is found. On the other hand,\\u000a when the

Alberto Carpinteri; Bernardino Chiaia; Giuseppe Ferro

1995-01-01

209

Predicting tensile strength, hardness and corrosion rate of friction stir welded AA6061-T 6 aluminium alloy joints  

Microsoft Academic Search

AA6061-T6 aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio and good corrosion resistance. The friction stir welding (FSW) process and tool parameters play major role in deciding the joint characteristics. In this research, the tensile strength and hardness along with the corrosion rate of friction-stir-butt welded joints of AA6061-T6

S. Rajakumar; C. Muralidharan; V. Balasubramanian

2011-01-01

210

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

Microsoft Academic Search

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

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

2005-01-01

211

Tensile bond strength of Er,Cr:YSGG laser-irradiated human dentin and analysis of dentin–resin interface  

Microsoft Academic Search

ObjectivesAs the bond strength of composite resin to Er,Cr:YSGG laser-irradiated dentin has not yet been evaluated, the objectives of this study were to investigate the tensile bond strength and to analyze the resin–dentin interface among bur-cut\\/acid-etched, Er,Cr:YSGG laser-ablated\\/acid-etched and Er,Cr:YSGG laser-ablated human dentin.

Bor-Shiunn Lee; Po-Yen Lin; Min-Huey Chen; Tseng-Ting Hsieh; Chun-Pin Lin; Juin-Yih Lai; Wan-Hong Lan

2007-01-01

212

Tensile Strength as a Function of Thermal History of Inconel 718 and Inconel 625 Alloys for Glass-Ceramic Headers.  

National Technical Information Service (NTIS)

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 ...

M. C. Rey W. R. Henderson

1982-01-01

213

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

214

Elastoplastic finite element stress analysis and strength evaluation of adhesive lap joints of hollow shafts subjected to tensile loads  

Microsoft Academic Search

The stress distributions in adhesive lap joints of dissimilar hollow shafts subjected to tensile loads have been analyzed by the elastoplastic finite element method, taking the nonlinear behaviors of the adhesive and the hollow shafts into consideration. A prediction method for the joint strength has been proposed based on the Mises equivalent stress distribution in the adhesive and the frictional

M. Kawawaki; Y. Nakano; T. Sawa

1998-01-01

215

Effects of carbon percentage, Stelmor cooling rate and laying head temperature on tensile strength gain in low carbon steels  

Microsoft Academic Search

Low carbon steel wire rods are used to produce finished products such as fine wire, coat hangers, staples, and roofing nails. These products are subjected to excessively high work hardening rates during wire drawing process resulting in a variation in wire tensile strength. This research analyzes the effects of carbon percentage, StelmorRTM cooling rate and laying head temperature on the

Surya Prakash Gade

2004-01-01

216

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

PubMed Central

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 ?g/kg/day, BPA, 10 ?g/kg/day, EE2, 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 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.

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

2011-01-01

217

Effect of Fiber Strength on the Room Temperature Tensile Properties of Sic/Ti-24Al-11Nb  

NASA Technical Reports Server (NTRS)

SCA-6 SiC fibers of known strength were incorporated into SiC/Ti-24Al-11Nb (at. percent) composites and the effect of fiber strength variability on room temperature composite strength was investigated. Fiber was etched out of a composite fabricated by the powder cloth technique and the effect of the fabrication process on fiber strength was assessed. The strength of the composite was directly correlated with the strength of the as-received fiber. The strength of composite plates containing mixed fiber strengths was dominated by the lower strength fiber. Fabrication by the powder cloth technique resulted in only a slight degradation of fiber strength. The strength of the composite was found to be overestimated by the rule of mixtures strength calculation. Examination of failed tensile specimens revealed periodic fiber cracks and the failure mode was concluded to be cumulative. With the variation in fiber strength eliminated, the composite UTS was found to have a positive correlation with volume fraction of fiber.

Draper, S. L.; Brindley, P. K.; Nathal, M. V.

1991-01-01

218

Numerical investigations on the role of micro-cracks in determining the compressive and tensile strength of rocks  

NASA Astrophysics Data System (ADS)

Bonded particle models implemented using the Discrete Element Method (DEM [1]) have proven a useful numerical laboratory to investigate the interplay between geological structure and mechanical response of rock specimens [4]. However, it is well-known that such bonded particle models fail to reproduce the ratios of compressive:tensile strength of rocks (typically ranging between 10:1 and 50:1). Since this strength ratio is a critical geotechnical engineering design parameter, it is important to resolve this discrepancy between rock and their DEM analogues. To date, the largest compressive:tensile strength ratio achieved in DEM rock analogue models ranges between 10:1 and 12:1 [3]. In said studies, the compressive:tensile strength ratio was found to depend on the number of particle bonds removed from the specimen prior to testing; a modelling analogy for changing the micro-crack density within the specimen. These results are consistent with the popular conjecture that the compressive and tensile strengths of rock are impacted by the opening (or closure) of micro-cracks oriented parallel (or perpendicular) to the loading direction. The current research consists of a rigorous analysis of the role of micro-cracks in governing the compressive:tensile strength ratio of DEM rock specimens. Micro-cracks are geometrically represented as planar surfaces of variable size and orientation. Spherical particles are packed around each planar micro-crack forming a surface that is flat on scales larger than the particle scale. This geometrical approach permits prescription of the sizes and orientations of micro-cracks, as well as the crack density. A series of cylindrical DEM rock specimens are prepared with varying micro-crack densities and orientations. Specimens with either or both micro-cracks sub-parallel to, or sub-perpendicular to the cylinder axis are consided. Each DEM rock specimen is subjected to both a numerical uniaxial compression test and a numerical direct tension test. From these tests, four macroscopic material properties are measured for each specimen: Young's modulus, Poisson's ratio, uniaxial compressive strength and unixial tensile strength. Fracture mechanisms are also examined. Preliminary results indicate that both micro-crack density and micro-crack orientation significantly impact the macroscopic mechanical properties of DEM rock specimens. Quantitative results will be presented at the meeting. The software employed for these experiments is ESyS-Particle [2], an Open Source DEM simulation package for multi-core PCs or supercomputers.

Weatherley, D.; Ayton, T.

2012-04-01

219

Transverse Strength of SCS-6 Silicon Carbide Fibers  

NASA Technical Reports Server (NTRS)

A diametral compression test used to measure the transverse strength of SCS-6 fibers before and after heat treatment. Subjecting fibers to diametral compression successfully produced transverse tensile failure in the form of fiber cracking along the same diametral plane in which the compressive load was applied. An analysis of the hoop stress along the diametral plane, in which the effect of the C core were included, showed that there is a large tensile hoop stress concentration in the SiC sheath at the interface between the C core and the SiC sheath, where the stress is 6.3 times greater than the stress present in a solid SiC fiber under identical loading. This high tensile hoop stress concentration promotes crack initiation near the core and significantly limits the capability of these fibers to withstand transverse compressive loading. The maximum tensile hoop stresses, located at the interface between the C core and SiC sheath, at the measured failure loads were 850 MPa for the as-received SCS-6 fiber and 1210 MPa for fibers exposed to a 1-h heat treatment at 1850 C in 138 Mpa of Ar.

Eldridge, Jeffrey I.; Wiening, Jonathan P.; Davison, Terry S.; Pindera, Marek-Jerzy

1993-01-01

220

Microstructure, hardness profile and tensile strength in welds of AA6013 T6 extrusions  

SciTech Connect

Alloy AA6013 is easily welded by conventional arc welding processes as well as by high-energy-density processes. However, some physical properties, which are inherent to all aluminum alloys, have to be considered during welding. In comparison to steel, the high thermal conductivity of aluminum alloys requires the use of higher heat input for welding. This is realized by a greater welding current during GTAW of aluminum alloys. One of the main problems associated with LBW of aluminum alloys is the high surface reflectivity. In particular, the threshold intensity for the development of a keyhole is much higher for aluminum than for steel. Finally, aluminum alloys, and particularly the heat-treatable alloys, are sensitive to weld cracking. This phenomenon can be avoided by proper filler and base metal alloy selection and adequate filler metal dilution. In order to improve the mechanical integrity of Al-Mg-Si weldments, it would be desirable to study the microstructure of the FZ and of the HAZ, as well as the residual stress distribution. The present study was performed in order to show differences in microstructure, hardness profile and tensile strength of gas tungsten arc (GTA) and laser beam (LB) welded AA6013-T6 extrusions. In addition, grain boundary liquations and hot tearing are discussed.

Guitterez, L.A. [Colorado School of Mines, Golden, CO (United States). Center for Welding and Joining Research; Neye, G.; Zschech, E. [Daimler-Benz Aerospace Airbus GmbH, Bremen (Germany)

1996-04-01

221

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

NASA Astrophysics Data System (ADS)

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.

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

2012-05-01

222

Strength of secondary-cured resin composite inlay repairs.  

PubMed

A study was designed to simulate the repair of an indirect resin composite restoration with conventionally cured resin composite. Two-part specimens were prepared to test the diametral tensile strength of the repair interface between the base material of an indirectly cured resin composite (Herculite XRV) and repairs carried out with three directly cured materials (Herculite XRV, TPH, and Charisma). The repairs were carried out with and without use of the bonding resin for the repair material. The diametral tensile strengths of all repaired specimens were significantly less than those of bulk unrepaired specimens. There were no significant differences between the diametral tensile strengths of repaired blocks when the repair materials were used without bonding resin. The use of an intermediate layer of bonding resin significantly increased the bond strengths obtained when Herculite XRV and TPH were used for repair. There was no significant difference between the strength values of Herculite XRV and TPH, but Charisma exhibited the lowest strengths of repaired specimens. PMID:9477907

Davies, B R; Millar, B J; Wood, D J; Bubb, N L

1997-06-01

223

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

SciTech Connect

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.

Hemanth, J.; Rao, K.V.S. (Siddaganga Inst. of Tech., Karnataka (India). Dept. of Mechanical Engineering)

1999-08-01

224

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

PubMed

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

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

1982-10-01

225

The effect of erbium family laser on tensile bond strength of composite to dentin in comparison with conventional method.  

PubMed

The purpose of this study was to evaluate the effect of Er:YAG and Er,Cr:YSGG laser on tensile bond strength of composite resin to dentine in comparison with bur-prepared cavities. Fifteen extracted caries-free human third molars were selected. The teeth were cut at a level below the occlusal pit and fissure plan and randomly divided into three groups. Five cavities were prepared by diamond bur, five cavities prepared by Er:YAG laser, and the other group prepared by Er,Cr:YSGG laser. Then, all the cavities were restored by composite resin. The teeth were sectioned longitudinally with Isomet and the specimens prepared in dumbbelled shape (n = 36). The samples were attached to special jigs, and the tensile bond strength of the three groups was measured by universal testing machine at a speed of 0.5 mm/min. The results of the three groups were analyzed with one-way ANOVA and Tamhane test. The means and standard deviations of tensile bond strength of bur-cut, Er:YAG laser-ablated, and Er,Cr:YSGG laser-ablated dentine were 5.04 ± 0.93, 13.37 ± 3.87, and 4.85 ± 0.93 MPa, respectively. There is little difference in tensile bond strength of composite resin in Er,Cr:YSGG lased-prepared cavities in comparison with bur-prepared cavities, but the Er:YAG laser group showed higher bond strength than the other groups. PMID:22491942

Shahabi, Sima; Chiniforush, Nasim; Bahramian, Hoda; Monzavi, Abbas; Baghalian, Ali; Kharazifard, Mohammad Javad

2013-01-01

226

The influence of freezing on the tensile strength of tendon grafts : a biomechanical study.  

PubMed

We investigated the influence of freezing on the tensile strength of fresh frozen tendon grafts. The biomechanical characteristics of tendons that are less commonly used in knee surgery (tibialis anterior, tibialis posterior, peroneus longus and medial and lateral half of Achilles tendons) were compared to those of a semitendinosus and gracilis graft harvested from the same 10 multi-organ donors. All right side tendons constituted the study group and were frozen at -80 degrees C and thawed at room temperature 5 times. All left side tendons were frozen at -80 degrees C and thawed at room temperature once. There were 59 tendons in the control group and 56 in the study group. The looped grafts were clamped at one side using a custom-made freeze clamp and loaded until failure on an Instron 4505 testing machine. The average ultimate failure load was not significantly different between the control and the study group (p > 0.05). The failure load of the medial tendon Achilles was the lowest in both study and control group (p < 0.001). There was no significant difference in maximum stress, maximum displacement, maximum strain and stiffness between the control and study group (p > 0.05). From our study, we conclude that freezing tendons at -80 degrees C and thawing several times does not influence the maximum load, maximum stress, maximum displacement, maximum strain and stiffness. The medial half of the Achilles tendon is clearly the weakest tendon (p < 0.001). These findings show that tendon grafts can be frozen at -80 degrees C and thawed at room temperature several times without altering their biomechanical properties. PMID:24205775

Arnout, Nele; Myncke, Jan; Vanlauwe, Johan; Labey, Luc; Lismont, Daniel; Bellemans, Johan

2013-08-01

227

Structural basis of the tensile strength of protein complexes mediating cell adhesion  

NASA Astrophysics Data System (ADS)

This study explores the behaviour of adhesive complexes of cell adhesion molecules undergoing forced detachment. Molecular-forces measurements combined with Steered Molecular Dynamic (SMD) simulations were used to investigate the mechanical response of the CD2 C58 and hemophilic C-cadherin bonds. The CD2-CD58 adhesive complex, important for the adaptive immune response, contains several salt-bridges in the adhesive interface. SMD simulations showed that these inter-protein salt bridges contribute independently to the tensile strength of the complex. Consistent with this, force measurements with the Surface Force Apparatus (SFA) demonstrated that the elimination of single salt bridges weakens the bond. The corresponding loss in adhesion energy of the CD2-CD58 complex correlates with the importance of the salt bridges observed in the simulations. These findings correlate closely with the effect of the elimination of single salt bridges observed in cell aggregation assays and binding measurements. On the other hand, the hemophilic C-cadherin interaction determines specific cell-cell adhesion during development in Xenopus laevis . Single molecule force spectroscopy was used to characterize the multiple bound states between C-cadherin ectodomains. The experiments showed two short-lived bound states associated with the two outermost ectodomains and two long-lived states associated with the full ectodomain. It is likely that the two short-lived states are involved in the specificity of the interaction since previous studies showed that the corresponding states in E-cadherin have different lifetimes. In addition, SMD simulations of the forced dissociation of the strand dieter of C-cadherin suggested a mechanism for the specificity of cadherin interactions.

Bayas, Marco Vinicio

228

Structural safety of coolant channel components under excessively high pressure tube diametral expansion rate at garter spring location  

NASA Astrophysics Data System (ADS)

Structural safety of coolant channel assembly in the event of high diametral expansion of pressure tube in a 220 MWe pressurised heavy water reactor was investigated using axisymmetric and 3-D finite element models. The axisymmetric analyses were performed and stresses were evaluated for pressure tube, girdle wire and calandria tube at different point of time for diametral expansion rates of 0.2%, 0.25% and 0.3% per year of the pressure tube inside diameter. The results of this study indicated that for the case of 0.3% per year of diametral expansion rate (worst case scenario), occurrence of complete circumferential interference of garter spring with calandria tube at the location of maximum expansion would take place much earlier at around 14 years or 4.2% of the total expansion of pressure tube as opposed to its anticipated design life (30 years). This fact was further corroborated by 3-D finite element analysis performed for the actual assembly configuration under actual loadings. The latter analysis revealed that net section yielding of calandria tube occurs in just 1 year after the occurrence of total circumferential interference between calandria tube and garter spring spacer. It has also been observed that the maximum stress intensity in girdle wire does not increase beyond the ultimate tensile strength even when maximum stress intensity in calandria tube reaches its yield strength. These analyses also revealed that the structural as well as functional integrity of pressure tube and the garter spring is not affected as result of this interference.

Aravind, M.; Sinha, S. K.

2013-08-01

229

Tensile bond strength of sealants following Er:YAG laser etching compared to acid etching in permanent teeth.  

PubMed

The aim of this in vitro study was to assess the effect of Er:YAG laser surface treatment on the tensile bond strength of a sealant in permanent teeth. A total of 30 sound third molars were selected and embedded in cold-cure acrylic resin. The enamel surfaces were flattened by a grinding. The teeth were randomly divided into three groups and pretreated as follows: (1) 37% phosphoric acid; (2) Er:YAG laser (1.5 ml/min water spray, 100 mJ energy output, 10 Hz frequency, focal distance 17 mm); (3) Er:YAG laser + 37% phosphoric acid. The treated surfaces were isolated by double adhesive Sellotape and after insertion of a split Teflon matrix at an isolated site, sealant was applied. The specimens were thermocycled and stored at 37°C in distilled water for 72 h, then subjected to a tensile bond strength test (50 kgf at 0.5 mm/min). The mean tensile bond strengths (± SD, in megapascals) were: 18.51 ± 5.68 in group 1, 8.06 ± 2.69 in group 2, and 17.33 ± 5.04 in group 3. Data were submitted to analysis of variance and the Tukey test. No significant difference were found between groups 1 (37% phosphoric acid) and group 3 (Er:YAG laser + 37% phosphoric acid) but treatment with the Er:YAG laser alone (group 2) resulted in significantly lower tensile bond strength than seen in the other groups. In this setting, the Er:YAG laser prepared the enamel surface for sealing but did not eliminate the need for acid etching before sealant application. PMID:21336680

Shahabi, Sima; Bagheri, Hossein G; Ramazani, Kosar

2012-03-01

230

Experimental study on clamping effects on the tensile strength of composite plates with a bolt-filled hole  

Microsoft Academic Search

An experimental study was performed to assess the effects of clamp-up on the net-tension failure of laminated composite plates with bolt-filled holes. Graphite\\/epoxy prepreg of T800\\/3900-2 was selected for fabricating the laminates for the tests. The tensile strength and failure response of specimens with an open hole and a bolt-filled hole were evaluated. Both 100% bypass load (no bolt bearing

Y. Yan; W.-D. Wen; F.-K. Chang; P. Shyprykevich

1999-01-01

231

Influences of process parameters on tensile strength of friction stir welded cast A319 aluminium alloy joints  

Microsoft Academic Search

Fusion welding of cast A319 (Al-Si-Cu) alloy will lead to many problems including porosity, micro-fissuring, and hot cracking.\\u000a Friction Stir Welding (FSW) can be used to weld A319 alloy without these defects. In this investigation, an attempt has been\\u000a made to study the effect of FSW process parameters on the tensile strength of A319 alloy welded joints. Joints were made

M. Jayaraman; R. Sivasubramanian; V. Balasubramanian; S. Babu

2009-01-01

232

Predicting ultimate tensile and bending strengths of three finger-jointed tropical African hardwoods using acoustic emissions  

Microsoft Academic Search

The acoustic emissions behaviour of finger-joints from three tropical African hardwoods, Obeche (Triplochiton scleroxylon), Makore (Tieghemella heckelii) and Moabi (Baillonella toxisperma) were examined with a view to establishing their potential usefulness for non-destructively predicting ultimate tensile and bending strengths. Stress at first acoustic emission event-count as well as the cumulative event-count at 80 percent of mean failure stress and the

J. Ayarkwa; Y. Hirashima; K. Ando; Y. Sasaki

2000-01-01

233

Factors which influence tensile strength of a SiC/Ti-24Al-11Nb (at. pct) composite  

NASA Technical Reports Server (NTRS)

Tensile and fiber pullout tests were used in conjunction with SEM to investigate structural and processing effects on SiC fiber, a neat Ti-24Al-11Nb matrix alloy, and a composite fabricated from the two. The effects of oxygen content, fiber spacing, fiber volume fraction, fiber-matrix reaction thickness, Teflon content, and matrix powder size, appear to be smaller than the effects of variability in fiber strength. Fiber spacing did not influence radial crack formation, interfacial bond shear strength, or stress-strain behavior in the composite. The temperature dependence of composite properties was investigated over the 23-815 C range.

Brindley, P. K.; Draper, S. L.; Nathal, M. V.; Eldridge, J. I.

1990-01-01

234

Simultaneous improvements in the cryogenic tensile strength, ductility and impact strength of epoxy resins by a hyperbranched polymer  

Microsoft Academic Search

Improvements in mechanical properties at low temperatures are desirable for epoxy resins such as diglycidyl ether of bisphenol A (DGEBA) that are often used in cryogenic engineering applications. In this study, a hydroxyl functionalized hyperbranched polymer (H30) is employed to improve the mechanical properties of a DGEBA epoxy resin at liquid nitrogen temperature (77K). The results show that the tensile

Jiao-Ping Yang; Zhen-Kun Chen; Guo Yang; Shao-Yun Fu; Lin Ye

2008-01-01

235

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

SciTech Connect

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.

Jonsen, P.; Haeggblad, H.-A. [Division of Solid Mechanics, Department of Applied Physics and Mechanical Engineering, Luleaa University of Technology, 971 87 Luleaa (Sweden)

2007-05-17

236

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

SciTech Connect

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.

Demirbas, A.; Simsek, T. [Selcuk University, Konya (Turkey)

2006-10-15

237

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

NASA Technical Reports Server (NTRS)

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.

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

2002-01-01

238

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

239

Effects of cross-sectional area on resin-enamel tensile bond strength  

Microsoft Academic Search

Objective.It was hypothesized that there is an inverse relationship between resin-enamel bond strength and bonded cross-sectional area, and that there are regional differences in resin-enamel bond strength.

Yasuo Shono; Masamichi Terashital; Edna L. Pashley; Phyllis D. Brewer; David H. Pashley

1997-01-01

240

On the tensile and shear strength of nano-reinforced composite interfaces  

Microsoft Academic Search

The tensile debonding and shear properties of composite interfaces reinforced by two different homogeneously dispersed nanofillers, carbon nanotubes and alumina nanopowder, are investigated. The composite adherends used are made of carbon fibre\\/epoxy laminate and aluminium alloy 6061-T6. The results reveal that varying the weight percentage of the nanofillers into the epoxy matrix adhesive favourably influences the debonding and shear characteristics

S. A Meguid; Y Sun

2004-01-01

241

Fibronectin Matrix Polymerization Increases the Tensile Strength of a Model Tissue  

Microsoft Academic Search

Abstract The composition and organization of the extracellular matrix (ECM) contribute to the mechanical properties of tissues. The polymerization of fibronectin into the ECM increases actin organization and regulates the composition of the ECM. In this study, we examined the ability of cell-dependent fibronectin matrix polymerization to affect the tensile properties of an established tissue model. Our data indicate that

Candace D. Gildner; Amy L. Lerner; Denise C. Hocking

2004-01-01

242

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

NASA Technical Reports Server (NTRS)

A study was made to determine the relevance of impacter shape to nonvisible damage and tensile residual strength of a 36 mm thick graphite/epoxy motor case. The shapes of the impacters were as follows: 12.7 mm and 25.4 mm diameter hemispheres, a sharp corner, and a 6.3 mm 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 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 and 25.4 mm 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.

Poe, Clarence C., Jr.

1991-01-01

243

First-principles study of He effects in a bcc Fe grain boundary: site preference, segregation and theoretical tensile strength.  

PubMed

We perform a first-principles calculation to investigate the effects of He in an Fe ?5(310)/[001] grain boundary (GB) with the SIESTA code, for which the reliability of the pseudopotential and the basis set are systematically tested. We calculate the formation and segregation energies for different substitutional and interstitial cases in order to determine the site preference and the segregation properties of He in the Fe GB. It is demonstrated that the He segregation either breaks (substitution) or weakens (interstitial) the surrounding interfacial Fe-Fe bonds, leading to the GB tensile strength reduction. PMID:21403193

Zhang, Lei; Shu, Xiaolin; Jin, Shuo; Zhang, Ying; Lu, Guang-Hong

2010-09-22

244

The effects of damage accumulation on the tensile strength and toughness of compact bovine bone.  

PubMed

Damage accumulation in compact bovine femur subjected to uniaxial tensile loading was examined by strong light illumination effects of microcracking. Imaging was done using a high-speed camera capturing image at 200 to 1500FPS. The tensile tests were performed in a multipurpose tensile testing system with cross-head speeds ranging from 0.5 to 10mm/min which leads to strain rates of 0.0001 to 0.0012s(-1) (physiologically relevant to walking and running Hansen et al., 2008). The post-failure images were then examined in a scanning electron microscopy (SEM) and effects of microstructure, strain rate, and orientation were evaluated. Correlation of the high-speed images with stress-strain curves indicated that optically visible microcracks were most likely initiated at yielding, and the specimens with dispersed microcracks exhibited a higher energy-absorption capacity compared to the specimens with coalesced local cracks. It was found that damage accumulation negatively correlates to strain rate and that transverse specimens exhibited a different failure pattern compared to the longitudinal specimens. Strain hardening and softening were found in the longitudinal and transverse specimens respectively. The microcracking in the transverse specimens instantly increased to peak after yielding compared to the gradual growth until failure in the longitudinal specimens. The average Young's modulus (21.5GPa) and ultimate stress (93.5MPa) of the specimens loaded in the longitudinal direction were more than twice that of the specimens (10.9GPa and 36.2MPa respectively) loaded in the transverse direction. The current technique has shown potential in relating damage accumulation real time in bone samples subjected to tensile loading condition. This information will be helpful in relating the role of micro damage accumulation in initiating failure and/or remodeling in bone. PMID:23337851

Zhang, Wei; Tekalur, Srinivasan Arjun; Baumann, Melissa; McCabe, Laura R

2013-03-15

245

On the tensile strength of rivets in thin sheet materials and fibre metal laminates  

Microsoft Academic Search

The low pull-through strength of mechanically fastened joints in composites is well known. The failure mode is frequently by the fastener head pulling through the laminate. Because experimental studies on multi-row joints in fibre metal laminates (ARALL and GLARE) have demonstrated a significant rivet strength reduction due to a similar failure mode, the problem assumes new importance. A pull-through strength

W. J. Slagter

1995-01-01

246

Tensile Strength and Microstructure of Al2O3-ZrO2 Hypo-Eutectic Fibers Studied  

NASA Technical Reports Server (NTRS)

Oxide eutectics offer high-temperature strength retention and creep resistance in oxidizing environments. Al2O3-ZrO2 eutectic strengths have been studied since the 1970's. Directionally solidified oxide eutectics exhibit improved resistance to slow crack growth and excellent strength retention at high temperatures up to 1400 C. Materials studied typically contain Y2O3 to metastably retain the high-temperature cubic and tetragonal polymorphs at room temperature. Al2O3-ZrO2 is of fundamental interest for creep studies because it combines a creep-resistant material, Al2O3, with a very low creep resistance material, ZrO2. Results on mechanical properties and microstructures of these materials will be used to define compositions for creep testing in future work. Substantial variations from the eutectic alumina to zirconia ratio can be tolerated without a loss in room-temperature strength. The effect of increasing Y2O3 addition on the room-temperature tensile strength of an Al2O3-ZrO2 material containing excess Al2O3 was examined at the NASA Glenn Research Center, where the materials were grown using Glenn's world-class laser growth facilities.

Farmer, Serene C.; Sayir, Ali

2001-01-01

247

Influence of core-finishing intervals on tensile strength of cast posts-and-cores luted with zinc phosphate cement.  

PubMed

The core finishing of cast posts-and-cores after luting is routine in dental practice. However, the effects of the vibrations produced by the rotary cutting instruments over the luting cements are not well-documented. This study evaluated the influence of the time intervals that elapsed between the cementation and the core-finishing procedures on the tensile strength of cast posts-and-cores luted with zinc phosphate cement. Forty-eight bovine incisor roots were selected, endodontically treated, and divided into four groups (n = 12): GA, control (without finishing); GB, GC, and GD, subjected to finishing at 20 minutes, 60 minutes, and 24 hours after cementation, respectively. Root canals were molded, and the resin patterns were cast in copper-aluminum alloy. Cast posts-and-cores were luted with zinc phosphate cement, and the core-finishing procedures were applied according to the groups. The tensile tests were performed at a crosshead speed of 0.5 mm/min for all groups, 24 hours after the core-finishing procedures. The data were subjected to one-way analysis of variance (ANOVA) and Tukey's test (? = 0.05). No significant differences were observed in the tensile strengths between the control and experimental groups, regardless of the time interval that elapsed between the luting and finishing steps. Within the limitations of the present study, it was demonstrated that the core-finishing procedures and time intervals that elapsed after luting did not appear to affect the retention of cast posts-and-cores when zinc phosphate cement was used. PMID:22790502

Iglesias, Michele Andrea Lopes; Mesquita, Gabriela Campos; Pereira, Analice Giovani; Dantas, Lucas Costa de Medeiros; Raposo, Luís Henrique Araújo; Soares, Carlos José; Mota, Adérito Soares da

2012-01-01

248

Waiting time for coronal preparation and the influence of different cements on tensile strength of metal posts.  

PubMed

This study aimed to assess the effect of post-cementation waiting time for core preparation of cemented cast posts and cores had on retention in the root canal, using two different luting materials. Sixty extracted human canines were sectioned 16?mm from the root apex. After cast nickel-chromium metal posts and cores were fabricated and luted with zinc phosphate (ZP) cement or resin cement (RC), the specimens were divided into 3 groups (n = 10) according to the waiting time for core preparation: no preparation (control), 15 minutes, or 1 week after the core cementation. At the appropriate time, the specimens were subjected to a tensile load test (0.5?mm/min) until failure. Two-way ANOVA (time versus cement) and the Tukey tests (P < 0.05) showed significantly higher (P < 0.05) tensile strength values for the ZP cement groups than for the RC groups. Core preparation and post-cementation waiting time for core recontouring did not influence the retention strength. ZP was the best material for intraradicular metal post cementation. PMID:22291705

Oliveira, Ilione Kruschewsky Costa Sousa; Arsati, Ynara Bosco de Oliveira Lima; Basting, Roberta Tarkany; França, Fabiana Mantovani Gomes

2012-01-01

249

Waiting Time for Coronal Preparation and the Influence of Different Cements on Tensile Strength of Metal Posts  

PubMed Central

This study aimed to assess the effect of post-cementation waiting time for core preparation of cemented cast posts and cores had on retention in the root canal, using two different luting materials. Sixty extracted human canines were sectioned 16?mm from the root apex. After cast nickel-chromium metal posts and cores were fabricated and luted with zinc phosphate (ZP) cement or resin cement (RC), the specimens were divided into 3 groups (n = 10) according to the waiting time for core preparation: no preparation (control), 15 minutes, or 1 week after the core cementation. At the appropriate time, the specimens were subjected to a tensile load test (0.5?mm/min) until failure. Two-way ANOVA (time versus cement) and the Tukey tests (P < 0.05) showed significantly higher (P < 0.05) tensile strength values for the ZP cement groups than for the RC groups. Core preparation and post-cementation waiting time for core recontouring did not influence the retention strength. ZP was the best material for intraradicular metal post cementation.

Oliveira, Ilione Kruschewsky Costa Sousa; Arsati, Ynara Bosco de Oliveira Lima; Basting, Roberta Tarkany; Franca, Fabiana Mantovani Gomes

2012-01-01

250

Measurement of ultimate tensile strength and Young modulus in LYSO scintillating crystals  

Microsoft Academic Search

Scintillating crystals are employed in high energy physics, in medical imaging, diagnostic and security. Two mechanical properties of lutetium–yttrium oxyorthosilicate cerium-doped Lu2(1?x)Y2xSiO5:Ce with x=0.1 (LYSO) crystals have been measured: the ultimate tensile stress (?UTS) and the Young elastic modulus (E). Measurements are made by means of a 4-points loading device and the experimental results account for an elastic–brittle stress–strain relation,

Lorenzo Scalise; Daniele Rinaldi; Fabrizio Davì; Nicola Paone

2011-01-01

251

Microstructural dependence of fracture energy and toughness of ceramics and ceramic composites versus that of their tensile strengths at 22 °C  

Microsoft Academic Search

The microstructural dependence of fracture energy and toughness of ceramics and ceramic particulate, platelet, and whisker composites is compared with the corresponding dependence of their tensile (flexure) strengths at 22 °C. These comparisons show that fracture energy and toughness often do not have the same porosity, or grainor particle-size dependence as strength. This is attributed to the scale of the

R. W. Rice

1996-01-01

252

Relationship of Tensile and Tear Strengths of Fabrics to Component Yarn Properties.  

National Technical Information Service (NTIS)

The investigation was conducted on six selected fabrics to determine the relationship of breaking load, elongation and tear strength of fabrics to the properties of the component yarns. A system for expressing fabric properties as ratios of the contributi...

C. J. Pope, V. K. Devarakonda

1970-01-01

253

Tensile strength at elevated temperature and its applicability as an accelerated testing methodology for unidirectional composites  

NASA Astrophysics Data System (ADS)

The applicability of a macroscopic time-temperature superposition principle (TTSP) to unidirectional composite strength is discussed based on the microscopic Simultaneous Fiber-Failure (SFF) model that has been presented by Koyanagi et al. (J. Compos. Mater. 43:1901-1914, 2009a). The SFF model estimates composite strengths as functions of fiber, matrix, and interface strengths. This paper first investigates the applicability of SFF to the complicated temperature dependence of composite strengths, i.e., one composite exhibits significant temperature dependence and another does not, considering the temperature dependence of the components, which results in successful estimations for the two composite systems used in the present study. The long-term durability predicted by the SFF and that predicted by the TTSP are then compared. They typically correspond to each other in various cases; accelerated testing methodology (ATM) employing TTSP is thus proved to be valid from the micromechanical viewpoint, assuming the SFF applicability.

Koyanagi, Jun; Nakada, Masayuki; Miyano, Yasushi

2012-02-01

254

Effects of environment and temperature on ceramic tensile strength–grain size relations  

Microsoft Academic Search

Overall strength (s)–grain size (G), i.e. s–G-1\\/2, relations retain the same basic two-branched character to at least 1200–1300°C. However, some polycrystalline as well as single crystal strength shifts or deviations are seen relative to each other, and especially relative to Young's moduli versus temperature for poly- and single crystals. The variety and complexity of these deviations are illustrated mainly by

R. W. RICE

1997-01-01

255

Stress Analysis and Strength Evaluation of Scarf Adhesive Joints with Dissimilar Adherends Subjected to Static Tensile Loadings  

NASA Astrophysics Data System (ADS)

The interface stress distributions in scarf adhesive joints with dissimilar adherends under static tensile loadings are analyzed using two-dimensional and three-dimensional finite element calculations. The effects of the adherends and adhesive Young's modulus, the scarf angle and the adhesive thickness on the interface stress distributions are examined. In addition, the joint strength is predicted using the interface stress distributions based on the maximum principal stress theory. It is found that when the scarf angle is around 60°, the singular stress at the edges of the interfaces is minimum in the 3-Dimensional FEM calculations. Furthermore, it is noticed that the strength of the joints with dissimilar adherends is smaller than that of the joints with similar adherends. For verification of the FEM calculations, the strains in the adherends and the joint strengths were measured in the experiments. The measured strains are in fairly good agreement with those obtained from FEM calculations. Also, the measured joint strength is fairly consistent with the calculated results.

He, Dan; Sawa, Toshiyuki; Karami, Atsushi

256

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

NASA Technical Reports Server (NTRS)

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.

Poe, C. C., Jr.

1990-01-01

257

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

NASA Technical Reports Server (NTRS)

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.

Dreshfield, R. L.; Johnson, W.

1982-01-01

258

Tensile bond strength of a composite resin cement for bonded prosthesis to various dental alloys.  

PubMed

The development of composite resin cements that chemically bond to dental alloys has improved the construction of resin-bonded prostheses. Composite resins can be selected for various situations, but specific clinical situations may require different alloys. This study evaluated the ability of a composite resin cement to bond to various dental alloys of different compositions. Ten pairs of disks for each alloy (two NiCr, two NiCrBe, one CuAl, one gold type IV, and one gold for metal ceramic) were bonded to a composite resin cement after air abrasion was performed with aluminum oxide. The disks were then rinsed in tap water and were ultrasonically cleaned in distilled water for 2 minutes. The tensile tests exhibited greater values for alloys ultrasonically cleaned, and the best results were recorded by NiCr and NiCrBe alloys. PMID:7473275

Rubo, J H; Pegoraro, L F

1995-09-01

259

Residual strength of composite laminates subjected to tensile-compressive fatigue loading  

NASA Technical Reports Server (NTRS)

Results are presented on the measurements of the residual strengths of T300/934 graphite epoxy laminates, in tension and in compression, after the samples were exposed to tension-compression fatigue loading (R = -1). Four laminate ocnfigurations were tested: unidirectional, cross-ply, angle-ply, and quasi-isotropic. It was found that the fatigue behavior of laminates was dependent on the quasi-static strengths and the specific structure of the laminate. No direct correlation was found between remaining residual strengths and the percentage of average fatigue life. However, a correlation scheme was developed for the individual specimen under test, based on a cumulative damage model and a stiffness change of the material.

Rotem, Assa; Nelson, H. G.

1990-01-01

260

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

NASA Technical Reports Server (NTRS)

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.

Poe, C. C., Jr.

1984-01-01

261

Deformation and fracture behavior of notched and unnotched unidirectional C\\/CMg composite with Young's modulus 520 GPa and tensile strength 1 GPa  

Microsoft Academic Search

Experimental study on tensile fracture behavior of the newly developed C\\/C-Mg composite, prepared by infiltration of Mg into the pores in the C\\/C composite heat-treated at 3000°C, was carried out. The volume fraction of the filled Mg was 9–10%. The composite had a specific density 2.1, Young's modulus 520 GPa and Poisson's ratio 0.26. The average tensile strength measured for

S. Ochiai; H. Okuda; N. Suzuki; M. Tanaka; M. Hojo; E. Tsushima

2003-01-01

262

Study on longitudinal tensile properties of SiC f\\/Ti–6Al–4V composites with different interfacial shear strength  

Microsoft Academic Search

Effect of interfacial shear strength on longitudinal tensile properties for SiCf\\/Ti–6Al–4V composites is investigated by Monte Carlo finite element method. A two-parameter Weibull function is employed to describe random distribution of fiber strength. Fiber breakage, matrix cracking and interfacial debonding are simulated by killing the element when stress applied to element exceeds corresponding strength and releasing coupled nodes when shear

J. H. Lou; Y. Q. Yang; Q. Sun; J. Li; X. Luo

2011-01-01

263

Simplified method measures changes in tensile yield strength using least number of specimens  

NASA Technical Reports Server (NTRS)

Simplified method determines yield strength due to heat treat, irradiation or mechanical treatment. Each specimen in a group of specimens is tested for yield stress point, subjected to heat treat or irradiation, and retested for new yield stress point which is a measure of change in material.

Dixon, C. E.

1967-01-01

264

A curved beam test specimen for determining the interlaminar tensile strength of a laminated composite  

NASA Technical Reports Server (NTRS)

A curved beam type of test specimen is evaluated for use in determining the through-the-thickness strength of laminated composites. Two variations of a curved beam specimen configuration (semicircular and elliptical) were tested to failure using static and fatigue loads. The static failure load for the semicircular specimens was found to be highly sensitive to flaw content, with the specimens falling into two distinct groups. This result supports the use of proof testing for structural validation. Static design allowables are derived based on the Weibull distribution. Fatigue data indicates no measured increase in specimen compliance prior to final fracture. All static and fatigue failures at room temperature dry conditions occurred catastrophically. The elliptical specimens demonstrated unusually high failure strengths indicating the presence of phenomena requiring further study. Results are also included for specimens exposed to a wet environment showing a matrix strength degradation due to moisture content. Further testing is underway to evaluate a fatigue methodology for matrix dominated failures based on residual static strength (wearout).

Hiel, Clement C.; Sumich, Mark; Chappell, David P.

1991-01-01

265

A curved beam test specimen for determining the interlaminar tensile strength of a laminated composite  

NASA Technical Reports Server (NTRS)

A curved beam type of test specimen is evaluated for use in determining the through-the-thickness strength of laminated composites. Two variations of a curved beam specimen configuration (semi-circular and elliptical) were tested to failure using static and fatigue loads. The static failure load for the semi-circular specimens was found to be highly sensitive to flaw content, with the specimens falling into two distinct groups. This result supports the use of proof testing for structural validation. Static design allowables are derived based on the Weibull distribution. Fatigue data indicates no measured increase in specimen compliance prior to final fracture. All static and fatigue failures at room temperature dry conditions occurred catastrophically. The elliptical specimens demonstrated unusually high failure strengths indicating the presence of phenomena requiring further study. Results are also included for specimens exposed to a wet environment showing a matrix strength degradation due to moisture content. Further testing is under way to evaluate a fatigue methodology for matrix dominated failures based on residual static strength (wearout).

Hiel, Clement C.; Sumich, Mark; Chappell, David P.

1990-01-01

266

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

NASA Technical Reports Server (NTRS)

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.

Poe, C. C., Jr.

1984-01-01

267

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

NASA Astrophysics Data System (ADS)

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 ?m) 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.

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

2014-04-01

268

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

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

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

2014-04-01

269

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

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.

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

2014-01-01

270

Micro-tensile bond strength of sound and caries-affected primary tooth dentin measured with original designed jig.  

PubMed

To measure the micro-tensile bond strength (MTBS) on sound and caries-affected primary tooth dentin using an original designed jig that was developed for making symmetric and uniformly-sized specimens for the micro-tensile strength testing. The MTBS of dumbbell-shaped specimens and matchstick-shaped specimens were measured. Dumbbell-shaped specimens: The occlusal surfaces of 15 sound primary molars were ground with a water-cooled air turbine using a diamond bur. The adhesive systems and resin-based composites were Clearfil SE Bond and Clearfil AP-X (SE group) and Single Bond and Z250 (SB group). Matchstick-shaped specimens: Sixteen primary molars (5 sound and 11 carious) were used. The occlusal surfaces of sound teeth were ground with a water-cooled air turbine using a diamond bur. Infected dentin was determined by a caries detecting dye solution and removed with a round-shaped steel bur under water-cooling and with a hand instrument. SE was applied. Data was statistically analyzed using ANOVA and Fisher's PLSD at p < 0.05. The MTBSs (MPa) for the dumbbell-shaped specimens were 8.9 +/- 7.0 in the SE group and 10.3 +/- 5.8 in the SB group and that for the matchstick-shaped specimens were 9.0 +/- 6.3 in the sound-SE group and 9.2 +/- 5.8 in the carious-SE group. No significant difference was observed among them. PMID:16211573

Hosoya, Yumiko; Kawada, Eiji; Ushigome, Toshiaki; Oda, Yutaka; Garcia-Godoy, Franklin

2006-05-01

271

Effect of surface treatments on tensile bond strength and on morphology of quartz-fiber posts.  

PubMed

This study evaluated the effect of three post surface treatments on quartz-fiber post (a) retention and (b) morphology. A control group was not treated. Different treatments were performed for the other posts: silanization; etching by hydrofluoric acid 9.5%; sandblasting with 50 microm Al2O3. Two specimens of each group were submitted to a qualitative scanning electron microscopy (SEM) analysis. Remaining specimens were luted in prepared root canals (n = 10) and retentions were determined using a universal testing machine. Retentive post bond strengths were significantly enhanced with any tested post surface pretreatment. The increase in retentive strength was more remarkable in sandblasted and etched posts. Significant changes of post surfaces were SEM observed after different conditioning treatments. PMID:17320710

D'Arcangelo, Camillo; D'Amario, Maurizio; Prosperi, Gianni Domenico; Cinelli, Marco; Giannoni, Mario; Caputi, Sergio

2007-03-01

272

The effect of growth factors on both collagen synthesis and tensile strength of engineered human ligaments.  

PubMed

Growth factors play a central role in the development and remodelling of musculoskeletal tissues. To determine which growth factors optimized in vitro ligament formation and mechanics, a Box-Behnken designed array of varying concentrations of growth factors and ascorbic acid were applied to engineered ligaments and the collagen content and mechanics of the grafts were determined. Increasing the amount of transforming growth factor (TGF) ?1 and insulin-like growth factor (IGF)-1 led to an additive effect on ligament collagen and maximal tensile load (MTL). In contrast, epidermal growth factor (EGF) had a negative effect on both collagen content and MTL. The predicted optimal growth media (50 ?g/ml TGF?, IGF-1, and GDF-7 and 200 ?M ascorbic acid) was then validated in two separate trials: showing a 5.7-fold greater MTL and 5.2-fold more collagen than a minimal media. Notably, the effect of the maximized growth media was scalable such that larger constructs developed the same material properties, but larger MTL. These results show that optimizing the interactions between growth factors and engineered ligament volume results in an engineered ligament of clinically relevant function. PMID:22698725

Hagerty, Paul; Lee, Ann; Calve, Sarah; Lee, Cassandra A; Vidal, Martin; Baar, Keith

2012-09-01

273

Pressure-Sensitivity and Tensile Strength of AN Elastomer at High Strain Rates  

NASA Astrophysics Data System (ADS)

Pressure-shear plate impact experiments have been conducted to study the mechanical response of an elastomer (polyurea) at very high strain rates: 105-106 s-1. Thin samples are cast between two hard steel plates. Longitudinal waves reverberating through the sample are used to determine the slope of the isentrope at compressive stresses greater than, say, 500 MPa-the initial pressure at impact. Shear waves measure the shearing resistance at the pressure attained after the ``ring-up'' of the pressure in the sample is complete. In the current work, release wave experiments and plane wave simulations are used to extend the isentrope into the tensile regime-and ultimately to failure. The previous work is also extended to determine the pressure-sensitivity of the material's shearing resistance at high shearing rates and low pressures. To achieve the latter, the impact configuration is designed so that an unloading longitudinal wave reflected from the rear surface of the target assembly arrives at the sample midway through its loading by the incident shear wave. As a result, the sample is sheared at high strain rates-at both high and low pressure-during a single experiment.

Jiao, T.; Clifton, R. J.; Grunschel, S. E.

2007-12-01

274

Polypropylene-elastomer (TPO) nanocomposites: 2. Room temperature Izod impact strength and tensile properties  

Microsoft Academic Search

Room temperature Izod impact strength was determined for polypropylene (PP)\\/ethylene-co-octene elastomer (EOR) blends and nanocomposites, containing organoclays based on montmorillonite (MMT), at fixed elastomer content of 30 wt% and 0–7 wt% MMT. A ratio of maleated polypropylene, PP-g-MA to organoclay of unity was used as a compatibilizer in the nanocomposites. The organoclay serves to reduce the size of the EOR

Rajkiran R. Tiwari; D. R. Paul

2011-01-01

275

Tensile bond strength to and SEM evaluation of ground and intact enamel surfaces  

Microsoft Academic Search

Objectives: The aim of this study was to evaluate the bonding of four commercially available adhesive systems to ground and intact enamel surfaces.Methods: Extracted human teeth were used to measure the microtensile bond strength to enamel and a field-emission scanning electron microscopy (FE-SEM) was used to observe the bonded interface and the effect of the surface conditioning of each material.

N Kanemura; H Sano; J Tagami

1999-01-01

276

Developing an Empirical Relationship to Predict Tensile Strength of Friction Stir Welded AA2219 Aluminum Alloy  

Microsoft Academic Search

AA2219 aluminum alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring\\u000a a high strength-to-weight ratio and good corrosion resistance. Friction stir welding (FSW) process is an emerging solid state\\u000a joining process in which the material that is being welded does not melt and recast. This process uses a nonconsumable tool\\u000a to generate frictional heat in

K. Elangovan; V. Balasubramanian; S. Babu

2008-01-01

277

Predicting tensile strength of friction stir welded AA6061 aluminium alloy joints by a mathematical model  

Microsoft Academic Search

AA6061 aluminium alloy (Al–Mg–Si alloy) has gathered wide acceptance in the fabrication of light weight structures requiring a high strength-to weight ratio and good corrosion resistance. Compared to the fusion welding processes that are routinely used for joining structural aluminium alloys, friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being

K. Elangovan; V. Balasubramanian; S. Babu

2009-01-01

278

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

NASA Technical Reports Server (NTRS)

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.

Choi, Sung R.; Gyekenyesi, John P.

2001-01-01

279

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)

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.

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

1991-01-01

280

First-principles study of the tensile strength and failure of alpha-Al2O3(0001)\\/Ni(111) interfaces  

Microsoft Academic Search

Tensile strength and failure of Al2O3(0001)\\/Ni(111) interfaces have been examined by the first-principles pseudopotential method, and compared with Al2O3(0001)\\/Cu(111) interfaces, and effects of the interface stoichiometry, configurations, and metal species have been analyzed. From rigid-type tensile tests, the Ni-O interfaces at the O-terminated interfaces are much stronger than the back Ni-Ni interlayers, while the strength of the Ni-Al interfaces at

Siqi Shi; Shingo Tanaka; Masanori Kohyama

2007-01-01

281

Tensile strength and adhesion formation of mesh fixation systems used in laparoscopic incisional hernia repair  

Microsoft Academic Search

Background  Mesh tearoff from the tissue is the most common reason for hernia recurrence after hernia surgery involving the use of a synthetic\\u000a mesh. Various fixation systems were critically compared in terms of their retention strength and the formation of adhesions.\\u000a \\u000a \\u000a \\u000a \\u000a Methods  In a prospective study with 25 Sprague–Dawley rats, two pieces of Parietex composite meshes measuring 2 × 3 cm were fixed\\u000a intraperitoneally in

Christian Hollinsky; Thomas Kolbe; Ingrid Walter; Anja Joachim; Simone Sandberg; Thomas Koch; Thomas Rülicke; Albert Tuchmann

2010-01-01

282

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

PubMed

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

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

1996-01-01

283

Tensile bone strength of Panavia Ex to a Ni-Cr alloy using different surface treatments.  

PubMed

Panavia Ex resin has been claimed to require only air abrasion of the alloy with 50 micrometers aluminum oxide particles to reach acceptable bond strength values. This study discusses the consequences of changes in the type of air abrasion and surface oxidation of the alloy. Thirty pairs of discs of a Ni-Cr alloy were treated by three methods: 1) air abrasion with 50 micrometers aluminum oxide (control); 2) air abrasion with glass beads; 3) air abrasion with a mixture of aluminum oxide and glass beads (ratio 1:1). The Tukey test showed statistical differences only for air abrasion with glass beads. PMID:8688655

Pinto Coelho, C M; Rubo, J H; Pegoraro, L F

1995-01-01

284

Can LigaSure™ be used to perform sleeve gastrectomy? - Tensile strength and histological changes.  

PubMed

Abstract Introduction: LigaSure™ was developed as an alternative to suture ligatures, hemoclips and staplers for ligating vessels and tissue bundles. The aim of the present study was to determine whether LigaSure can be used as a welding instrument in the performance of laparoscopic sleeve gastrectomy. Material and methods: Gastric specimens were assigned into four groups. Group 1 - specimens remained with the staple line intact. Group 2 - the staple line was oversewn. Group 3 - the staple line was resected with LigaSure. Group 4 - staple line was resected with LigaSure and the seal was oversewn. In all specimens the pressure tolerance was assessed using a portable sensor. Results: In group 1 the leak pressure was 34.7 ± 11.7 whereas in group 2 specimens the pressure increased three-fold (101.9 ± 21.4). The LigaSure seal alone (group 3) achieved a mean pressure of 13.7 mmHg. However, in group 4 there was an exponential increase on their burst strength up to 142 mmHg (p = 0.0005). Conclusion: According to our results, LigaSure could be used to perform laparoscopic sleeve gastrectomy with reduction of staple-line bleeding and, when reinforced with a running suture, it achieves a strength that approaches that of staples plus oversewing. PMID:24359311

Lopez, Julio; Vilallonga, Ramon; Targarona, Eduardo M; Balague, Carmen; Enriquez, Lenin; Rivera, Ramon; Balibrea, Jose M; Perez-Ochoa, Francisco; Rodriguez, Karime; Baeza, Miguel; Reyes, Arturo

2014-06-01

285

Tensile bond strength of a resinous cement to a nickel-chromium alloy modified with five surface treatments.  

PubMed

A problem associated with resin-bonded fixed partial dentures is inadvertent dislodgment at the metal/cement interface. It has been suggested that Panavia Ex resinous cement requires only air abrasion of the alloy with 50 microns aluminum oxide particles to record reliable bond strength values. The purpose of this study was to discuss the consequences of changes in the type of air abrasion and surface oxidation of the alloy. Fifty pairs of disks of a Ni-Cr alloy were treated by five methods: (1) air abrasion with 50 microns aluminum oxide (control), (2) air abrasion with 50 microns glass beads, (3) air abrasion with a mixture of aluminum oxide and glass beads (ratio 1:1), (4) air abrasion with aluminum oxide and immersion in acid solution of potassium permanganate, and (5) air abrasion with aluminum oxide and immersion in aqueous solution of potassium permanganate. The disks were cemented to each other with Panavia Ex composite resinous cement and tensile tests were conducted at a crosshead speed of 0.5 mm/ minute. No statistically significant differences were recorded among the treatments for the alloys used in this study except air abrasion with glass beads, which exhibited the lowest bond strength values. PMID:8887795

Coelho, C M; Rubo, J H; Pegoraro, L F

1996-09-01

286

Effects of Polymerization and Briquetting Parameters on the Tensile Strength of Briquettes formed from Coal Coke and Aniline-Formaldehyde Resin  

Microsoft Academic Search

In this work, the utilization of aniline (C6H7N) 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,

Ayhan Demirbas; Tuncay Simsek

2006-01-01

287

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

Microsoft Academic Search

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

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

2003-01-01

288

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

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.

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

1986-01-01

289

Degeneration at the insertion weakens the tensile strength of the supraspinatus tendon: a comparative mechanical and histologic study of the bone-tendon complex.  

PubMed

The purpose of this investigation was to determine the relationship between the degree of degeneration at the supraspinatus insertion, the tensile strength, and the site of failure of this tendon. Thirty-three fresh cadaveric shoulders (average age: 62 years; range: 39-83 years) were examined. A tensile load to failure was applied at a constant crosshead speed of 25.4 mm/min to a 10 mm wide strip of the supraspinatus tendon that remained attached to the bone. Preexisting degenerative changes at the insertion were assessed and scored histologically and compared with the ultimate tensile stress. Twenty tendons failed at the insertion (the insertion group), and 11 failed in the midsubstance (the midsubstance group). The histologic score of degeneration for the insertion group was significantly higher than that for the midsubstance group (p = 0.0026). There was a negative correlation between the ultimate tensile stress at the insertion and the degeneration score for the insertion group (r = -0.60; p = 0.013). Histologic observations revealed that disruptions of tendon fibers were located mostly in the articular half of the tendon and that they enlarged during mechanical testing in 90% of the specimens of the insertion group. It seems that degenerative changes at the supraspinatus insertion reduce the tensile strength of the tendon and constitute a primary pathogenetic factor of rotator cuff tear. PMID:9420602

Sano, H; Ishii, H; Yeadon, A; Backman, D S; Brunet, J A; Uhthoff, H K

1997-09-01

290

Tensile strength and creep behaviour of austenitic stainless steel type 18Cr - 12Ni with niobium additions at 700°C  

NASA Astrophysics Data System (ADS)

The effect of niobium additions up to 2.36 wt% on the creep behavior of a series of seven extra low carbon 18Cr-12Ni austenitic stainless steels at 700°C has been investigated. Grain size and hardness measurements, hot tensile tests and constant stress creep tests from 90 to 180 MPa were carried out for each alloy, in the solution treated condition at 1050, 1200 and 1300°C followed by quench in water. The mechanical behavior at high temperature was related to the amount of NbC precipitation occurring during the tests. Solid solution and intermetallic compound effects were also considered. Creep data analysis was done to determine the parameters of the creep power-law equation dot epsilon = A.?n and the Monkman-Grant relation dot epsilon.tmR = K. Niobium-carbide precipitation in these steels reduces the secondary stage dependence of strain rate with applied stress, resulting in n-values which indicate the possibility of operation of various creep mechanisms. The creep strength during the secondary stage is primarily controlled by the amount of NbC available for precipitation. However, the rupture times increase progressively with niobium content, as the amount of undissolved carbide particles in grain boundaries and the Laves phase precipitation increase.

Sordi, V. L.; Bueno, L. O.

2010-07-01

291

Unique metallic glass formability and ultra-high tensile strength in Al-Ni-Fe-Gd alloys  

SciTech Connect

The metallic glass formability of aluminum-rich Al-Ni-Fe-Gd alloys has been systematically investigated. The critical cooling rate required to form an amorphous state in this system is generally low, and comparable to that of some of the best metallic glass formers, such as Pd-Cu-Si. Amorphous ribbons up to 0.25 mm thick can easily be produced by the single-roller melt-spinning technique. Tensile strengths as high as 1280 MPa and Young's modulus of 75 GPa have been obtained. Bulk amorphous alloys with good mechanical properties are optimized in Al[sub 85]Ni[sub 6]Fe[sub 3]Gd[sub 6]. DSC and DTA studies reveal that the glass formability is unique for Al-based alloys because the reduced glass temperature T[sub rg] for Al-Ni-Fe-Gd can be as low as 0.44. This is much lower than conventional theory would suggest for easy glass forming systems. A mechanism for the unusual glass formability is suggested.

He, Y.; Poon, S.J. (Univ. of Virginia, Charlottesville, VA (United States). Dept. of Physics); Dougherty, G.M.; Shiflet, G.J. (Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science)

1993-02-01

292

The effect of using different rinsing angles on the micro-tensile bond strength of the sealant to the etched enamel  

PubMed Central

Background: Attempts to enhance bond strength of the sealant have been among the most important sides of dental research. Aim: The purpose of the present study was to evaluate the effect of using different rinsing angles on the micro-tensile bond strength of the sealant to the etched enamel. Settings and Design: Experimental study. Materials and Methods: Sixty first-premolars were randomly assigned to six groups based on the rinsing angle applied (15°, 30°, 45°, 60°, 75°, and 90°). Following etching and rinsing, a 4-mm height build up of sealant material was created. Bonded specimens were sectioned into sticks (1 × 1 mm), which were subjected to micro-tensile bond strength, testing at a cross-head speed of 0.5 mm/min. Statistical Analysis Used: The data were analyzed by Kolmogorov-Smirnov and post-hoc Tukey test. Results: The tensile bond strength in specimens rinsed at 90° were statistically higher compared to those rinsed at 15° and 30° (P < 0.05), and increasing the angle from 15° to 90° was correlated with a reduction in the number of specimens with adhesive failures. Conclusions: Rinsing the conditioned enamel surface at 90° may improve the bond strength and retention of the sealant.

Afshar, Hossein; Nakhjavani, Yahya Baradaran; Ahmadi, Rahil

2014-01-01

293

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)

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.

Kalluri, Sreeramesh; Verrilli, Michael J.

2003-01-01

294

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

PubMed Central

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.

Bauer, Georg; Speck, Thomas

2012-01-01

295

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

PubMed Central

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.

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

2013-01-01

296

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

PubMed

This study evaluated the degree of conversion (DC) and ultimate tensile strength (UTS) of dual-cured resin cements heated to 50º 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 25º C or 50º 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 50º C than at 25º C in all curing conditions. No significant difference in UTS was noted between most light-activated groups at 25º C and those at 50º C. VII SC groups showed higher UTS at 50º C than at 25º C (p < 0.05). Increased temperature led to higher DC, but its effects on resin cement UTS depended on the curing condition. PMID:21537644

França, Flávio Álvares; Oliveira, Michele de; Rodrigues, José Augusto; Arrais, César Augusto Galvão

2011-01-01

297

Effect of acid etching duration on tensile bond strength of composite resin bonded to erbium:yttrium–aluminium–garnet laser-prepared dentine. Preliminary study  

Microsoft Academic Search

The purpose of this study was to compare the tensile bond strength of composite resin bonded to erbium:yttrium–aluminium–garnet\\u000a (Er:YAG) laser-prepared dentine after different durations of acid etching. The occlusal third of 68 human third molars was\\u000a removed in order to expose the dentine surface. The teeth were randomly divided into five groups: group B (control group),\\u000a prepared with bur and

M. Chousterman; D. Heysselaer; S. M. Dridi; F. Bayet; B. Misset; L. Lamard; A. Peremans; C. Nyssen-Behets; S. Nammour

2010-01-01

298

The effect of HIPing on the fatigue and tensile strength of a case, porous-coated Co-Cr-Mo alloy.  

PubMed

The process required to sinter porous Co-Cr-Mo alloys results in the formation of substrate porosity through carbide dissolution. Since hot isostatic pressing (HIPing) has been shown to eliminate casting porosity in the Co-Cr-Mo alloy, it is possible that it may be equally effective on pores that are generated from the sintering operation. The effect that HIPing a porous-coated Co-Cr-Mo material has on the fatigue and tensile properties was investigated. Fatigue testing was performed on sintered materials as well as sintered and HIPed materials, both with and without a porous coating. Further, the effect of varying coating thickness on the resulting fatigue strength of sintered and HIPed materials was studied. Light microscopy was performed in order to define the microstructural changes brought about by the various thermal cycles. Scanning electron microscopy was utilized to define the crack initiation process. The fatigue strength of uncoated "as sintered" materials was found to be reduced by 34% relative to the "as cast" condition. The same material that was HIPed revealed a fatigue strength slightly lower than the "as cast" condition. It was found that porous coatings created preferential sites for fatigue crack initiation. However, the presence of the coating did not further reduce the fatigue strength of "as sintered" materials because of the already low strength created by the sintering operation. Materials that were sintered exhibited a lowering in both tensile strength and elongation to failure relative to the "as cast" condition. The HIPing of sintered materials improved both fatigue and tensile properties relative to the "as sintered" condition. PMID:3782180

Georgette, F S; Davidson, J A

1986-10-01

299

Simultaneous enhancement of tensile/compressive strength and ductility of magnesium alloy AZ31 using carbon nanotubes.  

PubMed

AZ31 nanocomposite containing carbon nanotube (CNT) reinforcement was fabricated using solidification processing followed by hot extrusion. The CNT reinforcement was integrated with AZ31 using an Al foil method. The AZ31 nanocomposite exhibited slightly smaller grain and intermetallic particle sizes than monolithic AZ31, reasonable CNT distribution, dominant (10 - 11) texture in the transverse and longitudinal directions unlike monolithic AZ31, and 48% higher hardness than monolithic AZ31. Compared to monolithic AZ31, the AZ31 nanocomposite exhibited higher 0.2%TYS, UTS, tensile failure strain and tensile work of fracture (WOF) (+10%, +17%, +68% and +92%, respectively). Similarly, compared to monolithic AZ31, the AZ31 nanocomposite exhibited higher 0.2%CYS, UCS, average compressive failure strain and compressive WOF (+58%, +3%, +5% and +17%, respectively). Inclusive of crystallographic texture changes, the effect of CNT integration on the enhancement of tensile and compressive properties of AZ31 is investigated in this paper. PMID:20352742

Paramsothy, M; Hassan, S F; Srikanth, N; Gupta, M

2010-02-01

300

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

NASA Technical Reports Server (NTRS)

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.

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

1999-01-01

301

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)

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.

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

2014-05-01

302

Experimental assessments of notch ductility and tensile strength of stainless steel weldments after 120°C neutron irradiation  

Microsoft Academic Search

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

J. R. Hawthorne; B. H. Menke; N. G. Awadalla; K. R. OKula

1986-01-01

303

Tensile strength of the cement-bone interface depends on the amount of bone interdigitated with PMMA cement  

Microsoft Academic Search

An experimental investigation was performed to (1) determine the general mechanical behavior and in particular, the post-yield behavior of the cement-bone interface under tensile loading, (2) determine where interface failure occurs, and (3) determine if the mechanical properties of the interface could be related to the density of bone at the interface and\\/or the amount of cement-bone interdigitation. Seventy-one cement-bone

K. A. Mann; D. C. Ayers; F. W. Werner; R. J. Nicoletta; M. D. Fortino

1997-01-01

304

Self-assembled smooth muscle cell tissue rings exhibit greater tensile strength than cell-seeded fibrin or collagen gel rings  

PubMed Central

In this study, we created self-assembled smooth muscle cell (SMC) tissue rings (comprised entirely of cells and cell-derived matrix; CDM) and compared their structure and material properties with tissue rings created from SMC-seeded fibrin or collagen gels. All tissue rings were cultured statically for 7 days in supplemented growth medium (with ?-amino caproic acid, ascorbic acid, and insulin-transferrin-selenium), prior to uniaxial tensile testing and histology. Self-assembled CDM rings exhibited ultimate tensile strength and stiffness values that were two-fold higher than fibrin gel and collagen gel rings. Tensile testing of CDM, fibrin gel and collagen gel rings treated with deionized water to lyse cells showed little to no change in mechanical properties relative to untreated ring samples, indicating that the ECM dominates the measured ring mechanics. In addition, CDM rings cultured in supplemented growth medium were significantly stronger than CDM rings cultured in standard, unsupplemented growth medium. These results illustrate the potential utility of self-assembled cell rings as model CDM constructs for tissue engineering and biomechanical analysis of ECM material properties.

Adebayo, Olufunmilayo; Gwyther, Tracy A.; Hu, Jason Z.; Billiar, Kristen L.; Rolle, Marsha W.

2012-01-01

305

Self-assembled smooth muscle cell tissue rings exhibit greater tensile strength than cell-seeded fibrin or collagen gel rings.  

PubMed

In this study, we created self-assembled smooth muscle cell (SMC) tissue rings (comprised entirely of cells and cell-derived matrix; CDM) and compared their structure and material properties with tissue rings created from SMC-seeded fibrin or collagen gels. All tissue rings were cultured statically for 7 days in supplemented growth medium (with ?-amino caproic acid, ascorbic acid, and insulin-transferrin-selenium), prior to uniaxial tensile testing and histology. Self-assembled CDM rings exhibited ultimate tensile strength and stiffness values that were two-fold higher than fibrin gel and collagen gel rings. Tensile testing of CDM, fibrin gel and collagen gel rings treated with deionized water to lyse cells showed little to no change in mechanical properties relative to untreated ring samples, indicating that the ECM dominates the measured ring mechanics. In addition, CDM rings cultured in supplemented growth medium were significantly stronger than CDM rings cultured in standard, unsupplemented growth medium. These results illustrate the potential utility of self-assembled cell rings as model CDM constructs for tissue engineering and biomechanical analysis of ECM material properties. PMID:22865465

Adebayo, Olufunmilayo; Hookway, Tracy A; Hu, Jason Z; Billiar, Kristen L; Rolle, Marsha W

2013-02-01

306

Strength properties of glued laminated timber made from edge-glued laminae II: bending, tensile, and compressive strength of glued laminated timber  

Microsoft Academic Search

The purpose of this study was to investigate the strength properties of glued laminated timber composed of edge-glued laminae\\u000a and to investigate the influence of edge gluing on the strength properties. Glued laminated timber composed of multiple-grade\\u000a laminae (symmetrical composition, strength grade E95-F270, 10 laminations) was produced from karamatsu (Larix kaempferi) edge-glued laminae according to the Japanese Agricultural Standard. The

Yasushi Hiramatsu; Kiyohiko Fujimoto; Atsushi Miyatake; Kenta Shindo; Hirofumi Nagao; Hideo Kato; Hirofumi Ido

2011-01-01

307

Biphasic calcium phosphate loading on polycaprolactone/poly(lacto-co-glycolic acid) membranes for improved tensile strength, in vitro biocompatibility, and in vivo tissue regeneration.  

PubMed

Electrospun polycaprolactone and poly(lacto-co-glycolide) membranes were loaded with biphasic calcium phosphate powder to facilitate osteoconductivity. Different concentrations of biphasic calcium phosphate powder were added to the polymer solution, and successful loading was confirmed by X-ray diffraction analysis, transmission electron microscope, and scanning electron microscope with energy-dispersive spectroscopy visualization. The effect of the added biphasic calcium phosphate on the polymer membrane was investigated in terms of the material's tensile strength and strain, in vitro cytocompatibility, and in vivo tissue regeneration. It was observed that the tensile strength of the membranes increased with the addition of the biphasic calcium phosphate powder. Immersion in simulated body fluid solution for seven days leads to the formation of apatite-like deposits in the fibers, which further improved the mechanical stability. Moreover, proliferation and adhesion of osteoblast-like cells were more apparent upon the addition of the biphasic calcium phosphate powder as seen with the increasing cell density from (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay and micrographs from scanning electron microscope and confocal microscopy. Sample membranes were also implanted to investigate the membrane's ability to regenerate bone in a rat calvarium. Histological staining and micro-CT histomorphometric analyses showed neo-bone formation in the implanted rat skull. PMID:24014247

Franco, Rose Ann; Sadiasa, Alexander; Seo, Hyung Seok; Lee, Byong-Taek

2014-04-01

308

Compatibilization by homopolymer: significant improvements in the modulus and tensile strength of PPC/PMMA blends by the addition of a small amount of PVAc.  

PubMed

Poly(propylene carbonate) (PPC), a polymer produced from CO2, has been melt-mixed with 30 wt % poly(methyl methacrylate) (PMMA) with the aim of enhancing the physical properties of PPC for practical use but keeping a relatively high CO2 fixing rate in the compound. The observation of a coarse phase structure with a large PMMA domain size and a large size distribution in the blend indicates the immiscibility between PPC and PMMA. The addition of a small amount of poly(vinyl acetate) (PVAc) not only shifts the glass transition temperatures (T(g)'s) of both PPC and PMMA markedly but also significantly increases the modulus and tensile strength of the blend. The prepared compound with 5 per hundred parts of resin PVAc shows a 26 times higher elastic modulus and an approximately 3.8 times higher tensile strength than pure PPC at room temperature. The morphological investigation indicates that the incorporation to PVAC not only induces the finer dispersion of PMMA in the PPC matrix but also results in the phase transformation from a sea-island to a co-continuous structure. PMID:20355779

Li, Yongjin; Shimizu, Hiroshi

2009-08-01

309

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

SciTech Connect

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.

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

2003-07-29

310

Effect on the tensile strength of human acellular dermis (Epiflex(R)) of in-vitro incubation simulating an open abdomen setting  

PubMed Central

Background The use of human acellular dermis (hAD) to close open abdomen in the treatment process of severe peritonitis might be an alternative to standard care. This paper describes an investigation of the effects of fluids simulating an open abdomen environment on the biomechanical properties of Epiflex® a cell-free human dermis transplant. Methods hAD was incubated in Ringers solution, blood, urine, upper gastrointestinal (upper GI) secretion and a peritonitis-like bacterial solution in-vitro for 3 weeks. At day 0, 7, 14 and 21 breaking strength was measured, tensile strength was calculated and standard fluorescence microscopy was performed. Results hAD incubated in all five of the five fluids showed a decrease in mean breaking strength at day 21 when compared to day 0. However, upper GI secretion was the only incubation fluid that significantly reduced the mechanical strength of Epiflex after 21days of incubation when compared to incubation in Ringer’s solution. Conclusion hAD may be a suitable material for closure of the open abdomen in the absence of upper GI leakage and pancreatic fistulae.

2014-01-01

311

A die pressing test for the estimation of agglomerate strength  

SciTech Connect

A die pressing test was developed for quick and inexpensive estimation of the agglomerate strength of ceramic powders. The critical nominal pressure (p[sub c]) at which contact areas between agglomerates start to increase rapidly was found from the relationship between change in sample height and applied pressure in uniaxial single-ended die pressing. A quantitative microscopic method was used for measuring the area fraction ([psi]) of agglomerates which transmits the force through the assembly. A die pressing agglomerate strength, [sigma][sub d], is defined as [sigma][sub d] = 0.7 p[sub c]/[Psi]. This strength was compared with the agglomerate tensile strength obtained from single agglomerate diametral compression tests and found to be 50% higher than the latter because of multipoint loading. A suggested guideline is that the mean agglomerate tensile strength is approximately 52% of p[sub c] determined in a die pressing test for spherical agglomerates. In addition to agglomerate tensile strength, the mean agglomerate size, the interior macropore structure of agglomerates, as well as the packing efficiencies between and inside agglomerates can be estimated by the procedure.

Song, Jia Hua; Evans, J.R.G. (Brunel Univ., Uxbridge (United Kingdom). Dept. of Materials Technology)

1994-03-01

312

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)

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 (37°C/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.

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

2005-03-01

313

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

USGS Publications Warehouse

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.

Fournier, R. O.

1996-01-01

314

Mechanical strength and stability of lithium aluminate  

NASA Astrophysics Data System (ADS)

Pacific Northwest Laboratory (PNL) investigated the strength and resistance to thermal shock of lithium aluminate annular pellets. The room temperature, axial compressive fracture strength of pellets made at Westinghouse Advanced Energy Systems (WAES) varied from 80 to 133 ksi. The strength at 430 C (806 F) was to 30 to 40 percent lower. The strength at 900 C (1652 F) showed a wide variation with one measurement near 90 ksi. These strength values are consistent with other data and predictions made in the literature when the grain size and porosity of the microstructure are taken into account. In diametral compression tests, the fracture strengths were much lower due to the existence of tensile stresses in some pellet regions from this type of loading. However, the fracture stresses were still generally higher than those reported in the literature; this fracture resistance probably reflects the better quality of the pellets tested in this study. Measurements on pellets made at PNL indicated lower strengths compared to the WAES material. This strength difference could be accounted for by different processing technologies: material made at PNL was cold-pressed and sintered with high porosity whereas the WAES material was isostatically hot-pressed with high density. Thermal shocking of the material by ramping to 900 C in two minutes did not have an observable effect on the microstructure or the strength of any of the pellets.

Brimhall, J. L.

1992-06-01

315

Experimental Tests on Tubular Bonded Butt Specimens: Effect of Relief Grooves on Tensile Strength of the Adhesive  

Microsoft Academic Search

This paper investigates experimentally a tubular bonded butt specimen with relief grooves carved close to the adherend-adhesive interface. The specimen is used to assess the strength of a thin adhesive layer, as usually occurs in structural bonded joints. Hence, this configuration overcomes the problems related to the differences in chemical and mechanical properties which could occur in bulk adhesive tests.

A. Spaggiari; D. Castagnetti; E. Dragoni

2012-01-01

316

Effect of metal as part of fillet on the tensile shear strength of adhesively bonded single lap joints  

Microsoft Academic Search

The effect of fillet containing metallic components on the strength of adhesively bonded single lap joints has been undertaken by alternating the shape and size of metallic components as a part of fillet or whole fillet at the end of the joints. Mild carbon steel and epoxy structural adhesive were used to prepare single lap-shear joints. Three types of steel

Min You; Yong Zheng; Xiao-Ling Zheng; Wen-Jun Liu

2003-01-01

317

Prediction of tensile strength of friction stir welded aluminium matrix TiC p particulate reinforced composite  

Microsoft Academic Search

The usage of particulate reinforced metal matrix composite (MMC) is steadily increasing due to its properties such as high specific strength, high specific modulus and good wear resistance. Aluminium matrix composite (AMC) plays an important role to meet the above requirements. Effective utilization of AMC is based on not only its production but also on fabrication methods. Among AMCs, those

S. Gopalakrishnan; N. Murugan

2011-01-01

318

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

NASA Technical Reports Server (NTRS)

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.

Choi, Sung R.; Gyekenyesi, John P.

2001-01-01

319

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

NASA Technical Reports Server (NTRS)

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.

Yun, Hee Mann; DiCarlo, James A.

1997-01-01

320

Investigation of the C-ring test for measuring hoop tensile strength of nuclear grade ceramic composites  

NASA Astrophysics Data System (ADS)

Silicon carbide (SiC) and silicon carbide fiber reinforced composites (SiC/SiCf) are currently being evaluated as a high temperature material for use in nuclear reactors. While methods to determine the mechanical properties of SiC/SiCf on planar test specimens are well established, mechanical testing methods for tubular SiC/SiCf are still being developed. In this study the C-ring test is evaluated for use with nuclear grade SiC/SiCf as a method of measuring hoop strength. For the samples tested in this work, hoop strengths from C-ring testing are shown to agree within 6% to those obtained using expanding plug testing and analysis shows that the expected composite behavior is observed during testing. While other techniques may give more accurate values for hoop stress, the small specimen requirements and ease of testing makes C-ring testing a valuable tool.

Jacobsen, G. M.; Stone, J. D.; Khalifa, H. E.; Deck, C. P.; Back, C. A.

2014-09-01

321

The microstructure, hardness and tensile properties of a new super high strength aluminum alloy with Zr addition  

Microsoft Academic Search

This research is based on the addition of zirconium to a new super high strength Al–12.24Zn–3.25Mg–2.46Cu alloy. The results showed that Zr addition decreases average grain size (approximately 20%), forms rosette-like microstructure and introduces proper distribution of the second phases. In addition, due to the presence of Al3Zr particles in Zr-refined specimen, the area fraction of recrystallized regions decreased by

S. H. Seyed Ebrahimi; M. Emamy; N. Pourkia; H. R. Lashgari

2010-01-01

322

Effects of build orientation on tensile strength for stereolithography-manufactured ASTM D-638 type I specimens  

Microsoft Academic Search

A statistical design of experiments (DOE) approach was used to determine if specific build orientation parameters impacted\\u000a mechanical strength of stereolithography (SL) fabricated parts. A single platform (25.4 × 25.4-cm cross-section) on the 3D\\u000a Systems Viper si2 SL machine was designed to hold 18 ASTM D-638 type I samples manufactured in different orientations. The\\u000a DOE tested three factors: axis, layout,

Rolando Quintana; Jae-Won Choi; Karina Puebla; Ryan Wicker

2010-01-01

323

Temporal changes in the tensile strength of ultra-high-molecular-weight polyethylene cable embedded in muscle tissue  

Microsoft Academic Search

BackgroundWires and cables have been used extensively for spinal sublaminar wiring, but damages to the spinal cord due to compression by metal wires have been reported. We have used more flexible ultra-high-molecular-weight polyethylene cable (Tekmilon tape) instead of metal wires since 1999 and have obtained good clinical outcomes. Although the initial strength of Tekmilon tape is equivalent to metal wires,

Hiroaki Matsumori; Yurito Ueda; Munehisa Koizumi; Kiyoshi Miyazaki; Hideki Shigematsu; Nobuhisa Satoh; Takuya Oshima; Masato Tanaka; Yasuhito Tanaka; Yoshinori Takakura

2010-01-01

324

Differences of tensile strength distributions between mechanically high-grade and low-grade Japanese larch lumber III: effect of knot restriction on the strength of lumber  

Microsoft Academic Search

It is well known that the presence of knots in structural lumber is one of the most important strengthreducing factors. For\\u000a practical purposes, visual grading including knot restriction is an effective method for nondestructive evaluation of strength.\\u000a Edge knot restriction for not only visually graded lumbers but also mechanically graded lumbers is specified in the Japanese\\u000a agricultural standards for glued

Takashi Takeda; Takeo Hashizume

2000-01-01

325

Comparative Evaluation of Tensile Bond Strength between Silicon Soft Liners and Processed Denture Base Resin Conditioned by Three Modes of Surface Treatment: An Invitro Study.  

PubMed

Soft denture liners act as a cushion for the denture bearing mucosa through even distribution of functional load, avoiding local stress concentrations and improving retention of dentures there by providing comfort to the patient. The objective of the present study was to compare and evaluate the tensile bond strengths of silicone-based soft lining materials (Ufi Gel P and GC Reline soft) with different surface pre treatments of heat cure PMMA denture base acrylic resin. Stainless steel dies measuring 40 mm in length; 10 mm in width and 10 mm in height (40 × 10 × 10) were machined to prepare standardized for the polymethyl methacrylate resin blocks. Stainless steel dies (spacer for resilient liner) measuring 3 mm thick; 10 mm long and 10 mm wide were prepared as spacers to ensure uniformity of the soft liner being tested. Two types of Addition silicone-based soft lining materials (room temperature polymerised soft lining materials (RTPSLM): Ufi Gel P and GC Reline soft) were selected. Ufi Gel P (VOCO, Germany), GC Reline soft (GC America) are resilient, chairside vinyl polysiloxane denture reliners of two different manufacturers. A total of 80 test samples were prepared of which 40 specimens were prepared for Group A (Ufi Gel P) and 40 specimens for Group B (GC Reline soft). In these groups, based on Pre-treatment of acrylic resin specimens each group was subdivided into four sub groups of 10 samples each. Sub-group I-without any surface treatment. Sub-group II-sand blasted Sub-group III-treated with Methyl Methacrylate monomer Sub-group IV-treated with chemical etchant Acetone. The results were statistically analysed by Kruscal Wallis test, Mann-Whitney U test, and Independent t test. The specimens treated with MMA monomer wetting showed superior and significant bond strength than those obtained by other surface treatments. The samples belonging to subgroups of GC Reline soft exhibit superior tensile bond strength than subgroups of Ufi Gel P. The modes of failure of all specimens were mostly adhesive in nature. Surface pre treatments by chemical means improved the bond strength between the silicone liners and denture base. PMID:24431747

Surapaneni, Hemchand; Ariga, Padma; Haribabu, R; Ravi Shankar, Y; Kumar, V H C; Attili, Sirisha

2013-09-01

326

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)

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).

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

2011-07-01

327

Elevated temperature tensile properties of borated 304 stainless steel: Effect of boride dispersion on strength and ductility  

SciTech Connect

This paper has documented the increase in strain to fracture and yield strength obtained with Grade A versions of types 304B5 and 304B7 relative to their respective Grade B, counterparts. The apparent microstructural reason for these property increases is the finer dispersion of boride in the Grade A material, obtained by means of a Powder Metallurgy process, relative to the conventional Grade B material which is produced using an Ingot Metallurgy process. The area size distribution of borides can be well approximated using a log-normal distribution, with the largest boride particles in the Grade B material having areas in the range of 450--600 {mu}m{sup 2}. By comparison, the largest boride particles in the Grade A material have areas nearly an order of magnitude smaller than the largest particles in their Grade B counterparts. A Section III ASME B&PV code case inquiry has been initiated for non-welded versions of 304B4A, 3045A and 3046A ,material.

Stephens, J.J.; Sorenson, K.B.; McConnell, P.

1991-12-31

328

Effects of mechanical and thermal load cycling on micro tensile bond strength of clearfil SE bond to superficial dentin  

PubMed Central

Background: Certain studies have been conducted on the effects of mechanical and thermal load cycling on the microtensile bond strength (microTBS) of composites to dentin, but the results were different. The authors therefore decided to evaluate these effects on the bonding of Clearfil SE bond to superficial dentin. Materials and Methods: Flat dentinal surface of 42 molar teeth were bonded to Filtek-Z250 resin composite by Clearfil SE bond. The teeth were randomly divided into 7 groups and exposed to different mechanical and thermal load cycling. Thermocycling was at 5-55°C and mechanical load cycling was created with a force of 125 N and 0.5 Hz. Then, the teeth were sectioned and shaped to hour glass form and subjected to microTBS testing at a speed of 0.5 mm/min. The results were statistically analyzed by computer with three-way analysis of variance and T-test at P < 0.05 significant. To evaluate the location and mode of failure, the specimens were observed under the stereomicroscope. Then, one of the specimens in each group was evaluated under Scanning Electron Microscopy (SEM) for mode of failure. Results: All of the study groups had a significantly lower microTBS as compared to the control group (P < 0.001). There was no statistically significant difference between mechanical cycling with 50K (kilo = 1000) cycles, and 50K mechanical cycles plus 1K thermal cycles. Most of the fractures in the control group were of adhesive type and this type of fracture increased after exposure to mechanical and thermal load cycling. Conclusion: Thermal and mechanical load cycling had significant negative effects on microTBS and the significant effects of mechanical load cycling started to be significant at 100K cycles.

Daneshkazemi, Ali Reza; Davari, Abdol Rahim; Ataei, Ebrahim; Dastjerdi, Fariba; Hajighasemi, Ehsan

2013-01-01

329

Studies on mechanical strength, thermal expansion of layering porcelains to alumina and zirconia ceramic core materials.  

PubMed

The aim of this study was to evaluate and clarify the various mechanical properties and behavior of layering porcelains (Tokuyama Dental Ceramic, IPS Empress 2, Cerabien, Vitadura, Creation) used for veneering high-strength ceramic core materials. The layering porcelains studied exhibited the following range of mechanical properties: compressive strength at 586-1091 MPa, bending strength at 30-97 MPa, diametral tensile strength at 16-28 MPa, Vickers hardness at 481-647 Hv, and fracture toughness at 1.36-2.05 MPa x m1/2. Results of this study indicated that the mechanical shortcomings of conventional porcelain, such as brittleness and hardness, have been overcome by the enhanced mechanical properties of layering porcelain, resulting in improved fracture toughness. PMID:19662735

Shijo, Yoshitaka; Shinya, Akikazu; Gomi, Harunori; Lassila, Lippo V J; Vallittu, Pekka K; Shinya, Akiyoshi

2009-05-01

330

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

PubMed

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 (200 mJ, VSP, 20 Hz). 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 (3 M 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

Jiang, Qianzhou; Chen, Minle; Ding, Jiangfeng

2013-12-01

331

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

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.

Honig, A.

1995-12-15

332

Simultaneous determination of the impurity and radial tensile strength of reduced glutathione tablets by a high selective NIR-PLS method  

NASA Astrophysics Data System (ADS)

This paper establishes a high-throughput and high selective method to determine the impurity named oxidized glutathione (GSSG) and radial tensile strength (RTS) of reduced glutathione (GSH) tablets based on near infrared (NIR) spectroscopy and partial least squares (PLS). In order to build and evaluate the calibration models, the NIR diffuse reflectance spectra (DRS) and transmittance spectra (TS) for 330 GSH tablets were accurately measured by using the optimized parameter values. For analyzing GSSG or RTS of GSH tablets, the NIR-DRS or NIR-TS were selected, subdivided reasonably into calibration and prediction sets, and processed appropriately with chemometric techniques. After selecting spectral sub-ranges and neglecting spectrum outliers, the PLS calibration models were built and the factor numbers were optimized. Then, the PLS models were evaluated by the root mean square errors of calibration (RMSEC), cross-validation (RMSECV) and prediction (RMSEP), and by the correlation coefficients of calibration (Rc) and prediction (Rp). The results indicate that the proposed models have good performances. It is thus clear that the NIR-PLS can simultaneously, selectively, nondestructively and rapidly analyze the GSSG and RTS of GSH tablets, although the contents of GSSG impurity were quite low while those of GSH active pharmaceutical ingredient (API) quite high. This strategy can be an important complement to the common NIR methods used in the on-line analysis of API in pharmaceutical preparations. And this work expands the NIR applications in the high-throughput and extraordinarily selective analysis.

Li, Juan; Jiang, Yue; Fan, Qi; Chen, Yang; Wu, Ruanqi

333

Effect of Stand-Off Height on Microstructure and Tensile Strength of the Cu/Sn9Zn/Cu Solder Joint  

NASA Astrophysics Data System (ADS)

To investigate the effect of stand-off height (SOH) on the microstructure and mechanical behavior of certain solder joints, Cu/Sn9Zn/Cu solder joints with a SOH of 100 ?m, 50 ?m, 20 ?m, and 10 ?m were prepared and studied. It was found that, as the SOH is reduced, the Zn content in the solder bulk experiences a rapid decrease due to consumption by metallurgical reaction in the reflow process; hence, the microstructure of the solder bulk is changed significantly from a Sn-Zn eutectic structure to a hypoeutectic structure. By contrast, Cu content in the solder bulk experiences a rapid increase with reducing SOH, and this leads to more dissociative intermetallic compounds (IMCs) in the solder bulk. These compositional and microstructural changes induced by reducing the SOH correlate closely with the mechanical properties of the solder joints. In our study it is found that, as SOH is reduced, the tensile strength of the solder joints decreases, the fracture path of the solder joint transfers from the solder bulk into the interface between the IMC layer and the solder bulk, and the fracture mode tends to change from ductile to brittle. These findings point to a probable way to improve the mechanical properties of miniaturized solder joints by controlling the composition and dissociative IMCs in the solder bulk.

Wu, Fengshun; Wang, Bo; Du, Bin; An, Bing; Wu, Yiping

2009-06-01

334

Synthesis, characterization and tensile strength of CVI C/SiC, SiC/SiC, SiC/B4C, and C/B4C composites  

SciTech Connect

CVD of carbon (derived from two different precursors) on SiC and B4C matrices has been employed to yield single-strand unidirectional composites. The tensile strength of carbon deposited via pyrolysis of propylene was higher than that of methane pyrolysis-deposited carbon matrices. A novel CVD boron-carbon interface has also been developed which does not degrade carbon yarns and yields composites exhibiting high strengths; these strength levels were, moreover, highly resistant to long-duration, high-temperature annealing. Coated fibers and composites have been characterized by SEM and XRD. 8 refs.

Kmetz, M.A.; Laliberte, J.M.; Suib, S.L.; Galasso, F.S.

1992-10-01

335

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

PubMed

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 (?TS) 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 ?TS 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 ?TS 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

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

2011-01-01

336

Prodrug and antedrug: Two diametrical approaches in designing safer drugs  

Microsoft Academic Search

The prodrug and antedrug concepts, which were developed to overcome the physical and pharmacological shortcomings of various\\u000a therapeutic classes of agents, employ diametrically different metabolic transformations. The prodrug undergoes a predictable\\u000a metabolic activation prior to exhibiting its pharmacological effects in a target tissue while the antedrug undergoes metabolic\\u000a deactivation in the systemic circulation upon leaving a target tissue. An increased

Henry J. Lee; John S. Cooperwood; Zhengqing You; Dong-Hoon Ko

2002-01-01

337

Quantification of the Existence Ratio of Non-Adhesion Grain Boundaries and Factors Governing the Strength of Coke Containing Low-Quality Coal  

NASA Astrophysics Data System (ADS)

“Non-adhesion grain boundaries” are formed when low-quality coal grains do not adhere to other grains in the carbonization process because of the low dilation of coke. To better understand the effects of non-adhesion grain boundaries on coke strength, the relationship between the existence ratio of non-adhesion grain boundaries and coke strength was investigated quantitatively. The existence ratio of non-adhesion grain boundaries were measured quantitatively by observing the fracture cross-section of coke using scanning electron microscopy (SEM). Coke strength was measured with a diametral-compression test and an I-shape drum index test. As a result, non-adhesion grain boundaries increased with an increase in the blending ratio of low-quality coal. In particular, non-adhesion grain boundaries increased rapidly when the blending ratio of low-quality coal was over 50%. When the ratio was less than 50%, low-quality coals adhered to other caking coal. However, not many low-quality coals adhered to other caking coals when the ratio was over 50%. The tensile strength of coke was not affected by the porosity of coke. However, the tensile strength and the drum index were affected by the existence ratio of non-adhesion grain boundaries. Tensile strength decreased rapidly even for a few non-adhesion grain boundaries because significant defects caused a fracture in the diametral-compression test. However, the I-shape drum index decreased linearly with the existence ratio of the non-adhesion grain boundaries because many fractures occurred during 600 rotations in the drum. The strength of coke containing low-quality coal is governed by the existence ratio of non-adhesion grain boundaries rather than mean values such as the porosity of coke.

Kanai, Tetsuya; Yamazaki, Yoshiaki; Zhang, Xiaoqing; Uchida, Ataru; Saito, Yasuhiro; Shoji, Masakazu; Aoki, Hideyuki; Nomura, Seiji; Kubota, Yukihiro; Hayashizaki, Hideyuki; Miyashita, Shigeto

338

The effect of air abrasion of metal implant abutments on the tensile bond strength of three luting agents used to cement implant superstructures: an in vitro study.  

PubMed

Purpose: To assess the effect of airborne particle abrasion of metal implant abutments on tensile bond strength (TBS) of TempBond, Retrieve, and Premier implant cements. Materials and Methods: Specimens were designed to replicate a single metal implant crown cemented to both smooth and airborne particle-abraded Osteo-Ti implant abutments with zero degrees of taper. Twenty castings were fabricated and cemented to either a smooth surface abutment (SSA) or to an airborne particle-abraded abutment (AAA). TBS was measured with a 50-kg load and a crosshead speed of 0.5 cm/min in a universal testing machine. Each cement was tested 10 times on both abutment types. Results: The mean TBS values (standard deviations, 95% confidence intervals) of SSAs for TempBond, Retrieve, and Premier cements were 115.89 N (26.44, 96.98-134.81), 134.43 N (36.95, 108.25-160.60), and 132.51 N (55.10, 93.09-171.93), respectively. The corresponding values for AAAs were 129.69 N (30.39, 107.95-151.43), 298.67 N (80.36, 241.19-356.16), and 361.17 N (133.23, 265.86-456.48), respectively. There was no significant difference in TBS among the dental cements when used with an SSA. Air abrasion of abutments did not increase the TBS of TempBond but significantly increased crown retention with Retrieve and Premier. For SSAs, all failures were adhesive on the abutment surface; for AAAs, mostly cohesive cement failures occurred. Conclusion: The retention of copings cemented with Retrieve or Premier to zero-degree-taper abutments was significantly increased after airborne particle abrasion of the abutments. However, this was not significant when TempBond was used. Airborne particle abrasion of abutments and the use of Retrieve or Premier can be recommended for nonretrievable prostheses. Although TempBond functioned similarly to the two other cements in SSAs, it is advisable to limit its use to provisional prostheses; its long-term performance needs to be assessed clinically. PMID:25032757

Jugdev, Jasvinder; Borzabadi-Farahani, Ali; Lynch, Edward

2014-01-01

339

Tensile properties of impact ices  

NASA Technical Reports Server (NTRS)

A special test apparatus was developed to measure the tensile strength of impact ices perpendicular to the direction of growth. The apparatus consists of a split tube carefully machined to minimize the effect of the joint on impact ice strength. The tube is supported in the wind tunnel by two carefully aligned bearings. During accretion the tube is turned slowly in the icing cloud to form a uniform coating of ice on the split tube specimen. The two halves of the split tube are secured firmly by a longitudinal bolt to prevent relative motion between the two halves during ice accretion and handling. Tensile test strength results for a variety of icing conditions were obtained. Both glaze and rime ice conditions were investigated. In general, the tensile strength of impact ice was significantly less than refrigerator ice. Based on the limited data taken, the median strength of rime ice was less than glaze ice. However, the mean values were similar.

Chu, M. L.; Scavuzzo, R. J.; Kellackey, C. J.

1992-01-01

340

Influence of Er:YAG laser on tensile bond strength of a self-etching system and a flowable resin in different dentin depths  

Microsoft Academic Search

Objective. The aim of this study was to evaluate the tensile resistance of a flowable resin in different dentin depths, after superficial treatment with Er:YAG laser.Methods. Eighteen molars were selected and roots were removed. Crowns were bisected in half, embedded in polyester resin and ground until dentin was exposed. The bonding site was delimited and samples were randomly assigned into

Aline Evangelista de Souza; Silmara Aparecida Milori Corona; Regina Guenka Palma Dibb; Maria Cristina Borsatto; Jesus Djalma Pécora

2004-01-01

341

The theoretical strength of rubber: numerical simulations of polyisoprene networks at high tensile strains evidence the role of average chain tortuosity  

NASA Astrophysics Data System (ADS)

The ultimate stress and strain of polyisoprene rubber were studied by numerical simulations of three-dimensional random networks, subjected to tensile strains high enough to cause chain rupture. Previously published molecular chain force extension models and a numerical network construction procedure were used to perform the simulations for network crosslink densities between 2 × 1019 and 1 × 1020 cm-3, corresponding to experimental dicumyl-peroxide concentrations of 1-5 parts per hundred. At tensile failure (defined as the point of maximum stress), we find that the fraction of network chains ruptured is between 0.1% and 1%, depending on the crosslink density. The fraction of network chains that are taut, i.e. their end-to-end distance is greater than their unstretched contour length, ranges between 10% and 15% at failure. Our model predicts that the theoretical (defect-free) failure stress should be about twice the highest experimental value reported. For extensions approaching failure, tensile stress is dominated by the network morphology and purely enthalpic bond distortion forces and, in this regime, the model has essentially no free parameters. The average initial chain tortuosity (?) appears to be an important statistical property of rubber networks; if the stress is scaled by ? and the tensile strain is scaled by ?-1, we obtain a master curve for stress versus strain, valid for all crosslink densities. We derive an analytic expression for the average tortuosity, which is in agreement with values calculated in the simulations.

Hanson, David E.; Barber, John L.

2013-10-01

342

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

National Technical Information Service (NTIS)

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 terephth...

C. Yen J. S. Snipes M. Grujicic R. Yavari S. Ramaswami

2013-01-01

343

Stresses and failure in rings of rock loaded in diametral tension or compression  

Microsoft Academic Search

The failure of rock materials in the form of rings subjected to line loadings on either their internal or external surfaces is studied. Formulae for the stresses and some numerical values are given. Experimental results for three fine-grained rocks are given and values of the tensile strengths so obtained are compared with those from direct tension, indirect tension (Brazilian) and

J C Jaeger; E R Hoskins

1966-01-01

344

Strength Distribution in Paper.  

National Technical Information Service (NTIS)

Tensile strength distributions are studied in four papers samples that exhibit a variety of brittle-to-ductile properties. 1005 tensile specimens were measured in each case. The standard Gumbel and Weibull distributions, and a recently proposed double exp...

M. J. Korteoja L. I. Salminen K. J. Niskanen M. Alava

1997-01-01

345

A Study of the Effect of Tool Pin Profiles on Tensile Strength of Welded Joints Produced Using Friction Stir Welding Process  

Microsoft Academic Search

Friction Stir Welding (FSW) has evolved into a process focused on joining of arc-weldable (5xxx and 6xxx) and which are difficult to weld (2xxx and 7xxx) aluminium alloys. The method described in this paper for the prediction of tensile properties and optimization can eliminate the need for performing experiments on the basis of conventional trial and error method. The present

C. N. Suresha; B. M. Rajaprakash; Sarala Upadhya

2011-01-01

346

49 CFR 571.221 - Standard No. 221; School bus body joint strength.  

Code of Federal Regulations, 2010 CFR

...a force of 60 percent of the tensile strength of the weakest joined body panel...joint strength, determine the tensile strengths of the joined body components...that material's thickness and tensile strength per unit of area shown in...

2009-10-01

347

49 CFR 571.221 - Standard No. 221; School bus body joint strength.  

Code of Federal Regulations, 2010 CFR

...a force of 60 percent of the tensile strength of the weakest joined body panel...joint strength, determine the tensile strengths of the joined body components...that material's thickness and tensile strength per unit of area shown in...

2010-10-01

348

The strength of bilayered tablets  

Microsoft Academic Search

The tensile strength of model materials (dicalcium phosphate dihydrate, microcrystalline cellulose and pregelatinised starch) compacted to form tablets in the form of beams consisting of two layers of equal thickness has been determined by three-point loading. The values of the tensile strength of the materials were sometimes higher and sometimes lower than the tensile strength of beams of the same

F. Podczeck; K. R. Drake; J. M. Newton; I. Haririan

2006-01-01

349

Modelling of the break force of tablets under diametrical compression.  

PubMed

A numerical method to predict the break force of curved faced tablets is proposed. The constitutive model and the failure criteria necessary to obtain predictions consistent with experimental data are identified. A modified Drucker-Prager cap model together with a maximum principal stress based failure criteria was found sufficient to predict the break force of tablets under diametrical compression loading. The conditions for the validity of the method were identified with reference to practical tablet shapes and failure patterns. Under these conditions the numerical procedures can be used as a practical tool to predict tablet breakage as an alternative to the empirical methods currently used in pharmaceutical product design and process development. PMID:23357256

Shang, C; Sinka, I C; Pan, J

2013-03-10

350

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

SciTech Connect

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.

Jadaan, Osama M. [University of Wisconsin, Platteville; Wereszczak, Andrew A [ORNL

2009-04-01

351

Strength of nonuniformly oxidized PGX graphite  

Microsoft Academic Search

Flexural and tensile tests were performed on PGX graphite oxidized to produce a steep surface oxidation gradient. Companion tensile specimens were oxidized under different conditions to produce uniform oxidation throughout the specimen, and their tensile strength and Young's modulus were measured. The flexural strength, flexural elastic modulus, and tensile strength were reduced much less by surface oxidation than by uniform

R. J. Price; L. A. Beavan

1981-01-01

352

Ceramic granule strength variability and compaction behavior.  

National Technical Information Service (NTIS)

Diametral compression strength distributions and the compaction behavior and of irregular shape 150--200 (mu)m ceramic granules and uniform-size 210 (mu)m glass spheres were measured to determine how granule strength variability relates to compaction beha...

S. J. Glass K. G. Ewsuk M. J. Readey

1995-01-01

353

Tensile testing of SiC whiskers  

SciTech Connect

The room temperature tensile mechanical properties of SiC whiskers have been examined using a micro-tensile-test apparatus. SiC whiskers exhibit an average tensile strength of 8.4 GPa for a 5 mm tested length, and an average elastic modulus of 581 GPa. These results indicate that SiC whiskers possess significant potential as short-fiber reinforcement elements in ceramic matrix composites.

Petrovic, J.J.

1984-01-01

354

Development of Controlled-Rolled 70 kgf/mm(2) and 80 kgf/mm(2) Class High Tensile Strength Steel Plate for Weld Structure.  

National Technical Information Service (NTIS)

To meet demands for higher strength steel plates for construcion machines with excellent cold formability and weldability, as-rolled HT70 steel plates (TS: 686 MPa) having a maximum thickness of 25.4 mm and as-rolled HT80 (TS: 784 MPa) steel plates of 12....

K. Amano O. Tanigawa C. Shiga T. Okumura

1989-01-01

355

Tensile deformation of electroplated copper nanopillars  

Microsoft Academic Search

The results are presented of uniaxial tensile testing of single crystalline electroplated copper nanopillars with diameters between 75 nm and 165 nm fabricated without the use of a focused ion beam (FIB). The experiments were performed in an in situ nanomechanical instrument, SEMentor, and reveal that the pillars’ ultimate tensile strengths follow a similar power law dependence on diameter as

Andrew T. Jennings; Julia R. Greer

2011-01-01

356

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)

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.

Eilers, Michael Glenn

357

49 CFR 192.107 - Yield strength (S) for steel pipe.  

Code of Federal Regulations, 2010 CFR

...whose specification or tensile properties are unknown, the yield strength to be used in the design...of the average yield strength determined by the tensile tests. (ii) The lowest yield strength determined by the tensile tests. (2)...

2009-10-01

358

49 CFR 192.107 - Yield strength (S) for steel pipe.  

Code of Federal Regulations, 2010 CFR

...whose specification or tensile properties are unknown, the yield strength to be used in the design...of the average yield strength determined by the tensile tests. (ii) The lowest yield strength determined by the tensile tests. (2)...

2010-10-01

359

Identification of a keratinase-producing bacterial strain and enzymatic study for its improvement on shrink resistance and tensile strength of wool- and polyester-blended fabric.  

PubMed

A wool-degrading bacterium was isolated from decomposition wool fabrics in China. The strain, named 3096-4, showed excellent capability of removing cuticle layer of wool fibers, as demonstrated by removing cuticle layer completely within 48 h. According to the phenotypic characteristics and 16S rRNA profile, the isolate was classified as Pseudomonas. Bacteria growth and keratinase activity of the isolate were determined during cultivation on raw wool at different temperatures, initial pH, and rotation speed using orthogonal matrix method. Maximum growth and keratinase activity of the bacterium were observed under the condition including 30 °C, initial pH 7.6, and rotational speeds 160 rpm. The keratinase-containing crude enzyme prepared from 3096-4 was evaluated in the treatment of wool fabrics. The optimal condition of our enzymatic improvement of shrink resistance was the combination of 30 °C, initial pH 7.6, and rotation speeds 160 rpm. After the optimized treatment, the wool fabrics felting shrink was 4.1% at 6 h, and textile strength was not lost. PMID:20607444

Cai, Shao-Bo; Huang, Zheng-Hua; Zhang, Xing-Qun; Cao, Zhang-Jun; Zhou, Mei-Hua; Hong, Feng

2011-01-01

360

An in vitro study to compare the effect of two etching techniques on the tensile bond strength of resin cement bonded to base metal alloy and enamel.  

PubMed

Resin-bonded retainers are being preferred for anterior restorations. To increase the retentive strength of the metal fixed to the tooth, the retainer surface has to be etched. Different etching techniques are described in the literature with different researchers expressing the superiority of one technique over the other. This study was conducted to compare electro chemical and chemical etching techniques and the mode of bond failure. Twenty human maxillary premolars with the crown portion separated from root were embedded in resin block such that mesial or distal portion of it was exposed on the top of the block. 4 × 5 mm area was marked on the tooth, and wax pattern was prepared to cover the exact area, with the opposite end having a hook like structure which was later attached to universal testing machine. Wiron99 Ni-Cr alloy was used for casting. Once the casting and etching procedures were finished, wax patterns were invested, casted and half the samples were etched chemically using Aqua-regia and the other half samples were etched electrochemically. The castings were cleaned and cemented to tooth structure using Rely-X ARC (3 M ESPE, USA) resin cement. Specimens were fixed to universal testing machine and de-bonded. The load required to de-bond and mode of de-bonding was noted. Results were subjected to five different statistical tests, each test specific to the variable being tested. The mean failure load was calculated as 5.95 kg for electrochemically etched samples and that of chemically etched samples was calculated as 11.15 kg. The standard deviation of the force required to debond the specimens (Kgf) was calculated and found to be 0.65 for electrochemically etched samples and 1.11 for chemically etched samples. The following conclusions have been drawn from the study. 1. Chemical etching of the samples created better retentive surfaces than electrochemical etching. 2. The results of mode of de-bonding show that in case of chemical etching maximum debonding occurred at resin-enamel interface and in electrochemical type it occurred at resin-metal interface. PMID:24431780

Sudheer, Arunachalam; Shetty, Gautam

2013-12-01

361

Direct Lentiviral-Cyclooxygenase 2 Application to the Tendon-Bone Interface Promotes Osteointegration and Enhances Return of the Pull-Out Tensile Strength of the Tendon Graft in a Rat Model of Biceps Tenodesis  

PubMed Central

This study sought to determine if direct application of the lentiviral (LV)-cyclooxygenase 2 (COX2) vector to the tendon-bone interface would promote osteointegration of the tendon graft in a rat model of biceps tenodesis. The LV-COX2 gene transfer strategy was chosen for investigation because a similar COX2 gene transfer strategy promoted bony bridging of the fracture gap during bone repair, which involves similar histologic transitions that occur in osteointegration. Briefly, a 1.14-mm diameter tunnel was drilled in the mid-groove of the humerus of adult Fischer 344 rats. The LV-COX2 or ?gal control vector was applied directly into the bone tunnel and onto the end of the tendon graft, which was then pulled into the bone tunnel. A poly-L-lactide pin was press-fitted into the tunnel as interference fixation. Animals were sacrificed at 3, 5, or 8 weeks for histology analysis of osteointegration. The LV-COX2 gene transfer strategy enhanced neo-chondrogenesis at the tendon-bone interface but with only marginal effect on de novo bone formation. The tendon-bone interface of the LV-COX2-treated tenodesis showed the well-defined tendon-to-fibrocartilage-to-bone histologic transitions that are indicative of osteointegration of the tendon graft. The LV-COX2 in vivo gene transfer strategy also significantly enhanced angiogenesis at the tendon-bone interface. To determine if the increased osteointegration was translated into an improved pull-out mechanical strength property, the pull-out tensile strength of the LV-COX2-treated tendon grafts was determined with a pull-out mechanical testing assay. The LV-COX2 strategy yielded a significant improvement in the return of the pull-out strength of the tendon graft after 8 weeks. In conclusion, the COX2-based in vivo gene transfer strategy enhanced angiogenesis, osteointegration and improved return of the pull-out strength of the tendon graft. Thus, this strategy has great potential to be developed into an effective therapy to promote tendon-to-bone healing after tenodesis or related surgeries.

Wergedal, Jon E.; Stiffel, Virginia; Lau, Kin-Hing William

2014-01-01

362

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

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

363

Compressive and tensile behaviour of aluminum foams  

Microsoft Academic Search

The uniaxial compressive and tensile modulus and strength of several aluminum foams are compared with models for cellular solids. The open cell foam is well described by the model. The closed cell foams have moduli and strengths that fall well below the expected values. The reduced values are the result of defects in the cellular microstructure which cause bending rather

E. Andrews; W. Sanders; L. J. Gibson

1999-01-01

364

Evolution of microstructure and tensile strength of rapidly solidified Al-4.7 pct Zn-2.5 pct Mg-0.2 pct Zr-X wt pct Mn alloys  

SciTech Connect

Analytical transmission electron microscopy and thermal analysis of as-extruded Al-4.7 pct Zn-2.5 pct Mg-0.2 pct Zr-X wt pct Mn alloys, with Mn contents ranging from 0.5 to 2.5 wt pct, were carried out to elucidate the microstructural change and accompanying mechanical properties during subsequent heat treatments. The as-extruded alloy was fabricated from rapidly solidified powder and consisted of a fine, metastable manganese dispersoid and the ternary eutectic T phase (Al{sub 2}Mg{sub 3}Zn{sub 3}). Solution heat treatment resulted in the formation of the stable Al{sub 6}Mn phase and complete dissolution of the T phase. Formation of stable Al{sub 6}Mn was made by two routes: by phase transition from metastable Mn dispersoids which already existed, and from the supersaturated solid solution by homogeneous nucleation. The density of the Al{sub 6}Mn phase increased with the addition of manganese, while the shape and average size remained unchanged. A significant increase in the hardness was observed to coincide with the formation of the Al{sub 6}Mn phase. Similarly, the tensile strength increased further after the aging treatment, and the increment was constant over the content of Mn in the alloy, which was explained by the contribution from the same amount of precipitates, MgZn{sub 2}. Results of thermal analysis indicated that the dissolution of the T phase started near 180 C and that formation of Al{sub 6}Mn occurred at about 400 C, suggesting that further enhancement of strength is possible with the modification of the heat-treatment schedule.

Chang, J.; Moon, I. [Korea Inst. of Science and Technology, Seoul (Korea, Republic of). Div. of Metals; Choi, C. [Yonsei Univ., Seoul (Korea, Republic of). Dept. of Metallurgical Engineering

1998-07-01

365

Microsample tensile testing of nanocrystalline metals  

Microsoft Academic Search

A novel non-contact strain measurement technique has been employed to measure the tensile properties of extremely small ‘microsamples’ of pure high-density ultrafine-grained Al (ufg-Al) nanocrystalline Cu (n-Cu) and nanocrystalline Ni (n-Ni). These microsample tests confirmed the absence of Young's modulus variations for metals with grain sizes approaching 25 nm. Significant strength enhancements were associated with the nanocrystalline specimens; the tensile

M. Legros; B. R. Elliott; M. N. Rittner; J. R. Weertman; K. J. Hemker

2000-01-01

366

THE ELASTICITY AND TENSILE STRENGTH OF STARCH  

Microsoft Academic Search

The importance of starch in the sizing of cotton warps depends very largely on the tenacity with which it binds the hairs in the yarn together. Since it is very difficult to find a material to which starch paste does not adhere very firmly on drying, it is presumed that its value in sizing is mainly determined by the mechanical

Sidney Maurice Neale

1924-01-01

367

Evaluation of Press-and-Sinter Parameters for Tantalum Pentoxide by the Diametral Compression Test.  

National Technical Information Service (NTIS)

Submicron Ta2O5 powder was consolidated by cold pressing using pressures between 24 MPa and 240 MPa followed by sintering at temperatures in the range 1300 degrees C to 1500 degrees C. The resulting disks were fractured in diametral compression tests (DCT...

Z. Livne R. J. Fields A. Agulyansky

1997-01-01

368

Stresses in a pressurized cylindrical shell with two unequal diametrically opposite reinforced circular holes  

Microsoft Academic Search

Summary This paper deals with an experimental determination of the stress distribution in a cylindrical shell with two diametrically opposite reinforced circular holes of different diameters. The shell is subjected to internal pressure. Both brittle coating and three-dimensional photoelasticity were used in the analysis. The results obtained are compared with those corresponding to a non-reinforced hole in a cylindrical shell

A. J. Durelli; V. J. Parks; Han-Chow Lee

1970-01-01

369

Failure Strength of Icy Lithospheres.  

National Technical Information Service (NTIS)

Lithospheric strengths derived from friction on pre-existing fractures and ductile flow laws show that the tensile strength of intact ice under applicable conditions is actually an order of magnitude stronger than widely assumed. It is demonstrated that t...

M. P. Golombek W. B. Banerdt

1987-01-01

370

Tensile properties of nanoclay reinforced epoxy composites  

NASA Astrophysics Data System (ADS)

Kinetic epoxy resin was filled with nanoclay to increase tensile properties of the composite for civil and structural. This project manufactured samples with different percentages by weight of nanoclay in the composites in steps of 1 wt %, which were then post-cured in an oven. The samples were then subjected to tensile tests. The results showed that the composite with 3 wt % of nanoclay produced the highest yield and tensile strengths. However, the Young's modulus increased with increasing nanoparticulate loading. It is hoped that the discussion and results in this work would not only contribute towards the further development of nanoclay reinforced epoxy composites with enhanced material properties, but also provide useful information for the studies of fracture toughness, tensile properties and flexural properties of other composites.

Ku, H.; Trada, Mohan

2013-08-01

371

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

NASA Technical Reports Server (NTRS)

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.

Sharoni, A.; Etsion, I.

1979-01-01

372

Prediction of Tensile Matrix Failure in Composite Laminates  

Microsoft Academic Search

A conceptually simple mixed mode fracture analysis method is presented for the prediction of tensile matrix failure in composite laminates. The analysis technique, which makes use of a mixed mode strain energy release rate fracture criteria in con junction with an approximate two-dimensional shear-lag model, is cast in terms of a tensile matrix strength criterion. In contrast to presently available

D. L. Flaggs

1985-01-01

373

Tensile properties of stainless steel sandwich sheets with fibrous cores  

Microsoft Academic Search

The unnotched and notched tensile properties of flocked and brazed stainless steel sandwiches with fibrous cores were examined. The tensile stress-strain responses show that the fibres do not carry any load in the flocked sheets and that the load transfer is better facilitated in the brazed sandwich sheets. Notched strength results show that the flocked sheets are notch-insensitive whereas the

M. A. Azeem; C. Shortall; U. Ramamurty

2007-01-01

374

Experimental study on tensile mechanical behaviors of 5A06 aluminum alloy under short time elevated temperature  

NASA Astrophysics Data System (ADS)

In this work, the tensile mechanical properties of 5A06 aluminum alloy are tested in the temperature range 20°C ~ 500°C on an MTS 810 material testing machine. The curves of the tensile stress vs. strain, the Young's modulus vs. temperature, the yield strength vs. temperature, and the tensile strength vs. temperature are obtained. Results shows that the elastic modulus, yield stress and tensile strength decrease with increasing temperature .Based on the experiment results, the functions of the elastic modulus, yield strength and tensile strength versus temperature are represented by polynomial. The simplified constitutive model JC finally is established under the high temperature considering the thermal softening.

Li, Weifen; Niu, Wei; Hao, Zhiming; Li, Minghai; Hu, Shaoqun; Chen, Yongmei

2009-12-01

375

Correlating macrohardness and tensile behavior in discontinuously reinforced metal matrix composites  

Microsoft Academic Search

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

Y.-L. Shen; E. Fishencord; N. Chawla

2000-01-01

376

High strength, superplastic superalloy  

NASA Technical Reports Server (NTRS)

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.

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

1969-01-01

377

Weldability evaluation of high tensile plates using GMAW process  

Microsoft Academic Search

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\\u000a Authority of India Ltd., up to 32 mm plate thickness. Since then the steel has been extensively used for the fabrication of\\u000a impellers, bridges,

R. Datta; D. Mukerjee; K. L. Rohira; R. Veeraraghavan

1999-01-01

378

Effects of added mannitol on the setting reaction and mechanical strength of apatite cement.  

PubMed

Apatite cement containing porogen can be a useful material for the fabrication of biporous (macro- and microporous) apatite, which has gained much attention as a bone substitute material because of its large surface area and that it improves cell penetration. In the present study, the effects of added mannitol on the setting reaction and mechanical strength of apatite cement were evaluated. Apatite cements containing 0-40 wt% of mannitol were prepared and allowed to set in 0.9% saline kept at 37 degrees C for 1-7 days. Although the diametral tensile strength (DTS) value increased with time, it decreased with the amount of added mannitol. SEM observation and XRD analysis revealed that mannitol had no inhibitory effect on the transformation reaction of apatite cement to apatite. It was thus concluded that mannitol was a good candidate for the fabrication of biporous apatite because it is biocompatible, exhibits satisfactory dissolution behavior, and that it caused no inhibitory effects on the compositional transformation to apatitic material. PMID:19822995

Shimogoryo, Ryoji; Eguro, Toru; Kimura, Eiichiro; Maruta, Michito; Matsuya, Shigeki; Ishikawa, Kunio

2009-09-01

379

Assessing the Strength Enhancement of Heterogeneous Networks of Miscible Polymer Blends  

NASA Astrophysics Data System (ADS)

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.

Giller, Carl; Roland, Mike

2013-03-01

380

Diametrically opposed.  

PubMed

As states continue to grapple with rising healthcare costs and budget constraints, two have set themselves on divergent paths. In Vermont, Gov. Peter Shumlin, left, is set to sign a bill that would steer the state toward a single-payer system in which residents will have their care paid for out of a single fund. Meanwhile, Florida is on the verge of turning its Medicaid program into a managed-care system to be overseen by private insurers. PMID:21717629

Vesely, Rebecca

2011-05-16

381

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

NASA Astrophysics Data System (ADS)

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.

Naito, Kimiyoshi

2014-03-01

382

Experimental study on tensile mechanical behaviors of 5A06 aluminum alloy under short time elevated temperature  

Microsoft Academic Search

In this work, the tensile mechanical properties of 5A06 aluminum alloy are tested in the temperature range 20°C ~ 500°C on an MTS 810 material testing machine. The curves of the tensile stress vs. strain, the Young's modulus vs. temperature, the yield strength vs. temperature, and the tensile strength vs. temperature are obtained. Results shows that the elastic modulus, yield

Weifen Li; Wei Niu; Zhiming Hao; Minghai Li; Shaoqun Hu; Yongmei Chen

2009-01-01

383

Approaches for Tensile Testing of Braided Composites  

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

384

Tensile properties of irradiated surveillance coupons  

SciTech Connect

Tensile testing of austenitic steel and superalloy samples irradiated in the HMO 13 assembly was performed in support of the Fast Flux Test Facility (FFTF) Surveillance Program. Postirradiation yield stress, ultimate tensile stress, uniform elongation, total elongation, and reduction in area of 304 stainless steel (SS), 308 SS weld, 316 SS, A286, In718, and In718 weld were determined. Results showed the strength of austenitic steels increased while the ductility decreased as a result of irradiation. Low irradiation exposure produced little property change in In718. Overall, the tensile properties of HMO 13 surveillance coupons showed a lower magnitude of irradiation-induced property change than was expected based on earlier studies. Results from these tests gave no indications of unexpectedly severe irradiation damage to FFTF components.

Huang, F.H.; Blackburn, L.D.

1994-06-01

385

Tensile Properties of Polycarbonate\\/Polymethyl Methacrylate Blend Coated Natural Fabric Hildegardia Populifolia  

Microsoft Academic Search

The uniaxial natural fabric Hildegardia populifolia was coated with polycarbonate\\/polymethyl methacrylate blend and its tensile strength, modulus and percentage of elongation at break were determined. The effect of alkali treatment on the tensile properties of the fabric was also studied. The tensile properties were enhanced by alkali treatment. The morphology of the fabric before and after coating was studied by

D. Jagadeesh; A. Varada Rajulu; B. R. Guduri

2010-01-01

386

Tensile behavior of cement-based composites with random discontinuous steel fibers  

SciTech Connect

In this paper, the tensile properties of cement-based composites containing random discontinuous steel fibers are reported. Direct tensile tests were performed to study the effects of fiber length (hence fiber aspect ratio), interfacial bonding, and processing conditions on composite properties. Composite tensile strength and ductility are highlighted and discussed.

Li, V.C.; Wu, H.C.; Maalej, M.; Mishra, D.K. [Univ. of Michigan, Ann Arbor, MI (United States); Hashida, Toshiyuki [Tohoku Univ., Sendai (Japan). Research Inst. for Fracture Technology

1996-01-01

387

Tensile properties of textile composites  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

388

Effects of Coating and Diametric Load on Fiber Bragg Gratings as Cryogenic Temperature Sensors  

NASA Technical Reports Server (NTRS)

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.

Wu, meng-Chou; Pater, Ruth H.; DeHaven, Stanton L.

2008-01-01

389

Strength of Rewelded Inconel 718  

NASA Technical Reports Server (NTRS)

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.

Bayless, E.; Lovoy, C. V.; Mcllwain, M. C.; Munafo, P.

1982-01-01

390

Anisotropy and Strength of Ceramic Bodies.  

National Technical Information Service (NTIS)

The experimental and theoretical efforts in the report can be divided into 5 groups: computation of the theoretical tensile, compressive and shear strength as depending on the orientation of the applied stress (bulk strength anisotropy) based on higher or...

W. R. Buessem H. A. McKinstry

1969-01-01

391

Improve the Strength of PLA/HA Composite Through the Use of Surface Initiated Polymerization and Phosphonic Acid Coupling Agent  

PubMed Central

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.

Wang, Tongxin; Chow, Laurence C.; Frukhtbeyn, Stanislav A.; Ting, Andy Hai; Dong, Quanxiao; Yang, Mingshu; Mitchell, James W.

2012-01-01

392

Tensile Properties of Under-Matched Weld Joints for 950 MPa Steel.  

NASA Astrophysics Data System (ADS)

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.

Yamamoto, Kouji; Arakawa, Toshiaki; Akazawa, Nobuki; Yamamoto, Kousei; Matsuo, Hiroki; Nakagara, Kiyoyuki; Suita, Yoshikazu

393

Tensile properties of titanium electrolytically charged with hydrogen  

NASA Technical Reports Server (NTRS)

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.

Smith, R. J.; Otterson, D. A.

1971-01-01

394

Distribution of tensile property and microstructure in friction stir weld of 6063 aluminum  

Microsoft Academic Search

Dominant microstructural factors governing the global tensile properties of a friction-stir-welded joint of 6063 aluminum\\u000a were examined by estimating distribution of local tensile properties corresponding to local microstructure and hardness. Yield\\u000a and ultimate tensile strengths of the as-welded weld were significantly lower than those of the base material. Postweld aging\\u000a and postweld solution heat-treatment and aging (SHTA) restored the strengths

Yutaka S. Sato; Hiroyuki Kokawa

2001-01-01

395

Strength enhancement process for prealloyed powder superalloys  

NASA Technical Reports Server (NTRS)

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.

Waters, W. J.; Freche, J. C.

1977-01-01

396

Deformation behavior of human dentin in liquid nitrogen: A diametral compression test.  

PubMed

Contribution of the collagen fibers into the plasticity of human dentin is considered. Mechanical testing of dentin at low temperature allows excluding the plastic response of its organic matrix. Therefore, deformation and fracture behavior of the dentin samples under diametral compression at room temperature and liquid nitrogen temperature are compared. At 77K dentin behaves like almost brittle material: it is deformed exclusively in the elastic regime and it fails due to growth of the sole crack. On the contrary, dentin demonstrates the ductile response at 300K. There are both elastic and plastic contributions in the deformation of dentin samples. Multiple cracking and crack tip blunting precede the failure of samples. Organic phase plays an important role in fracture of dentin: plasticity of the collagen fibers could inhibit the crack growth. PMID:25063091

Zaytsev, Dmitry; Panfilov, Peter

2014-09-01

397

Treatment of High Temperature Tensile Data for Alloy 617 and Alloy 230  

SciTech Connect

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.

Sham, Sam [ORNL; Eno, Daniel R. [Lockheed Martin Corporation; Jensen, Krista P. [Lockheed Martin Corporation

2008-01-01

398

Tensile properties of amorphous diamond films  

SciTech Connect

The strength and modulus of amorphous diamond, a new material for surface micromachined MEMS and sensors, was tested in uniaxial tension by pulling laterally with a flat tipped diamond in a nanoindenter. Several sample designs were attempted. Of those, only the single layer specimen with a 1 by 2 {micro}m gage cross section and a fixed end rigidly attached to the substrate was successful. Tensile load was calculated by resolving the measured lateral and normal forces into the applied tensile force and frictional losses. Displacement was corrected for machine compliance using the differential stiffness method. Post-mortem examination of the samples was performed to document the failure mode. The load-displacement data from those samples that failed in the gage section was converted to stress-strain curves using carefully measured gage cross section dimensions. Mean fracture strength was found to be 8.5 {+-} 1.4 GPa and the modulus was 831 {+-} 94 GPa. Tensile results are compared to hardness and modulus measurements made using a nanoindenter.

Lavan, D.A.; Hohlfelder, R.J.; Sullivan, J.P.; Friedmann, T.A.; Mitchell, M.A.; Ashby, C.I.

1999-12-02

399

Temperature controlled tensile testing of individual nanowires  

NASA Astrophysics Data System (ADS)

We present a novel experimental method for quantitatively characterizing the temperature-dependent mechanical behavior of individual nanostructures during uniaxial straining. By combining a microelectromechanical tensile testing device with a low thermal mass and digital image correlation providing nm-level displacement resolution, we show successful incorporation of a testing platform in a vacuum cryostat system with an integrated heater and temperature control. Characterization of the local sample temperature and time-dependent response at both low and high temperature demonstrates a testing range of ˜90-475 K and steady-state drift rates less than 0.04 K/min. In situ operation of the tensile testing device employing resistively heated thermal actuators while imaging with an optical microscope enables high-resolution displacement measurements, from which stress-strain behavior of the nanoscale specimens is deduced. We demonstrate the efficacy of our approach in measuring the temperature dependence of tensile strength in nominally defect-free ?110? Pd nanowhiskers. We uncover a pronounced sensitivity of the plastic response to testing temperature over a range of ˜300 K, with an ultimate strength in excess of 6 GPa at low temperature. The results are discussed in the context of thermally activated deformation mechanisms and defect nucleation in defect-free metallic nanostructures.

Chen, Lisa Y.; Terrab, Soraya; Murphy, Kathryn F.; Sullivan, John P.; Cheng, Xuemei; Gianola, Daniel S.

2014-01-01

400

Temperature controlled tensile testing of individual nanowires.  

PubMed

We present a novel experimental method for quantitatively characterizing the temperature-dependent mechanical behavior of individual nanostructures during uniaxial straining. By combining a microelectromechanical tensile testing device with a low thermal mass and digital image correlation providing nm-level displacement resolution, we show successful incorporation of a testing platform in a vacuum cryostat system with an integrated heater and temperature control. Characterization of the local sample temperature and time-dependent response at both low and high temperature demonstrates a testing range of ?90-475 K and steady-state drift rates less than 0.04 K/min. In situ operation of the tensile testing device employing resistively heated thermal actuators while imaging with an optical microscope enables high-resolution displacement measurements, from which stress-strain behavior of the nanoscale specimens is deduced. We demonstrate the efficacy of our approach in measuring the temperature dependence of tensile strength in nominally defect-free ?110? Pd nanowhiskers. We uncover a pronounced sensitivity of the plastic response to testing temperature over a range of ?300 K, with an ultimate strength in excess of 6 GPa at low temperature. The results are discussed in the context of thermally activated deformation mechanisms and defect nucleation in defect-free metallic nanostructures. PMID:24517776

Chen, Lisa Y; Terrab, Soraya; Murphy, Kathryn F; Sullivan, John P; Cheng, Xuemei; Gianola, Daniel S

2014-01-01

401

Fracture toughness and fracture mechanisms of PBT\\/PC\\/IM blends: Part V Effect of PBT-PC interfacial strength on the fracture and tensile properties of the PBT\\/PC blends  

Microsoft Academic Search

To investigate the effect of PBT-PC interfacial strength on the fracture toughness and toughening mechanisms of the PBT\\/PC system, a series of PBT\\/PC blends with different content of in situ formed PBT-PC copolymers were made by melt blending. The in situ copolymer was separately prepared via reactive blending of the PBT and PC in the presence of a transesterification catalyst

Jingshen Wu; Ke Wang; Demei Yu

2003-01-01

402

Column strength of magnesium alloy AM-57S  

NASA Technical Reports Server (NTRS)

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.

Holt, M

1942-01-01

403

The Effect of Variability in the Powder/Liquid Ratio on the Strength of Zinc Phosphate Cement  

PubMed Central

Aim. To investigate (a) variability in powder/liquid proportioning and (b) effect of variability on diametral tensile strength (DTS), in a zinc phosphate cement. Statistical analyses (? = 0.05) were by Student's t-test in the case of powder/liquid ratio and one-way ANOVA and Tukey HSD for pair-wise comparisons of mean DTS. The Null hypotheses were that (a) the powder-liquid mixing ratios would not differ from the manufacturer's recommended ratio (b) DTS of the set cement samples using the extreme powder/liquid ratios would not differ from those made using the recommended ratio. Methodology. 34 dental students dispensed the components according to the manufacturer's instructions. The maximum and minimum powder/liquid ratios, together with the manufacturer's recommended ratio, were used to prepare samples for DTS testing. Results. Powder/liquid ratios ranged from 2.386 to 1.018. The mean ratio (1.644) was not significantly different from the recommended value of 1.718 (P = 0.189). DTS values for the maximum and minimum ratios were both significantly different from each other (P < 0.001) and from the mean value obtained from the recommended ratio (P < 0.001). Conclusions. Variability exists in powder/liquid ratio for hand dispensed zinc phosphate cement. This variability can affect the DTS of the set material.

McKenna, Jill E.; Ray, Noel J.; McKenna, Gerald; Burke, Francis M.

2011-01-01

404

Tensile and creep properties of titanium-vanadium, titanium-molybdenum, and titanium-niobium alloys  

NASA Technical Reports Server (NTRS)

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.

Gray, H. R.

1975-01-01

405

Tensile deformation mechanisms at different temperatures in the Ni-base superalloy GTD-111  

Microsoft Academic Search

The Ni-base superalloy GTD-111 is employed in high-power stationary gas turbines because of its high temperature strength and oxidation resistance. The temperature dependence of the tensile behavior of GTD-111 has been studied by tensile tests in the temperature range of 25–900°C with a constant strain rate of 10?4s?1. The results showed an abnormal tensile property variation with increasing temperature. The

Seyed Abdolkarim Sajjadi; Said Nategh; Mihaiela Isac; Seyed Mojtaba Zebarjad

2004-01-01

406

A second study of tensile fatigue properties of human articular cartilage.  

PubMed Central

The tensile fatigue properties of the collagen fibre meshwork in normal human articular cartilage were measured by subjecting isolated specimens of post-mortem femoral head cartilage to cyclic tensile stress. The results of the study showed (1) that the collagen fibre meshwork is fatigue prone and (2) that its fatigue strength decreases rapidly with age. Extrapolation of the data to physiologically possible stress levels suggests that tensile fatigue failure of the collagen meshwork could occur in life.

Weightman, B; Chappell, D J; Jenkins, E A

1978-01-01

407

The prediction of tensile failure in titanium-based thermoplastic fibre–metal laminates  

Microsoft Academic Search

The tensile properties of a titanium-based fibre–metal laminate have been investigated at quasi-static rates of strain. Initial attention focused on investigating the effect of varying the fibre orientation, ?, on the tensile modulus and strength of a range of [Ti,±?]s carbon-fibre\\/PEEK FMLs. Here, as expected, increasing the offset angle, ?, resulted in a decrease in the tensile properties of the

P. Cortés; W. J. Cantwell

2006-01-01

408

Dynamic Tensile Failure by Glycerol.  

National Technical Information Service (NTIS)

A tensile strain was induced in shock-loaded glycerol by the intersection of two rarefaction waves, one of which was caused by the partial reflection of a shock from an interface with octane, a material of lower shock impedance. The maximum tensile stress...

D. C. Erlich D. C. Wooten R. C. Crewdson

1971-01-01

409

Tensile Properties of Resin-infiltrated Demineralized Human Dentin  

Microsoft Academic Search

The ability of adhesive resins to restore the physical properties of demineralized dentin has not been well-documented. The unfilled resins that are used for adhesion have relatively low moduli of elasticity and limited ability to increase dentin stiffness, although they may increase the ultimate tensile strength of dentin. This study tested the hypothesis that resin infiltration of demineralized dentin can

H. Sano; T. Takatsu; B. Ciucchi; C. M. Russell; D. H. Pashley

1995-01-01

410

Tensile and fatigue properties of Inconel 718 at cryogenic temperatures  

NASA Technical Reports Server (NTRS)

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.

Malin, C. O.; Schmidt, E. H.

1969-01-01

411

Research on shear strength of galvannealed coatings  

Microsoft Academic Search

Lap shear test can be generally performed by two kinds of methods. However, the shear strengths measured in both methods (bare and compound sample) may be quite different, which results in some influence on evaluating powdering of galvannealed coating. Samples in uniaxial tensile test are modified to measure their yield stress. The stress–strain curves in tensile test are compared with

Chun Xu; Z. Q. Lin; S. H. Li; W. G. Zhang

2007-01-01

412

Effects of acid-etching on the tensile properties of demineralized dentin matrix  

Microsoft Academic Search

Objectives. Little research has been done to evaluate the effects of acids commonly used in adhesive dentistry, on the tensile properties of the demineralized dentin matrix. The purpose of this study was to evaluate the effects of a number of acidic conditioners on the ultimate tensile strength (UTS) and modulus of elasticity (E) of human coronal dentin matrix.Methods. Small hour-glass

Yi Zhang; Kelli Agee; Jacques Nör; Ricardo Carvalho; Bhupinder Sachar; Carl Russell; David Pashley

1998-01-01

413

Technique for studying dynamic tensile failure in liquids: application to glycerol  

Microsoft Academic Search

A new experimental technique has been developed for the study of the dynamic tensile strength of liquids. The liquid is confined between a solid plate and a stretched aluminized Mylar film. Pulsed electron beam deposition in the plate generates a stress wave which traverses the liquid and gives a high tensile stress during reflection at the Mylar-covered free surface. Interferometric

G. A. Carlson; K. W. Henry

1973-01-01

414

Tensile properties of carbon nanotube reinforced aluminum nanocomposite fabricated by plasma spray forming  

Microsoft Academic Search

Uniaxial tensile tests were performed on plasma spray formed (PSF) Al–Si alloy reinforced with multiwalled carbon nanotubes (MWCNTs). The addition of CNTs leads to 78% increase in the elastic modulus of the composite. There was a marginal increase in the tensile strength of CNT reinforced composite with degradation in strain to failure by 46%. The computed critical pullout length of

T. Laha; Y. Chen; D. Lahiri; A. Agarwal

2009-01-01

415

High-Strength Aluminum--Silicon Alloys.  

National Technical Information Service (NTIS)

The results of a study to examine the influence of sodium, strontium and antimony additions on the density, radiographic appearance, mechanical tensile properties and micrographic structure of high-strength aluminum-silicon alloys are presented. (ERA cita...

1976-01-01

416

Tensile Properties of Unirradiated PCA (Prime Candidate Alloy) from Room Temperature to 700 exp 0 C.  

National Technical Information Service (NTIS)

The tensile properties of Prime Candidate Alloy (PCA) austenitic stainless steel after three different thermomechanical treatments were determined from room temperature to 700 exp 0 C. The solution-annealed PCA had the lowest strength and highest ductilit...

D. N. Braski P. J. Maziasz

1983-01-01

417

Anisotropic strain localization in tensile prestrained sheet steel  

NASA Astrophysics Data System (ADS)

Multiple forming operations are often needed to stamp complex shapes out of sheet metal. Large changes in strain path can occur from such operations. This study examined the effects of a particular strain path change, tensile-tensile, on the mechanical properties of an aluminum-killed steel. Large tensile specimens were prestrained various amounts in one direction followed by machining smaller tensile specimens at 0, 45, and/or 90 deg to the prestrain direction. The smaller samples were then pulled to failure. For samples pulled in the same direction as the prestrain, the residual strength and ductility were equivalent to those obtained from an interrupted tensile test. In contrast, both the 45 and the 90 deg prestrained specimens showed a larger than expected flow stress and an abrupt change in the nature of the residual ductility at prestrains of 7.5 pct and larger. At 7.5 pct prestrain, the uniform strain, as measured by the maximum-load point on the load vs elongation tensile curve, decreased abruptly. The decrease was accompanied by a corresponding increase in the post-uniform strain. This unusual behavior is explained in terms of a rapid increase in strain-hardening with strain.

Laukonis, Joseph V.

1981-03-01

418

Strength enhancement process for prealloyed powder superalloys  

NASA Technical Reports Server (NTRS)

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.

Waters, W. J.; Freche, J. C.

1977-01-01

419

Effect of heat treatment on microstructures and tensile properties of Ni-base superalloy M963  

Microsoft Academic Search

The effect of solution treatment (ST) on tensile properties of M963 Ni-base superalloy tested at 800°C has been investigated. The detailed microstructures, fracture surfaces and dislocation structures are examined through energy dispersive X-ray analysis (EDAX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). With increasing solution treated temperature, the yield strength (YS) and ultimate tensile strength (UTS) increase, however,

L. Z. He; Q. Zheng; X. F. Sun; H. R. Guan; Z. Q. Hu; A. K. Tieu; C. Lu; H. T. Zhu

2005-01-01

420

Characterization of tensile behaviour of hybrid short glass fibre\\/calcite particle\\/ABS composites  

Microsoft Academic Search

The tensile properties of hybrid, injection molded, short glass fibre (SGF)\\/calcite particle\\/acrylonitrile-butadiene-styrene (ABS) composites have been investigated. To gain an insight into some possible combined effect of the SGF\\/ABS interfacial adhesion strength and the calcite particle\\/ABS adhesion strength on the tensile properties of the hybrid composites, the glass fibres employed in the investigation were as-received and sized with an aminosilane\\/polyurethane

Shao-Yun Fu; Bernd Lauke

1998-01-01

421

Effects of sensitisation-induced martensitic transformation on the tensile behaviour of 304 austenitic stainless steel  

Microsoft Academic Search

The effects of sensitisation-induced martensitic transformation on the tensile behaviour of 304 austenitic stainless steel have been investigated. Yield strength is reduced by sensitisation, but ultimate tensile strength is nearly unaffected. Strain-hardening behaviour is changed by sensitisation, too. Although sensitisation may induce martensite formation near grain boundary, twin boundary, and austenite\\/martensite interface, the sensitisation-induced martensite does not exert a great

K. H. Lo; D. Zeng; C. T. Kwok

2011-01-01

422

Temperature dependence of tensile mechanical properties in SiC fiber-reinforced Ti matrix composite  

Microsoft Academic Search

Temperature dependence of longitudinal Young's modulus, tensile strength, and interfacial shear stress in SiC(SCS-6) fiber-reinforced commercially pure Ti matrix composites have been examined experimentally in the temperature range from room temperature to 873 K. Young's modulus and tensile strength of the composite was discussed in relation to the interfacial shear stress transfer mechanism. Young's modulus was independent of interfacial shear

Y. Kagawa; T. Fujita; A. Okura

1994-01-01

423

Automatic Balance for Measurement of the Strength of Glass Fibers  

Microsoft Academic Search

The semiautomatic balance used to measure the tensile strength and Young's modulus of glass fibers when bent into a loop has been made fully automatic. A differential transformer and servomotor are used to apply chain-weight as the tension in the looped fiber is increased by the loading motor.All measurements needed to calculate the tensile strength and Young's modulus are automatically

David Sinclair

1956-01-01

424

Tensile Testing: A Simple Introduction  

ERIC Educational Resources Information Center

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.

Carr, Martin

2006-01-01

425

Manufacturing of Plutonium Tensile Specimens  

SciTech Connect

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.

Knapp, Cameron M [Los Alamos National Laboratory

2012-08-01

426

Degradation of tensile and shear properties of composites exposed to fire or high temperature  

NASA Technical Reports Server (NTRS)

The decrease in ultimate tensile strength, shear strength, tensile modulus, and shear modulus of fiber reinforced composites exposed to fire or to high temperature was investigated. A simple model was developed for calculating the mass loss of the material and the thickness of the char layer. The mass loss as well as the degradation in tensile and shear properties of Fiberite T300/1034 and Hercules AS/3501-6 graphite epoxy composites exposed to fire were measured. A correlation between the degradation in properties and the calculated mass loss and the char layer thickness was developed. A technique was proposed for predicting material damage through the use of such correlations.

Pering, G. A.; Farrell, P. V.; Springer, G. S.

1980-01-01

427

Rod Has High Tensile Strength And Low Thermal Expansion  

NASA Technical Reports Server (NTRS)

Thoriated tungsten extension rod fabricated to replace stainless-steel extension rod attached to linear variable-differential transformer in gap-measuring gauge. Threads formed on end of rod by machining with special fixtures and carefully chosen combination of speeds and feeds.

Smith, D. E.; Everton, R. L.; Howe, E.; O'Malley, M.

1996-01-01

428

Examination of the Tensile Strength of Graphite Fibers.  

National Technical Information Service (NTIS)

The Single Fiber Graphite Tester was developed to measure the failure load and fiber diameter of graphite fibers. Data have been taken on a number of commercially available fibers with the tester. These data have been examined in order to understand the d...

E. C. Goeke S. C. Chou

1989-01-01

429

Strength of nonuniformly oxidized PGX graphite  

SciTech Connect

Flexural and tensile tests were performed on PGX graphite oxidized to produce a steep surface oxidation gradient. Companion tensile specimens were oxidized under different conditions to produce uniform oxidation throughout the specimen, and their tensile strength and Young's modulus were measured. The flexural strength, flexural elastic modulus, and tensile strength were reduced much less by surface oxidation than by uniform oxidation. The test data were in good agreement with a simple linear elastic model in which Young's modulus at any point is a function of oxidation burnoff, and the strain at failure is independent of oxidation. The unoxidized interior of the specimens appears unaffected by the surface burnoff and remains able to fulfill its load-bearing function. 18 figures, 8 tables.

Price, R.J.; Beavan, L.A.

1981-05-01

430

Dynamic Tensile Failure of the Rock Interface Between Tuff and Basalt  

NASA Astrophysics Data System (ADS)

The dynamic tensile strength properties of the rock interface and its host rocks sampled from the Baihetan Hydropower Station from Western China were measured using a split Hopkinson pressure bar (SHPB). The results were compared with those for its two host rocks. The dynamic tensile strengths of the two host rocks, tuff and basalt have typical loading rate dependence. However, the dynamic response of the rock interface is much more complicated and at a given loading rate, varies between those of tuff and basalt. To explain the observation, numerical simulation using the discrete element method (DEM) was conducted to determine the detailed tensile failure process of the rock interface. The numerical simulation verifies that the variation of the dynamic tensile strength of the rock interface is a result of the variation of the interface geometry.

Yan, Fei; Feng, Xia-Ting; Chen, Rong; Xia, Kaiwen; Jin, Changyu

2012-05-01

431

The effect of structure on tensile properties of directionally solidified Zn-based alloys  

NASA Astrophysics Data System (ADS)

The main objective of this study was to measure thermal (cooling rates, temperature gradients and velocities of the liquidus and solidus isotherms), structural (grain size and primary and secondary dendritic arm spacings) and tensile parameters (maximum tensile strength (MTS), yield strength (YS) and ultimate tensile strength (UTS)) in zinc-aluminum (ZA) hypoeutectic (Zn-3 wt%Al) and hypereutectic (Zn-10 wt%Al, Zn-15 wt%Al, Zn-20 wt%Al, Zn-30 wt%Al, Zn-37 wt%Al and Zn-50 wt%Al) alloys directionally solidified, which present columnar, equiaxed and columnar-to-equiaxed transition (CET) structures. The different types of structures were analyzed with optical and Scanning Electron Microscopy (SEM). Correlations between temperature gradient, cooling rate, local solidification time, grain size and dendritic spacings and tensile tests parameters are presented and discussed. The results show the influence of concentration, microstructural arrangement and thermal conditions on the mechanical properties during the solidification process.

Ares, A. E.; Schvezov, C. E.

2011-03-01

432

Powder processing for the fabrication of SiâNâ ceramics. 1: Influence of spray-dried granule strength on pore size distribution in green compacts  

Microsoft Academic Search

The effect of spray-dried granule strength on the microstructure of green compacts obtained by isostatic pressing was quantitatively analyzed. The fracture strength of single granules of SiâNâ powder made with ultrafine AlâOâ and YâOâ powders was measured directly by diametral compression. It was found that fracture strength increased notably with the increasing relative density of the granule and the decreasing

Hidehiro Kamiya; Kenji Isomura; Genji Jimbo; Tsubaki Jun-ichiro

1995-01-01

433

Tensile-strained germanium microdisks  

NASA Astrophysics Data System (ADS)

We show that a strong tensile strain can be applied to germanium microdisks using silicon nitride stressors. The transferred strain allows one to control the direct band gap emission that is shifted from 1550 nm up to 2000 nm, corresponding to a biaxial tensile strain around 1%. Both Fabry-Perot and whispering gallery modes are evidenced by room temperature photoluminescence measurements. Quality factors up to 1350 and limited by free carrier absorption of the doped layer are observed for the whispering gallery modes. We discuss the strain profile in the microdisks as a function of the disk geometry. These tensile-strained microdisks are promising candidates to achieve Ge laser emission in compact microresonators.

Ghrib, A.; El Kurdi, M.; de Kersauson, M.; Prost, M.; Sauvage, S.; Checoury, X.; Beaudoin, G.; Sagnes, I.; Boucaud, P.

2013-06-01

434

Carbon fibre compressive strength and its dependence on structure and morphology  

Microsoft Academic Search

The axial compressive strength of carbon fibres varies with the fibre tensile modulus and precursor material. While the development of tensile modulus and strength in carbon fibres has been the subject of numerous investigations, increasing attention is now being paid to the fibre and the composite compressive strength. In the present investigation, pitch- and PAN-based carbon fibres with wide-ranging moduli

S. Kumar; D. P. Anderson; A. S. Crasto

1993-01-01

435

The tensile fatigue of wire rope: A new approach  

SciTech Connect

The fatigue behaviour in air and seawater of zinc coated steel wire taken from a 40 mm diameter wire rope has been studied. Seawater had little effect on short term tensile strength but it reduced fatigue life by an amount which increased with increasing mean stress and decreasing test frequency. The application of fretting during fatigue testing resulted in very low endurances, which were similar to those measured in fatigue tests on wire ropes.

Thorpe, T.W.; Rance, A.

1983-05-01

436

Cryogenic insulation strength and bond tester  

Microsoft Academic Search

A method and apparatus for testing the tensile strength and bonding strength of sprayed-on foam insulation attached to metal cryogenic fuel tanks. A circular cutter is used to cut the insulation down to the surface of the metal tank to form plugs of the insulation for testing ''in situ'' on the tank. The apparatus comprises an electro-mechanical pulling device powered

P. H. Schuerer; J. H. Ehl; W. P. Prasthofer

1985-01-01

437

Cryogenic Insulation Strength and Bond Tester.  

National Technical Information Service (NTIS)

A method and apparatus for testing the tensile strength and bonding strength of sprayed-on foam insulation attached to metal cryogenic fuel tanks is described. A circular cutter is used to cut the insulation down to the surface of the metal tank to form p...

P. H. Schuerer J. H. Ehl W. P. Prasthofer

1983-01-01

438

The Cryogenic Tensile Properties of an Extruded Aluminum-Beryllium Alloy  

NASA Technical Reports Server (NTRS)

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."

Gamwell, W. R.

2002-01-01

439

Tensile, Compressive, and Shear Properties of a 96 kg cubic meter Polyurethane Foam at Low Temperatures.  

National Technical Information Service (NTIS)

Polyurethane foam, having a density of 96 kg/cu m, was tested at 295, 111, 76, and 4 K. The material properties reported are Young's modulus, proportional limit, yield strength (at 0.2% offset), tensile, shear, and compressive strengths, and elongation (e...

J. M. Arvidson R. S. Bell L. L. Sparks C. Guobang

1983-01-01

440

Probabilistic Modeling of Ceramic Matrix Composite Strength  

NASA Technical Reports Server (NTRS)

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.

Shan, Ashwin R.; Murthy, Pappu L. N.; Mital, Subodh K.; Bhatt, Ramakrishna T.

1998-01-01

441

The Effects of Silanized Ultrafine Silica on the Curing Characteristics, Tensile Properties, and Morphological Study of Natural Rubber Compounds  

Microsoft Academic Search

The curing characteristics, tensile properties, and morphological of untreated and silanized ultrafine silica filled natural rubber with bis[(3-triethoxysilylpropyl)tetra sulfide] (Si-69) were studied. The results show the scorch time and cure time of silanized silica was shorter as compared to untreated silica at the same filler loading. On tensile properties, the presence of Si-69 had improved the tensile strength, elongation at