These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

Relationship of z-tensile strength with in-plane strength properties of paper  

Microsoft Academic Search

Several methods are available for the measurement of strength of paper in the thickness direction. However, the values obtained from these methods are highly correlated with each other and also with the in-plane strength measurements. The relationship between z-direction tensile strength and in-plane tensile index of handsheets made at varying extents of pulp beating, types of strength aids and doses

S P Singh

2

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

3

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

4

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

5

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

6

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

NASA Astrophysics Data System (ADS)

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

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

2008-06-01

7

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

Microsoft Academic Search

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

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

2008-01-01

8

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

NASA Astrophysics Data System (ADS)

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

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

2009-12-01

9

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

10

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

SciTech Connect

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

Zweben, C.

1981-07-22

11

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

12

Effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded high strength aluminium alloy  

Microsoft Academic Search

This paper reveals the effect of pulsed current and post weld aging treatment on tensile properties of argon arc welded AA7075 aluminium alloy. This alloy has gathered wide acceptance in the fabrication of light weight structures requiring high strength-to-weight ratio, such as transportable bridge girders, military vehicles, road tankers and railway transport systems. The preferred welding processes of high strength

V. Balasubramanian; V. Ravisankar; G. Madhusudhan Reddy

2007-01-01

13

CHARACTERIZATION OF TENSILE STRENGTH OF GLOVEBOX GLOVES  

SciTech Connect

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

Korinko, P.; Chapman, G.

2012-02-29

14

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

PubMed

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

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

2011-01-01

15

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

16

Tensile & shear strength of porous dust agglomerates  

E-print Network

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

Alexander Seizinger; Roland Speith; Wilhelm Kley

2013-08-23

17

The effects of laser trimming on the tensile strength and fatigue resistance properties of titanium - 6Al-4V  

E-print Network

The effect of laser trimming on the tensile strength and fatigue resistance of titanium-6% aluminum-4% vanadium specimens was investigated. Due to the nature of laser processing, the microstructure of the titanium alloy was altered in an area local...

Whitesel, Dean Adam

1994-01-01

18

Effects of strain-rate and pre-fatigue on tensile properties of laser welded joint of high strength steel plates  

NASA Astrophysics Data System (ADS)

The impact tensile properties of laser welded butt joints of two kinds of high strength steel plates with the tensile strength level of 590 MPa and 780 MPa (denoted by HR590 and HR780, respectively), were investigated using split Hopkinson bar tensile testing apparatus. Impact tension tests for the joint specimens pre-fatigued were also carried out to examine the effect of pre-fatigue. There were no significant effects of strain-rate and pre-fatigue on the dynamic and quasi-static tensile strength of laser welded butt joints. However, the decrease in the elongation of HR780 welded joints subjected high cycle pre-fatigue was observed only at a high strain-rate. From the observation of fracture surface, it was found that the decrease in the elongation may be caused by a number of damages due to the combination of high cycle pre-fatigue and high strain-rate.

Kobayashi, H.; Daimaruya, M.; Tsuda, H.; Horikawa, K.

2006-08-01

19

Surfactant effects on soil aggregate tensile strength  

Technology Transfer Automated Retrieval System (TEKTRAN)

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

20

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

SciTech Connect

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

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

1995-08-01

21

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

22

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

23

Tensile & shear strength of porous dust agglomerates  

E-print Network

Context.Within the sequential accretion scenario of planet formation, planets are build up through a sequence sticking collisions. The outcome of collisions between porous dust aggregates is very important for the growth from very small dust particles to planetesimals. In this work we determine the necessary material properties of dust aggregates as a function the porosity. Aims: Continuum models such as SPH that are capable of simulating collisions of macroscopic dust aggregates require a set of material parameters. Some of them such as the tensile and shear strength are ?difficult to obtain from laboratory experiments. The aim of this work is to determine these parameters from ab-initio molecular dynamics simulations. Methods: We simulate the behavior of porous dust aggregates using a detailed micro-physical model of the interaction of spherical grains that includes adhesion forces, rolling, twisting, and sliding. Using different methods of preparing the samples we study the strength behavior of our samples...

Seizinger, Alexander; Kley, Wilhelm

2013-01-01

24

Effect of Tensile Strength by Variations in Peel Strength in Laminated Film for Liquid Package  

NASA Astrophysics Data System (ADS)

Good tensile strength of a laminated film for packaging is an indispensable property in preventing leakage. It is known that the peel strength between laminated film layers is closely related to the tensile strength of the film. In this study, we have measured the tensile strength for various peel strengths of two kinds of three layered laminated film; Nylon + Aluminum + Polyethylene and Nylon + Polyester + Polyethylene. These films have two peel layers, so we escalated one peel strength and fix another one. Then we found that the peel strength between the sealant and the boundaries strongly influences the tensile strength. About Nylon + Polyester + Polyethylene film, we researched applied amount of adhesive and observed cross section of specimen at measurement of peel strength. Then we found that there is difference in specimen condition at measurement of peel strength, and examined about relationship of peel strength and stiffness of specimen.

Machida, Yukihiko; Shimamoto, Akira; Aoki, Hiroyuki; Futase, Katsunori

25

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

26

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

27

Composition–property relationships for an experimental composite nerve guidance conduit: evaluating cytotoxicity and initial tensile strength  

Microsoft Academic Search

The objective of this work was to examine the main (individual), combined (interaction) and second-order (quadratic) effects\\u000a of: (i) poly(d,l-lactide-co-glycolide) (PLGA), (ii) F127, and (iii) a zinc-silicate based bioactive glass, on the cytotoxicity and ultimate tensile strength\\u000a of an experimental nerve guidance conduit (NGC). The experimental plan was carried out according to a Box–Behnken design matrix.\\u000a The effects of each

S. Kehoe; X. F. Zhang; D. Boyd

2011-01-01

28

Tensile Properties of GRCop-84  

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

29

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

30

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

31

Tensile strength of liquid 4He  

NASA Astrophysics Data System (ADS)

Experiments to measure the tensile strength of liquids have often failed to reach the predicted value, presumably due to the onset of heterogeneous nucleation. Since it seemed impossible to completely eliminate all heterogeneous nucleation, we adopted a strategy that minimized its effect. A piezoelectric transducer in the form of a hemispherical shell was used to focus a short burst of ultrasound into a small volume of liquid 4He. The onset of cavitation was detected by the scattering of laser light. The experimental results both above and below the ? transition are in agreement with homogeneous-nucleation theory for a nucleation rate of approximately 1015 critical-size bubbles/s cm3. An apparent lowering of the tensile strength near the extension of the ? line into the metastable liquid is noted and discussed. This experiment extends the range of confirmation of the theoretically predicted tensile strength of liquids to a reduced pressure eight times further into the negative-pressure region than previous studies in any other liquid.

Nissen, J. A.; Bodegom, E.; Brodie, L. C.; Semura, J. S.

1989-10-01

32

The tensile strength of liquid helium four  

NASA Astrophysics Data System (ADS)

It is well known that most liquids exhibit a tensile strength which is much smaller in magnitude than the tensile strength predicted by homogeneous nucleation theory. Liquid helium occupies a unique place among liquids for tensile strength measurements because all foreign gases are frozen out at liquid temperatures. Moreover, superfluid He-4 should fill all crevises on solid surfaces, eliminating the chance of heterogeneous nucleation on helium vapor pockets. A piezoelectric transducer in the form of a hemispherical shell was used to focus high intensity ultrasound into a small volume of He-4. 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 nucleation was detected from the absorption of acoustic energy and the scattering of laser light from microscopic bubbles. A theory for light diffraction 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 transducer, calculations based on the acoustic power radiated into the liquid and nonlinear sound absorption.

Nissen, Joel Alan

1988-08-01

33

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

34

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

35

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

36

Tensile strength of the chromaffin granule membrane.  

PubMed

Catecholamine release from chromaffin granules, suspended in sucrose solutions of various osmotic strengths, was determined at different temperatures between 2 degrees and 44 degrees C. Dynamic measurements showed that steady state is achieved within 15 min of incubation at all temperatures. The effect of temperature on the release was established in terms of the median granular fragility (MGF) defined as the concentration of sucrose solution causing 50% lysis. The MGF was determined as the inflection point of the Gaussian distribution of granular fragility. The MGF was found to decrease with fall in temperature implying a corresponding increase of the tensile strength of the vesicle membrane. Critical resultant forces at lysis were calculated and found to vary from 8.2 dyn/cm at 2 degrees C to 4.2 dyn/cm at 44 degrees C. These compare well with tensions at lysis found earlier for erythrocytes. PMID:7104452

Hiram, Y; Nir, A; Zinder, O

1982-07-01

37

Tensile Strength of the Chromaffin Granule Membrane  

PubMed Central

Catecholamine release from chromaffin granules, suspended in sucrose solutions of various osmotic strengths, was determined at different temperatures between 2° and 44°C. Dynamic measurements showed that steady state is achieved within 15 min of incubation at all temperatures. The effect of temperature on the release was established in terms of the median granular fragility (MGF) defined as the concentration of sucrose solution causing 50% lysis. The MGF was determined as the inflection point of the Gaussian distribution of granular fragility. The MGF was found to decrease with fall in temperature implying a corresponding increase of the tensile strength of the vesicle membrane. Critical resultant forces at lysis were calculated and found to vary from 8.2 dyn/cm at 2°C to 4.2 dyn/cm at 44°C. These compare well with tensions at lysis found earlier for erythrocytes. PMID:7104452

Hiram, Yael; Nir, Avinoam; Zinder, Oren

1982-01-01

38

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

39

Microstructure-based simulations of the tensile strength of snow  

NASA Astrophysics Data System (ADS)

The mechanical behavior of snow is essential to understand the formation of snow avalanches. In particular, the failure properties of snow are determinant in snow slab avalanche release. Direct experiments on snow are difficult to conduct and to interpret. First, seasonal snow is often a very fragile material which can be easily damaged before a mechanical test is finished. Second, natural snow is generally not homogenous, but consists of many thin layers. Thus, a direct mechanical test is in this case very difficult to interpret. This motivated us to implement a numerical simulation that uses the full 3D-structure of snow. The microstructure of snow samples was captured with a micro-computer tomograph and the tensile strength of the same samples was measured. A subvolume (about 30 mm3) of the zone where the fracture occurred in the mechanical test was numerically simulated. To this purpose, the mechanical properties of monocrystalline ice were considered to model the constitutive material of snow. Because the orientation of ice grains cannot be determined in adsorption tomography, orientation-averaged properties were used as a first approximation. The results show that the average simulated tensile strength is in good agreement with the measurements for the tested snow, rounded grains at a density of about 350 kg m-3. In a second approach, a geometrical grain selection algorithm was used to associate to each ice grain a specific c-axis and the corresponding oriented anisotropic stiffness and strength. This artificial orientation of ice grains does not modify significantly the elastic stress distribution in the snow sample but decreases slightly the effective tensile strength of snow compared to the simulation using orientation-averaged properties of ice. As a conclusion, even if the size of the simulated volume remains relatively small (about 30 mm3), the direct numerical simulation of the tensile strength of snow is possible and enables the investigation of the failure behavior of snow at a microscopic scale.

Hagenmuller, P.; Theile, T.; Schneebeli, M.

2012-04-01

40

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

41

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

NASA Astrophysics Data System (ADS)

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

Okayasu, Mitsuhiro; Takeuchi, Shuhei; Ohfuji, Hiroaki

2014-11-01

42

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

43

Tensile strength and fracture of cemented granular aggregates.  

PubMed

Cemented granular aggregates include a broad class of geomaterials such as sedimentary rocks and some biomaterials such as the wheat endosperm. We present a 3D lattice element method for the simulation of such materials, modeled as a jammed assembly of particles bound together by a matrix partially filling the interstitial space. From extensive simulation data, we analyze the mechanical properties of aggregates subjected to tensile loading as a function of matrix volume fraction and particle-matrix adhesion. We observe a linear elastic behavior followed by a brutal failure along a fracture surface. The effective stiffness before failure increases almost linearly with the matrix volume fraction. We show that the tensile strength of the aggregates increases with both the increasing tensile strength at the particle-matrix interface and decreasing stress concentration as a function of matrix volume fraction. The proportion of broken bonds in the particle phase reveals a range of values of the particle-matrix adhesion and matrix volume fraction for which the cracks bypass the particles and hence no particle damage occurs. This limit is shown to depend on the relative toughness of the particle-matrix interface with respect to the particles. PMID:23160765

Affes, R; Delenne, J-Y; Monerie, Y; Radjaï, F; Topin, V

2012-11-01

44

Dynamic compressive and tensile strengths of spark plasma sintered alumina  

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

45

Dynamic compressive and tensile strengths of spark plasma sintered alumina  

SciTech Connect

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

Girlitsky, I.; Zaretsky, E. [Department of Mechanical Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel); Kalabukhov, S.; Dariel, M. P.; Frage, N. [Department of Materials Engineering, Ben-Gurion University of the Negev, P.O. Box 653, Beer-Sheva 84105 (Israel)

2014-06-28

46

Tensile-property characterization of thermally aged cast stainless steels  

SciTech Connect

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

Michaud, W.F.; Toben, P.T.; Soppet, W.K.; Chopra, O.K. [Argonne National Lab., IL (United States)

1994-02-01

47

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

48

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

49

General and mechanistic optimal relationships for tensile strength of doubly convex tablets under diametrical compression.  

PubMed

We propose a general framework for determining optimal relationships for tensile strength of doubly convex tablets under diametrical compression. This approach is based on the observation that tensile strength is directly proportional to the breaking force and inversely proportional to a non-linear function of geometric parameters and materials properties. This generalization reduces to the analytical expression commonly used for flat faced tablets, i.e., Hertz solution, and to the empirical relationship currently used in the pharmaceutical industry for convex-faced tablets, i.e., Pitt's equation. Under proper parametrization, optimal tensile strength relationship can be determined from experimental results by minimizing a figure of merit of choice. This optimization is performed under the first-order approximation that a flat faced tablet and a doubly curved tablet have the same tensile strength if they have the same relative density and are made of the same powder, under equivalent manufacturing conditions. Furthermore, we provide a set of recommendations and best practices for assessing the performance of optimal tensile strength relationships in general. Based on these guidelines, we identify two new models, namely the general and mechanistic models, which are effective and predictive alternatives to the tensile strength relationship currently used in the pharmaceutical industry. PMID:25683146

Razavi, Sonia M; Gonzalez, Marcial; Cuitiño, Alberto M

2015-04-30

50

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

51

Characterizing Curing-Cement Slurries by Permeability, Tensile Strength,  

E-print Network

Characterizing Curing-Cement Slurries by Permeability, Tensile Strength, and Shrinkage K.R. Backe oilwell cements. The results show that the curing characteristics are a function of temperature and that there is a correlation between shrinkage and cement content. The paper also introduces a new mechanism for gas migration

Backe, Knut

52

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

53

Influence of surface defects on the tensile strength of carbon fibers  

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

54

Compressive and diametral tensile strengths of current adhesive luting agents.  

PubMed

Strength parameters greatly influence the selection of luting agents. This study compared the compressive and diametral tensile strengths of six classes of new adhesive luting agents (ALAs) with zinc phosphate as the controls. The 11 materials tested were prepared according to the manufacturers' instructions for use as luting agents. Mean compressive and diametral strengths and standard errors were calculated for each luting agent (n = 10). Analysis of variance was computed (p < 0.0011) and multiple comparisons tests were performed. Compressive strengths varied from 41.5 MPa for a hydroxyapatite ALA to 178.5 MPa for a composite resin ALA. Diametral tensile strengths ranged from 8.1 MPa for a hydroxyapatite ALA to 45.1 MPa for a composite resin ALA. Conventional powder-liquid glass ionomer ALAs, an encapsulated glass ionomer ALA, a composite resin-glass ionomer hybrid ALA, and the composite resin ALAs demonstrated significantly greater compressive and diametral strengths than the zinc phosphate cements. PMID:8391577

White, S N; Yu, Z

1993-06-01

55

The Effect of Reprocessing on the Tensile Properties of Composites  

NASA Astrophysics Data System (ADS)

In this study, waste cotton fabric reinforced polymer matrix composite material has been manufactured by a custom made recycling extruder. Composites with different reinforcement ratios as 12,5%wt ( 12,5%wtRPE ) and 25%wt ( 25%wtRPE ) were tested for their mechanical properties such as tensile strength and young's modulus. The material was then granulated down to the size enough to be used in the extrusion process in order to observe the effects of reprocessing. Reprocessing leads to improve Tensile Strength of composite materials and slows down the reduction of tensile strength of polyethylene. It was observed that composite materials were highly affected by the fiber orientation and acts as anisotropic material under the load.

Bodur, Mehmet Safa; Bakkal, Mustafa; Berkalp, Omer Berk; Sadikoglu, Telem Gok

2011-01-01

56

Tensile fatigue properties of fibre Bragg grating optical fibre sensors  

Microsoft Academic Search

This paper presents an experimental study into the tensile strength and fatigue properties of uncoated optical glass fibres containing Bragg grating (FBG) sensors. The protective polymer coating of the optical fibres must be removed by chemical or mechanical stripping methods to produce the Bragg gratings in the fibre core. This paper investigates the effects of chemical or mechanical stripping on

J. Ang; H. C. H. Li; I. Herszberg; M. K. Bannister; A. P. Mouritz

2010-01-01

57

Modeling of the temperature-dependent ideal tensile strength of solids  

NASA Astrophysics Data System (ADS)

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

Cheng, Tianbao; Li, Weiguo; Fang, Daining

2014-08-01

58

The ultimate tensile strength of metal and ceramic-matrix composites  

Microsoft Academic Search

The tensile strength of ceramic and metal matrix composites is subject to an important role of the fiber\\/matrix interface. The mechanical properties of this interface dictate the stress concentration that develops in fibers that surround a failed fiber. An analysis of this phenomenon is used to illustrate interface conditions that sufficiently diminish the stress concentration that a global load sharing

M. Y. He; A. G. Evans; W. A. Curtin

1993-01-01

59

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. PMID:25006377

Champirat, Tharee; Jirajariyavej, Bundhit

2014-01-01

60

A micromechanics model for predicting the tensile strength of unidirectional metal matrix composites  

SciTech Connect

In this paper, a micromechanics model has been developed to predict the tensile strength of unidirectional metal matrix composites (MMC). A simplified shear lag analysis is used to estimate the local stresses in the various constituents (fiber/matrix/interface). In this work, the matrix is assumed to carry both normal and shear stresses. Global matrix plasticity is considered by assuming that the matrix behaves in an elastic-perfectly plastic manner. Local interfacial debonding is assumed to occur when the average interfacial shear stress exceeds the interfacial shear strength value. The shear lag analysis including the effects of interfacial debonding and global matrix plasticity is used to estimate the stress concentration in fibers adjacent to broken fibers and the ineffective length. The tensile strength is estimated by considering the accumulation of fiber fractures. The effects of residual thermal stresses and statistical distribution of strength of the fibers are also included in this analysis. Parametric studies were conducted to investigate the influence of various parameters such as fiber volume fraction, temperature, interfacial shear strength, matrix properties and fiber strength, on the unidirectional tensile strength of MMC. The model was also used to predict the effects of volume fraction and temperature, on the strength of SCS6/Ti 24-11 composites. The predicted values compared well with the experimental results.

Subramanian, S. [Ad Tech Systems Research, Beavercreek, OH (United States)

1995-12-31

61

A novel indirect tensile test method to measure the biaxial tensile strength of concretes and other quasibrittle materials  

SciTech Connect

A novel indirect tensile test method, the biaxial flexure test (BFT) method, has been developed to measure the biaxial tensile strength of concretes. The classical modulus of rupture (MOR) test has been generalized to three dimensions. In this method, we use a circular plate as the new test specimen. This plate is supported by an annular ring. We apply an external load to this specimen through a circular edge. The centers of the specimen, the loading device and the support are identical. The biaxial tensile strength measured by this new method is about 19% greater than the uniaxial tensile strength obtained from the classical modulus of rupture test as reported by other researchers. However, at the same time, we also found that the stochastic deviation of the biaxial tensile strength is about 63% greater than the uniaxial strength.

Zi, Goangseup [Department of Civil, Environmental and Architectural Engineering, Korea, University, 5 Ga 1, An-Am Dong, Sung-Buk Gu, Seoul, 136-701 (Korea, Republic of)], E-mail: g-zi@korea.ac.kr; Oh, Hongseob [Department of Civil Engineering, Jinju National University, 150 Chilam Dong, Jinju, Kyongnam, 660-758 (Korea, Republic of); Park, Sun-Kyu [Department of Civil Engineering, Sungkyunkwan University, 300 Cheoncheon Dong, Jangan Gu, Suwon, Gyeonggi, 440-746 (Korea, Republic of)

2008-06-15

62

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes  

Microsoft Academic Search

Gigacycle fatigue behaviors of two SNCM439 steels with different tensile strengthes were experimentally studied by rotating\\u000a bending tests, to investigate the effects of the tensile strength obtained by different heat treatment processes on very high\\u000a cycle fatigue failure mechanisms. The material with higher tensile strength of 1 710MPa exhibited typical gigacycle fatigue\\u000a failure characteristics, whereas one with lower tensile strength

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

63

Tensile properties of welded helium charged 304L stainless steel  

NASA Astrophysics Data System (ADS)

The room-temperature tensile properties of helium-containing 304L stainless steel subjected to thermal cycles simulating fusion welding conditions have been measured. Helium was introduced into tensile specimens by tritium charging, and aged to generate 526 appm 3He by radioactive decay. The specimens were then vacuum annealed to remove the tritium. The helium-charged samples were subjected to transient thermal cycles simulating those occurring in the heat affected zone of a gas tungsten arc weld. Peak temperatures above 1073 K caused severe ductility losses, fracture mode changes (from ductile transgranular rupture to ductile intergranular fracture), and losses in ultimate tensile strength. These effects are attributed to helium redistribution and void growth on the grain boundary. Subsequently, grain boundary failure occurs during tensile testing because of the large quantity of trapped helium on the boundary.

Robinson, S. L.

1988-05-01

64

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

65

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

66

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

67

Tensile and compressive properties of flax fibres for natural fibre reinforced composites  

Microsoft Academic Search

Mechanical properties of standard decorticated and hand isolated flax bast fibres were determined in tension as well as in compression. The tensile strength of technical fibre bundles was found to depend strongly on the clamping length. The tensile strength of elementary flax fibres was found to range between 1500 MPa and 1800 MPa, depending on the isolation procedure. The compressive

H. L. Bos; M. J. A. Van Den Oever; O. C. J. J. Peters

2002-01-01

68

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

69

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

70

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

71

Tensile strength and the mining of black holes.  

PubMed

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. PMID:24313473

Brown, Adam R

2013-11-22

72

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

NASA Technical Reports Server (NTRS)

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

Haddock, M. Reed; McLennan, Michael L.

2000-01-01

73

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

74

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

75

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

76

The Effect of Temperature on Compressive and Tensile Strengths of Commonly Used Luting Cements: An In Vitro Study  

PubMed Central

Background: The luting cements must withstand masticatory and parafunctional stresses in the warm and wet oral environment. Mouth temperature and the temperature of the ingested foods may induce thermal variation and plastic deformation within the cements and might affect the strength properties. The objectives of this study were to evaluate the effect of temperature on the compressive and diametral tensile strengths of two polycarboxylate, a conventional glass ionomer and a resin modified glass ionomer luting cements and, to compare the compressive strength and the diametral tensile strength of the selected luting cements at varying temperatures. Materials and Methods: In this study, standardized specimens were prepared. The temperature of the specimens was regulated prior to testing them using a universal testing machine at a crosshead speed of 1 mm/min. Six specimens each were tested at 23°C, 37°C and 50°C for both the compressive and diametral tensile strengths, for all the luting cements. Results: All the luting cements showed a marginal reduction in their compressive and diametral tensile strengths at raised temperatures. Fuji Plus was strongest in compression, followed by Fuji I > Poly F > Liv Carbo. Fuji Plus had the highest diametral tensile strength values, followed by Poly F = Fuji I = Liv Carbo, at all temperatures. Conclusion: An increase in the temperature caused no significant reduction in the compressive and diametral tensile strengths of the cements evaluated. The compressive strength of the luting cements differed significantly from one another at all temperatures. The diametral tensile strength of resin modified glass ionomers differed considerably from the other cements, whereas there was no significant difference between the other cements, at all the temperatures.

Patil, Suneel G; Sajjan, MC Suresh; Patil, Rekha

2015-01-01

77

Tensile Properties of Hydrogels and of Snake Skin  

NASA Technical Reports Server (NTRS)

Stimulus-responsive or 'smart' gels are of potential interest as sensors and actuators, in industrial separations, and as permeable delivery systems. In most applications, a certain degree of mechanical strength and toughness will be required, yet the large-strain behavior of gels has not been widely reported. Some exceptions include work on gelatin and other food gels, some characterization of soft gels applicable for in-vitro cell growth studies, and toughness determinations on commercial contact lens materials. In general, it can be anticipated that the gel stiffness will increase with increasing degree of crosslinking, but the tensile strength may go through a maximum. Gel properties can be tailored by varying not only the degree of crosslinking, but also the polymer concentration and the nature of the polymer backbone (e.g. its stiffness or solubility). Polypeptides provide an especially interesting case, where secondary structure affects trends in moduli and conformational transitions may accompany phase changes. A few papers on the tensile properties of responsive gels have begun to appear. The responsive hydrogel chosen for the present study, crosslinked hydroxypropylcellulose, shrinks over a rather narrow temperature range near 44 C. Some vertebrate skin is also subject to substantial strain. Among reptiles, the morphologies of the skin and scales show wide variations. Bauer et al. described the mechanical properties and histology of gecko skin; longitudinal tensile properties of snake skin were examined by Jayne with reference to locomotion. The present measurements focus on adaptations related to feeding, including the response of the skin to circumferential tension. Tensile properties will be related to interspecific and regional variation in skin structure and folding.

Hinkley, Jeffrey A.; Savitzky, Alan H.; Rivera, Gabriel; Gehrke, Stevin H.

2002-01-01

78

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. PMID:24931632

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

2014-01-01

79

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

80

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

81

Optical absorption as a sensitive monitor of tensile strength loss in thermally aged nylon 6,6  

Microsoft Academic Search

Chemical changes which take place in polymers during thermal aging often adversely affect the bulk physical properties of the material. Aging rates under ambient conditions are usually so slow as to require extremely long aging cycles to achieve measurable losses in such properties as tensile strength. Therefore, accelerated aging under more stressful conditions (e.g., higher temperatures) with Arrhenius-plot extrapolations to

1985-01-01

82

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

83

Effect of surface treatment on the hydrolytic stability of E-glass fiber bundle tensile strength  

E-print Network

Effect of surface treatment on the hydrolytic stability of E-glass fiber bundle tensile strength E surface treatment on the hydrolytic stability of tensile strength is investigated for E-glass fiber and silane, starch and wax, and epoxy surface treatments are tested following exposure to 10%, 40%, 80

Sottos, Nancy R.

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

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

86

The role of defects in the tensile properties of silicene  

NASA Astrophysics Data System (ADS)

Effects of vacancies and Stone-Wales defects on the mechanical properties of silicene are investigated through molecular dynamic finite element method with Tersoff potential. Young's modulus, Poisson's ratio and uniaxial tensile stress-strain curves are considered in the armchair and zigzag directions. It is found that pristine and lowly defective silicene sheets exhibit almost the same elastic nature up to fracture points. However, a single defect weakens significantly the silicene sheet, resulting in a considerable reduction in the fracture strength. One 2-atom vacancy in the sheet's center reduces 18-20 % in fracture stress and 33-35 % in fracture strain. The weakening effects of Stone-Wales defects vary with the tensile direction and the orientation of these defects.

Le, Minh-Quy; Nguyen, Danh-Truong

2015-03-01

87

The postirradiation tensile properties and microstructure of several vanadium alloys  

SciTech Connect

Tensile specimens of V-15Cr-5Ti, Vanstar-7, V-3Ti-1si, and V-20Ti were irradiated at 420)degrees)C in FFTF-MOTA to a damage level of 82 dpa. Helium was preimplanted to levels up to 480 appm in selected specimens using a modified tritium trick. Irradiation hardening was the dominant effect influencing the postirradiation tensile properties, and it markedly increased the yield strength and reduced the total elogation. The V-15Cr-5Ti alloy was very sensitive to helium embrittlement, but Vanstar-7 and V-3Ti-1Si were only slightly affected. Without helium, negligible swelling (<1%) were measured in V-3Ti-1Si and V-20Ti. Preimplanted helium increased swelling in V-3Ti-1Si by increasing cavity nucleation. 11 refs., 11 figs., 3 tabs.

Braski, D.N.

1988-01-01

88

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

PubMed

Carbyne and carbyne-based low-dimensional structures are promising for several applications including ultra-compact circuits and purification devices. Designing any applied carbyne-based structure requires a fundamental understanding of the mechanical strength of carbyne chains with different lengths at different temperatures and operating chemical environment. Here we use molecular dynamics simulations to investigate the strength of carbyne chains with different lengths at different temperatures. A theoretical framework based on statistical mechanics and molecular dynamics results is presented, proving a fast and insightful method for predicting the rupture force and its physical mechanism. The effect of water molecules' interaction is also studied on the mechanical properties and it is shown that both the tensile strength and rupture strain are improved by the water interaction. The results of this work can be used for designing and analyzing the robustness and reliability of various carbyne-based materials and applied devices for varies working conditions. PMID:25148690

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

2014-09-19

89

Biocomposites from abaca strands and polypropylene. Part I: Evaluation of the tensile properties.  

PubMed

In this paper, abaca strands were used as reinforcement of polypropylene matrix and their tensile mechanical properties were studied. It was found relevant increments on the tensile properties of the abaca strand-PP composites despite the lack of good adhesion at fiber-matrix interface. Afterwards, it was stated the influence of using maleated polypropylene (MAPP) as compatibilizer to promote the interaction between abaca strands and polypropylene. The intrinsic mechanical properties of the reinforcement were evaluated and used for modeling both the tensile strength and elastic modulus of the composites. For these cases, the compatibility factor for the ultimate tensile strength was deduced from the modified rule of mixtures. Additionally, the experimental fiber orientation coefficient was measured, allowing determining the interfacial shear strengths of the composites and the critical fiber length of the abaca strand reinforcement. The mechanical improvement was compared to that obtained for fiberglass-reinforced PP composites and evaluated under an economical and technical point of view. PMID:19700312

Vilaseca, Fabiola; Valadez-Gonzalez, Alex; Herrera-Franco, Pedro J; Pèlach, M Angels; López, Joan Pere; Mutjé, Pere

2010-01-01

90

Tensile Properties of Austenitic Stainless Steel  

E-print Network

the non­linear trends of steel strength, attention was diverted to neural networks, which can allow to be in good agreement with the literature and the use of contour plots demonstrated the ability to capture non­linear to optimise the properties. The data are generally analysed using linear regression models [1,2] to reveal

Cambridge, University of

91

SIZE EFFECTS IN THE TENSILE STRENGTH OF UNIDIRECTIONAL FIBER COMPOSITES  

SciTech Connect

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

M. SIVASAMBU; ET AL

1999-08-01

92

Effect of strain rate on formability in warm deep drawing of high tensile strength steel sheet  

NASA Astrophysics Data System (ADS)

In tensile test of the high tensile strength steel, tensile strength isdrastically decreased as the temperature is raised. Then, the strain rate sensitivity exponent of high tensile strength steel (SUS631) in this study is high at 800 degrees especially. Also, elongation is increased as the temperature is raised. In deep drawing, the maximum punch load of the high tensile strength steel is examined on difference punch speed at 600 and 800 degrees. On the other hand, finite element (FE) simulation was used for the possibility to evaluate the forming load on difference punch speed in warm deep drawing. In FE simulation, we have considered both the strain hardening exponent and the strain rate sensitivity exponent (m-value) because we cannot neglect m-value 0.184 at 800 degrees. The tendency of the forming load in the experiments agrees the results in FE simulation.

Yoshihara, Shoichiro; Iwamatsu, Go

2014-10-01

93

Dependence of the Tensile Strength of Pitch-Based Carbon and Para-Aramid Fibres on the Rate of Strain  

Microsoft Academic Search

Understanding the rate dependencies of the tensile strength of reinforcing fibres is a key for the understanding of the rate dependencies of the properties of the corresponding composite materials. Hence, in this study it is attempted to clarify the mechanical responses of aramid and carbon fibres at different rates of strain in the light of our previous observations of strain

H. D. Wagner; J. Aronhime; G. Marom

1990-01-01

94

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

NASA Technical Reports Server (NTRS)

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

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

2014-01-01

95

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

SciTech Connect

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

Haghparast, Amin [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)] [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nourimotlagh, Masoud [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of)] [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of); Alipour, Mohammad, E-mail: Alipourmo@ut.ac.ir [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)] [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

2012-09-15

96

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

97

Predicting the Open-Hole Tensile Strength of Composite Plates Based on Probabilistic Neural Network  

NASA Astrophysics Data System (ADS)

Tensile experiments were performed for open-hole composite plates with three different layups. With the limited number of experimental results, a probabilistic neural network (PNN) based approach is proposed to predict the tensile strength of composite plates with an open-hole. The predictive model takes the geometric parameters, the layup features and the average tensile stress of open-hole composite plates as the inputs and produces the safety status as the intermediate output with the classification function of PNN. Then the critical safety point, that is the open-hole tensile strength, where the safety status turns from survival to failure, is determined with the bi-section searching method. The predictions produce acceptable results whose errors are comparable to the coefficient of variation of experimental results. With experimental data from other studies, further assessments are also made to prove the capability of this model in predicting the open-hole tensile strength of composite plates.

Fan, Hai-Tao; Wang, Hai

2014-12-01

98

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

SciTech Connect

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 sizes of 5-80 nm and bulk densities on the order of 95% of theoretical density are increased 2--5 times over that measured in pure, annealed samples of the same composition with micrometer grain sizes. Ductility in the nanocrystalline Cu has exceeded 6% true strain, however, nanocrystalline Pd samples were much less ductile. Constant load creep tests performed at room temperature at stresses of >100 MPa indicate logarithmic creep. The mechanical properties results are interpreted to be due to grain size-related strengthening and processing flaw-related weakening. 26 refs., 2 figs.

Nieman, G.W.; Weertman, J.R. (Northwestern Univ., Evanston, IL (USA). Dept. of Materials Science and Engineering); Siegel, R.W. (Argonne National Lab., IL (USA))

1990-12-01

99

Optimization of tensile strength of ferritic/austenitic laser-welded components  

NASA Astrophysics Data System (ADS)

Ferritic/austenitic (F/A) joints are a popular dissimilar metal combination used in many applications. F/A joints are usually produced using conventional processes. Laser beam welding (LBW) has recently been successfully used for the production of F/A joints with suitable mechanical properties. In this study, a statistical design of experiment (DOE) was used to optimize selected LBW parameters (laser power, welding speed and focus length). Taguchi approach was used for the selected factors, each having five levels (L-25; 5×3). Joint strength was determined using the notched-tensile strength (NTS) method. The results were analysed using analyses of variance (ANOVA) and the signal-to-noise ( S/ N) ratios for the optimal parameters, and then compared with the base material. The experimental results indicate that the F/A laser-welded joints are improved effectively by optimizing the input parameters using the Taguchi approach.

Anawa, E. M.; Olabi, A. G.

2008-08-01

100

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

101

Concrete Material Models Concrete_1: Concrete Model with No Tensile Strength  

E-print Network

Concrete Material Models Concrete_1: Concrete Model with No Tensile Strength INPUT Concrete_1, matID ¢f fc cu u, , ,e e0 Definitions (Fig. 1): fc : concrete compressive strength at 28 days (compression is negative) A0 : concrete strain at maximum strength (compression is negative) fcu : concrete crushing

Filippou, Filip C.

102

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

103

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. PMID:24883355

Min, Fanlu; Yao, Zhanhu; Jiang, Teng

2014-01-01

104

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

105

Low-velocity impact and residual tensile strength analysis to carbon fiber composite laminates  

Microsoft Academic Search

In this paper, low-velocity impact characteristics and residual tensile strength of carbon fiber composite laminates 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 finite element (FE) software, ABAQUS\\/Explicit is employed to simulate low-velocity impact characteristics and predict

Shi-Xun Wang; Lin-Zhi Wu; Li Ma

2010-01-01

106

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

NASA Astrophysics Data System (ADS)

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

Fukushi, Miyuki; Miyata, Hiroshi; Murakami, Akira

107

Effect of plastic anisotropy on tensile strength of single crystals of an Ni-based superalloy  

SciTech Connect

Turbine blades are designed so that their primary orientation is within 10 to 15{degree} of the <001> axis to insure a low modulus. The secondary dendritic direction (<010> direction) is usually randomly orientated with respect to the longitudinal direction of the turbine blade. The strengths of single crystals are influenced by the crystallographic orientations not only in the tensile direction but also in the normal direction of the specimen because a single crystal possesses intrinsic plastic anisotropy. The air-cooled turbine blades, which have a complicated hollow structure, are composed of sections of various thicknesses. Therefore, the mechanical properties of each blade section will depend on plastic anisotropy and the stress state as well as stress in the longitudinal direction. In previous studies, in an experimental single crystal alloy of an Ni-based superalloy, it has been revealed that {l_brace}111{r_brace}<101>-type slip systems were activated during tensile tests. In this study, by using the experimental alloy which shows distinct active slip systems, the influence of crystallographic orientations and plastic anisotropy on the strength and ductility of single crystals of the Ni-based superalloy have been investigated on the assumption that the {l_brace}111{r_brace}<101> slip systems operate.

Kakehi, K.

1999-12-31

108

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

109

Enzymatic surface erosion of high tensile strength polycarbonates based on natural phenols.  

PubMed

Surface erosion has been recognized as a valuable design tool for resorbable biomaterials within the context of drug delivery devices, surface coatings, and when precise control of strength retention is critical. Here we report on high tensile strength, aromatic-aliphatic polycarbonates based on natural phenols, tyrosol (Ty) and homovanillyl alcohol (Hva), that exhibit enzymatic surface erosion by lipase. The Young's moduli of the polymers for dry and fully hydrated samples are 1.0 to 1.2 GPa and 0.8 to 1.2 GPa, respectively. Typical characteristics of enzymatic surface erosion were confirmed for poly(tyrosol carbonate) films with concomitant mass-loss and thickness-loss at linear rates of 0.14 ± 0.01 mg cm(-2) d(-1) and 3.0 ± 0.8 ?m d(-1), respectively. The molecular weight and the mechanical properties of the residual films remained constant. Changing the ratio of Ty and Hva provided control over the glass transition temperature (T(g)) and the enzymatic surface erosion: increasing the Hva content in the polymers resulted in higher T(g) and lower enzymatic erosion rate. Polymers with more than 50 mol % Hva were stable at 37 °C in enzyme solution. Analysis on thin films using quartz crystal microbalance with dissipation (QCM-D) demonstrated that the onset temperature of the enzymatic erosion was approximately 20 °C lower than the wet T(g) for all tested polymers. This new finding demonstrates that relatively high tensile strength polycarbonates can undergo enzymatic surface erosion. Moreover, it also sheds light on the connection between T(g) and enzymatic degradation and explains why few of the high strength polymers follow an enzyme-meditated degradation pathway. PMID:24432806

Sommerfeld, Sven D; Zhang, Zheng; Costache, Marius C; Vega, Sebastián L; Kohn, Joachim

2014-03-10

110

Tensile and fatigue properties of 17-4 PH stainless steel at high temperatures  

Microsoft Academic Search

The tensile and high-cycle fatigue properties for 17-4 PH* stainless steels in three different conditions were investigated\\u000a at temperatures ranging from room temperature to 400 C. Results indicated that the yield strength and fatigue strength for\\u000a the three conditions at a given temperature took the following order: condition H900 > condition A> condition H1150. The yield\\u000a strength of each condition

Jui-Hung Wu; Chih-Kuang Lin

2002-01-01

111

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.

112

Study of the tensile properties of living skin equivalents.  

PubMed

The living skin equivalent is one of the more advanced clinical applications in the field of tissue engineering. It is a promising therapeutic option for burn victims and a strong potential for manifold in vitro experiments. However, researchers have encountered major drawbacks in the reconstruction of the dermal layer. Peripheral anchorage of the dermal equivalent component has been a valuable solution to many of these problems. In this work, we have carried out the mechanical analysis of skin equivalent models, based on this dermal anchoring technique, with a study of their biaxial tensile properties. Differences between models were related to the origin of collagen, either bovine or human, and on the culture techniques: immersion or at the air-liquid interface. The study was accomplished in vitro using 25.4-mm-diameter disk-shaped specimens with an indentation test. In appropriate wet condition, the specimens were punctured with a spherical tip at a quasi-static rate. We measured the load applied against the tip vs deflection up to the breaking point. Our results show that skin equivalents presented a typical exponential load-deflection relationship. All skin equivalents presented large extensibility up to 1.41 expressed in a ratio of deflection vs specimen's radius. The maximum tensile strength (0.871-1.169 Newton) and energy calculations (3.75-6.432 N.mm) was offered by living skin equivalent, made with human types I and III collagens, cultured at the air-liquid interface. In these conditions, our results suggest the tensile properties of living skin equivalents were enhanced due to the development of well stratified stratum corneum. PMID:8785505

Lafrance, H; Yahia, L; Germain, L; Guillot, M; Auger, F A

1995-01-01

113

Tensile properties in the oriented blends of high-density polyethylene and isotactic polypropylene obtained by dynamic packing injection molding  

Microsoft Academic Search

In this article, tensile properties have been discussed in terms of phase morphology, crystallinity and molecular orientation in the HDPE\\/iPP blends, prepared via dynamic packing injection molding, with aid of scanning electron microscopy (SEM), differential scanning calorimetry (DSC) as well as two dimensional X-ray scattering (2D WAXS). For the un-oriented blends, the tensile properties (tensile strength and modulus) are mainly

Bing Na; Ke Wang; Qin Zhang; Rongni Du; Qiang Fu

2005-01-01

114

Microstructure-Tensile Properties Correlation for the Ti-6Al-4V Titanium Alloy  

NASA Astrophysics Data System (ADS)

Finding the quantitative microstructure-tensile properties correlations is the key to achieve performance optimization for various materials. However, it is extremely difficult due to their non-linear and highly interactive interrelations. In the present investigation, the lamellar microstructure features-tensile properties correlations of the Ti-6Al-4V alloy are studied using an error back-propagation artificial neural network (ANN-BP) model. Forty-eight thermomechanical treatments were conducted to prepare the Ti-6Al-4V alloy with different lamellar microstructure features. In the proposed model, the input variables are microstructure features including the ? platelet thickness, colony size, and ? grain size, which were extracted using Image Pro Plus software. The output variables are the tensile properties, including ultimate tensile strength, yield strength, elongation, and reduction of area. Fourteen hidden-layer neurons which can make ANN-BP model present the most excellent performance were applied. The training results show that all the relative errors between the predicted and experimental values are within 6%, which means that the trained ANN-BP model is capable of providing precise prediction of the tensile properties for Ti-6Al-4V alloy. Based on the corresponding relations between the tensile properties predicted by ANN-BP model and the lamellar microstructure features, it can be found that the yield strength decreases with increasing ? platelet thickness continuously. However, the ? platelet thickness exerts influence on the elongation in a more complicated way. In addition, for a given ? platelet thickness, the yield strength and the elongation both increase with decreasing ? grain size and colony size. In general, the ? grain size and colony size play a more important role in affecting the tensile properties of Ti-6Al-4V alloy than the ? platelet thickness.

Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing; Guo, Ping

2015-04-01

115

Microstructure-Tensile Properties Correlation for the Ti-6Al-4V Titanium Alloy  

NASA Astrophysics Data System (ADS)

Finding the quantitative microstructure-tensile properties correlations is the key to achieve performance optimization for various materials. However, it is extremely difficult due to their non-linear and highly interactive interrelations. In the present investigation, the lamellar microstructure features-tensile properties correlations of the Ti-6Al-4V alloy are studied using an error back-propagation artificial neural network (ANN-BP) model. Forty-eight thermomechanical treatments were conducted to prepare the Ti-6Al-4V alloy with different lamellar microstructure features. In the proposed model, the input variables are microstructure features including the ? platelet thickness, colony size, and ? grain size, which were extracted using Image Pro Plus software. The output variables are the tensile properties, including ultimate tensile strength, yield strength, elongation, and reduction of area. Fourteen hidden-layer neurons which can make ANN-BP model present the most excellent performance were applied. The training results show that all the relative errors between the predicted and experimental values are within 6%, which means that the trained ANN-BP model is capable of providing precise prediction of the tensile properties for Ti-6Al-4V alloy. Based on the corresponding relations between the tensile properties predicted by ANN-BP model and the lamellar microstructure features, it can be found that the yield strength decreases with increasing ? platelet thickness continuously. However, the ? platelet thickness exerts influence on the elongation in a more complicated way. In addition, for a given ? platelet thickness, the yield strength and the elongation both increase with decreasing ? grain size and colony size. In general, the ? grain size and colony size play a more important role in affecting the tensile properties of Ti-6Al-4V alloy than the ? platelet thickness.

Shi, Xiaohui; Zeng, Weidong; Sun, Yu; Han, Yuanfei; Zhao, Yongqing; Guo, Ping

2015-02-01

116

The degradation in tensile strength of polymer-coated glass optical fibres under ?-irradiation  

Microsoft Academic Search

The tensile strength of glass optical fibres when coated with various polymers has been measured as a function of ?-ray dose. Fibres protected with acrylate, silicone + acrylate or polyimide coatings showed little degradation after receiving a total dose of 1 MGy (they retained >95% of their preirradiated strength). For a fibre with an extruded nylon overcoat the nylon became

J. O. W. Norris; S. A. Norman; M. J. Tribble

1991-01-01

117

[Biomechanic study of the tensile strength of lyophilized and deep frozen human Achilles tendons following gamma and ethylene oxide sterilization].  

PubMed

By a failed first operation allogenic tissues, as human Achilles tendons are offered for anterior cruciate ligament replacement. The effects of freeze-drying and primary Gamma- or EO-sterilization on the mechanical properties of 62 complete and 74 bisected tendons again fresh frozen controls were investigated under axial tension. A significant decrease of tensile strength for the freeze-dried preparations of 33% for the whole and 43% for the bisected tendons were observed, while Gamma- or EO-sterilizations showed a smaller deleterious effect on the tendons. Considering only the primary mechanical strength complete freeze-dried or complete and bisected irradiated Achilles tendons show sufficient tensile strength for anterior cruciate ligament replacement. PMID:1836694

Rauch, G; Gerbersdorf, M; Dörner, P; Lengsfeld, M; Griss, P

1991-01-01

118

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

119

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

120

Establishing Correlations for Predicting Tensile Properties Based on the Shear Punch Test and Vickers Microhardness data  

NASA Astrophysics Data System (ADS)

A series of mechanical tests was performed on a matrix of pressure vessel alloys to establish correlations between shear punch tests (SPT), microhardness (Hv), and tensile data. The purpose is to estimate tensile properties from SPT and Hv data. Small specimen testing is central to characterization of irradiation-induced changes in alloys used for nuclear applications. SPT have the potential for estimating tensile yield and ultimate strengths, strain hardening and ductility data, by using TEM disks, for example. Additional insight into SPT was gained by performing finite element analysis (FEA) simulations.

Milot, Timothy S.

121

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

122

Optical absorption as a sensitive monitor of tensile strength loss in thermally aged nylon 6,6  

SciTech Connect

Chemical changes which take place in polymers during thermal aging often adversely affect the bulk physical properties of the material. Aging rates under ambient conditions are usually so slow as to require extremely long aging cycles to achieve measurable losses in such properties as tensile strength. Therefore, accelerated aging under more stressful conditions (e.g., higher temperatures) with Arrhenius-plot extrapolations to ambient conditions is often employed. Since this scheme requires that there is no change in the predominate aging mechanism at higher temperatures, one would prefer to increase the sensitivity of aging detection so one could measure aging at lower temperatures on a reasonable time scale. We describe here the use of optical absorption spectrophotometry as a sensitive monitor of thermal aging in nylon 6,6 which correlates with tensile strength loss. 8 refs., 3 figs.

Renschler, C.L.

1985-01-01

123

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

PubMed Central

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

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

1988-01-01

124

On the Compressive and Tensile Strength of Magnesium Aluminate Spinel  

NASA Astrophysics Data System (ADS)

Magnesium aluminate spinel is a strong polycrystalline transparent ceramic. Spinel is an attractive material for armor applications and its behavior under shock wave loading is of obvious interest. The purpose of the present study was to determine the Hugoniot elastic limit (HEL) of this material, its Hugoniot response above the HEL, and its spall strength. Planar impact experiments were performed over the 2 to 40 GPa stress range using the Velocity Interferometer System for Any Reflector (VISAR) as a principal diagnostics tool. According to these tests, spinel has a HEL of about 11.3 GPa. The spall strength of the material was found to be close to zero at low, about 2 GPa, impact stress.

Paris, V.; Hayun, S.; Dariel, M. P.; Frage, N.; Zaretsky, E.

2009-12-01

125

Tensile strengths of hydrous vesicular glasses: An experimental study  

Microsoft Academic Search

We have measured the pressures of decrepitation of vesicles in synthetic glasses of feldspar compositions (NaAlSi30g-KAlSi30g). Vesicles filled with Xe do not decrepitate at internal pressures of 160 MPa, indicating that the unflawed surface of the vesicle wall has an intrinsic strength > 80 MPa. Vesicles containing C02 escaped decrepitation and displayed ductile deformation when the Tg was reached at

C. ROMANO; J. E. MUNGALL; T. SHARP; B. DINGWELL

126

Differences of tensile strength distribution between mechanically high-grade and low-grade Japanese larch lumber 11: Effect of knots on tensile strength distribution  

Microsoft Academic Search

The tensile strength (TS) test results of Japanese larch (Larix kaempferi, Carriere) lumber of varying length have shown that the length effects on TS were different between high-grade (H) and low-grade\\u000a (L) lumber. In this paper, we examined the effect of knots on the TS distribution by measuring the number of knots and the\\u000a knot area ratio of each specimen.

Takashi Takeda; Takeo Hashizume

1999-01-01

127

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

NASA Astrophysics Data System (ADS)

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 pulse loading for postmortem examination. Tests without and with pulse shaping are conducted on rock specimens. The evolution of tensile stress at the failure spot is determined via dynamic and quasistatic finite element analyses with the dynamic loads measured from SHPB as inputs. Given properly shaped incident pulse, far-field dynamic force balance is achieved and the peak of the loading matches in time with the rupture onset of the specimen. In addition, the dynamic tensile stress history at the failure spot obtained from the full dynamic finite element analysis agrees with the quasistatic analysis. The opposite occurs for the test without pulse shaping. These results demonstrate that when the far-field dynamic force balance is satisfied, the inertial effects associated with stress wave loading are minimized and thus one can apply the simple quasistatic analysis to obtain the tensile strength in the SCB-SHPB testing. This method provides a useful and cost effective way to measure indirectly the dynamic tensile strength of rocks and other brittle materials.

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

2008-12-01

128

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

PubMed

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 pulse loading for postmortem examination. Tests without and with pulse shaping are conducted on rock specimens. The evolution of tensile stress at the failure spot is determined via dynamic and quasistatic finite element analyses with the dynamic loads measured from SHPB as inputs. Given properly shaped incident pulse, far-field dynamic force balance is achieved and the peak of the loading matches in time with the rupture onset of the specimen. In addition, the dynamic tensile stress history at the failure spot obtained from the full dynamic finite element analysis agrees with the quasistatic analysis. The opposite occurs for the test without pulse shaping. These results demonstrate that when the far-field dynamic force balance is satisfied, the inertial effects associated with stress wave loading are minimized and thus one can apply the simple quasistatic analysis to obtain the tensile strength in the SCB-SHPB testing. This method provides a useful and cost effective way to measure indirectly the dynamic tensile strength of rocks and other brittle materials. PMID:19123575

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

2008-12-01

129

Elevated-temperature tensile and creep properties of several ferritic stainless steels  

NASA Technical Reports Server (NTRS)

The elevated-temperature mechanical properties of several ferritic stainless steels were determined. The alloys evaluated included Armco 18SR, GE 1541, and NASA-18T-A. Tensile and creep strength properties at 1073 and 1273 K and residual room temperature tensile properties after creep testing were measured. In addition, 1273 K tensile and creep tests and residual property testing were conducted with Armco 18SR and GE 1541 which were exposed for 200 hours to a severe oxidizing environment in automotive thermal reactors. Aside from the residual tensile properties for Armco 18SR, prior exposure did not affect the mechanical properties of either alloy. The 1273 K creep strength parallel to the sheet-rolling direction was similar for all three alloys. At 1073 K, NASA-18T-A had better creep strength than either Armco 18SR or GE 1541. NASA-18T-A possesses better residual properties after creep testing than either Armco 18SR or Ge 1541.

Whittenberger, J. D.

1977-01-01

130

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

131

Vol. 79, No. 2, 2002 261 Tensile Properties of Extruded Corn Protein  

E-print Network

Vol. 79, No. 2, 2002 261 Tensile Properties of Extruded Corn Protein Low-Density Polyethylene Films. 79(2):261­264 The strength of films extruded from powder blends of corn zein or corn gluten meal (CGM focused on the production of solvent- cast films. Corn and wheat protein (Aydt et al 1991; Herald et al

132

Tensile and shear bond strength of resin-reinforced glass ionomer cement to glazed porcelain.  

PubMed

The purpose of this study was to measure the tensile and shear bond strength of resin-reinforced glass ionomer cement (RGIC) to glazed porcelain, to evaluate the durability of RGIC by thermal cycling, and to examine the RGIC remaining on the surface of the porcelain after the bond strength test to evaluate bonding conditions. Three adhesives were used in this study: Concise (CO) as a chemically cured composite resin, Fuji ORTHO (FO) as a chemically cured RGIC, and Fuji ORTHO LC (FOLC) as a light-cured RGIC. Tensile and shear bond strengths were measured 24 hours after bonding orthodontic brackets and also after thermal cycling. Tensile bond strength after 24 hours was 6.6 +/- 3.2 MPa in CO, 7.3 +/- 1.4 MPa in FO, and 8.6 +/- 1.9 MPa in FOLC, and the strength significantly decreased after the thermal cycling test. Shear bond strength after 24 hours was 32.5 +/- 8.9 MPa in CO, 23.3 +/- 6.8 MPa in FO, and 24.7 +/- 6.5 MPa in FOLC, and in contrast to tensile bond strength, no decreases in the strength were detected after the thermal cycling test. CO showed significantly higher shear bond strength than did FO and FOLC. When using the shear bond strength test and CO, destruction of porcelain surfaces frequently occurred after 24 hours and was observed in every specimen after the thermal cycling. RGIC was found to be an advantageous alternative to resin adhesive for bracket bonding to porcelain and to enamel. PMID:12940567

Kitayama, Yoshitaka; Komori, Akira; Nakahara, Rizako

2003-08-01

133

Preparation and tensile properties of amorphous Fe 78Si 9B 13\\/nano-Ni laminated composite  

Microsoft Academic Search

Amorphous Fe78Si9B13\\/nano-Ni laminated composite was prepared by electrodeposition method. The tensile properties of laminated composite at room temperature were examined. The laminated composite exhibits a very high tensile strength and reasonable tensile elongation. This is attributed to a good bonding between amorphous Fe78Si9B13 layer and nano-Ni layers. The amorphous layer can deform in conformity with Ni layers and be significantly

X. F. Li; K. F. Zhang; G. F. Wang

2007-01-01

134

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

135

Tensile properties of SiC/aluminum filamentary composites - Thermal degradation effects  

NASA Technical Reports Server (NTRS)

Aluminium metal matrix composites with a low cost fiber, e.g. SiC, provide for an attractive combination of high elastic modulus and longitudinal strengths coupled with a low density. SiC (volume fraction 0.55)-aluminum (6061) systems have been studied in order to optimize fiber composite strength and processing parameters. A comparison of two SiC/aluminum composites produced by AVCO and DWA is provided. Fiber properties are shown to alter composite tensile properties and fracture morphology. The room temperature tensile strengths appear to be insensitive to thermal exposures at 500 C up to 150 h. The elastic modulus of the composites also appears to be stable up to 400 C, however variations in the loss modulus are apparent. The fracture morphology reflects the quality of the interfacial bond, fiber strengths and fiber processing.

Skinner, A.; Koczak, M. J.; Lawley, A.

1982-01-01

136

Tensile properties of palladium-silver alloys with absorbed hydrogen  

NASA Technical Reports Server (NTRS)

The alloys 90Pd-10Ag, 80Pd-20Ag, 70Pd-30Ag, 60Pd-40Ag, and 50Pd-50Ag containing absorbed hydrogen were tested in tension. The results show the tensile properties to be independent of the phase transition. Also, hydrogen in the lattice does not necessarily cause embrittlement or poor elongation. The changes in the tensile properties appear dependent on the electron to atom site ratio.

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

1975-01-01

137

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

138

Development of Yield and Tensile Strength Design Curves for Alloy 617  

SciTech Connect

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

Nancy Lybeck; T. -L. Sham

2013-10-01

139

The effects of ZnO2 nanoparticles on split tensile strength of self-compacting concrete  

Microsoft Academic Search

In this study, split tensile strength of self-compacting concrete (SCC) with different amounts of ZnO2 nanoparticles has been investigated. ZnO2 nanoparticles with the average particle size of 15?nm were added partially to SCC and split tensile strength of the specimens has been measured. The results indicate that ZnO2 nanoparticles are able to improve the split tensile strength of SCC and

Ali Nazari; Shadi Riahi

2012-01-01

140

A Novel Ni-Containing Powder Metallurgy Steel with Ultrahigh Impact, Fatigue, and Tensile Properties  

NASA Astrophysics Data System (ADS)

The impact toughness of powder metallurgy (PM) steel is typically inferior, and it is further impaired when the microstructure is strengthened. To formulate a versatile PM steel with superior impact, fatigue, and tensile properties, the influences of various microstructures, including ferrite, pearlite, bainite, and Ni-rich areas, were identified. The correlations between impact toughness with other mechanical properties were also studied. The results demonstrated that ferrite provides more resistance to impact loading than Ni-rich martensite, followed by bainite and pearlite. However, Ni-rich martensite presents the highest transverse rupture strength (TRS), fatigue strength, tensile strength, and hardness, followed by bainite, pearlite, and ferrite. With 74 pct Ni-rich martensite and 14 pct bainite, Fe-3Cr-0.5Mo-4Ni-0.5C steel achieves the optimal combination of impact energy (39 J), TRS (2170 MPa), bending fatigue strength at 2 × 106 cycles (770 MPa), tensile strength (1323 MPa), and apparent hardness (38 HRC). The impact energy of Fe-3Cr-0.5Mo-4Ni-0.5C steel is twice as high as those of the ordinary high-strength PM steels. These findings demonstrate that a high-strength PM steel with high-toughness can be produced by optimized alloy design and microstructure.

Wu, Ming-Wei; Shu, Guo-Jiun; Chang, Shih-Ying; Lin, Bing-Hao

2014-08-01

141

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

142

Effect of particle size and volume fraction on tensile properties of fly ash/polyurea composites  

NASA Astrophysics Data System (ADS)

Fly ash, which consists of hollow particles with porous shells, was introduced into polyurea elastomer. A one-step method was chosen to fabricate pure polyurea and the polyurea matrix for the composites based on Isonate® 2143L (diisocyanate) and Versalink® P-1000 (diamine). Scanning electron microscopy was used to observe the fracture surfaces of the composites. Particle size and volume fraction were varied to study their effects on the tensile properties of the composites. The tensile properties of the pure polyurea and fly ash/polyurea (FA/PU) composites were tested using an Instron load frame with a 1 kN Interface model 1500ASK-200 load cell. Results showed that fly ash particles were distributed homogeneously in the polyurea matrix, and all of the composites displayed rubber-like tensile behavior similar to that of pure polyurea. The tensile strength of the composites was influenced by both the fly ash size and the volume fraction. Compared to the largest particle size or the highest volume fraction, an increase in tensile strength was achieved by reducing particle size and/or volume fraction. The strain at break of the composites also increased by using fine particles. In addition, the composites filled with 20% fly ash became softer. These samples showed lower plateau strength and larger strain at break than the other composites.

Qiao, Jing; Schaaf, Kristin; Amirkhizi, Alireza V.; Nemat-Nasser, Siavouche

2010-04-01

143

Shear strength properties of wet granular materials  

NASA Astrophysics Data System (ADS)

We investigate shear strength properties of wet granular materials in the pendular state (i.e., the state where the liquid phase is discontinuous) as a function of water content. Sand and glass beads were wetted and tested in a direct shear cell and under various confining pressures. In parallel, we carried out three-dimensional molecular dynamics simulations by using an explicit equation expressing capillary force as a function of interparticle distance, water bridge volume, and surface tension. We show that, due to the peculiar features of capillary interactions, the major influence of water content over the shear strength stems from the distribution of liquid bonds. This property results in shear strength saturation as a function of water content. We arrive at the same conclusion by a microscopic analysis of the shear strength. We propose a model that accounts for the capillary force, the granular texture, and particle size polydispersity. We find fairly good agreement of the theoretical estimate of the shear strength with both experimental data and simulations. From numerical data, we analyze the connectivity and anisotropy of different classes of liquid bonds according to the sign and level of the normal force as well as the bond direction. We find that weak compressive bonds are almost isotropically distributed whereas strong compressive and tensile bonds have a pronounced anisotropy. The probability distribution function of normal forces is exponentially decreasing for strong compressive bonds, a decreasing power-law function over nearly one decade for weak compressive bonds, and an increasing linear function in the range of tensile bonds. These features suggest that different bond classes do not play the same role with respect to the shear strength.

Richefeu, Vincent; El Youssoufi, Moulay Saïd; Radjaï, Farhang

2006-05-01

144

Tensile Properties and Fracture Behavior of Different Carbon Nanotube-Grafted Polyacrylonitrile-Based Carbon Fibers  

NASA Astrophysics Data System (ADS)

The tensile properties and fracture behavior of different carbon nanotube (CNT)-grafted polyacrylonitrile-based (T1000GB) single carbon fibers were investigated. Grafting of CNTs was achieved via chemical vapor deposition (CVD). When Fe(C5H5)2 (also applied via CVD) was used as the catalyst, the tensile strength and Weibull modulus of the carbon fibers were improved, possibly due to the growth of dense CNT networks on the carbon fibers, which may have led to a reduction in the number of strength-limiting defects. Separately, at lower concentrations of an Fe(NO3)3·9H2O catalyst in ethanol, which was applied via dipping, the tensile strength of CNT-grafted fibers was nearly identical to that of the as-received fibers, although the Weibull modulus was higher. For higher concentrations of the Fe(NO3)3·9H2O catalyst, however, the tensile strength and the Weibull modulus were lower than those for the as-received material. Although the density of the CNT network increased with the concentration of the Fe(NO3)3·9H2O catalyst in the ethanol solution, heating of the ethanolic Fe(NO3)3·9H2O catalyst solution generated nitric acid (HNO3) due to decomposition, which damaged the fiber surfaces, resulting in an increase in the number of flaws and consequently a reduction in the tensile strength. Therefore, the tensile strength and Weibull modulus of CNT-grafted carbon fibers vary due to the combination of these effects and as a function of the catalyst concentration.

Naito, Kimiyoshi

2014-11-01

145

Aggregate tensile strength and friability characteristics of furrow and sprinkler irrigated fields in Southern Idaho  

Technology Transfer Automated Retrieval System (TEKTRAN)

Agricultural crops grown in southern Idaho are furrow or sprinkler irrigated. Therefore, the soil experiences several wetting and drying cycles each growing season that can contribute to changes in aggregate tensile strength and friability. The objective of the research was to evaluate the influence...

146

Abaca Fiber Reinforced Phosphogypsum Concrete Panels (modulus Of Rupture, Toughness, Splitting Tensile Strength)  

Microsoft Academic Search

In this experimental study the possibilities of utilization of phosphogypsum--industrial waste--in concrete, reinforced with abaca vegetable fibers, were investigated. Effects of varying the abaca fiber content and the phosphogypsum content on flexural, tensile and compressive strengths and ductility of concrete were examined. The flexural behavior of abaca fiber reinforced phosphogypsum concrete panels was studied extensively and compared with gypsum wall

Selcuk Yetimoglu

1984-01-01

147

Change in tensile properties of neoprene and nitrile gloves after repeated exposures to acetone and thermal decontamination.  

PubMed

This study investigated the change in tensile properties of neoprene and nitrile gloves after repeated cycles of exposure to acetone, followed by thermal decontamination. The glove was exposed to acetone (outer surface in contact with chemical), subjected to thermal decontamination, and tested for the tensile strength and the ultimate elongation. Thermal decontamination was carried out inside an oven for 16 hours at 100 degrees C. The exposure/decontamination procedure was repeated for a maximum of 10 cycles. For neoprene versus acetone, the mean tensile strength consistently decreased after each exposure/decontamination cycle. Multiple comparisons indicated that the mean tensile strengths between the new swatches and each exposure/decontamination group were significantly different (p < 0.05). The loss of either tensile strength or ultimate elongation was less than 23% compared with new swatches after four exposure/decontamination cycles. Swatches with out acetone exposure were then cycled through the oven in the same manner. It was found that both the heat used for thermal decontamination and acetone exposure significantly affected the tensile strength and ultimate elongation. For nitrile gloves exposed to acetone, the mean tensile strength remained virtually unchanged (p > 0.05). The mean tensile strength for the new swatches was 37.1 MPa and the mean tensile strength after nine exposure/decontamination cycles was 36.0 MPa, with a loss less than 3%. The largest single cycle loss for ultimate elongation occurred during the first exposure/decontamination cycle for both glove materials. In our previous study, decisions regarding the effectiveness of the decontamination process were based on having no discernible change in the breakthrough time and steady-state permeation rate. The results of this study indicate that the effectiveness of the decontamination process cannot be based on permeation parameters alone but must also take into account the change in physical properties. PMID:16276643

Gao, Pengfei; Tomasovic, Beth

2005-11-01

148

Tensile bond strength of glass fiber posts luted with different cements.  

PubMed

Proper selection of the luting agent is fundamental to avoid failure due to lack of retention in post-retained crowns. The objective of this study was to investigate the tensile bond strength and failure mode of glass fiber posts luted with different cements. Glass fiber posts were luted in 40 mandibular premolars, divided into 4 groups (n = 10): Group 1--resin-modified glass ionomer RelyX Luting; Group 2--resin-modified glass ionomer Fuji Plus; Group 3--resin cement RelyX ARC; Group 4--resin cement Enforce. Specimens were assessed by tensile strength testing and light microscopy analysis for observation of failure mode. The tensile bond strength values of each group were compared by ANOVA and Tukey test. The significance level was set at 5%. The failure modes were described as percentages. The following tensile strength values were obtained: Group 1--247.6 N; Group 2--256.7 N; Group 3--502.1 N; Group 4--477.3 N. There was no statistically significant difference between Groups 1 and 2 or between Groups 3 and 4, yet the resin cements presented significantly higher tensile bond strength values than those presented by the glass ionomer cements. Group 1 displayed 70% of cohesive failures, whereas Groups 2, 3 and 4 exhibited 70% to 80% of adhesive failures at the dentin-cement interface. We concluded that resin cements and glass ionomer cements are able to provide clinically sufficient retention of glass fiber posts, and that glass ionomer cements may be especially indicated when the application of adhesive techniques is difficult. PMID:17589652

Bonfante, Gerson; Kaizer, Osvaldo Bazzan; Pegoraro, Luiz Fernando; do Valle, Accácio Lins

2007-01-01

149

Effect of TiO2 Nanoparticles on Tensile Strength of Dental Acrylic Resins  

PubMed Central

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

Shirkavand, Saeed; Moslehifard, Elnaz

2014-01-01

150

Effect of Thermal Exposure on the Tensile Properties of Aluminum Alloys for Elevated Temperature Service  

NASA Technical Reports Server (NTRS)

Tensile properties were evaluated for four aluminum alloys that are candidates for airframe applications on high speed transport aircraft. These alloys included the Al-Cu-Mg-Ag alloys C415 and C416 and the Al-Cu-Li-Mg-Ag alloys RX818 and ML377. The Al-Cu-Mg alloys CM001, which was used on the Concorde SST, and 1143, which was modified from the alloy used on the TU144 Russian supersonic aircraft, were tested for comparison. The alloys were subjected to thermal exposure at 200 F, 225 F and 275 F for times up to 30,000 hours. Tensile tests were performed on thermally-exposed and as-received material at -65 F, room temperature, 200 F, 225 F and 275 F. All four candidate alloys showed significant tensile property improvements over CM001 and 1143. Room temperature yield strengths of the candidate alloys were at least 20% greater than for CM001 and 1143, for both the as-received and thermally-exposed conditions. The strength levels of alloy RX818 were the highest of all materials investigated, and were 5-10% higher than for ML377, C415 and C416 for the as-received condition and after 5,000 hours thermal exposure. RX818 was removed from this study after 5,000 hours exposure due to poor fracture toughness performance observed in a parallel study. After 30,000 hours exposure at 200 F and 225 F, the alloys C415, C416 and ML377 showed minor decreases in yield strength, tensile strength and elongation when compared to the as-received properties. Reductions in tensile strength from the as-received values were up to 25% for alloys C415, C416 and ML377 after 15,000 hours exposure at 275 F.

Edahl, Robert A., Jr.; Domack, Marcia

2004-01-01

151

Effect of cold working and sandblasting on the microhardness, tensile strength and corrosion resistance of AISI 316L stainless steel  

NASA Astrophysics Data System (ADS)

The aim of this work is to investigate the effect of cold working and sandblasting on the microhardness, tensile strength and corrosion rate of AISI 316L stainless steel. The specimens were deformed from 17% to 47% and sandblasted for 20 min using SiC particles with a diameter of 500-700 ?m and an air flow with 0.6-0.7 MPa pressure. The microhardness distribution and tensile test were conducted and a measurement on the corrosion current density was done to determine the corrosion rate of the specimens. The result shows that the cold working enhances the bulk microhardness, tensile and yield strength of the specimen by the degree of deformation applied in the treatment. The sandblasting treatment increases the microhardness only at the surface of the specimen without or with a low degree of deformation. In addition, the sandblasting enhances the surface roughness. The corrosion resistance is improved by cold working, especially for the highly deformed specimen. However the follow-up sandblasting treatment reduces the corrosion resistance. In conclusion, the cold working is prominent to be used for improving the mechanical properties and corrosion resistance of AISI 316L stainless steel. Meanwhile, the sandblasting subjected to the cold worked steel is only useful for surface texturing instead of improving the mechanical properties and corrosion resistance.

Suyitno; Arifvianto, Budi; Widodo, Teguh Dwi; Mahardika, Muslim; Dewo, Punto; Salim, Urip Agus

2012-12-01

152

Tensile and creep rupture properties of (16) uncoated and (2) coated engineering alloys at elevated temperatures  

NASA Technical Reports Server (NTRS)

Sixteen test materials were supplied by NASA-Lewis Research Center as wrought bar or cast remelt stock. The cast remelt stock was cast into test blanks with two such materials being also evaluated after Jocoat coating was applied. Mechanical properties evaluated included tensile, modulus of elasticity, Poisson's Ratio, creep properties and creep rupture strength. Tests were conducted at temperatures applicable to the service temperature of the various alloys. This range extended from room temperature to 1000 C.

Fritz, L. J.; Koster, W. P.

1977-01-01

153

Impact Tensile Properties of YAG Laser Welded Butt Joints Made by Different Steel Sheets for Vehicles  

NASA Astrophysics Data System (ADS)

The tensile properties of YAG laser welded butt joints using different high strength steel sheets with a tensile strength of 270 MPa, 590 MPa and 980 MPa (denoted HR270, HR590 and HR980, respectively) were investigated at static and dynamic rates, together with the three kinds of laser welded joints made by the same steel sheets. The impact tensile tests were performed by using the vertical type of split Hopkinson tension bar apparatus, while the static tensile tests were carried out using a universal testing machine INSTRON5586. The impact tensile strengths were significantly increased in comparison with the static ones due to the effect of strain rate, which might be the contribution of the part of HR270 base metal. And in both of static and impact tests, the fracture strains of HR270-HR590 joint, HR270-HR980 joint and HR590-HR980 joint were about one half of the fracture strains observed in the same steel welded joints of HR270-HR270, HR270-HR270 and HR590-HR590, respectively.

Takahashi, Y.; Daimaruya, M.; Kobayashi, H.; Tsuda, H.; Fujiki, H.

154

A comparison of direct and indirect methods of determining tensile strength of concrete  

E-print Network

A COMPARISON OF DIRECT AND INDIRECT METHODS OF DETERMINING TENSILE STRENGTH OF CONCRETE JAMES TIMON BROWN A Thesis Submitted to ths Graduate School of the Agricultural and . Mechanical College of Texas in partial fulfillment of the requirements... for the degree of MASTER OF SCIENCE August~ 1957 Ma3or Sub]ect: Civil Engineering A COMPARISON OF DIRECT AND IiiDIR?'CT METIiODS OF DETERMINING TENSILE STRENGTii OF CONCRETE A Thesis JAMES TIMON BHONN Approved as to style and content by: a rman o omm ee...

Brown, James Timon

1957-01-01

155

Amplitude distribution modelling and ultimate strength prediction of ASTM D-3039 graphite/epoxy tensile specimens  

NASA Astrophysics Data System (ADS)

As the aerospace industry increases its usage of composite materials in primary structures, techniques must be developed to nondestructively predict and monitor structural integrity at low proof stresses. This paper demonstrates the feasibility of predicting ultimate strengths at stress levels less than 25 percent of the expected ultimate strength, thereby reducing the unintentional structural damage caused by higher proof loads. The research presented herein has shown that an ultimate strength prediction equation can be generated for ASTM D-3039 unidirectional graphite/epoxy tensile specimens. From an original sample set of six specimens, a multivariate statistical analysis was used to generate an ultimate strength prediction equation. The variables of the multivariate statistical analysis were obtained through the mathematical modelling of the low amplitude (matrix cracking) portion of the specimens' AE amplitude distributions produced during the early stages of proof testing. A Weibull distribution was used to represent the amplitude band, and its parameters were correlated with known failure strengths to produce ultimate strength prediction equations. Ultimate strengths were then accurately predicted at proof stresses less than 25 percent of the expected failure stress for several randomly drawn tensile coupons.

Walker, James L., II; Hill, Eric V. K.

156

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

NASA Astrophysics Data System (ADS)

AA2219 aluminum alloy (Al-Cu-Mn alloy) has gathered wide acceptance in the fabrication of lightweight structures requiring a high strength-to-weight ratio and good corrosion resistance. Friction stir welding (FSW) process is an emerging solid state joining process in which the material that is being welded does not melt and recast. This process uses a nonconsumable tool to generate frictional heat in the abutting surfaces. The welding parameters such as tool rotational speed, welding speed, axial force, etc., and tool pin profile play a major role in deciding the joint strength. An attempt has been made to develop an empirical relationship between FSW variables to predict tensile strength of the friction stir welded AA2219 aluminum alloy. To obtain the desired strength, it is essential to have a complete control over the relevant process parameters to maximize the tensile strength on which the quality of a weldment is based. Therefore, it is very important to select and control the welding process parameter for obtaining maximum strength. To achieve this various prediction methods such as response surface method (RSM), analysis of variance (ANOVA), Student’s t-test, coefficient of determination, etc., can be applied to define the desired output variables through developing mathematical models to specify the relationship between the output parameters and input variables. Four factors, five levels central composite design have been used to minimize number of experimental conditions. The developed mathematical relationship can be effectively used to predict the tensile strength of FSW joints of AA2219 aluminum alloy at 95% confidence level.

Elangovan, K.; Balasubramanian, V.; Babu, S.

2008-12-01

157

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

158

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

159

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

NASA Technical Reports Server (NTRS)

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

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

1979-01-01

160

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

NASA Astrophysics Data System (ADS)

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

Wang, Jiangchao; Rashed, Sherif; Murakawa, Hidekazu

2014-12-01

161

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

NASA Astrophysics Data System (ADS)

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

Wang, Jiangchao; Rashed, Sherif; Murakawa, Hidekazu

2014-09-01

162

Tensile bond strength of gold and porcelain inlays to extracted teeth using three cements.  

PubMed

This in vitro study compared the tensile bond strength of gold and porcelain inlays to extracted molars in standardized cavities. Three cements were used: zinc phosphate, glass-ionomer, and a resin composite cement. The gold inlays were cemented using zinc phosphate or glass-ionomer cement, and the porcelain inlays were luted using resin composite or glass-ionomer cement. Surface treatments included, for gold inlays, either no treatment (zinc phosphate cement) or airborne particle abraded and tinplated (glass-ionomer cement); and for porcelain inlays, either no treatment (glass-ionomer cement) or etched and silane-treated (resin composite cement). Statistical analysis was performed using the Weibull distribution. Results showed no significant differences between gold inlays cemented using zinc phosphate or glass-ionomer cements and porcelain inlays luted using glass-ionomer cements. The bonded porcelain inlays (resin composite cement) showed tensile bond strengths two to three times higher than those obtained for cemented gold inlays. PMID:7575974

Michelini, F S; Belser, U C; Scherrer, S S; De Rijk, W G

1995-01-01

163

Ab initio study of the ideal tensile strength and mechanical stability of transition-metal disilicides  

NASA Astrophysics Data System (ADS)

The ideal tensile test in transition metal disilicides MoSi2 and WSi2 with a C11b structure is simulated by ab initio electronic structure calculations using the full-potential linearized augmented plane wave method. The theoretical tensile strength for [001] loading is determined for both disilicides and compared with that of other materials. A full relaxation of all external and one internal structural parameter is performed, and the influence of each relaxation process on energetics and strength of materials studied is investigated. Differences in the behavior of various interatomic bonds including tension-compression asymmetry are analyzed and their origin in connection with the changes of the internal structural parameter is traced. For comparison, the response of bonds in MoSi and CoSi with B2 structure to the [001] loading is also studied.

Friák, M.; Šob, M.; Vitek, V.

2003-11-01

164

Tensile strength of sand, palygorskite and calcium carbonate mixtures and interpretation with the effective stress theory  

Microsoft Academic Search

Many soils in arid regions of the world including those of central Iran contain palygorskite and carbonates in their mineral fraction. There is, however, little information on the effects of these minerals on soil physical and mechanical behaviour. A laboratory experiment was carried out to evaluate tensile strength of artificial mixtures of sand–palygorskite–calcium carbonate (CaCO3). Palygorskite and calcium carbonate were

M. R. Mosaddeghi; M. A. Hajabbasi; H. Khademi

2006-01-01

165

Dependence of fatigue limit of high-tension bolts on mean stress and ultimate tensile strength  

Microsoft Academic Search

High tension bolts in critical joints in internal combustion engines are susceptible to fatigue failure. Computeraided bolted\\u000a joint design procedures require knowledge of the dependence of bolt fatigue limit on the mean stress and ultimate tensile\\u000a strength. This dependence is investigated with staircase fatigue limit tests. The test results show that when the bolt fatigue\\u000a limit is estimated with the

S.-S. Cho; H. Chang; K. W. Lee

2009-01-01

166

Influence of Bolting Parameters on the Ultimate Tensile Strength and Stiffness of Composite-Metal Joints  

Microsoft Academic Search

The joining of dissimilar materials poses a challenge in mechanical structures. The objective of this research was to investigate the effect of joining parameters such as bolt spacing, geometry configuration, and overlap length on ultimate failure strength and stiffness of composite-metal hybrid joints. Woven fiberglass\\/epoxy and unidirectional carbon-fiber\\/epoxy composites have been manufactured and tested under tensile loads to obtain their

William S. Slovinsky; Parsaoran Hutapea

2010-01-01

167

Continuous extrusion and tensile strength of self-reinforced HDPE\\/UHMWPE sheet  

Microsoft Academic Search

A specially designed fish-tail shaped extrusion die was used to continuously extrude self-reinforcing sheet of HDPE\\/UHMWPE. The result indicated that under conventional extrusion conditions, the tensile strength of extruded sheet was comparable to conventional molded HDPE samples and was almost the same in both MD (machine direction) and TD (transverse direction) directions. While at temperatures slightly above the melting point

Jun Chen; Wei Yang; Guo-ping Yu; Min Wang; Hai-ying Ni; Kai-zhi Shen

2008-01-01

168

Effect of laser welding on the titanium ceramic tensile bond strength  

PubMed Central

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

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

2011-01-01

169

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

NASA Astrophysics Data System (ADS)

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

Nizamuddin, Syed

170

The Effect of Teucrium Polium Hney on the Wound Healing and Tensile Strength in Rat  

PubMed Central

Objective(s) Wound healing represents a dynamic physiological process influenced by many factors. The aim of the present study was to evaluate the effects of Teucrium polium honey on the wound healing and tensile strength in rat. Materials and Methods Thirty-six Sprague-Dawley rats were randomly divided into four equal (n= 9) treatment and control groups. Two full-thickness wounds were made over the dorsal thoracic region according to the incision and excision models. Animals were treated with topical Teucrium polium honey twice a day post surgery until complete healing was achieved. Histopathology and tensiometry were then studied. Results The wound healing process occurred faster in the incision model than excision ones (P< 0.05). Teucrium polium honey promoted wound contraction, closure time and tensile strength (P< 0.05). Histopathological study also showed relative epithelial proliferation, improved angiogenesis granulation, and fibrous connective tissue in Teucrium polium honey treated animals. Conclusion The present study demonstrates that Teucrium polium honey can accelerate wound healing as well as tensile strength in rat skin wounds. PMID:23493667

Alizadeh, Ali Mohammad; Sohanaki, Hamid; Khaniki, Mahmod; Mohaghgheghi, Mohammad Ali; Ghmami, Giti; Mosavi, Maryamsadat

2011-01-01

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

The tensile bond strength of new and rebonded stainless steel orthodontic brackets.  

PubMed

The study investigated the effect on the tensile/peel bond strength of the variables associated with the bracket base, the enamel surface, and the type of adhesive when both new and used brackets were rebonded to a previously bonded enamel surface. The tensile/peel bond strength was firstly evaluated for three different types of stainless steel orthodontic bracket/base combinations. The cast integral base gave a significantly lower bond strength than the foil-mesh and photo-etched bases. Following debonding, a group of new brackets were bonded to the teeth using a chemically-activated or a light-cured adhesive. The old adhesive had been removed from the enamel by either a hand scaler or a tungsten-carbide bur. The rebonded new brackets demonstrated a small, but statistically significant fall in bond strength. No differences were found between the enamel preparations or the adhesives. A further group of previously debonded brackets were rebonded to the same teeth. The bracket bases were prepared by either smoothing with a green stone or heating in a bunsen flame followed by sandblasting and electropolishing. Highly significant falls in bond strength were obtained with all the bases. No significant differences were found between the two methods of bracket preparation. PMID:8500538

Regan, D; LeMasney, B; van Noort, R

1993-04-01

173

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

NASA Technical Reports Server (NTRS)

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

Bansal, Narottam P.

1998-01-01

174

Tensile properties of 0.05 to 0.20 Pct C TRIP steels  

Microsoft Academic Search

The uniaxial tensile properties of a series of TRIP steels of varying carbon contents and processing histories were determined\\u000a over a wide range of test temperatures. The yield strengths at room temperature varied both with the deformation temperature\\u000a (over the range 250 to 550C) and with the carbon content (0.05 to 0.20 pct). Possible reasons for these variations are advanced.

G. R. Chanani; V. F. Zackay; Earl R. Parker

1971-01-01

175

Tensile Properties of Polyimide Composites Incorporating Carbon Nanotubes-Grafted and Polyimide-Coated Carbon Fibers  

NASA Astrophysics Data System (ADS)

The tensile properties and fracture behavior of polyimide composite bundles incorporating carbon nanotubes-grafted (CNT-grafted) and polyimide-coated (PI-coated) high-tensile-strength polyacrylonitrile (PAN)-based (T1000GB), and high-modulus pitch-based (K13D) carbon fibers were investigated. The CNT were grown on the surface of the carbon fibers by chemical vapor deposition. The pyromellitic dianhydride/4,4'-oxydianiline PI nanolayer coating was deposited on the surface of the carbon fiber by high-temperature vapor deposition polymerization. The results clearly demonstrate that CNT grafting and PI coating were effective for improving the Weibull modulus of T1000GB PAN-based and K13D pitch-based carbon fiber bundle composites. In addition, the average tensile strength of the PI-coated T1000GB carbon fiber bundle composites was also higher than that of the as-received carbon fiber bundle composites, while the average tensile strength of the CNT-grafted T1000GB, K13D, and the PI-coated K13D carbon fiber bundle composites was similar to that of the as-received carbon fiber bundle composites.

Naito, Kimiyoshi

2014-09-01

176

A new concept for the determination of tensile properties of nanofilms and materials via nanoindentation  

NASA Astrophysics Data System (ADS)

Here we present a new concept to determine tensile properties of nanofilms and materials via nanoindentation. The proposed methodology utilizes a conical or truncated conical indenter and requires the fabrication of an upwardly obtruded well shaped tube from the substrate. The downward stroke of the indenter along the centreline of the tube mainly produces tensile hoop stress in the upper region of the tube where the nanofilm exists. In the present work, the feasibility of the proposed method has been demonstrated through finite element analysis, as the first stage of a longer project on the topic. It has been demonstrated that Young's modulus and the yield strength of the nanofilm can be suitably determined in tensile mode from the load-stroke relation.

Kim, Jong-Bong; Yoo, Yo-Han; Shin, Hyunho

2005-09-01

177

Vinyl Ester Resin: Rheological Behaviors, Curing Kinetics, Thermomechanical, and Tensile Properties  

E-print Network

Vinyl Ester Resin: Rheological Behaviors, Curing Kinetics, Thermomechanical, and Tensile Properties, thermomechanical properties, tensile mechanical properties Introduction The development of vinyl ester resins (VERs rheometry (TSR),7 and dynamic-mechanical thermal analysis.8 For the isothermal curing process

Guo, John Zhanhu

178

Tensile bond strength of four denture resins to porcelain teeth with different surface treatment  

PubMed Central

PURPOSE This study evaluated the bond strength between porcelain denture teeth (Bioblend 43D) and four different polymerized denture resins (Lucitone 199, Palapress, Acron MC, Triad) with and without a bonding agent and after four different types of surface treatment (polished, HF etched, sandblasted, air-abraded). MATERIALS AND METHODS Central incisor porcelain denture teeth were divided into 32 groups of 5 each. Tensile bond strength (MPa) was determined using a testing machine at crosshead speed of 0.5 mm/min. Mean and standard deviation are listed. Data were analyzed by two-way ANOVA. Means were compared by Tukey-Kramer intervals at 0.05 significance level. RESULTS All surface treatment increased bond strength compared to polished surface and the highest bond strength was found with Palapress resin with etched porcelain surface (8.1 MPa). Bonding agent improved the bond strength of all denture resins to porcelain teeth. Superior bonding was found with Palapress and air-abraded porcelain (39 MPa). CONCLUSION Resins with different curing methods affect the bond strength of porcelain teeth to denture bases. Superior bonding was found with auto-polymerized resin (Palapress). Application of ceramic primer and bonding agent to porcelain teeth with and without surface treatment will improve the bond strength of all denture resins to porcelain teeth. PMID:24353880

Powers, John

2013-01-01

179

Dynamic Tensile Strength of Low Temperature Ice and Kuiper Belt Size Distributions  

NASA Astrophysics Data System (ADS)

We model mutual gravitationally driven impact interactions in a nearly gas-free environment of the Kuiper belt (KB) and use low-temperature (< 100 K) ice dynamic strength dependent collisional out-come (accretion vs. erosion and fragmentation) models. These lead to theoretically predictable distributions of object number density, vs. mass distributions. These derived mass distributions are comparable to the now rapidly growing KB survey data. Tensional failure of single and polycrystalline ice in the temperature range from 263 to 128 K was measured for high strain rate, c.a. 104 s-1, dynamic loading conditions. Experiments, similar to Lange and Ahrens(1991)(LA), were conducted using a gas gun launched Lexan projectile. The liquid nitrogen cooled ice target approaching KB-like temperatures was partially confined, rather than using the LA confined geometry. Another set of experiments used a drop tube projectile launcher within the 263 K Caltech Ice Laboratory and at 163 K in a liquid nitrogen cooled chamber. New experiments give tensile strengths of 7.6±1.5 MPa at 263 K and 9.1±1.5 MPa at 163 K for unconfined, free of visual initial defects and measurable imperfections ice samples. The new strengths are lower than the earlier LA data ( 17 MPa). The major differences arise from ice target assembly. LA used polycrystalline ice samples confined in annular stainless steel target rings. New measurements were partially confined, in not initially contacting concentric target rings. Later shots used unconfined configurations with ice pellets affixed to aluminum foil. Circumferential confinement is known to increase the material damage threshold upon both compression and tensile loading. Previous confinement in LA is the main cause of the above discrepancy. Present tensile strengths are only a few times higher than 0.7 - 3.0 MPa summarized in Petrovic (2003) for quasistatic tension at 10-7 to 10-3 s-1 strain rate.

Ahrens, Thomas J.; Fat'yanov, O. V.; Engelhardt, H.; Fraser, W. C.

2009-09-01

180

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

181

Hoop Tensile Properties of Ceramic Matrix Composite Cylinders  

NASA Technical Reports Server (NTRS)

Tensile stress-strain properties in the hoop direction were obtained for 100-mm diameter SiC/SiC ceramic matrix composite cylinders using ring specimens machined form the cylinder ends. The cylinders were fabricated from 2D balanced SiC fabric with several material variants, including wall thickness (6,8, and 12 plies), SiC fiber type (Sylramic, Sylramic-iBN, Hi-Nicalon, and Hi-Nicalon S), fiber sizing type, and matrix type (full CVI SiC, and partial CVI SiC plus slurry cast + melt-infiltrated SiC-Si). Fiber ply splices existed in all the hoops. Tensile hoop measurements are made at room temperature and 1200 C using hydrostatic ring test facilities. The failure mode of the hoops, determined through microstructural examination, is presented. The hoop properties are compared with in-plane data measured on flat panels using same material variants, but containing no splices.

Verrilli, Michael J.; DiCarlo, James A.; Yun, HeeMan; Barnett, Terry

2004-01-01

182

Tensile strength and disintegration of tableted silicified microcrystalline cellulose: influences of interparticle bonding.  

PubMed

The effects of some material variables (particle size and moisture content) on the tensile strength and disintegration time of tableted standard microcrystalline cellulose (MCC, Avicel) and a silicified brand (SMCC, Prosolv) were studied. Three particle size fractions were employed, after equilibration in three levels of environmental relative humidity (RH%), and the tensile strength and disintegration time were determined at different levels of total tablet porosity or packing fraction (p(f)). The MCC grade or silicification affects the moisture sorption and the packing during tapping as well as the particle deformation (yield pressure, P(y)) during tableting. There was a slight increase in the tensile strength but a marked increase in the disintegration time of Prosolv compared with Avicel in the p(f) range 0.7-0.9, which corresponds the range for pharmaceutical tablets. These increases are explained in terms of the range and magnitude of the interparticle forces developed and the interparticle separation. Despite the higher moisture content of Prosolv after equilibration compared with Avicel, compression of Prosolv results in higher P(y), in tablets of higher energy of interparticle bonding, longer interparticle separation, and extended disintegration compared with Avicel. The incorporated SiO(2) is thought to play the role of barrier or sink for the moisture sorbed, but only for RH up to 52%, which is a moisture content range less than twice that of tightly bound water. At higher RH (72%), the incorporated SiO(2) does not increase the P(y), but reduces the energy of interparticle bonding and the interparticle separation because of its probable saturation. The latter, in turn, results in more extended disintegration times due to reduced uptake of water into the tablets and to the probable reduction of water available for the deployment of the microcrystalline cellulose activity as disintegrant. PMID:12820153

Kachrimanis, Kyriakos; Nikolakakis, Ioannis; Malamataris, Stavros

2003-07-01

183

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

184

Tensile and Charpy impact properties of irradiated reduced-activation ferritic steels  

SciTech Connect

Tensile tests were conducted on 8 reduced-activation Cr-W steels after irradiation to 15-17 and 26-29 dpa, and Charpy impact tests were conducted on steels irradiated to 26-29 dpa. Irradiation was in Fast Flux Test Facility at 365 C on steels containing 2.25-12% Cr, varying amounts of W, V, and Ta, and 0.1%C. Previously, tensile specimens were irradiated to 6-8 dpa and Charpy specimens to 6-8, 15- 17, and 20-24 dpa. Tensile and Charpy specimens were also thermally aged to 20,000 h at 365 C. Thermal aging had little effect on tensile properties or ductile-brittle transition temperature (DBTT), but several steels showed a slight increase in upper-shelf energy (USE). After 7 dpa, strength increased (hardened) and then remained relatively unchanged through 26-29 dpa (ie, strength saturated with fluence). Post-irradiation Charpy impact tests after 26-29 dpa showed that the loss of impact toughness (increased DBTT, decreased USE) remained relatively unchanged from the values after 20-24 dpa, which had been relatively unchanged from the earlier irradiations. As before, the two 9Cr steels had the most irradiation resistance.

Klueh, R.L.; Alexander, D.J.

1996-10-01

185

Determination of Tensile Properties of Polymers at High Strain Rates  

NASA Astrophysics Data System (ADS)

In the field of high rate testing of polymers the measured properties are highly dependent on the applied methodology. Hence, the test setup as whole but in particular also the geometrical type of specimen plays a decisive role. The widely used standard for the determination of tensile properties of polymers (ISO527-2) was extended by a novel standard (ISO18872:2007), which is targeted on the determination of tensile properties at high strain rates. In this standard also a novel specimen shape is proposed. Hand in hand with the introduction of new specimen geometry the question of comparability arises. To point out the differences in stress-strain response of the ISO18872 specimen and the ISO527-2 multipurpose specimen tensile tests over a wide loading rate range were conducted in this paper. A digital image correlation system in combination with a high speed camera was used to characterize the local material behaviour. Different parameters like nominal stress, true stress, nominal strain, true strain as well as volumetric strain were determined and used to compare the two specimen geometries.

Reiter, M.; Major, Z.

2010-06-01

186

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

187

Tensile bond strength of dental adhesives bonded to simulated caries-exposed dentin.  

PubMed

This study investigated the possibility of resin bonding to carious dentin. The study was divided into two parts, to determine first whether an in vitro model for caries could be developed for testing bond strength and second whether chemical modification of the caries model dentin surface, instead of mechanical removal of the carious layer, would enhance resin bond strengths. Dentin samples were exposed to an artificial caries decalcification solution (lactic acid+nitrocellulose) for 7 days. The depth of the decalcified surface was determined by microhardness and the nature of the surfaces analyzed by use of the scanning electron microscope. After bur removal of the decalcified dentin, samples were bonded with three different dentin bonding systems and the tensile bond strengths were determined. Control specimens were prepared and bonded with no decalcification or bur preparation. These values were compared with specimens prepared by decalcification but with no mechanical removal of the decalcified surface layer before bonding. Additional decalcified samples were treated with phosphoric acid to modify the decalcified surface before dentin bond testing. Bond strengths were significantly higher (p < 0.05) for the decalcified and mechanically prepared dentin as compared with either the unmodified or the phosphoric acid modified decalcified dentin. The highest bond strengths for all systems were found for the undecalcified control group. These results suggest that it may be possible to bond to the collagenous structures remaining in carious dentin. This could lead to conservation of tooth structure and rethinking of cavity preparation design. PMID:8126672

Ehudin, D Z; Thompson, V P

1994-02-01

188

Fatigue Properties of Automobile High-Strength Bolts  

NASA Astrophysics Data System (ADS)

This study is focused on the fatigue properties of automobile high-strength bolts, including the effect of mean stress level, pre-processing schedule and the residual stresses. And the mean stress levels are 0.3, 0.5 and 0.7 times to the tensile strength (?B) of the material respectively. The main results obtained are as follows: 1) the fatigue strength increases under the mean stress loading, but the differences between the loading levels are not so evident; 2) most of the cases in this study are broken from the bottom of the screw thread, and the crack initiated from the impurities.

Zhou, Congling; Nishida, Shin-Ichi; Hattori, Nobusuke

189

[Effect of magnesium stearate on the tensile strength of tablets made with the binder Prosolv SMCC 90].  

PubMed

The present paper evaluated the tensile strength of tablets made from the dry binder Prosolv SMCC 90 and the influence of three concentrations of the lubricant magnesium stearate on the tensile strength of tablets manufactured from this material. The results were compared with the same evaluation in Avicel PH 102. The tested concentrations of the stearate were 0.4, 0.8 and 1.2%. The tablets were compressed by three press powers (3, 3.5, and 4 kN). On the basis of obtained results it can be stated that under the same press powers Prosolv SMCC 90 alone yields stronger compacts than Avicel PH 102. From the viewpoint of decreased strength of compacts by adding magnesium stearate, the dry binder Prosolv SMCC 90 is much less sensitive than Avicel PH 102. In Avicel PH 102 a marked decrease in tensile strength was recorded with an addition of 0.4%, which was not observed with Prosolv SMCC90. A more significant decrease in the strength of compacts was shown by the substance not until a stearate concentration of 0.8%. The highest employed stearate concentration of 1.2% decreases the tensile strength of tablets made from Prosolv SMCC 90 in the press powers of 3.5 and 4 kN two times less than the tensile strength of the compacts from Avicel PH 102. PMID:11910741

Muzíková, J

2002-01-01

190

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

191

Effect on the tensile strength of human acellular dermis (Epiflex®) 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. PMID:24468201

2014-01-01

192

Measured iron-gallium alloy tensile properties under magnetic fields  

NASA Astrophysics Data System (ADS)

Tension testing is used to identify Galfenol material properties under low level DC magnetic bias fields. Dog bone shaped specimens of single crystal Fe100-xGax, where 17<=x<=33, underwent tensile testing along two crystalographic axis orientations, [110] and [100]. The material properties being investigated and calculated from measured quantities are: Young's modulus and Poisson's ratio. Data are presented that demonstrate the dependence of these material properties on applied magnetic field levels and provide a preliminary assessment of the trends in material properties for performance under varied operating conditions. The elastic properties of Fe-Ga alloys were observed to be increasingly anisotropic with rising Ga content for the stoichiometries examined. The largest elastic anisotropies were manifested in [110] Poisson's ratios of as low as -0.63 in one specimen. This negative Poisson's ratio creates a significant in-plane auxetic behavior that could be exploited in applications that capitalize on unique area effects produced under uniaxial loading.

Yoo, Jin-Hyeong; Flatau, Alison B.

2004-07-01

193

Tensile properties and fracture reliability of a glass-coated Co-based amorphous microwire  

NASA Astrophysics Data System (ADS)

Co68.15Fe4.35Si12.25B15.25 (at%) amorphous microwires with a smooth surface and a circular cross-section were fabricated by the glass-coated melt spinning method. Their mechanical properties were evaluated through tensile tests of the glass-coated amorphous microwires, and their fracture reliability was estimated using two- and three-parameter Weibull analysis. X-ray diffraction and transmission electron microscopy results showed that these glass-coated Co-based microwires were mostly amorphous. The coated Co-based microwires exhibit a tensile strength of 1145 to 2457 MPa, with a mean value of 1727 MPa and a variance of 445 MPa. Weibull statistical analysis showed that the tensile two-parameter Weibull modulus of the amorphous microwires is 4.16 and the three-parameter Weibull modulus is 1.61 with a threshold value as high as 942 MPa. These results indicate that the fabricated microwires exhibit good tensile properties and fracture reliability, and thus appear to be good candidates for electronics reliability engineering applications.

Wang, Xiao-dong; Wang, Huan; Shen, Hong-xian; Qin, Fa-xiang; Xing, Da-wei; Liu, Jing-shun; Chen, Dong-ming; Sun, Jian-fei

2014-06-01

194

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

195

A Discrete Element Model for Predicting Shear Strength and Degradation of Rock Joint by Using Compressive and Tensile Test Data  

NASA Astrophysics Data System (ADS)

A discrete element model is proposed to examine rock strength and failure. The model is implemented by UDEC, which is developed for this purpose. The material is represented as a collection of irregular-sized deformable particles interacting at their cohesive boundaries. The interface between two adjacent particles is viewed as a flexible contact whose constitutive law controls the material fracture and fragmentation properties. To reproduce rock anisotropy, an orthotropic cohesive law is developed for the contacts, which allows their shear and tensile behaviors to be different from each other. Using a combination of original closed-form expressions and statistical calibrations, a unique set of the contact microparameters are found based on the uniaxial/triaxial compression and Brazilian tension test data of a plaster. Applying the obtained microparameters, joint specimens, made of the same plaster, are simulated, where the comparison of the obtained results to laboratory data shows a reasonable agreement.

Kazerani, T.; Yang, Z. Y.; Zhao, J.

2012-09-01

196

The influence of tensile fatigue damage on residual compressive strength of woven composites  

SciTech Connect

The long term mechanical fatigue of a Celion G30-500/PMR-15 woven composite system is investigated to study the interrelationship between thermo-mechanical properties, namely the thermal expansion coefficient (TEC) and the compressive strength. Residual compressive strength measurements (IITRI fixture) conducted on specimens subjected to tension-tension fatigue cycling indicate that this material property is sensitive to cracks and delaminations which form during mechanical cycling. Measured compressive strength degradation are as large as 49% for this material undergoing mechanical fatigue cycling with TEC degradation as large as 61%. Experimental results show that a correlation exists between TEC measurements and compressive strength. This correlation suggests that TEC measurements may be used as a damage evaluation technique.

Mitrovic, M.; Carman, G.P. [Univ. of California, Los Angeles, CA (United States). Mechanical, Aerospace and Nuclear Engineering Dept.

1995-12-31

197

Mechanical properties of individual InAs nanowires studied by tensile tests  

SciTech Connect

Mechanical properties of individual InAs nanowires (NWs) synthesized by metal organic chemical vapor deposition (MOCVD) and molecular beam epitaxy (MBE) methods are studied by in-situ tensile tests in a scanning electron microscope and their fracture strength and Young's modulus are obtained. The two types of NWs both exhibit brittle fracture with a maximum elastic strain up to ?10%. Their fracture strength distributes in a similar range of ?2–5?GPa with a general trend of increasing with NW volume decrease, which is well described by Weibull statistic with a smaller Weibull modulus and a higher characteristic strength for MOCVD NWs. Young's modulus is determined to be 16–78?GPa with an average value of 45?GPa and no dependence on NW diameter for MOCVD NWs and 34–79?GPa with an average value of 58?GPa for MBE NWs.

Li, X.; Wei, X. L., E-mail: weixl@pku.edu.cn, E-mail: qingchen@pku.edu.cn; Xu, T. T.; Ning, Z. Y.; Shu, J. P.; Chen, Q., E-mail: weixl@pku.edu.cn, E-mail: qingchen@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China); Wang, X. Y.; Pan, D.; Zhao, J. H.; Yang, T. [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)] [Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083 (China)

2014-03-10

198

Reinforcement of nylon 6 with functionalized silica nanoparticles for enhanced tensile strength and modulus  

NASA Astrophysics Data System (ADS)

Pristine and functionalized silica (SiO2) nanoparticles were dispersed into nylon 6 and drawn into filaments through melt extrusion. The loading fraction of particles in both cases was 1.0 wt%. Fourier transform infrared (FTIR) studies revealed that reinforcement of pristine silica nanoparticles enhances the bond strength of each of the three basic bonds of nylon 6 namely, hydroxyl, amide, and carbonyl. As a result, the improvement over neat nylon in strength and modulus was 36% and 28% respectively, without any loss of fracture strain (80%). A silane coupling agent was then used through wet chemical treatment to functionalize silica nanoparticles. Functionalization induced an additional covalent Si-O-Si (siloxane) bond between silica particles and nylon backbone polymer while the enhancement in the basic bonds was retained. FTIR and x-ray photoelectron spectroscopy (XPS) studies confirmed the formation of the siloxane bond. This added chemical bond resulted in 76% and 55% improvement in tensile strength and modulus, and still retained 30% fracture strain. Calculation of the upper bound on Young's modulus indicates that one can reach within 5% of the bound with pristine silica particles, but it is exceeded by 15% when particles are functionalized.

Mahfuz, Hassan; Hasan, Mohammad; Dhanak, Vinod; Beamson, Graham; Stewart, Justin; Rangari, Vijaya; Wei, Xin; Khabashesku, Valery; Jeelani, Shaik

2008-11-01

199

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

200

Tensile properties of a boron/nitrogen-doped carbon nanotube–graphene hybrid structure  

PubMed Central

Summary Doping is an effective approach that allows for the intrinsic modification of the electrical and chemical properties of nanomaterials. Recently, a graphene and carbon nanotube hybrid structure (GNHS) has been reported, which extends the excellent properties of carbon-based materials to three dimensions. In this paper, we carried out a first-time investigation on the tensile properties of the hybrid structures with different dopants. It is found that with the presence of dopants, the hybrid structures usually exhibit lower yield strength, Young’s modulus, and earlier yielding compared to that of a pristine hybrid structure. For dopant concentrations below 2.5% no significant reduction of Young’s modulus or yield strength could be observed. For all considered samples, the failure is found to initiate at the region where the nanotubes and graphene sheets are connected. After failure, monatomic chains are normally observed around the failure region. Dangling graphene layers without the separation of a residual CNT wall are found to adhere to each other after failure with a distance of about 3.4 Å. This study provides a fundamental understanding of the tensile properties of the doped graphene–nanotube hybrid structures, which will benefit the design and also the applications of graphene-based hybrid materials. PMID:24778956

Xia, Kang; Zhan, Haifei; Wei, Ye

2014-01-01

201

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

202

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

203

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

PubMed

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

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

1997-08-01

204

Tensile bond strength of intracanal posts in primary anterior teeth: an in vitro study.  

PubMed

The aim of this study was to measure in vitro; the tensile bond strength of three intracanal posts used in anterior primary teeth. A total of 45 single rooted primary anterior teeth were selected for the study and the crowns sectioned leaving 1mm above the cement-enamel junction. The roots were then assigned to three groups according the type of retention used. All roots were endodonticaly treated, a 4-mm of the canal was cleansed and a base of glass ionomer cement was put at the bottom of the prepared canal. The roots were then prepared to receive intracanal posts using a # 4137 diamond bur (KG Sorensen) used in a depth of 3-mm of the length of the canal All the prepared roots were acid etched with a 37% phosphoric acid gel for 15 seconds, rinsed, dried and the dentin adhesive Single Bond (3M) was applied. Group I received intracanal posts and cores made of composite resin (Filtek Z 250, 3M). Group II intracanal posts were made from a 0.6mm orthodontic wire bent as a Greek letter type (gamma), fixed with the Z 250 composite resin and cores were built with the same composite. Finally Group III received intracanal retention made of a fiber glass post (Fibrekor Post, Generic/Pentron) with 1.25 mm diameter, fixed with Z 250 and cores were made like the other groups. The samples were submitted to tension in a universal-testing machine (Instron, model 4444). Statistical analysis (ANOVA) revealed that there were no statistically significant differences between the groups. On the basis of the results of this in vitro study it was concluded that the type of intracanal post did not interfere with the tensile strength and the most frequent type of failure was of adhesive type, corresponding to 74% of the sample. PMID:12413170

Pithan, Silvia; Vieira, Ricardo de Sousa; Chain, Marcelo Carvalho

2002-01-01

205

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. PMID:22437672

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

2012-01-01

206

High Temperature Tensile Properties of Unidirectional Hi-Nicalon/Celsian Composites In Air  

NASA Technical Reports Server (NTRS)

High temperature tensile properties of unidirectional BN/SiC-coated Hi-Nicalon SiC fiber reinforced celsian matrix composites have been measured from room temperature to 1200 C (2190 F) in air. Young's modulus, the first matrix cracking stress, and the ultimate strength decreased from room temperature to 1200 C (2190 F). The applicability of various micromechanical models, in predicting room temperature values of various mechanical properties for this CMC, has also been investigated. The simple rule of mixtures produced an accurate estimate of the primary composite modulus. The first matrix cracking stress estimated from ACK theory was in good agreement with the experimental value. The modified fiber bundle failure theory of Evans gave a good estimate of the ultimate strength.

Gyekenyesi, John Z.; Bansal, Narottam P.

2000-01-01

207

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

NASA Astrophysics Data System (ADS)

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

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

2013-10-01

208

Effect of storage on tensile material properties of bovine liver.  

PubMed

Cadaveric tissue models play an important role in the assessment and optimization of novel restraint systems for reducing abdominal injuries. However, the effect of tissue preservation by means of freezing on the material properties of abdominal tissues remains unknown. The goal of this study was to investigate the influence of frozen storage time on the material responses of the liver parenchyma in tensile loading. Specimens from ten bovine livers were equally divided into three groups: fresh, 30-day frozen storage, and 60-day frozen storage. All preserved specimens were stored at -12°C. Dog-bone specimens from each preservation group were randomly assigned to one of three strain rates (0.01s(-1), 0.1s(-1), and 1.0s(-1)) and tested to failure in tensile loading. The local material response recorded at the tear location and the global material response of the whole specimen of the liver parenchyma specimens were investigated based on the experimental data and optimized analytical material models. The local and global failure strains decreased significantly between fresh specimens and specimens preserved for 30 days (p<0.05), and between fresh specimens and specimens preserved for 60 days (p<0.05) for all three loading rates. Changes on the material model parameters were also observed between fresh and preserved specimens. Preservation by means of frozen storage was found to affect both the material and failure response of bovine liver parenchyma in tensile loading. The stiffness of the tissue increased with increased preservation time and increased strain rate. In summary, significant changes (p<0.05) between the failure strain of previously frozen liver parenchyma samples and fresh samples were demonstrated at both global and local levels in this study. In addition, nonlinear and viscoelastic characteristics of the liver parenchyma were observed in tension for both fresh and preserved samples. PMID:24148876

Lu, Yuan-Chiao; Kemper, Andrew R; Untaroiu, Costin D

2014-01-01

209

Clean Cast Steel Technology: Effect of Micro-porosity on Tensile and Charpy Properties of Four Cast Steels  

SciTech Connect

The effect of these large shrink cavities on mechanical properties could be easily calculated using well established engineering formulas. Over the years, increases in computational and metallurgical resources have allowed the modeler to improve accuracy and increase the complexity of numerical predictors. An accurate prediction of micro-porosity, not observable using conventional radiographic techniques, and an engineering understanding of the effect on mechanical properties would give a designer confidence in using a more efficient casting design and a lower safety factor. This will give castings an additional design advantage. The goal of this project is to provide current and future modelers/designers with a tensile and Charpy property dataset for validation of micro-porosity predictors. The response of ultimate strength, elongation, and reduction in area to micro-porosity was very similar in all four alloys. Ultimate strength was largely unaffected by tensile fracture surface porosity until values of about 25% were reached and decreased linearly with increasing values. Elongation and reduction in area decreased sharply after less than 5% fracture surface porosity. Niyama values of about 0.7 were produced sound material and acceptable tensile properties. Ultrasonic velocities of 0.233 in/usec and higher produced acceptable tensile properties. Metallographic examination revealed a ratio of 4-6 to 1 in fracture surface porosity to metallographic porosity. Charpy impact properties were largely unaffected by the microporosity concentrations examined in this study and did not correlate to either Niyama values, fracture surface porosity, or metallographic porosity.

Griffin, John, A.; Bates, Charles, E.

2005-09-19

210

Tensile Mechanical Properties of Swine Cortical Mandibular Bone  

PubMed Central

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

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

2014-01-01

211

Effect of Ni–P Thickness on the Tensile Strength of Cu\\/Electroless Ni–P\\/Sn–3.5Ag Solder Joint  

Microsoft Academic Search

Tensile strength and fracture behavior of thermally aged Cu\\/electroless Ni-P\\/Sn-3.5Ag solder joint were investigated for three different Ni-P thicknesses (3.9, 7.3, and 9.9mum) to examine the mechanical reliability of the solder joint. The tensile testing results showed that Ni-P thickness influences the solder joint strength considerably. In the case of thin Ni-P, the tensile strength decreased with increase in aging

Aditya Kumar; Zhong Chen

2006-01-01

212

Drying time of tray adhesive for adequate tensile bond strength between polyvinylsiloxane impression and tray resin material  

PubMed Central

STATEMENT OF PROBLEM Use of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material. PURPOSE This study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive. MATERIAL AND METHODS Adhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material (Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level. RESULTS The results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile bonding strength to Silfix-Imprint II at all drying periods. CONCLUSION Significant increase in tensile bonding strength with Silfix-Aquasil and VPS Tray adhesive-Imprint II combination until 10 and 15 minutes respectively. Tray adhesive-impression material combination from the same company presented higher tensile bonding strength at all drying time intervals than when using tray adhesive-impression material of different manufactures. PMID:21165257

Yi, Myong-Hee; Shim, Joon-Sung; Lee, Keun-Woo

2009-01-01

213

Use of Spherical Instrumented Indentation to Evaluate the Tensile Properties of 3D Combined Structures  

NASA Astrophysics Data System (ADS)

In this paper we propose a novel method, spherical indentation, for evaluation of the plastic properties of combined structures. Three-dimensional (3D) printed products, for example gradient metal alloys consisting of different kinds of material, contain interfaces that can act as weak points and threaten the mechanical reliability of products. Combined structures containing an interface between Cu alloy and Ag were prepared for testing. Samples were heat-treated at 100°C and 200°C for 3 h to optimize processing conditions. The indentation tensile properties of the samples were estimated by analyzing multiple loading-unloading curves obtained by use of the representative stress and strain method. A continuous increase in both yield strength and tensile strength was observed for the Cu alloy and the Cu/Ag interface after heat treatment at up to 200°C, because of precipitation hardening. These experimental results show that mechanical characterization of combined structures by spherical indentation is highly useful on the nano and micro scales.

Song, Won-Seok; Kim, Seung-Gyu; Kim, Young-Cheon; Kwon, Dongil

2015-03-01

214

Structural and High-Temperature Tensile Properties of Special Pitch-Coke Graphites  

NASA Technical Reports Server (NTRS)

The room-temperature structural properties and the tensile properties up to 5000 F (275O C) were determined for ten grades of specially prepared petroleum-coke coal-tar-pitch graphites which were graphitized at 5430 F (3000 C). One impregnation with coal-tar pitch increased the bulk density from 1.41 to 1.57 g/cm3 and the maximum strength at 4500 F (2500 C) from 4000 to 5700 psi. None of the processing parameters studied had a marked effect on the closed porosity or the X-ray structure or the per cent graphitization. The coarse-particle filler resulted in the lowest coefficient of thermal expansion and the fine-particle filler in the highest coefficient. A marked improvement in uniformity of tensile strength was observed. A standard-deviation analysis gave a one-sigma value of approximately 150 psi for one of these special grades and values of 340-420 psi for three commercial grades.

Kotlensky, W. V.; Martens, H. E.

1961-01-01

215

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

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. PMID:22088916

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

2011-01-01

217

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

218

Simulation of the tensile properties of silica aerogels: the effects of cluster structure and primary particle size.  

PubMed

A new two-level model is proposed to investigate the relationship between the mechanical properties and microstructure of silica aerogels. This two-level model consists of the particle-particle interaction model and the cluster structure model. The particle-particle interaction model is proposed to describe interactions between primary particles, in which the polymerization reaction between primary particles is considered. The cluster structure model represents the geometrical structure of silica aerogels, and it is established using a modified diffusion-limited colloid aggregation (DLCA) algorithm. This two-level model is used to investigate the tensile behavior of silica aerogels based on the discrete element method (DEM). The numerical results show that the primary particle size has significant effects on the elastic modulus and tensile strength of silica aerogels. Moreover, the power-law relationships between tensile properties and aerogel density are dependent on the variation of the primary particle radius with density. The present results can explain the difference among different experimental exponents to a certain extent. In comparison with experimental data within a wide density range, this two-level model provides good quantitative estimations of the elastic modulus and tensile strength of silica aerogels after the size effects of the primary particle are considered. This paper provides a fundamental understanding of the relationship between the mechanical properties and microstructure of silica aerogels. The two-level model can be extended to study the mechanical properties of other aerogels and aerogel composites. PMID:25022232

Liu, Qiang; Lu, Zixing; Zhu, Man; Yuan, Zeshuai; Yang, Zhenyu; Hu, Zijun; Li, Junning

2014-09-01

219

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

220

Loop security and tensile properties of polyblend and traditional suture materials.  

PubMed

Tensile and knot properties of new generation (polyblend) and traditional suture materials in orthopedic surgery were investigated in standard laboratory conditions. Study focused on Fiberwire No. 5 and 2, Ethibond No. 5, 2 and 00, Orthocord No. 2, MaxBraid No. 2, Prolene No. 0 and 00, PDS No. 0 and 00, and Vicryl No. 2, 0 and 00. A 27-cm suture loop was fastened with 10 knots for ten samples for each type. Test parameters were tensile load to failure, elongation at failure point and knot slippage, and volume of 10-fold knots. Results were compared using ANOVA test. Failure load of No. 5 Fiberwire (625.0 ± 30.0 N) was significantly higher compared to all other suture types. Tensile strengths of MaxBraid No. 2 (287 ± 11 N) was significantly stronger compared to two other No. 2 polyblend sutures types and Ethibond No. 5. Knot slippage of Fiberwire No. 5 (14 ± 1.9 mm) was significantly higher compared to all other suture types. Ethibond No. 2 (0.1 ± 0.3 mm) had the lowest knot slippage. Elongation at the failure point of Fiberwire No. 2 (5%) was significantly lower than all other suture types. Mean calculated knot volume of #5 Fiberwire (73 ± 6.9 mm(3)) was significantly higher compared to #5 Ethibond (53 ± 4.8 mm(3)). Results of the study proved presence of significant differences between tensile and knot properties of various suture types and sizes. Loop security of larger diameter sutures is not always higher than thinner sutures. Suture elongation and knot slippage are important failure modes for high-diameter sutures and short-suture loops. PMID:20535447

Türker, Mehmet; K?l?ço?lu, Onder; Salduz, Ahmet; Bozda?, Ergun; Sünbülo?lu, Emin

2011-02-01

221

Strength properties of fly ash based controlled low strength materials.  

PubMed

Controlled low strength material (CLSM) is a flowable mixture that can be used as a backfill material in place of compacted soils. Flowable fill requires no tamping or compaction to achieve its strength and typically has a load carrying capacity much higher than compacted soils, but it can still be excavated easily. The selection of CLSM type should be based on technical and economical considerations for specific applications. In this study, a mixture of high volume fly ash (FA), crushed limestone powder (filler) and a low percentage of pozzolana cement have been tried in different compositions. The amount of pozzolana cement was kept constant for all mixes as, 5% of fly ash weight. The amount of mixing water was chosen in order to provide optimum pumpability by determining the spreading ratio of CLSM mixtures using flow table method. The shear strength of the material is a measure of the materials ability to support imposed stresses on the material. The shear strength properties of CLSM mixtures have been investigated by a series of laboratory tests. The direct shear test procedure was applied for determining the strength parameters Phi (angle of shearing resistance) and C(h) (cohesion intercept) of the material. The test results indicated that CLSM mixtures have superior shear strength properties compared to compacted soils. Shear strength, cohesion intercept and angle of shearing resistance values of CLSM mixtures exceeded conventional soil materials' similar properties at 7 days. These parameters proved that CLSM mixtures are suitable materials for backfill applications. PMID:17331642

Türkel, S

2007-08-25

222

Research on tensile strength characteristics of bridge deck pavement bonding layers  

NASA Astrophysics Data System (ADS)

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

Wu, Shaopeng; Han, Jun

2010-03-01

223

Root diversity in alpine plants: root length, tensile strength and plant age  

NASA Astrophysics Data System (ADS)

A high diversity of plant species and functional groups is hypothesised to increase the diversity of root types and their subsequent effects for soil stability. However, even basic data on root characteristics of alpine plants are very scarce. Therefore, we determined important root characteristics of 13 plant species from different functional groups, i.e. grasses, herbs and shrubs. We excavated the whole root systems of 62 plants from a machine-graded ski slope at 2625 m a.s.l. and analysed the rooting depth, the horizontal root extension, root length and diameter. Single roots of plant species were tested for tensile strength. The age of herbs and shrubs was determined by growth-ring analysis. Root characteristics varied considerably between both plant species and functional groups. The rooting depth of different species ranged from 7.2 ± 0.97 cm to 20.5 ± 2.33 cm, but was significantly larger in the herb Geum reptans (70.8 ± 10.75 cm). The woody species Salix breviserrata reached the highest horizontal root extensions (96.8 ± 25.5 cm). Most plants had their longest roots in fine diameter classes (0.5

Pohl, M.; Stroude, R.; Körner, C.; Buttler, A.; Rixen, C.

2009-04-01

224

Demineralization resistance and tensile bond strength of four luting agents after acid attack.  

PubMed

Resistance to acid demineralization provided by luting agents adjacent to enamel was evaluated for four different luting agents: composite resin, glass ionomer, polycarboxylate, and zinc phosphate cement. Cement solubility and enamel demineralization after acid attack at pH 3.0 were measured radiographically and calculated using computer-aided design. Tensile bond strength of a miniature crown seated on an accurately prepared preparation was evaluated after acid attack using an Instron instrument. Crown retention after 12 days was greater for the polycarboxylate (2,000 kg/m2) than the zinc phosphate cement (500 kg/m2). Crown retention for the glass ionomer (1,100 kg/m2) and composite resin luting agent (1,400 kg/m2) were similar statistically after 21 days of acid exposure. Cement washouts for zinc phosphate and polycarboxylate were similar, and were greater than either glass ionomer or composite resin luting agent. The amount of demineralization related to cements was, from greatest to least: zinc phosphate, polycarboxylate, composite resin, glass ionomer. Fluoride release was concluded to be initially effective in reducing enamel solubility in spite of cement solubility. PMID:2640123

Stannard, J G; Sornkul, E

1989-01-01

225

Improving wet and dry strength properties of recycled old corrugated carton (OCC) pulp using various polymers.  

PubMed

In this study, the application of different dosages of low and high molecular weights (MW) of chitosan (Ch), cationic starch (CS) and poly vinyl alcohol (PVA) were systematically investigated using old corrugated carton (OCC) furnishes. Various sequences of above-mentioned polymeric additives were also examined to find out the optimal combination for improving both wet and dry tensile strength. For each treatment, 4 handsheets, each having basis weight of 100 g/m(2), were made. In general, the tensile strength of handsheets was significantly affected by the addition of polymeric agents. The enhancing effect of additives on dry tensile property was much higher than wet condition. The results also showed that the tensile strength of the samples made from OCC furnishes were improved upon the addition of high molecular weight chitosan (ChI) compared to the untreated ones (control). The low MW chitosan did not change the properties of handsheets dramatically. Application of polymeric agents moderately decreased the stretch to rupture, however with increasing dosage the stretch was improved. Sequential addition of used polymers showed that triple application of polymers was beneficial to both dry and wet tensile strength, although the effect was larger for dry. The best results in wet and dry tensile strengths were achieved using sequential of PVA-ChI-CS. Sequential addition of oppositely charged polymers forms a macromolecular layered structure of polyelectrolytes. PMID:23544577

Hamzeh, Yahya; Sabbaghi, Sanaz; Ashori, Alireza; Abdulkhani, Ali; Soltani, Farshid

2013-04-15

226

Effect of Ultrasonic Treatment on The Tensile and Impact Properties of Thermoplastic Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

This study investigates the effect of ultrasonic treatment on the mechanical properties of thermoplastic natural rubber (TPNR) nanocomposites reinforced with multi-walled nanotubes. The TPNR nanocomposites were prepared using melt blending method from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, respectively, with 1% of Multi-wall nanotubes. The nanocomposite was prepared using the indirect technique (IDT) with the optimum processing parameters at 180° C with 80 rpm mixing speed and 11 minutes processing time. The results have showed that the good dispersion on nanotubes was achieved by ultrasonic treatment. The optimization of ultrasonic time indicated that the maximum tensile and impact properties occurred with 1 h ultrasonic treatment. The Young's modulus, tensile strength, elongation at break and impact strength have increased by almost 11%, 21%, 43% and 50%, respectively. The results from our study indicate that nanotubes have as excellent reinforcement filler in TPNR matrix.

Tarawneh, Mou'ad A.; Ahmad, Sahrim Hj.; Yahya, S. Y.; Rasid, Rozaidi

2009-06-01

227

Effect of Ultrasonic Treatment on The Tensile and Impact Properties of Thermoplastic Natural Rubber Nanocomposites Reinforced with Carbon Nanotubes  

SciTech Connect

This study investigates the effect of ultrasonic treatment on the mechanical properties of thermoplastic natural rubber (TPNR) nanocomposites reinforced with multi-walled nanotubes. The TPNR nanocomposites were prepared using melt blending method from polypropylene (PP), natural rubber (NR) and liquid natural rubber (LNR) as a compatibilizer, respectively, with 1% of Multi-wall nanotubes. The nanocomposite was prepared using the indirect technique (IDT) with the optimum processing parameters at 180 deg. C with 80 rpm mixing speed and 11 minutes processing time. The results have showed that the good dispersion on nanotubes was achieved by ultrasonic treatment. The optimization of ultrasonic time indicated that the maximum tensile and impact properties occurred with 1 h ultrasonic treatment. The Young's modulus, tensile strength, elongation at break and impact strength have increased by almost 11%, 21%, 43% and 50%, respectively. The results from our study indicate that nanotubes have as excellent reinforcement filler in TPNR matrix.

Tarawneh, Mou'ad A.; Ahmad, Sahrim Hj.; Rasid, Rozaidi [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia (UKM), 43600 Bangi, Selangor (Malaysia); Yahya, S. Y. [Institute of Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Selangor (Malaysia)

2009-06-01

228

Tensile and compressive properties of wrought magnesium alloys at high rates of strain  

NASA Astrophysics Data System (ADS)

Impact tensile and compressive properties of three different wrought magnesium alloys (AZ31B-F, AZ61A-F and ZK60A-T5) are determined using two different versions of the split Hopkinson bar. Tension and compression specimens are machined from extruded bars parallel to the extrusion axis. Tensile and compressive stress-strain data at strain rates of 1000-2000/s are presented and compared with those at quasi-static and medium strain rates obtained on an Instron 4505 testing machine. The effects of strain rate and loading mode on the ultimate strength, ultimate strain and absorbed energy are examined in details. It is shown that the wrought magnesium alloys exhibit a pronounced asymmetric yield behavior in tension and compression at both low and high rates of strain. It is also shown that the ultimate strengths increase with increasing strain rate, and the strain rate dependence of the ultimate strain and absorbed energy differs, depending the wrought magnesium alloys tested.

Yokoyama, T.

2003-09-01

229

Tensile Properties and Work Hardening Behavior of Laser-Welded Dual-Phase Steel Joints  

NASA Astrophysics Data System (ADS)

The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in the heat-affected zone was caused by partial vanishing and tempering of the pre-existing martensite. The extent of softening was much larger in the DP980-welded joints than in the DP600-welded joints. Despite the reduction in ductility, the ultimate tensile strength (UTS) remained almost unchanged, and the yield strength (YS) indeed increased stemming from the appearance of yield point phenomena after welding in the DP600 steel. The DP980-welded joints showed lower YS and UTS than the base metal owing to the appearance of severe soft zone. The YS, UTS, and strain hardening exponent increased slightly with increasing strain rate. While the base metals had multi-stage strain hardening, the welded joints showed only stage III hardening. All the welded joints failed in the soft zone, and the fracture surfaces exhibited characteristic dimple fracture.

Farabi, N.; Chen, D. L.; Zhou, Y.

2012-02-01

230

Maximizing Tensile Strain in Germanium Nanomembranes for Enhanced Optoelectronic Properties  

NASA Astrophysics Data System (ADS)

Silicon, germanium, and their alloys, which provide the leading materials platform of microelectronics, are extremely inefficient light emitters because of their indirect fundamental energy band gap. This basic materials property has so far hindered the development of group-IV photonic-active devices, including light emitters and diode lasers, thereby significantly limiting our ability to integrate electronic and photonic functionalities at the chip level. Theoretical studies have predicted that tensile strain in Ge lowers the direct energy band gap relative to the indirect one, and that, with sufficient strain, Ge becomes direct-band gap, thus enabling facile interband light emission and the fabrication of Group IV lasers. It has, however, not been possible to impart sufficient strain to Ge to reach the direct-band gap goal, because bulk Ge fractures at much lower strains. Here it is shown that very thin sheets of Ge(001), called nanomembranes (NMs), can be used to overcome this materials limitation. Germanium nanomembranes (NMs) in the range of thicknesses from 20nm to 100nm were fabricated and then transferred and mounted to a flexible substrate [a polyimide (PI) sheet]. An apparatus was developed to stress the PI/NM combination and provide for in-situ Raman measurements of the strain as a function of applied stress. This arrangement allowed for the introduction of sufficient biaxial tensile strain (>1.7%) to transform Ge to a direct-band gap material, as determined by photoluminescence (PL) measurements and theory. Appropriate shifts in the emission spectrum and increases in PL intensities were observed. The advance in this work was nanomembrane fabrication technology; i.e., making thin enough Ge sheets to accept sufficiently high levels of strain without fracture. It was of interest to determine if the strain at which fracture ultimately does occur can be raised, by evaluating factors that initiate fracture. Attempts to assess the effect of free edges (enchant access holes) on the NM were made and an increase of 35% in the strain to at which crack first formed was found on NMs that lack etchant access holes. Ge NMs were used as a platform to investigate the relationships between surface passivation / functionalization and the physical properties of the material.

Sanchez Perez, Jose Roberto

231

Effect of chemical treatment on the tensile properties of short sisal fibre-reinforced polyethylene composites  

Microsoft Academic Search

The effect of chemical treatment on the tensile properties of sisal fibre-reinforced LDPE (low density polyethylene) composites was investigated. Treatments using chemicals such as sodium hydroxide, isocyanate, permanganate and peroxide were carried out to improve the bonding at the fibre polymer interface. The treatments enhanced the tensile properties of the composites considerably, but to varying degrees. The SEM (scanning electron

C. Pavithran

1996-01-01

232

Tensile and elastic properties of segmented copolyetheresteramides with uniform aramid units  

Microsoft Academic Search

The tensile and elastic properties of segmented copolyetheresteramides with crystallisable aramid units of uniform length were investigated. The aramid concentration ranged from 3 to 30wt%. The effect of type of poly(tetramethyleneoxide) (PTMO) segment, having a different tendency to crystallise, on the tensile and elastic properties was studied. The fracture stress of the polymers was found to be mainly affected by

M. C. E. J. Niesten; R. J. Gaymans

2001-01-01

233

Effect of particle size and volume fraction on tensile properties of fly ash/polyurea composites  

E-print Network

Effect of particle size and volume fraction on tensile properties of fly ash/polyurea composites of the composites. The tensile properties of the pure polyurea and fly ash/polyurea (FA/PU) composites were tested of the composites was influenced by both the fly ash size and the volume fraction. Compared to the largest particle

Nemat-Nasser, Sia

234

Biocomposites from abaca strands and polypropylene. Part I: Evaluation of the tensile properties  

Microsoft Academic Search

In this paper, abaca strands were used as reinforcement of polypropylene matrix and their tensile mechanical properties were studied. It was found relevant increments on the tensile properties of the abaca strand-PP composites despite the lack of good adhesion at fiber–matrix interface. Afterwards, it was stated the influence of using maleated polypropylene (MAPP) as compatibilizer to promote the interaction between

Fabiola Vilaseca; Alex Valadez-Gonzalez; Pedro J. Herrera-Franco; M. Àngels Pèlach; Joan Pere López; Pere Mutjé

2010-01-01

235

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

236

Correlating microstructural features and mechanical properties with abrasion resistance of a high strength low alloy steel  

Microsoft Academic Search

A study towards the examination of the abrasive wear behaviour and other characteristics, viz. microstructure, tensile properties and hardness of a high strength low alloy steel has been carried out in order to establish a correlation amongst the parameters and to optimize the microstructural features and mechanical properties for superior wear performance. The steel was subjected to various heat treatment

A. K. Jha; B. K. Prasad; O. P. Modi; S. Das; A. H. Yegneswaran

2003-01-01

237

The effect of microalloying additions on the tensile properties of polycrystalline NiAl  

NASA Technical Reports Server (NTRS)

The presently evaluated 0.1 at. pct Fe and Ga additions to NiAl, while beneficial in the case of monocrystalline NiAl ductility, does not improve ductility in the polycrystalline case; it also has little effect on tensile properties. A similar microalloying addition of Zr, by contrast, significantly depressed the tensile ductility of NiAl, and nearly doubled the brittle-to-ductile transition temperature (BDTT). The dependence of tensile properties on temperature was in all cases similar; tensile elongations remained low and constant until the BDTT was reached, and then dramatically increased.

Noebe, R. D.; Behbehani, M. K.

1992-01-01

238

Root tensile strength relationships and their slope stability implications of three shrub species in the Northern Apennines (Italy)  

NASA Astrophysics Data System (ADS)

The role of root strength is important in stabilising steep hillslopes which are seasonally affected by storm-induced shallow landslides. In the Italian Apennines, steep (25-40°) slopes underlain by mudstone are generally stable if they are covered by shrubs whose roots anchor into the soil mantle. To quantify the mechanical reinforcement of roots to soil, the root tensile breaking force and the root tensile strength of three autochthonous shrub species commonly growing on stiff clay soils of the Northern Italian Apennines, Rosa canina (L.), Inula viscosa (L.) and Spartium junceum (L.), were measured by means of field and laboratory tests. For each test approximately 150 root specimens were used. The tensile force increases with increasing root diameter following a second-order polynomial regression curve. The tensile strength decreases with increasing root diameter following a power law curve. The field in situ tensile force required to break a root is always smaller than that obtained from laboratory tests for the same root diameter, although their difference becomes negligible if the root diameter is smaller than 5 mm. The influence of root tensile strength on soil shear strength was verified based on the infinite slope stability model. The root reinforcement was calculated using the number and mean diameter of roots. The factor of safety was calculated for three different soil thickness values (0.1, 0.3, and 0.6 m) and topographic slopes between 10° and 45°. The factor of safety for the combination of 0.6 m soil thickness, slopes smaller than 30°, and vegetation of I. viscosa (L.) or S. junceum (L.) is always larger than 1. If a slope is steeper, the factor of safety may be smaller than 1 for I. viscosa (L.), although it is still larger than 1 for S. junceum (L.). In the stiff clayey areas of the Northern Italian Apennines, I. viscosa (L.) mainly colonizes fan/cone/taluses and stabilises these zones up to a topographic gradient < 30° for a soil 0.6 m thick. S. junceum (L.) colonizes not only fan/cone/taluses but also headwalls and cliffs and, for a 0.6 m thick soil, it stabilises these areas up to 45°. The effectiveness of this reinforcement, however, depends strongly on the frequency of soil and seasonal grass vegetation removal due to shallow landsliding before the entrance of the shrub species.

Tosi, Matteo

2007-07-01

239

Effect of Postweld Heat Treatment on Microstructure, Hardness, and Tensile Properties of Laser-Welded Ti-6Al-4V  

NASA Astrophysics Data System (ADS)

The effects of postweld heat treatment (PWHT) on 3.2-mm- and 5.1-mm-thick Ti-6Al-4V butt joints welded using a continuous wave (CW) 4-kW Nd:YAG laser welding machine were investigated in terms of microstructural transformations, welding defects, and hardness, as well as global and local tensile properties. Two postweld heat treatments, i.e., stress-relief annealing (SRA) and solution heat treatment followed by aging (STA), were performed and the weld qualities were compared with the as-welded condition. A digital image correlation technique was used to determine the global tensile behavior for the transverse welding samples. The local tensile properties including yield strength and maximum strain were determined, for the first time, for the laser-welded Ti-6Al-4V. The mechanical properties, including hardness and the global and local tensile properties, were correlated to the microstructure and defects in the as-welded, SRA, and STA conditions.

Kabir, Abu Syed H.; Cao, Xinjin; Gholipour, Javad; Wanjara, Priti; Cuddy, Jonathan; Birur, Anand; Medraj, Mamoun

2012-11-01

240

Measurement of the dynamic mechanical properties of high-strength steel using wave propagation characteristics  

NASA Astrophysics Data System (ADS)

The dynamic mechanical properties of different high-strength steels were measured and compared based on their respective microstructures. Beam-shaped test specimens were excited using an electric shaker while vibration responses were measured using a non-contact laser sensor. Flexural wave propagation was analyzed to precisely determine material damping. Measured properties were compared to those of carbon steels. In addition, the effects of grain size determined by optical micrographs on the dynamic properties were investigated. The influence of the tensile strength on the measured properties was analyzed. The high-strength steels exhibited smaller damping with a similar Young's modulus compared to carbon steels, although the tensile strength was much greater.

Park, Jeongwon; Kim, Do-Hyung; Kim, Hak-Sung; Park, Junhong; Yoo, Ji Woo

2014-06-01

241

Effects of curing time and end pressure on the tensile strength of finger-joined black spruce lumber  

Microsoft Academic Search

Finger-joined black spruce (Picea mariana (Mill.) B.S.P) specimens from eastern Canada were prepared to assess the effect of curing time and end pressure on the tensile strength of the joints. An isocyanate adhesive cured at room temperature and a feather joint configuration were used for this purpose. The joints were machined at a 18.3 m\\/min. (60 ft.\\/min) feed rate, 3500

Cecilia Bustos; Mohammad Mohammad; Roger E. Hernández; Robert Beauregard

242

Tensile and mixed-mode strength of a thin film-substrate interface under laser induced pulse loading  

Microsoft Academic Search

Laser induced stress waves are used to characterize intrinsic interfacial strength of thin films under both tensile and mixed-mode conditions. A short-duration compressive pulse induced by pulsed-laser ablation of a sacrificial layer on one side of a substrate is allowed to impinge upon a thin test film on the opposite surface. Laser-interferometric measurements of test film displacement enable calculation of

Junlan Wang; Nancy R. Sottos; Richard L. Weaver

2004-01-01

243

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

244

Evaluation of tensile strength and surface topography of orthodontic wires after infection control procedures: An in vitro study  

PubMed Central

Aim: The aim of this study is to evaluate, the influence of four types of sterilization/disinfection procedures (autoclave, hot air oven, glutaraldehyde, and ultraviolet [UV] light) on the tensile strength and surface topography of three orthodontic wires (stainless steel (SS), titanium - molybdenum alloy [TMA], and cobalt chromium (CoCr)). Materials and Methods: Sample comprised of three types of 8 inches straight length segments of orthodontic wires. They were divided into three groups according to wire composition comprising of 50 samples each. Totally 50 samples of each group were then equally divided into five subgroups according to sterilization method. After sterilization and disinfection of the experimental group, surface topography was examined with scanning electron microscope (SEM) and tensile strength was tested using universal testing machine. Result: The results of this study show that the mean ultimate tensile strength (UTS) of SS wire after four sterilization procedures were similar to the control group (1845.815 ± 142.29 MPa). The mean UTS of TMA wire increases after four sterilization procedures when compared with the control group (874.107 ± 275.939 MPa). The mean UTS of CoCr wire remains same after UV light disinfection, but increases after other three sterilization procedures when compared with the control group (1449.759 ± 156.586 MPa). SEM photographs of the present study shows gross increase in pitting roughness of the surface topography of all the three types of wires after four types of sterilization. Conclusion: Orthodontists who want to offer maximum safety for their patients can sterilize orthodontic wires before placement, as it does not deteriorate the tensile strength and surface roughness of the alloys. PMID:25210383

Brindha, M.; Kumaran, N. Kurunji; Rajasigamani, K.

2014-01-01

245

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

246

Differences of tensile strength distribution between mechanically high-grade and low-grade Japanese larch lumber I: Effect of length on the strength of lumber  

Microsoft Academic Search

An experimental study was conducted to evaluate the effect of length on the parallel-to-grain tensile strength of Japanese\\u000a larch (Larix kaempferi, Carriere) lumber. Six hundred pieces of mechanically graded lumber were tested at gauge lengths of 60, 100, and 180 cm.\\u000a The lumber was sorted into matched groups according to the dynamic Young's modulus measured by the longitudinal vibration\\u000a method

Takashi Takeda; Takeo Hashizume

1999-01-01

247

Influence of repair welding of aged 18Ni 250 maraging steel weldments on tensile and fracture properties  

SciTech Connect

The effects of repair welding on tensile strength and fracture toughness of aged weldments of 18 Ni 250-grade maraging steel have been studied. It has been established that aged weldments in the steel can be repaired and approximately 95% of the tensile strength of the initial welds could be achieved by postrepair aging treatment. Also, the repairs had practically no effect on the fracture toughness (K[sub IC]) of the weldment. These results have been discussed in terms of microstructural conditions in the various affected and unaffected zones of the initial weld. One important inference that emerges from the mechanical properties-microstructural correlation in the study is that (K[sub IC]) of the weld is independent of the gross microstructural features of the dendritic size and shapes in the ranges observed in this study. It has, however, been cautioned that the above statement is not valid in cases in which heavy segregation occurs along the interdendritic boundaries resulting in heavily banded microstructure. This can result from faulty weld parameters such as excessive heat input. A second aging to recover the mechanical properties of the repaired zone has additional beneficial effects on tensile strengths and helps in maintaining fracture toughness to the original level of the initial weld.

Sinha, P.P.; Arumugham, S.; Nagarajan, K.V. (Vikram Sarabhai Space Center, Trivandrum (India). Materials and Metallurgy Group)

1993-08-01

248

Influence of Width of Specimen on Tensile Properties of NiCo Thin Film  

Microsoft Academic Search

This paper represents the results of tensile test for NiCo thin films, to investigate the size effect on tensile properties. An axial loading tensile tester developed by authors was used to measure the mechanical characteristics of thin film materials. The tester has a load cell with maximum capacity of 0.5N and a non-contact position measuring system based on the principle

Jun-Hyub Park; Joong-Hyok An; Yun-Bae Jeon; Yun-Jae Kim; Yong-Hak Huh

2009-01-01

249

Evaluation of tensile properties of 5052 type aluminum-magnesium alloy at warm temperatures  

Microsoft Academic Search

Purpose: The purpose of the paper is to evaluate the tensile properties of 5052 type aluminum-manganese alloy in warm temperatures. Design\\/methodology\\/approach: In this research, uniaxial tensile deformation behavior of 5052-H32 type aluminum magnesium alloy was studied range between room to 300°C and in the strain rate range of 0.0083-0.16 s-1. Findings: It was observed that the uniaxial tensile elongation of

F. Ozturk; S. Toros; S. Kilic

250

The effects of specimen width on tensile properties of triaxially braided textile composites  

NASA Technical Reports Server (NTRS)

The objective of this study was to examine the effect of the unit cell architecture on the mechanical response of textile reinforced composite materials. Specifically, the study investigated the effect of unit cell size on the tensile properties of 2D triaxially braided graphite epoxy laminates. The figures contained in this paper reflect the presentation given at the conference. They may be divided into four sections: (1) a short definition of the material system tested; (2) a statement of the problem and a review of the experimental results; (3) experimental results consist of a Moire interferometry study of the strain distribution in the material plus modulus and strength measurements; and (4) a short summary and a description of future work will close the paper.

Masters, John E.; Ifju, Peter G.; Pastore, Christopher M.; Bogdanovich, Alexander E.

1993-01-01

251

Acoustic emission monitoring of tensile testing of corroded and un-corroded clad aluminum 2024-T3 and characterization of effects of corrosion on AE source events and material tensile properties  

NASA Astrophysics Data System (ADS)

Corrosion damage affects structural integrity and deteriorates material properties of aluminum alloys in aircraft structures. Acoustic Emission (AE) is an effective nondestructive evaluation (NDE) technique for monitoring such damages and predicting failure in large structures of an aircraft. For successful interpretation of data from AE monitoring, sources of AE and factors affecting it need to be identified. This paper presents results of AE monitoring of tensile testing of corroded and un-corroded clad Aluminum 2024-T3 test specimens, and characterization of the effects of strain-rate and corrosion damage on material tensile properties and AE source events. Effect of corrosion was studied by inducing corrosion in the test specimens by accelerated corrosion testing in a Q-Fog accelerated corrosion chamber for 12 weeks. Eight (8) masked dog-bone shaped specimens were placed in the accelerated corrosion chamber at the beginning of the test. Two (2) dog-bone shaped specimens were removed from the corrosion chamber after exposure time of 3, 6, 9, and 12 weeks respectively, and subjected to tension testing till specimen failure along with AE monitoring, as well as two (2) reference samples not exposed to corrosion. Material tensile properties (yield strength, ultimate tensile strength, toughness, and elongation) obtained from tension test and AE parameters obtained from AE monitoring were analyzed and characterized. AE parameters increase with increase in exposure period of the specimens in the corrosive environment. Aluminum 2024-T3 is an acoustically silent material during tensile deformation without any damage. Acoustic emission events increase with increase of corrosion damage and with increase in strain rate above a certain value. Thus AE is suitable for structural health monitoring of corrosion damage. Ultimate tensile strength, toughness and elongation values decrease with increase of exposure period in corrosion chamber.

Okafor, A. Chukwujekwu; Natarajan, Shridhar

2014-02-01

252

Effect of boron on tensile properties of B2 BeAl  

NASA Technical Reports Server (NTRS)

Small additions of boron were shown to improve the room temperature ductility of the intermetallic compound Ni3Al. Boron is believed to segregate to the gain boundaries and strengthen them, allowing the inheret ductility of the grains to be achieved. The present study was undertaken to see if boron has a similar effect on the low temperature tensile properties of the equiatomic intermetallic compound FeAl. A binary alloy without boron is compared with an alloy containing 0.78 at % B (0.2 wt %) B, by tensile testing over the temperature range of 300 K to 640 K. Both alloys were processed by powder metallurgy. Results showed that 0.78 at % B addition to FeAl does indeed change the room temperature fracture mode from intergranular to transgranular, suggesting a strengthening of grain boundaries. The alloy containing boron is, however, still brittle at room temperature. A slight decrease in the ductile to brittle transition temperature is, nevertheless, observed. In addition a significant increase in strength of the alloy is observed with boron addition.

Crimp, M.; Vedula, K.

1986-01-01

253

Improved tensile creep properties of yttrium-and lanthanum-doped alumina: a solid solution effect  

E-print Network

Improved tensile creep properties of yttrium- and lanthanum-doped alumina: a solid solution effect, Pennsylvania 18015 (Received 16 March 2000; accepted 30 October 2000) The tensile creep behavior of yttrium ppm yttrium, 100 ppm lanthanum) exhibited a uniform microstructure consisting of fine, equiaxed grains

Cho, Junghyun

254

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

255

Tensile strength and dilatational elasticity of giant sarcolemmal vesicles shed from rabbit muscle.  

PubMed Central

1. Mechanical properties of the surface membrane of skeletal muscle were determined on sarcolemmal vesicles (mean diameter, 71 microns) shed by rabbit psoas muscle swelling in 140 mM KC1 containing collagenase. 2. Vesicles were stressed by partial aspiration into parallel bore pipettes. The isotropic membrane tension so created caused an increase in membrane area which expresses itself in an elongation of the vesicle projection into the pipette. 3. For individual vesicles, a linear relationship between membrane tension and membrane area increase was found up to the point when the vesicle burst, i.e. sarcolemmal vesicles behaved as perfectly elastic structures. 4. The maximum tension sarcolemmal vesicles could sustain before bursting was 12.4 +/- 0.2 mN m-1 (median +/- 95% confidence interval), and the corresponding fractional increase in membrane area was 0.026 +/- 0.005 (median +/- 95% confidence interval). The elastic modulus of area expansion was 490 +/- 88 mN m-1 (mean +/- S.D.). 5. In conformity with cited comparable work on red blood cells and artificial lipid vesicles, the strength and area elasticity of the skeletal muscle membrane are considered properties of the fluid lipid matrix of the membrane and of the degree to which the bilayer is perturbed by lipid-protein interaction. Images Figure 2 PMID:8735704

Nichol, J A; Hutter, O F

1996-01-01

256

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

257

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

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

258

Space environmental effects on graphite-epoxy compressive properties and epoxy tensile properties  

NASA Technical Reports Server (NTRS)

This study characterizes the effects of electron radiation and temperature on a graphite-epoxy composite material. Compressive properties of the T300/934 material system were obtained at -250 F (-157 C), room temperature, and 250 F (121 C). Tensile specimens of the Fiberite 934 epoxy resin were fabricated and tested at room temperature and 250 F (121 C). Testing was conducted in the baseline (nonirradiated) and irradiated conditions. The radiation exposure was designed to simulate 30 year, worst-case exposure in geosynchronous Earth orbit. Mechanical properties tended to degrade at elevated temperature and improve at cryogenic temperature. Irradiation generally degraded properties at all temperatures.

Fox, Derek J.; Sykes, George F., Jr.; Herakovich, Carl T.

1987-01-01

259

Microstructures and tensile properties of an Al-12 wt pct Si alloy produced by reciprocating extrusion  

SciTech Connect

A reciprocating extrusion (RE) process has been developed for producing Al-12 wt pct Si bulk alloys with fine and uniform microstructures and superior properties. Two starting forms were used: disks produced by the hammer-and-anvil method and cast billets produced by casting. Variations of microstructure and mechanical properties with the number of extrusion passes are investigated for these two starting forms. The results show that the porosity along the interfaces between the rapidly solidified layers could be completely eliminated to give a sound matrix. The Si-phase particles in both cases could be refined and distributed uniformly. The strength and ductility of all specimens are also enhanced, until the microstructure reaches an optimum state, as the number of extrusion passes increases. The tensile properties of the rapidly solidified Al-Si alloys are found to be superior to those of ingot-processed alloys, due to the inherent finer particles produced by rapid solidification. The mechanism for the improvement of the microstructures and properties is also discussed.

Yeh, J.W.; Yuang, S.Y.; Peng, C.H. [National Tsing Hua Univ., Hsinchu (Taiwan, Province of China). Dept. of Materials Science and Engineering

1999-09-01

260

The effect of ultrasonics on the strength properties of carbon steel processed by cold plastic deformation  

NASA Technical Reports Server (NTRS)

A study was made of the influence of ultrasounds on the mechanical properties of OLT 35 carbon steel tubes cold-drawn on a plug ultrasonically activated by longitudinal waves. Experimental results indicate that: 1. The reduction in the values of the flow limit and tensile strength is proportional to the increase in acoustic energy introduced into the material subjected to deformation. 2. The diminution in influence of ultrasounds on tensile strength and flow rate that is due to an increased degree of deformation is explained by a reduction in specific density of the acoustic energy at the focus of deformation. 3. The relations calculated on the basis of the variation in the flow limit and tensile strength as a function of acoustic energy intensity was verified experimentally.

Atanasiu, N.; Dragan, O.; Atanasiu, Z.

1974-01-01

261

Microstructure and tensile properties of Inconel 718 pulsed Nd-YAG laser welds  

Microsoft Academic Search

Pulsed Nd-YAG laser welding characteristics of Inconel 718 sheet material (2mm thick) were investigated. Welds were subjected to three different post-weld heat treatments: direct aging, 980°C solution treatment+aging (980STA), and 1080°C solution treatment+aging (1080STA). Weld microstructures and room temperature tensile properties were evaluated. Weld tensile properties in direct aged condition were found to be inferior in relation to the base

G. D. Janaki Ram; A. Venugopal Reddy; K. Prasad Rao; G. M. Reddy; J. K. Sarin Sundar

2005-01-01

262

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

263

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

NASA Astrophysics Data System (ADS)

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

Hidayat, Irpan; Siauwantara, Alice

2014-03-01

264

Strength, Hardening, and Failure Observed by In Situ TEM Tensile Testing**  

PubMed Central

We present in situ transmission electron microscope tensile tests on focused ion beam fabricated single and multiple slip oriented Cu tensile samples with thicknesses in the range of 100–200 nm. Both crystal orientations fail by localized shear. While failure occurs after a few percent plastic strain and limited hardening in the single slip case, the multiple slip samples exhibit extended homogenous deformation and necking due to the activation of multiple dislocation sources in conjunction with significant hardening. The hardening behavior at 1% plastic strain is even more pronounced compared to compression samples of the same orientation due to the absence of sample taper and the interface to the compression platen. Moreover, we show for the first time that the strain rate sensitivity of such FIB prepared samples is an order of magnitude higher than that of bulk Cu. PMID:23447712

Kiener, Daniel; Kaufmann, Petra; Minor, Andrew M.

2012-01-01

265

Strength, Hardening, and Failure Observed by In Situ TEM Tensile Testing.  

PubMed

We present in situ transmission electron microscope tensile tests on focused ion beam fabricated single and multiple slip oriented Cu tensile samples with thicknesses in the range of 100-200 nm. Both crystal orientations fail by localized shear. While failure occurs after a few percent plastic strain and limited hardening in the single slip case, the multiple slip samples exhibit extended homogenous deformation and necking due to the activation of multiple dislocation sources in conjunction with significant hardening. The hardening behavior at 1% plastic strain is even more pronounced compared to compression samples of the same orientation due to the absence of sample taper and the interface to the compression platen. Moreover, we show for the first time that the strain rate sensitivity of such FIB prepared samples is an order of magnitude higher than that of bulk Cu. PMID:23447712

Kiener, Daniel; Kaufmann, Petra; Minor, Andrew M

2012-11-01

266

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

NASA Astrophysics Data System (ADS)

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

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

2012-08-01

267

Friction Stir Welded AZ31 Magnesium Alloy: Microstructure, Texture, and Tensile Properties  

NASA Astrophysics Data System (ADS)

This study was aimed at characterizing the microstructure, texture and tensile properties of a friction stir welded AZ31B-H24 Mg alloy with varying tool rotational rates and welding speeds. Friction stir welding (FSW) resulted in the presence of recrystallized grains and the relevant drop in hardness in the stir zone (SZ). The base alloy contained a strong crystallographic texture with basal planes (0002) largely parallel to the rolling sheet surface and < {11bar{2}0} rangle directions aligned in the rolling direction (RD). After FSW the basal planes in the SZ were slightly tilted toward the TD determined from the sheet normal direction (or top surface) and also slightly inclined toward the RD determined from the transverse direction (or cross section) due to the intense shear plastic flow near the pin surface. The prismatic planes (10bar{1}0) and pyramidal planes (10bar{1}1) formed fiber textures. After FSW both the strength and ductility of the AZ31B-H24 Mg alloy decreased with a joint efficiency in-between about 75 and 82 pct due to the changes in both grain structure and texture, which also weakened the strain rate dependence of tensile properties. The welding speed and rotational rate exhibited a stronger effect on the YS than the UTS. Despite the lower ductility, strain-hardening exponent and hardening capacity, a higher YS was obtained at a higher welding speed and lower rotational rate mainly due to the smaller recrystallized grains in the SZ arising from the lower heat input.

Chowdhury, S. H.; Chen, D. L.; Bhole, S. D.; Cao, X.; Wanjara, P.

2013-01-01

268

Tensile and fatigue properties of two titanium alloys as candidate materials for fusion reactors  

NASA Astrophysics Data System (ADS)

Titanium alloys have been identified as candidate structural materials for the first wall, the blanket and the magnetic coil structures of fusion reactors. Titanium alloys are interesting materials because of their high specific strength and low elastic modulus, their low swelling tendency and their fast induced radioactivity decay. Other attractive properties are an excellent resistance to corrosion and good weldability, even in thick sections. Furthermore titanium alloys are suitable for components exposed to heat loads since they have a low thermal stress parameter. Titanium alloys with an ? structure are believed to have a good resistance against radiation embrittlement and ?+? alloys should possess the best tolerance to hydrogen embrittlement. Two classical industrially available alloys in the two families, the Ti5Al2.4Sn and the Ti6Al4V alloys have been used in this study. The tensile properties between room temperature and 450°C are reported. A low cycle fatigue analysis has been performed under strain control at total strain ranges between 0.8% and 2% and at a temperature of 350°C. The microstructure of both alloys was investigated before and after both types of deformation. Both alloys exhibit excellent mechanical properties comparable to or better than those of ferritic martensitic steels.

Marmy, P.; Leguey, T.; Belianov, I.; Victoria, M.

2000-12-01

269

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

270

The effects of incorporation Fe 2 O 3 nanoparticles on tensile and flexural strength of concrete  

Microsoft Academic Search

In this Paper, the split tensile and flexural stren gth together with the setting time of concrete by p artial replacement of cement with nano-phase Fe 2O3 particles has been studied. Fe 2O3 nanoparticles with the average diameter of 15 nm were used with four different contents of 0.5%, 0.1%, 1. 5% and 2.0% by weight. The results showed that

Ali Nazari; Shadi Riahi; Shirin Riahi; Seyedeh Fatemeh Shamekhi; A. Khademno

2010-01-01

271

The effect of different light-curing units on tensile strength and microhardness of a composite resin.  

PubMed

The aim of this study was to evaluate the influence of different light-curing units on the tensile bond strength and microhardness of a composite resin (Filtek Z250 - 3M/ESPE). Conventional halogen (Curing Light 2500 - 3M/ESPE; CL) and two blue light emitting diode curing units (Ultraled - Dabi/Atlante; UL; Ultrablue IS - DMC; UB3 and UB6) were selected for this study. Different light intensities (670, 130, 300, and 600 mW/cm(2), respectively) and different curing times (20s, 40s and 60s) were evaluated. Knoop microhardness test was performed in the area corresponding to the fractured region of the specimen. A total of 12 groups (n=10) were established and the specimens were prepared using a stainless steel mold composed by two similar parts that contained a cone-shaped hole with two diameters (8.0 mm and 5.0 mm) and thickness of 1.0 mm. Next, the specimens were loaded in tensile strength until fracture in a universal testing machine at a crosshead speed of 0.5 mm/min and a 50 kg load cell. For the microhardness test, the same matrix was used to fabricate the specimens (12 groups; n=5). Microhardness was determined on the surfaces that were not exposed to the light source, using a Shimadzu HMV-2 Microhardness Tester at a static load of 50 g for 30 seconds. Data were analyzed statistically by two-way ANOVA and Tukey's test (p<0.05). Regarding the individual performance of the light-curing units, there was similarity in tensile strength with 20-s and 40-s exposure times and higher tensile strength when a 60-s light-activation time was used. Regarding microhardness, the halogen lamp had higher results when compared to the LED units. For all light-curing units, the variation of light-exposure time did not affect composite microhardness. However, lower irradiances needed longer light-activation times to produce similar effect as that obtained with high-irradiance light-curing sources. PMID:19089182

Franco, Eduardo Batista; dos Santos, Patrícia Aleixo; Mondelli, Rafael Francisco Lia

2007-12-01

272

Estimation of the Tensile Strength Reduction of a Composite Laminate with a Hole  

Microsoft Academic Search

The strength problem for a body with an artificial defect in the form of a hole is considered. To solve this problem, an approach is suggested according to which the local strength of a material in the area of stress concentration is assumed to depend on the size of this area. The scale of the problem is introduced via the

S. V. Suknyov

2000-01-01

273

Tensile Properties of Poly (N-vinyl caprolactam) Gels  

NASA Technical Reports Server (NTRS)

N-vinyl caprolactam was copolymerized with ethylene glycol dimethacrylate using a free-radical initiator in alcohol/water solution. The resulting gels were thermally-responsive in water, undergoing an approximate fivefold reversible volume shrinkage between room temperature and ca. 50 C. Tensile testing showed that the stress-strain behavior was qualitatively different in the collapsed state above the temperature-induced transition. At the higher temperature, gels were stiffer, more ductile, and showed greater time dependence. Implications for the design of gel actuators are briefly discussed.

Morgret, Leslie D.; Hinkley, Jeffrey A.

2004-01-01

274

Composites: Part B 44 (2013) 584591 584 Tensile Properties of Carbon Nanofiber Reinforced Multiscale Syntactic Foams  

E-print Network

that the presence of CNFs leads to increased values of strength and modulus in syntactic foams containing 50 vol.% microballoons compared to unreinforced syntactic foams. The specific tensile modulus of all CNF reinforced foams without decreasing the particle packing limit in the material structure. Among different

Gupta, Nikhil

275

Microstructures and tensile properties of AZ31 magnesium alloy by continuous extrusion forming process  

Microsoft Academic Search

The objective of this study is to investigate the possibility of continuous extrusion forming (Conform process) of AZ31 magnesium alloy. The results indicate that continuous extrusion forming can refine the structure, improve the degree of the structure homogeneity and change the crystal orientation of basal plane and hence enhance the ductility but decrease tensile strength at room temperature. The fracture

Hui Zhang; Qiqi Yan; Luoxing Li

2008-01-01

276

Effects of helium implantation on the tensile properties and microstructure of Ni73P27 metallic glass nanostructures.  

PubMed

We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ?130 nm diameter Ni73P27 metallic glass nanocylinders. The nanocylinders were fabricated by a templated electroplating process and implanted with He(+) at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ?3 atom % throughout the nanocylinders. Transmission electron microscopy imaging and through-focus analysis reveal that the specimens contained ?2 nm helium bubbles distributed uniformly throughout the nanocylinder volume. In situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens with no sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation. PMID:25084487

Liontas, Rachel; Gu, X Wendy; Fu, Engang; Wang, Yongqiang; Li, Nan; Mara, Nathan; Greer, Julia R

2014-09-10

277

Studies of Microtexture and Its Effect on Tensile and High-Cycle Fatigue Properties of Laser-Powder-Deposited INCONEL 718  

NASA Astrophysics Data System (ADS)

The current work studies the microstructure, texture, and mechanical properties of INCONEL 718 alloy (IN718) produced by laser direct metal deposition. The grain microstructure exhibits an alternative distribution of banded fine and coarse grain zones as a result of the rastering scanning pattern. The effects of the anisotropic crystallographic texture on the tensile and high-cycle fatigue (HCF) properties at room temperature are investigated. Tensile test results showed that the tensile strength of laser-deposited IN718 after direct aging or solution heat treatment is equivalent to the minimum-forged IN718 properties. The transverse direction (relative to the laser scanning direction) produces >10 pct stiffer modulus of elasticity but 3 to 6 pct less tensile strength compared to the longitudinal direction due to the preferential alignment of grains having <111> and <100> directions parallel to the tensile loading direction. Laser-deposited IN718 with good metallurgical integrity showed equivalent HCF properties compared to the direct-aged wrought IN718, which can be attributed to the banded grain size variation and cyclic change of inclining grain orientations resulted from alternating rastering deposition path.

Qi, Huan; Azer, Magdi; Deal, Andrew

2012-11-01

278

Effect of service usage on tensile, fatigue, and fracture properties of 7075-T6 and 7178-T6 aluminum alloys  

NASA Technical Reports Server (NTRS)

A study has been made to determine the effects of extensive service usage on some basic material properties of 7075-T6 and 7178-T6 aluminum alloy materials. The effects of service usage were determined by comparing material properties for new material (generally obtained from the literature) with those for material cut from the center wing box of a C-130B transport airplane with 6385 flight-hours of service. The properties investigated were notched and unnotched fatigue strengths, fatigue-crack-growth rate, fracture toughness, and tensile properties. For the properties investigated and the parameter ranges considered (crack length, stress ratio, etc.), the results obtained showed no significant difference between service and new materials.

Everett, R. A., Jr.

1975-01-01

279

In-Situ Observations on the Fracture Mechanism of Diffusion-Alloyed Ni-Containing Powder Metal Steels and a Proposed Method for Tensile Strength Improvement  

NASA Astrophysics Data System (ADS)

The mechanical properties of Ni-containing powder metal (PM) steels are usually inferior to those of their wrought counterparts. The main problem is attributed to the non-uniform Ni distribution, in addition to the problems caused by porosity. The effects of this non-uniform alloying on the mechanical properties were investigated in this study using mini tensile bars that were made of diffusion-alloyed FD-0405 (Fe-4Ni-1.5Cu-0.5Mo-0.5C) powders. In-situ observations under a scanning electron microscope (SEM) were carried out during the tensile testing. The results indicated that the soft Ni-rich/C-lean area around the pore, which was identified as ferrite using electron backscattered diffraction (EBSD) analysis, was responsible for the failures. By adding Cr in the form of prealloyed powders, the distribution of Ni and C became more uniform, and the Ni-rich/C-lean ferrite was replaced by bainite and martensite. After sintering at 1250 °C for 1 hour, the tensile strength of the Fe-4Ni-1.5Cr-0.2Mo-0.5C and Fe-4Ni-3Cr-0.5Mo-0.5C reached 1178 and 1323 MPa, respectively, without employing any accelerated cooling system. These properties are higher than all those reported to date in the literature for sinter-hardened PM alloys that were rapidly cooled after sintering. This significant improvement was attributed to the homogeneous alloying, particularly due to the reduction of the repelling effect between Ni and C, as was explained through the thermodynamics analysis using the Thermo-Calc program.

Wu, M. W.; Hwang, K. S.; Huang, H. S.

2007-07-01

280

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

281

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

282

Apparatus for measuring tensile and compressive properties of solid materials at cryogenic temperatures  

DOEpatents

An apparatus for evaluating the tensile and compressive properties of material samples at very low or cryogenic temperatures employs a stationary frame and a dewar mounted below the frame. A pair of coaxial cylindrical tubes extend downward towards the bottom of the dewar. A compressive or tensile load is generated hydraulically and is transmitted by the inner tube to the material sample. The material sample is located near the bottom of the dewar in a liquid refrigerant bath. The apparatus employs a displacement measuring device, such as a linear variable differential transformer, to measure the deformation of the material sample relative to the amount of compressive or tensile force applied to the sample.

Gonczy, John D. (Oaklawn, IL); Markley, Finley W. (St. Charles, IL); McCaw, William R. (Burr Ridge, IL); Niemann, Ralph C. (Downers Grove, IL)

1992-01-01

283

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

284

Effect of the strain rate on the tensile strength of a copper shaped-charge jet  

Microsoft Academic Search

The data on the penetration depth of a rotating shaped-charge jet were used to estimate the strength of the material of a\\u000a copper jet formed from a “low” conical linear with an apex angle of120° under the action of centrifugal forces. The estimates0.07–0.15 GPa obtained are close to the static yield point of deformed copper. The jet strength, which is

V. V. Silvestrov; N. N. Gorshkov

1997-01-01

285

Effect of laser welding on the titanium composite tensile bond strength.  

PubMed

The aim of this study was to analyze the shear bond strength between commercially pure titanium, with and without laser welding, after airbone-particle abrasion (Al(2)O(3)) and 2 indirect composites. Sixty-four specimens were cast and divided into 2 groups with and without laser welding. Each group was divided in 4 subgroups, related to Al(2)O(3) grain size: A - 250 microm; B - 180 microm; C- 110 microm; and D - 50 microm. Composite rings were formed around the rods and light polymerized using UniXS unit. Specimens were invested and their shear bond strength at failure was measured with a universal testing machine at a crosshead speed of 2.0 mm/min. Statistical analysis was carried out with ANOVA and Tukey's test (alpha=0.05). The highest bond strength means were recorded in 250 microm group without laser welding. The lowest shear bond strength means were recorded in 50 microm group with laser welding. Statistically significant differences (p<0.05) were found between all groups. In conclusion, airborne particle abrasion yielded significantly lower bond strength as the Al(2)O(3) particle size decreased. Shear bond strength decreased in the laser welded specimens. PMID:20126909

Galo, Rodrigo; Ribeiro, Ricardo Faria; Rodrigues, Renata Cristina Silveira; Pagnano, Valéria de Oliveira; de Mattos, Maria da Glória Chiarello

2009-01-01

286

Effect of irradiation on the tensile properties of niobium-base alloys  

SciTech Connect

The alloys Nb-1Zr and PWC-11 (Nb-1Zr-0.1C) were selected as prime candidate alloys for the SP-100 reactor. Since the mechanical properties of niobium alloys irradiated to end-of-life exposure levels of about 2 x 10SW neutrons/mS (E > 0.1 MeV) at temperatures above 1300 K were not available, an irradiation experiment (B-350) in EBR-II was conducted. Irradiation creep, impact properties, bending fatigue, and tensile properties were investigated; however, only tensile properties will be reported in this paper. The tensile properties were studied since they easily reveal the common irradiation phenomena of hardening and embrittlement. Most attention was directed to testing at the irradiation temperature. Further testing was conducted at lower temperatures in order to scope the behavior of the alloys in cooldown conditions.

Grossbeck, M.L.; Heestand, R.L.; Atkin, S.D.

1986-11-01

287

Physical Property Measurements: Unconfined Compressive Strength (UCS)  

NSDL National Science Digital Library

This site, by the Colorado School of Mines, addresses the properties of a measurement technique called unconfined compression strength (UCS). Along with defining the technique, the website shows different experiments, pictures and diagrams associated with UCS. This well organized work will be a valuable asset for any geology or engineering classroom.

Ozdemir, Levent

288

Rate and temperature effects on the flow stress and tensile strength of metals  

NASA Astrophysics Data System (ADS)

Some new and obtained earlier experimental data on the elastic precursor decay and rise times of plastic shock waves in several metals and alloys at normal and elevated temperatures are systematized. The data on precursor decay include last measurements at micron and submicron distances where realized shear stresses are comparable with their ultimate (``ideal'') values. Results of measurements have been transformed into dependences of plastic strain rate on the shear stress. It has been found the precursor decay may occur in several regimes which are characterized by different decay rates. Anomalous growth of the Hugoniot elastic limit with heating correlates with a fast decay regime and is not observed when the decay is relatively slow. An analysis of the rise times of plastic shock waves shows by order of magnitude faster plastic strain rates at corresponding shear stresses than that at the HEL. Results of measurements of the resistance to high-rate fracture (``spall strength'') show gradual increase of the later with increasing rate of tension and approaching the ``ideal'' strength in a picosecond time range. The spall strength usually decreases with heating although in less degree than the strength at low strain rates does. In general, the temperature dependences of the spall strength do not correlate with dependences of the yield stress that points on larger contribution of the fracture nucleation processes as compared to the void growth. Requirements to constitutive models for high-rate plastic deformation and fracture are formulated on the base of experimental observations.

Kanel, Gennady I.

2011-06-01

289

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

290

The tensile and shear bond strength of a conventional and a 4-meta self-cure acrylic resin to various surface finishes of CoCr alloy.  

PubMed

This study was designed to compare the tensile and shear bond strengths of two self-cure acrylic resins to cobalt-chromium alloy (CoCr) samples, prepared with six surface finishes. The strongest mean tensile bond strength was recorded between the 4-Meta acrylic resin and Silicoated cobalt-chromium alloy. The strongest mean shear bond strengths showed little variation between the 4-Meta acrylic resin and Silicoated, sandblasted and sandblasted/tinplated cobalt-chromium. This laboratory based study may have important implications for the future design of CoCr dentures. PMID:8603150

Barclay, C W; Williams, R

1994-09-01

291

Alternative chromophores for use in light-activated surgical adhesives: optimization of parameters for tensile strength and thermal damage profile  

NASA Astrophysics Data System (ADS)

The use of indocyanine green-doped albumin protein solders has been shown to vastly improve the anastomotic strength that can be achieved by laser tissue repair techniques, while at the same time minimizing collateral thermal tissue damage. However, the safety of the degradation products of the chromophore following laser irradiation is uncertain. Therefore, we studied the feasibility of using alternative chromophores in terms of temperature rise at the solder/tissue interface, the extent of thermal damage in the sourrounding tissue, and the tensile strength of repairs. Biodegradable polymer scaffolds of controlled porosity were fabricated with poly(L-lactic-co-glycolic acid), using a solvent-casting and particulate-leaching technique. The porous scaffold acted as a carrier to the traditional protein solder composition of serum albumin and an absorbing chromophore mixed in deionized water. Two commonly used chromophores, indocyanine green and methylene blue were investigated, as well as blue and green food colorings. Temperature rise at the solder surface and at the interface between the solder and tissue were monitored by an IR temperature monitoring system and a type-K thermocouple, respectively, and the extent of thermal damage in the underlying tissue was determined using light microscopy. As expected, temperature rise at the solder/tissue interface, and consequently the degree of collateral thermal tissue damage, was directly related to the penetration depth of the laser light in the protein solder. Optimal tensile strength of repairs was achieved by selecting a chromophore concentration that resulted in a temperature of 66 +/- 3°C at the solder/tissue interface.

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

2003-06-01

292

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

293

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

PubMed Central

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

TÜRKMEN, Cafer; DURKAN, Meral; C?M?LL?, Hale; ÖKSÜZ, Mustafa

2011-01-01

294

Effect of copper-rich regions on tensile properties of VPPA weldments of 2219-T87 aluminum  

NASA Technical Reports Server (NTRS)

This study examines the relations between tensile properties and microstructural features of variable polarity plasma arc (VPPA) weldments of 2219-T87 aluminum. Crack initiation and weld failure of transverse tensile specimens of single and multipass weldments were studied. The specimens fractured on the rising portion of the stress-strain curve prior to necking, signifying that an increase in strength would accompany an increase in ductility. Of particular interest is a shallow, typically 0.001-0.003-in. (0.03-0.08-mm) deep, copper-rich region located in the crown and root corners of the weld. This region is a primary source of crack initiation and growth, due to its brittle nature and highly strained location. The brittle regions were removed by electropolishing and machining to determine their effect on weld tensile properties. The removal increased the ductility of the weld specimens, and in the case of single pass welds, actually increased the load carrying capacity. Local strain measurements and metallographic and chemical analyses are presented.

Hartman, J. A.; Beil, R. J.; Hahn, G. T.

1987-01-01

295

Effect of the Conservation Treatment of Historical Ceramic Tiles on the Tensile Adhesion Strength  

Microsoft Academic Search

The present work describes some preliminary results of a first attempt to study the effect of a conservation treatment on the adhesion strength of ancient ceramic tiles. Several tiles from the 16th through 20th centuries were submitted to a conservation treatment. The treatment involves the impregnation with Paraloid B-72 using a protocol widely used in most museum restoration departments. Treated

Ariana Russo; Maria Rosário Veiga; Maria Fátima Vaz; Ana Paula Carvalho

2011-01-01

296

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

297

Microstructure and tensile properties of Fe-40 at. pct Al alloys with C, Zr, Hf, and B additions  

NASA Technical Reports Server (NTRS)

The influence of small additions of C, Zr, and Hf, alone or in combination with B, on the microstructure and tensile behavior of substoichiometric FeAl was investigated. Tensile properties were determined from 300 to 1100 K on powder which was consolidated by hot extrusion. All materials possessed some ductility at room temperature, although ternary additions generally reduced ductility compared to the binary alloy. Adding B to the C- and Zr-containing alloys changed the fracture mode from intergranular to transgranular and restored the ductility to approximately 5 percent elongation. Additions of Zr and Hf increased strength up to about 900 K. Fe6Al6Zr and Fe6Al6Hf precipitates, both with identical body-centered tetragonal structures, were identified as the principal second phase in these alloys. Strength decreased steadily as temperature increased above 700 K, as diffusion-assisted mechanisms became operative. Although all alloys had similar strengths at 1100 K, Hf additions significantly improved high-temperature ductility by suppressing cavitation.

Gaydosh, D. J.; Draper, S. L.; Nathal, M. V.

1989-01-01

298

Influence of tensile stress on permeability properties of type 304 stainless steel  

NASA Astrophysics Data System (ADS)

The permeability properties of type SUS304 stainless steel (SUS304 steel) were evaluated under different values of tensile stress using the electromagnetic impedance method. The impedance-magnetic-field curve of SUS304 steel, which corresponds to the permeability-magnetic field-curve, was measured under tensile stresses of 0, 70, and 140 MPa for specimens subjected to prestrains of 5% to 40% to change the martensite fraction. The impedance curves were measured in the length (tensile) direction and the width direction. The results showed that the tensile direction was the magnetic hard axis of the martensite phase in SUS304 steel. The applied stress sensitivity of the permeability in SUS304 steel was affected by the volume fraction, residual stress, stress distribution according to the orientation angle of the martensite phase, and their interactions.

Kinoshita, K.

2015-05-01

299

Tuning electronic and magnetic properties of partially hydrogenated graphene by biaxial tensile strain: a computational study  

PubMed Central

Using density functional theory calculations, we have investigated the effects of biaxial tensile strain on the electronic and magnetic properties of partially hydrogenated graphene (PHG) structures. Our study demonstrates that PHG configuration with hexagon vacancies is more energetically favorable than several other types of PHG configurations. In addition, an appropriate biaxial tensile strain can effectively tune the band gap and magnetism of the hydrogenated graphene. The band gap and magnetism of such configurations can be continuously increased when the magnitude of the biaxial tensile strain is increased. This fact that both the band gap and magnetism of partially hydrogenated graphene can be tuned by applying biaxial tensile strain provides a new pathway for the applications of graphene to electronics and photonics. PMID:25258610

2014-01-01

300

Effects of Microstructure on Tensile, Charpy Impact, and Crack Tip Opening Displacement Properties of Two API X80 Pipeline Steels  

NASA Astrophysics Data System (ADS)

The effects of microstructure on tensile, Charpy impact, and crack tip opening displacement (CTOD) properties of two API X80 pipeline steels were investigated in this study. Two API X80 pipeline steels consisting of acicular ferrite and granular bainite, and a small amount of hard phases such as martensite and secondary phases have elongated grains along the rolling direction, so that they show different mechanical properties as the specimens' directions change. The 90 deg specimens have high tensile strength due to the low stress concentration on the fine hard phases and the high loads for the deformation of the elongated grains. In contrast, the 30 deg specimens have less elongated grains and larger hard phases such as martensite, with the size of about 3 ?m, than the 90 deg specimens. Hence, the 30 deg specimens have low tensile strength because of the high stress concentration on the large hard phases and the low loads to deform grains. In the 90 deg specimen, brittle crack propagation surfaces are even since cracks propagate in a straight line along the elongated grain structure. In the 30 deg specimen, however, brittle crack propagation surfaces are uneven, and secondary cracks are observed, because of the zigzag brittle crack propagation path. In the CTOD properties, the 90 deg specimens have maximum forces of higher magnitude than the 30 deg specimens, because of the elongated grain structure. However, CTODs of the 90 deg specimens are lower than those of the 30 deg specimens because of the low plastic deformation areas by the elongated grains in the 90 deg specimens.

Shin, Sang Yong

2013-06-01

301

Microstructure and tensile properties after thermohydrogen processing of Ti-6 Al-4V.  

PubMed

Thermohydrogen processing (THP), a technique in which hydrogen is used as a temporary alloying element, can refine the microstructure and improve the final mechanical properties of the Ti-6 Al-4V alloy. THP allows microstructural modification of titanium alloys near net shape such as biomaterial components obtained by powder metallurgy and castings, since it does not require mechanical working. Two THP, called THP-A and THP-B, have been evaluated in samples of Ti-6Al-4V with a coarse and lamellar microstructure typical of castings and powder metallurgy. The THP-A is based in the eutectoid decomposition of the beta(H) phase to alpha phase and hydride phase. The THP-B is based in the isothermal decomposition of alpha('') martensite phase, obtained by quenching of hydrogenated samples. The refinement of the microstructure due to THP has been evaluated by means of optical and electron microscopy. Tensile tests showed that while both processes were able to increase the strength of the alloy as compared with the starting material, the ductility in samples subjected to THP-B was severely reduced. PMID:19627819

Guitar, A; Vigna, G; Luppo, M I

2009-04-01

302

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

303

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

304

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

NASA Astrophysics Data System (ADS)

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

Tsouvalis, Nicholas G.; Karatzas, Vassilios A.

2011-04-01

305

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

306

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

307

Effects of interphase conditions on the tensile and fatigue properties of short-fiber reinforced rubber  

Microsoft Academic Search

The effects of the amount of nylon-66 short-fiber and its bonding to a chloroprene rubber were studied. The following results were obtained: (a) The tensile strength of short-fiber reinforced rubber (SFRR) exhibits a dilution effect in each interphase. It was found that the interphase conditions have an important effect on the dilution ratio and the critical fiber content. The specimen

S. R. Ryu; D. J. Lee

2003-01-01

308

Tensile properties of cellulose acetate butyrate composites reinforced with bacterial cellulose  

Microsoft Academic Search

Composites of cellulose acetate butyrate reinforced with cellulose sheets synthesised by Gluconacetobacter xylinus were produced by solvent evaporation casting. The composites contained 10% and 32% volume cellulose, and showed a Young’s modulus of 3.2 and 5.8 GPa, and a strength of 52.6 and 128.9 MPa, respectively, in tensile tests. Stress–strain curves showed bi-phasic material characteristics, with an initial linear behaviour,

Wolfgang Gindl; Jozef Keckes

2004-01-01

309

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. PMID:24876703

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

2014-01-01

310

Mechanical shear and tensile properties of selected biomass stems  

Technology Transfer Automated Retrieval System (TEKTRAN)

Lignocellulosic biomass, such as big bluestem, corn stalk, intermediate wheat grass and switchgrass stem are abundant and dominant species in the Midwest region of US. There is a need to understand the mechanical properties for these crops for better handling and processing of the biomass feedstocks...

311

Effect of filler loading of nickel zinc ferrite on the tensile properties of PLA nanocomposites  

NASA Astrophysics Data System (ADS)

The mechanical strength of magnetic polymer nanocomposite (MPNC) of nickel zinc (NiZn) ferrite nanoparticles incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer is reported. The matrix was prepared from PLA and LNR in the ratio of 90:10. The MPNC were prepared at constant mixing temperature at 180°C, mixing time of 15 min. and mixing speed of 100 rpm. In order to achieve a good dispersion of NiZn ferrite in the matrix, firstly an ultrasonic treatment had been employed to mix the LNR and NiZn ferrite for 1 hour. The MPNC of PLA/LNR/NiZn ferrite then were prepared via Thermo Haake internal mixer using melt-blending method from different filler loading from 1-5 wt% NiZn ferrite. The result of tensile tests showed that as the filler loading increases the tensile strength also increases until an optimum value of filler loading was reached. The Young's modulus, tensile strength and elongation at break have also increased. The study proves that NiZn ferrite is excellent reinforcement filler in PLA matrix. Scanning electron micrograph (SEM) and energy dispersive X-ray spectroscopy (EDX) were meant to show the homogeneity dispersion of nanoparticles within the matrix and to confirm the elemental composition of NiZn ferrites-PLA/LNR nanocomposites respectively.

Shahdan, Dalila; Ahmad, Sahrim Hj

2013-05-01

312

The Tensile Properties of Advanced Nickel-Base Disk Superalloys During Quenching Heat Treatments  

NASA Technical Reports Server (NTRS)

There is a need to increase the temperature capabilities of superalloy turbine disks. This would allow full utilization of higher temperature combustor and airfoil concepts under development. One approach to meet this goal is to modify the processing and chemistry of advanced alloys, while preserving the ability to use rapid cooling supersolvus heat treatments to achieve coarse grain, fine gamma prime microstructures. An important step in this effort is to understand the key high temperature tensile properties of advanced alloys as they exist during supersolvus heat treatments. This could help in projecting cracking tendencies of disks during quenches from supersolvus heat treatments. The objective of this study was to examine the tensile properties of two advanced disk superalloys during simulated quenching heat treatments. Specimens were cooled from the solution heat treatment temperatures at controlled rates, interrupted, and immediately tensile tested at various temperatures. The responses and failure modes were compared and related to the quench cracking tendencies of disk forgings.

Gabb, Timothy P.; Gayda, John; Kantzos, Pete T.; Biles, Tiffany; Konkel, William

2001-01-01

313

MATERIALS CHARACTERISATION Material properties such as strength, toughness or hardness  

E-print Network

. Strength, toughness or hardness, which are determined by the chemical composition and thermal treatmentMATERIALS CHARACTERISATION Material properties such as strength, toughness or hardness are usually (shear and longitudinal). However, strength or hardnesscannotbedetermineddirectlyfromthoseparameters

314

Tensile properties of nicalon fiber-reinforced carbon following aerospace turbine engine testing  

NASA Astrophysics Data System (ADS)

The durability of coated Nicalon silicon carbide fiber-reinforced carbon (SiC/C) as the flap and seal exhaust nozzle components in a military aerospace turbine engine was studied. Test specimens machined from both a flap and a seal component were tested for residual strength following extended ground engine testing on a General Electric F414 afterburning turbofan engine. Although small amounts of damage to the protective exterior coating were identified on each component following engine testing, the tensile strengths were equal to the as-fabricated tensile strength of the material. Differences in strength between the two components and variability within the data sets could be traced back to the fabrication process using witness coupon test data from the manufacturer. It was also observed that test specimens machined transversely across the flap and seal components were stronger than those machined along the length. The excellent retained strength of the coated SiC/C material after extended exposure to the severe environment in the afterburner exhaust section of an aerospace turbofan engine has resulted in this material being selected as the baseline material for the F414 exhaust nozzle system.

Pierce, J. L.; Zawada, L. P.; Srinivasan, R.

2003-06-01

315

Influence of crystallization conditions on the tensile properties of radiation crosslinked, vitamin E stabilized UHMWPE.  

PubMed

Radiation crosslinking for ultra-high molecular weight polyethylene results in improved wear resistance but a reduction in mechanical properties. Incorporation of vitamin E has been known to decrease the rate of oxidative degradation occurring through radiation crosslinking and prevents the need for post-irradiation melting with subsequent loss of crystallinity. In this study, we aimed to determine the effect of thermal treatments prior to crosslinking on the morphology and tensile properties of vitamin-E-containing polyethylene. Vitamin-E-blended polyethylene was melted and subsequently quenched in ice water in order to induce high rate crystallization. A second group was additionally annealed at 126°C following quenching and all samples were irradiated using electron beam radiation to a dose of 100kGy. The morphology of control, quenched and quench-annealed polyethylene was characterized using small angle x-ray scattering and differential scanning calorimetry. Tensile properties of these polyethylenes were measured before and after radiation crosslinking with equilibrium swelling experiments performed to assess the crosslink density of irradiated samples. This study shows how the tensile properties of polyethylene can be enhanced by varying thermal treatments prior to crosslinking; and thus how it may be possible to offset the reduction in tensile properties afforded by the crosslinking process. PMID:25305634

George, A; Ngo, H D; Bellare, A

2014-12-01

316

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

NASA Astrophysics Data System (ADS)

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

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

2014-12-01

317

Alternatives to ceramic brackets: the tensile bond strengths of two aesthetic brackets compared ex vivo with stainless steel foil-mesh bracket bases.  

PubMed

The mean tensile/peel bond strengths were evaluated for three types of aesthetic brackets (a ceramic-reinforced bracket and two generations of a ceramic/polycarbonate combination bracket). These were found to be significantly lower than the mean tensile/peel bond strength of a convention foil-mesh stainless steel bracket base. Failure of the ceramic-reinforced polycarbonate brackets occurred predominantly by fracture of the tie wings during testing. With the ceramic/polycarbonate combination brackets, the majority of the specimens failed due to separation of the ceramic and polycarbonate parts of the bracket. PMID:9218111

Arici, S; Regan, D

1997-05-01

318

Weibull statistical analysis of tensile strength of vascular bundle in inner layer of moso bamboo culm in molecular parasitology and vector biology.  

PubMed

Bamboo is a radial gradient variation composite material against parasitology and vector biology, but the vascular bundles in inner layer are evenly distributed. The objective is to determine the regular size pattern and Weibull statistical analysis of the vascular bundle tensile strength in inner layer of Moso bamboo. The size and shape of vascular bundles in inner layer are similar, with an average area about 0.1550 mm2. A statistical evaluation of the tensile strength of vascular bundle was conducted by means of Weibull statistics, the results show that the Weibull modulus m is 6.1121 and the accurate reliability assessment of vascular bundle is determined. PMID:25016270

Le, Cui; Wanxi, Peng; Zhengjun, Sun; Lili, Shang; Guoning, Chen

2014-07-01

319

Tensile, Compression and Fracture Properties of Thick-Walled Ductile Cast Iron Components  

NASA Astrophysics Data System (ADS)

The article presents the outcome of a comprehensive program of tensile, compression and fracture toughness experiments, addressing thick-walled ductile cast iron inserts used for the production of three nuclear waste canisters. The resulting data are required as input to the assessment of the failure probability of the canisters. Moreover, these data are useful for the improvement of the casting technique as such. Although the same material specification is always used, material properties are found to show significant variation. Considerable attention is paid to linking the scatter in tensile properties to fractographic and microstructural observations. The main finding is that low ductility tensile test results can be primarily connected to the presence of specific casting defects, from which oxide films have the most detrimental effect. Another important observation is that compression experiments do not result in low ductility failure. During fracture testing, stable ductile crack propagation is observed. Basic fracture analysis of a tensile test is performed in order to better understand the effect of defect size, stress-strain behavior and fracture toughness on the ductility measured through tensile testing. Two opposing specimen size effects are observed.

Minnebo, P.; Nilsson, K.-F.; Blagoeva, D.

2007-02-01

320

Carboxyl functionalization of carbon fibers through a grafting reaction that preserves fiber tensile strength  

Microsoft Academic Search

Composite materials can be enhanced by grafting a secondary material to a functional group on the surface of the reinforcing fibers to improve thermal, electrical or mechanical properties. Grafting secondary materials onto carbon fibers is often limited by the low reactivity of graphitic carbon and there is strong demand to create novel grafting methods with versatile functional groups. One desirable

Gregory J. Ehlert; Yirong Lin; Henry A. Sodano

2011-01-01

321

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

322

Plasticizers for Zein: Their Effect on Tensile Properties and Water Absorption of Zein Films  

Microsoft Academic Search

Cereal Chem. 81(1):1-5 Cast zein films are brittle at room conditions, so plasticizers are added to make them more flexible. The tensile properties of these films are known to be affected by the relative humidity (RH) of the ambient air. However, little is known about how the plasticizers are affected by RH. Cast zein films were plasticized with either glycerol

J. W. Lawton

2004-01-01

323

Tensile and thermal properties of nanocellulose-reinforced poly(vinyl alcohol) nanocomposites  

Microsoft Academic Search

This work reports on the mechanical and thermal properties of poly(vinyl alcohol) (PVA) nanocomposites reinforced with nanocelluloses isolated by the sulfuric acid hydrolysis using commercial microcrystalline cellulose (MCC). Nanocellulose-reinforced PVA nanocomposite films were prepared by the casting method with different nanocellulose loadings, which were exposed to tensile test, thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The nanocellulose obtained by

Mi-Jung Cho; Byung-Dae Park

2011-01-01

324

Hardness distribution and tensile properties in an electron beam weldment of F82H irradiated in HFIR  

NASA Astrophysics Data System (ADS)

F82H-IEA and its EB-weld joint were irradiated at 573 and 773 K up to 9.6 dpa and the irradiation effect on its mechanical properties and microstructure were investigated. A hardness profile across the weld joint before irradiation showed the hardness in transformed region (TR) was high and especially that in the edge of TR was the highest (high hardness region: HHR) compared to base metal (BM). These hardness distribution was correspond to grain size distribution. After irradiation, hardening in HHR was small compared to other region in the sample. In tensile test, the amount of hardening in yield strength and ultimate tensile strength of F82H EB-weld joint was almost similar to that of F82H-IEA but the fracture position of EB-weld joint was at the boundary of TR and BM. Therefore, the TR/BM boundary is the structural weak point in F82H EB-weld joint after irradiation. As the plastic instability was observed, the dislocation channeling deformation can be expected though the dislocation channel was not observed in this study.

Oka, H.; Hashimoto, N.; Muroga, T.; Kimura, A.; Sokolov, M. A.; Yamamoto, T.; Ohnuki, S.

2014-12-01

325

Microscale material testing of single crystalline silicon: process effects on surface morphology and tensile strength  

Microsoft Academic Search

The mechanical properties of single-crystalline silicon are measured by uniaxial tension tests from microscale beam specimens patterned by four different common silicon etchants — KOH, EDP, TMAH and XeF2. SOI wafers are used to prepare test samples, which are 3–5 ?m thick, 20–100 ?m wide, and 6 mm long beam specimens; these are monolithically mounted on a temporary frame. A

Taechung Yi; Lu Li; Chang-Jin Kim

2000-01-01

326

Compression and tensile strength of low-density straw-protein particleboard  

Microsoft Academic Search

Wheat straw can be used as a raw material for particleboard, and soybean protein can be used as an adhesive in particleboard fabrication. The objective of this research was to characterize the mechanical properties of low-density wheat straw-soy protein particleboard as affected by protein modification\\/denaturation, initial straw moisture content, and chemical treatment of the straw. Methylene diphenyl diisocyanate (MDI), considered

Xiaoqun Mo; Jie Hu; X. Susan Sun; Jo A Ratto

2001-01-01

327

Effect of flowing sodium on corrosion and tensile properties of AISI type 316LN stainless steel at 823 K  

NASA Astrophysics Data System (ADS)

AISI type 316LN stainless steel was exposed to flowing sodium in mass transfer loop (MTL) at 823 K for 16 000 h and then examined for changes in the tensile properties due to the mass transfer and corrosion effects. Comparisons in microstructural and mechanical properties were made between annealed, thermally aged and sodium exposed materials. Microstructural examination of thermally aged and sodium exposed materials revealed precipitation of carbides at the grain boundaries. The sodium exposed samples contained a degraded layer at the surface up to a depth of around 10 ?m and a surface carburized layer of about 30 ?m. There was about 15% increase in yield strength and a decrease of about 20% in ductility for the sodium exposed material vis-a-vis thermally aged material and this was attributed to carburization effects and microstructural changes.

Sivai Bharasi, N.; Thyagarajan, K.; Shaikh, H.; Balamurugan, A. K.; Bera, Santanu; Kalavathy, S.; Gurumurthy, K.; Tyagi, A. K.; Dayal, R. K.; Rajan, K. K.; Khatak, H. S.

2008-07-01

328

EFFECT OF CARBAMIDE PEROXIDE-BASED BLEACHING AGENTS CONTAINING FLUORIDE OR CALCIUM ON TENSILE STRENGTH OF HUMAN ENAMEL  

PubMed Central

Objective: The aim of this study was to evaluate the effects of carbamide peroxide-based bleaching agents (CPG) containing fluoride (CF) or calcium (CCa) on the ultimate tensile strength of enamel (UTS). Method: A "cube-like" resin composite structure was built-up on the occlusal surface of twenty-two sound third molars to facilitate specimen preparation for the micro-tensile test. The restored teeth were serially sectioned in buccal-lingual direction in slices with approximate 0.7 mm thickness. Each slice was trimmed with a fine diamond bur to reduce the buccal, internal slope enamel of the cusps to a dumb-bell shape with a cross-sectional area at the "neck" of less than 0.5 mm2. The samples were randomly divided into 12 groups (n=11). The control groups were not submitted to the bleaching regimen. Specimens were treated with 10% CPG gel or with 10% CPG formulations containing CF (0.2% and 0.5%) or CCa (0.05% and 0.2%). Bleached groups received the application of the 10% CPGs for 6 hours/day at 37° C, during 14 consecutive days and were stored in artificial saliva (AS) or 100% relative humidity (RH) among each application. After bleaching, specimens were tested with the microtensile method at 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (5%). Results: No significant difference was observed between groups stored in AS or RH. Specimens treated with CF or CCa presented similar UTS as unbleached control groups. Conclusion: Either 10% CPG formulations containing CF or CCa can preserve the UTS after bleaching regimen. PMID:19089036

Giannini, Marcelo; Silva, Alessandra Peres; Cavalli, Vanessa; Leme, Adriana Franco Paes

2006-01-01

329

Apparatus for measuring tensile and compressive properties of solid materials at cryogenic temperatures  

DOEpatents

An apparatus for evaluating the tensile and compressive properties of material samples at very low or cryogenic temperatures employs a stationary frame and a dewar mounted below the frame. A pair of coaxial cylindrical tubes extend downward towards the bottom of the dewar. A compressive or tensile load is generated hydraulically and is transmitted by the inner tube to the material sample. The material sample is located near the bottom of the dewar in a liquid refrigerant bath. The apparatus employs a displacement measuring device, such as a linear variable differential transformer, to measure the deformation of the material sample relative to the amount of compressive or tensile force applied to the sample. 7 figs.

Gonczy, J.D.; Markley, F.W.; McCaw, W.R.; Niemann, R.C.

1992-04-21

330

Ideal mechanical properties of vanadium by a first-principles computational tensile test  

NASA Astrophysics Data System (ADS)

We employ first-principles total energy method based on the density functional theory with the generalized gradient approximation to investigate the ideal tensile strengths of a bcc vanadium (V) single crystal systemically. The ideal tensile strengths are calculated to be 19.1, 32.8 and 31.0 GPa for bcc V in the [1 0 0], [1 1 0] and [1 1 1] directions, respectively. We show that the [0 0 1] direction is the weakest direction due to the occurrence of structure transition at the lower strain and the [1 1 0] direction is strongest because of the stronger interaction of atoms between the (1 1 0) planes in comparison with the (0 0 1) and (1 1 1) planes. We derive the Young's modulus formula V single crystal in different tensile directions and give detailed analysis. According to the elastic constants of V single crystal, we have estimated some mechanical quantities of polycrystalline V, which are the bulk modulus of B, the shear modulus of G, Young's modulus of E and the Poisson's ratio of ?. The results might provide a useful reference for V as a candidate structural material in the fusion Tokamak.

Liu, Yue-Lin; Zhou, Hong-Bo; Zhang, Ying

2011-09-01

331

Effect of severe plastic deformation on tensile properties of a cast Al–11 mass% Si alloy  

Microsoft Academic Search

Up to now, investigations for the effect of the severe plastic deformation on mechanical properties of the processed materials are not enough. In the present work, tensile properties of a cast Al–11mass% Si alloy processed by rotary-die equal-channel angular pressing (RD-ECAP) with 4–32 passes were investigated at room temperature. Elongation to failure significantly increased with the number of RD-ECAP passes

Aibin Ma; Naobumi Saito; Makoto Takagi; Yoshinori Nishida; Hiroyuki Iwata; Kazutaka Suzuki; Ichinori Shigematsu; Akira Watazu

2005-01-01

332

Tensile and Friction Properties of Tin Bronze Matrix Composites Reinforced by Carbon Fibers  

Microsoft Academic Search

Copper-coated carbon fibers and carbon fiber (CF)-reinforced tin bronze matrix composites were prepared by chemical plating\\u000a and powder metallurgy, respectively. Copper-coated CFs were characterized with field emission scanning electron microscope.\\u000a The effects of CF volume fraction on the friction properties and tensile properties of the composites were investigated. The\\u000a results showed that the composites exhibited lower friction coefficient and higher

Zeng Jun

2010-01-01

333

The effects of environmental conditioning on tensile properties of high performance aramid fibers at near-ambient temperatures  

Microsoft Academic Search

Aramid and aramid copolymer fibers are used in a wide variety of military and civilian applications; however, the long-term effects of environmental exposure on tensile properties are still not well understood. The current effort investigates the effect of hygrothermal conditioning on the tensile properties of Kevlar® KM2 ®, Twaron®, and the newly available Russian copolymer, Armos® high performance fibers. Moisture

A. Abu Obaid; J. M. Deitzel; J. W. Gillespie; J. Q. Zheng

2011-01-01

334

Report on thermal aging effects on tensile properties of ferritic-martensitic steels.  

SciTech Connect

This report provides an update on the evaluation of thermal-aging induced degradation of tensile properties of advanced ferritic-martensitic steels. The report is the first deliverable (level 3) in FY11 (M3A11AN04030103), under the Work Package A-11AN040301, 'Advanced Alloy Testing' performed by Argonne National Laboratory, as part of Advanced Structural Materials Program for the Advanced Reactor Concepts. This work package supports the advanced structural materials development by providing tensile data on aged alloys and a mechanistic model, validated by experiments, with a predictive capability on long-term performance. The scope of work is to evaluate the effect of thermal aging on the tensile properties of advanced alloys such as ferritic-martensitic steels, mod.9Cr-1Mo, NF616, and advanced austenitic stainless steel, HT-UPS. The aging experiments have been conducted over a temperature of 550-750 C for various time periods to simulate the microstructural changes in the alloys as a function of time at temperature. In addition, a mechanistic model based on thermodynamics and kinetics has been used to address the changes in microstructure of the alloys as a function of time and temperature, which is developed in the companion work package at ANL. The focus of this project is advanced alloy testing and understanding the effects of long-term thermal aging on the tensile properties. Advanced materials examined in this project include ferritic-martensitic steels mod.9Cr-1Mo and NF616, and austenitic steel, HT-UPS. The report summarizes the tensile testing results of thermally-aged mod.9Cr-1Mo, NF616 H1 and NF616 H2 ferritic-martensitic steels. NF616 H1 and NF616 H2 experienced different thermal-mechanical treatments before thermal aging experiments. NF616 H1 was normalized and tempered, and NF616 H2 was normalized and tempered and cold-rolled. By examining these two heats, we evaluated the effects of thermal-mechanical treatments on material microstructures and associated mechanical properties during long-term aging at elevated temperatures. Thermal aging experiments at different temperatures and periods of time have been completed: 550 C for up to 5000 h, 600 C for up to 7500 h, and 650 C for more than 10,000 h. Tensile properties were measured on thermally aged specimens and aging effect on tensile behavior was assessed. Effects of thermal aging on deformation and failure mechanisms were investigated by using in-situ straining technique with simultaneous synchrotron XRD measurements.

Li, M.; Soppet, W.K.; Rink, D.L.; Listwan, J.T.; Natesan, K. (Nuclear Engineering Division)

2012-05-10

335

Effect of ultrasonic treatment on tensile properties of PLA/LNR/NiZn ferrite nanocomposite  

SciTech Connect

The influence of sonication treatment time on the morphological and mechanical properties of LNR/PLA composite impregnated with different filler loadings of NiZn ferrite nanoparticles was investigated. The nanocomposite was prepared using melt blending method with assistance of ultrasonic treatment of 0, 1 and 2 hrs. Structural characterization of the nanocomposites was examined using scanning electron microscopy (SEM) with their elemental composition being confirmed by energy dispersive X-ray spectroscopy (EDX). The tensile properties of LNR/PLA composite treated with different ultrasonication times have improved with increasing magnetic nanofiller signature in the nanocomposite. Further, the optimum sonication time of 1 hr was found to produce nanocomposite with maximum tensile properties.

Shahdan, Dalila; Ahmad, Sahrim Hj.; Flaifel, Moayad Husein [School of Applied Physics, Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor (Malaysia)

2013-11-27

336

Studies on Tensile Properties of Eri Silk/Polyester Blended Yarn Using Design of Experiment Methodology  

NASA Astrophysics Data System (ADS)

Eri silk is one of the four varieties of silk available in India which has excellent thermal insulation property. With a view to explore its blending possibilities with polyester, manufacturing of eri/polyester blended yarn at different blend ratio in ring spinning system has been successfully performed following drawframe blending technique. The Box and Behnken design of experiment for three variables and three levels has been used to study the influence of count of the yarn spun (Ne), twist multiplier and proportion of eri fibre in the blends on some important tensile properties of the yarns produced. The chosen level of variables remaining within the industrially acceptable limits shows that fibre character and yarn parameters are the determining factors to influence yarn tensile properties. Validity of Hamburger model for the prediction of blended yarn tenacity has also been assessed for the blended yarn produced.

Choudhuri, Prabir Kumar; Majumdar, Prabal Kumar; Sarkar, Bijon

2013-03-01

337

Development of India-specific RAFM steel through optimization of tungsten and tantalum contents for better combination of impact, tensile, low cycle fatigue and creep properties  

NASA Astrophysics Data System (ADS)

Effects of tungsten and tantalum contents on impact, tensile, low cycle fatigue and creep properties of Reduced Activation Ferritic-Martensitic (RAFM) steel were studied to develop India-specific RAFM steel. Four heats of the steel have been melted with tungsten and tantalum contents in the ranges 1-2 wt.% and 0.06-0.14 wt.% respectively. Increase in tungsten content increased the ductile-to-brittle transition temperature (DBTT), low cycle fatigue and creep strength of the steel, whereas the tensile strength was not changed significantly. Increase in tantalum content increased the DBTT and low cycle fatigue strength of the steel whereas the tensile and creep strength decreased. Detailed TEM investigations revealed enhanced microstructural stability of the steel against creep exposure on tungsten addition. The RAFM steel having 1.4 wt.% tungsten with 0.06 wt.% tantalum was found to possess optimum combination of impact, tensile, low cycle fatigue and creep properties and is considered for Indian-specific RAFM steel. Low temperature impact energy of the RAFM steel is quite sensitive to the contents of tungsten and tantalum. The DBTT increased with both the tungsten and tantalum contents. Tungsten and tantalum contents in the investigated ranges had no appreciable effect on the tensile properties of the RAFM steel. Low cycle fatigue life of the RAFM steel increased with the increase in tungsten and tantalum contents. The softening rate with cyclic exposure was lowest for tungsten content of 1.4 wt.%, further increase in tungsten led to an increase in softening rate. Creep deformation and rupture strength of the RAFM steel were found to be quite sensitive to the tungsten and tantalum contents. Creep strength of the steel increased with increase in tungsten content and decreased with increase in tantalum content. Based on the study, the chemical composition of India-specific RAFM steel has been established as 9Cr-1.4W-0.06Ta-V, having optimum combination of strength and toughness and is designated as Indian Reduced Activation Ferritic Martensitic (INRAFM) steel.

Laha, K.; Saroja, S.; Moitra, A.; Sandhya, R.; Mathew, M. D.; Jayakumar, T.; Rajendra Kumar, E.

2013-08-01

338

Tensile strength of acrylic plastics (PPM) in the presence of a temperature gradient over the thickness of the material  

Microsoft Academic Search

Experimental values of the strength and deformation are presented for SO-95, SO-120, and SO-140 acrylic plastics (polymethyl methacrylate: plasticized, unplasticized, and copolymer) stressed in unaxial tension at v=10 mm\\/min, stationary temperature gradients of from 2.5 to 17.5 deg\\/mm over the thickness of the material, and a constant cold-face temperature of 25°C. The deformation properties under these conditions are described: in

B. I. Panshin; V. D. Kasyuk

1969-01-01

339

Microstructure and tensile properties of iron parts fabricated by selective laser melting  

NASA Astrophysics Data System (ADS)

Iron, as the basic industry material was extensively studied in the past, but it could still offer extended possibilities with the use of new processing techniques such as selective laser melting (SLM). In this work, the manufacturing of iron parts using SLM technology was investigated. The effect of processing parameters on density of the iron parts was studied. Fully dense iron parts have been fabricated at the laser power of 100 W using different laser scanning speeds. By means of metallographic observation and TEM characterization, it can be found that the grains size decreased with increasing scanning speed and high dislocation density was observed. Tensile specimens were fabricated using optimal parameters and mechanical tests allowed observing an ultimate tensile strength of 412 MPa and the yield strength of 305 MPa. Multiple self-strengthening mechanisms during SLM process are proposed to explain this high mechanical strength. The grain refinement seems to be the most significant strengthening mechanism, followed by work hardening arising from the high cooling rate.

Song, Bo; Dong, Shujuan; Deng, Sihao; Liao, Hanlin; Coddet, Christian

2014-03-01

340

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

341

Can extended photoactivation time of resin-based fissure sealer materials improve ultimate tensile strength and decrease water sorption/solubility?  

PubMed Central

Objective: This study aimed to evaluate the impact of extended photoactivation time on ultimate tensile strength (UTS), water sorption (WS) and solubility (WSB) of resin-based materials used as fissure-sealants. Methods: A fissure-sealant (Fluroshield) and a flowable composite (Permaflo) polymerized for 20 and 60 seconds were tested. For UTS, 20 hourglass shaped samples were prepared representing two materials and two photoactivation time (n=5). After 24-h dry-storage, samples were tested in tension using a universal testing machine at a cross-head speed of 0.5 mm/min (UTS was calculated in MPa). For WS and WSB, 20 disks with 5 mm diameter and 1 mm height (n=5) were prepared and volumes were calculated (mm3). They were transferred to desiccators until a constant mass was obtained (m1) and were subsequently immersed in distilled water until no alteration in mass was detected (m2). Samples were reconditioned to constant mass in desiccators (m3). WS and WSB were determined using the equations m2-m3/V and m1-m3/V, respectively. Data were subjected to two-way ANOVA and Tukey’s HSD test (P<.05). Results: There was no significant difference between materials or photoactivation times for the UTS and WS. Permaflo presented lower but negative WSB compared to Fluroshield. Conclusions: Extended photoactivation time did not improve the physical properties tested. Fluroshield presented physical properties that were similar to or better than Permaflo. PMID:23077420

Borges, Boniek Castillo Dutra; Souza-Júnior, Eduardo José; Catelan, Anderson; Paulillo, Luís Alexandre Maffei Sartini; Aguiar, Flávio Henrique Baggio

2012-01-01

342

The effects of recycling on the tensile bond strength of new and clinically used stainless steel orthodontic brackets: an in vitro study.  

PubMed

The tensile bond strength was evaluated for three different types of stainless steel orthodontic bracket/base combinations (both cast and machined integral bases, and a foil-mesh base). The cast base gave a significantly higher initial bond strength than the other two brackets. Following recycling by either chemical or thermal methods, all the bases demonstrated a significant reduction in bond strength. However, thermal recycling produced an unacceptably large reduction in the bond strength of the cast base and this method of reconditioning should be avoided with these brackets. Recycling the brackets an additional four times was found to result in a further reduction in bond strength, but this was not statistically significant. Clinically used brackets demonstrated a slightly lower, though not statistically significant, bond strength compared to unused brackets following one recycling with either the chemical or thermal method. PMID:2192762

Regan, D; van Noort, R; O'Keeffe, C

1990-05-01

343

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

344

Transverse tensile and stress rupture properties of gamma/gamma prime-delta directionally solidified eutectic  

NASA Technical Reports Server (NTRS)

Tensile and stress rupture properties were determined primarily at 760 C for specimens oriented at various angles (0 deg, 10 deg, 45 deg, and 90 deg) from the solidification direction of bars and/or slabs of the Ni-20Cb-6Cr-2.5A (gamma/gamma prime-delta) eutectic. Threaded-head specimens yielded longer rupture lives with significantly less scatter than did tapered-head specimens. Miniature specimens are suitable for determining traverse tensile and rupture properties of 1.2 centimeter diameter bar stock. The 300 hour rupture stress at 760 C for specimens oriented at 10 deg from the solidification direction was reduced from 740 to 460 MPa, and to 230 MPa for material oriented at either 45 deg or 90 deg.

Gray, H. H.

1976-01-01

345

Shear strength properties of wet granular materials Vincent Richefeu,  

E-print Network

Shear strength properties of wet granular materials Vincent Richefeu, Moulay Sa¨id El Youssoufi shear strength properties of wet granular materials in the pendular state (i.e. the state where of capillary interactions, the major influence of water content over the shear strength stems from

Paris-Sud XI, Université de

346

Microstructure, tensile properties, and biodegradability of aliphatic polyester\\/clay nanocomposites  

Microsoft Academic Search

Novel biodegradable aliphatic polyester (APES)\\/organoclay nanocomposites were prepared through melt intercalation method. Two kinds of organoclays, Cloisite 30B and Cloisite 10A with different ammonium cations located in the silicate gallery, were chosen for the nanocomposites preparation. The dispersion of the silicate layers in the APES hybrids was characterized by using X-ray diffraction (XRD) and transmission electron microscopy (TEM). Tensile properties

Sang-Rock Lee; Hwan-Man Park; Hyuntaek Lim; Taekyu Kang; Xiucuo Li; Won-Jei Cho; Chang-Sik Ha

2002-01-01

347

Retrogression and re-aging treatment on short transverse tensile properties of 7010 aluminium alloy extrusions  

Microsoft Academic Search

The influence of retrogression and re-aging treatment (RRA) on short transverse tensile properties of 7010 aluminium alloy extrusions was studied. The short transverse ductility of extrusions, which was much lower in the T6 condition, was improved to the optimum level after retrogression and re-aging treatment. It is found that short transverse ductility is influenced by the nature of precipitate particles

M. Angappan; V. Sampath; B. Ashok; V. P. Deepkumar

2011-01-01

348

Application of micromechanical models to tensile properties of wood–plastic composites  

Microsoft Academic Search

Wood–plastic composites (WPC) were produced with white birch pulp fibers of different aspect ratios (length-to-diameter),\\u000a high-density polyethylene, and using two common processes: extrusion or injection molding. Three additive levels were also\\u000a used: no additive, compatibility agent, and process lubricant. Fiber size was measured with an optical fiber quality analyzer.\\u000a Tensile properties of WPC were measured and modeled as a function

Sébastien Migneault; Ahmed Koubaa; Fouad Erchiqui; Abdelkader Chaala; Karl Englund; Michael P. Wolcott

2011-01-01

349

Tensile Properties and Work Hardening Behavior of Laser-Welded Dual-Phase Steel Joints  

Microsoft Academic Search

The aim of this investigation was to evaluate the microstructural change after laser welding and its effect on the tensile\\u000a properties and strain hardening behavior of DP600 and DP980 dual-phase steels. Laser welding led to the formation of martensite\\u000a and significant hardness rise in the fusion zone because of the fast cooling, but the presence of a soft zone in

N. Farabi; D. L. Chen; Y. Zhou

2011-01-01

350

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

351

Notch tensile properties of laser-surface-annealed 17-4 PH stainless steel in hydrogen-related environments  

Microsoft Academic Search

Slow displacement rate tensile tests were performed to determine the notched tensile strength (NTS) of 17-4 PH stainless steel with various microstructures in hydrogen-related environments. Solution-annealed (SA), peak-aged (H900), over-aged (H1025), and laser-annealed (LA) specimens were included in the study. Based on the results of NTS in air, the NTS loss in both gaseous hydrogen and H2S-saturated solution was used

L. W. Tsay; W. C. Lee; R. K. Shiue; J. K. Wu

2002-01-01

352

Effect of processing parameter and filler content on tensile properties of multi-walled carbon nanotubes reinforced polylactic acid nanocomposite  

NASA Astrophysics Data System (ADS)

Polymer nanocomposite of multi-walled carbon nanotubes (MWCNT) nanoparticles incorporated with polylactic acid (PLA) and liquid natural rubber (LNR) as compatibilizer were prepared via melt blending method using the Haake Rheomix internal mixer. In order to obtain the optimal processing parameter, the nanocomposite with 89 wt % of PLA was blended with 10 wt % of LNR and 1 wt % of MWCNTs were mixed with various mixing parameter condition; mixing temperature, mixing speed and mixing time. The optimum processing parameter of the composites was obtained at temperature of 190°C, rotation speed of 90 rpm and mixing time of 14 min. Next, the effect of MWCNTs loading on the tensile properties of nanocomposites was investigated. The nanocomposites were melt blended using the optimal processing parameter with MWCNTs loading of 0.5, 1.0, 1.5, 2.0, 2.5, 3.0, 3.5 and 4 wt %. The result showed that the sample with 3.5 wt % of MWCNTs gave higher tensile strength and Young's modulus. The SEM micrographs confirmed the effect of good dispersion of MWCNTs and their interfacial bonding in PLA nanocomposites. However, the elongation at break decreased with increasing the percentage of MWCNTs.

Ali, Adilah Mat; Ahmad, Sahrim Hj.

2013-05-01

353

Improvement of tensile properties of nano-SiO 2\\/PP composites in relation to percolation mechanism  

Microsoft Academic Search

Low nano-silica loaded polypropylene composites are produced by conventional compounding technique in which the nanoparticles are grafted by polystyrene using irradiation beforehand. A high interfacial stress transfer efficiency is demonstrated by both strengthening and toughening effects perceived in tensile tests. The role of the modified nanoparticles in improvement of tensile properties of the nanocomposites is discussed in terms of percolation

Min Zhi Rong; Ming Qiu Zhang; Yong Xiang Zheng; Han Min Zeng; K Friedrich

2001-01-01

354

Effects of Friction Stir Processing Parameters and In Situ Passes on Microstructure and Tensile Properties of Al-Si-Mg Casting  

NASA Astrophysics Data System (ADS)

Friction stir processing (FSP) was applied to modify the microstructure of an as-cast A356 alloy. The effects of rotation rate, travel speed, in situ FSP pass, FSP direction, and artificial aging on microstructures and tensile properties were investigated. FSP broke up the coarse eutectic Si phase into 2.5 to 3.5 ?m particles and distributed them homogeneously, and resulted in the dissolution of the coarse Mg2Si particles and the elimination of porosity, thereby improving both the strength and the ductility of the casting. Increasing the rotation rate was beneficial to breaking up and dissolving the particles, but it contributed little to eliminating the porosity. The travel speed did not affect the size of the particles apparently, but lower speed was beneficial to eliminating the porosity. 2-pass FSP showed an obvious advantage in the microstructure modification and tensile properties compared with the single-pass. However, a further increase of FSP passes only resulted in slight improvement. The FSP direction of the following pass did not show distinct effect on the microstructure and tensile properties. After post-FSP artificial aging, the strengthening phase (??-Mg2Si) precipitated, which increased the strength and decreased the ductility of the FSP samples.

Cui, G. R.; Ni, D. R.; Ma, Z. Y.; Li, S. X.

2014-11-01

355

Tensile Properties of Molybdenum and Tungsten from 2500 to 3700 F  

NASA Technical Reports Server (NTRS)

Specimens of commercially pure sintered tungsten, arc-cast unalloyed molybdenum, and two arc-cast molybdenum-base alloys (one with 0.5 percent titanium, the other with 0.46 percent titanium and 0.07 percent zirconium) were fabricated from 1/2-inch-diameter rolled or swaged bars. All specimens were evaluated in short-time tensile tests in the as-received condition, and all except the molybdenum-titanium-zirconium alloy were tested after a 30-minute recrystallization anneal at 3800 F in a vacuum of approximately 0.1 micron. Results showed that the tungsten was considerably stronger than either the arc-cast unalloyed molybdenum or the molybdenum-base alloys over the 2500 to 3700 F temperature range. Recrystallization of swaged tungsten at 3800 F considerably reduced its tensile strength at 2500 F. However, above 3100 F, the as-swaged tungsten specimens recrystallized during testing, and had about the same strength as when recrystallized at 3800 F before evaluation. The ductility of molybdenum-base materials was very high at all test temperatures; the ductility of tungsten decreased sharply above about 3120 F.

Hall, Robert W.; Sikora, Paul F.

1959-01-01

356

Contributions of adipose tissue architectural and tensile properties toward defining healthy and unhealthy obesity  

PubMed Central

The extracellular matrix (ECM) plays an important role in the maintenance of white adipose tissue (WAT) architecture and function, and proper ECM remodeling is critical to support WAT malleability to accomodate changes in energy storage needs. Obesity and adipocyte hypertrophy place a strain on the ECM remodeling machinery, which may promote disordered ECM and altered tissue integrity and could promote proinflammatory and cell stress signals. To explore these questions, new methods were developed to quantify omental and subcutaneous WAT tensile strength and WAT collagen content by three-dimensional confocal imaging, using collagen VI knockout mice as a methods validation tool. These methods, combined with comprehensive measurement of WAT ECM proteolytic enzymes, transcript, and blood analyte analyses, were used to identify unique pathophenotypes of metabolic syndrome and type 2 diabetes mellitus in obese women, using multivariate statistical modeling and univariate comparisons with weight-matched healthy obese individuals. In addition to the expected differences in inflammation and glycemic control, approximately 20 ECM-related factors, including omental tensile strength, collagen, and enzyme transcripts, helped discriminate metabolically compromised obesity. This is consistent with the hypothesis that WAT ECM physiology is intimately linked to metabolic health in obese humans, and the studies provide new tools to explore this relationship. PMID:24302007

Lackey, Denise E.; Burk, David H.; Ali, Mohamed R.; Mostaedi, Rouzbeh; Smith, William H.; Park, Jiyoung; Scherer, Philipp E.; Seay, Shundra A.; McCoin, Colin S.; Bonaldo, Paolo

2013-01-01

357

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

358

Tensile Properties and Swelling Behavior of Sealing Rubber Materials Exposed to High-Pressure Hydrogen Gas  

NASA Astrophysics Data System (ADS)

Rubber O-rings exposed to high-pressure hydrogen gas swell, and the volume increase induced by swelling influences tensile properties of the O-rings. Samples of nonfilled (NF), carbon black-filled (CB), and silica-filled (SC) sulfur-vulcanized acrylonitrile-butadiene rubber were exposed to hydrogen at 30 °C and pressures of up to 100 MPa, and the effect of hydrogen exposure on the volume increase, hydrogen content, and tensile properties was investigated. The residual hydrogen content, measured 35 minutes after decompression, increased with increasing hydrogen pressure in the range 0.7-100 MPa for all three samples. In contrast, the volumes of NF, CB, and SC barely changed at pressures below 10 MPa, whereas they increased at pressures above 10 MPa. This nonlinear volume increase is probably related to the free volume of the rubber structure. The volume increase of the CB and SC samples was smaller than that of the NF samples, possibly because of the superior tensile properties of CB and SC. As the volumes of the NF, CB, and SC samples increased, their tensile elastic moduli decreased as a result of a decrease in crosslink density and elongation by volume increase. Although the true fracture stress of NF was barely dependent on the volume of the specimen, those of CB and SC clearly decreased as the volume increased. The decrease in the true fracture stress of CB and SC was related to the volume increase by swelling, showing that the boundary structure between the filler and the rubber matrix was changed by the volume increase.

Yamabe, Junichiro; Nishimura, Shin

359

Cleavage fracture properties of high strength steel weldments  

SciTech Connect

The qualification of consumables and welding of steels in critical naval applications, including submarine construction, is dependent upon the achievement of high levels of toughness at low temperature. The principal technique employed is the Charpy impact test at temperatures down to {minus}115 C ({minus}175 F). In the investigation described here, low temperature toughness properties were investigated by breaking notched specimens in slow four point bending and measuring the critical tensile stress for cleavage initiation. Multi-pass Flux Cored Arc (FCA) welds joining 690 MPa (100 ksi) yield strength, quenched and tempered steel were tested to identify cleavage fracture micromechanisms and to investigate the role of microstructural features in the cleavage fracture process. Cleavage fracture stress values in the range 2,018 to 2,381 MPa were recorded in weld metal when testing at sub-zero temperatures. Detailed examination of fracture surfaces by scanning electron microscope (SEM) revealed that weld metal inclusions play a critical role in acting as cleavage initiation sites. Changing welding position from downhand to vertical-up resulted in a small number of widely spaced inclusions approaching or exceeding 10 {micro}m in diameter but these were not observed to act as cleavage initiation sites. The cleavage fracture resistance of multi-pass Manual Metal Arc (MMA) welds which are currently under investigation is compared with FCA weldments.

Hughes, R.K.; Ritter, J.C. [DSTO Aeronautical and Maritime Research Lab., Melbourne (Australia)

1996-12-31

360

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. PMID:24324301

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

2013-01-01

361

A comparison of tensile properties of polyester composites reinforced with pineapple leaf fiber and pineapple peduncle fiber  

NASA Astrophysics Data System (ADS)

Pineapple fiber which is rich in cellulose, relatively inexpensive, and abundantly available has the potential for polymer reinforcement. This research presents a study of the tensile properties of pineapple leaf fiber and pineapple peduncle fiber reinforced polyester composites. Composites were fabricated using leaf fiber and peduncle fiber with varying fiber length and fiber loading. Both fibers were mixed with polyester composites the various fiber volume fractions of 4, 8 and 12% and with three different fiber lengths of 10, 20 and 30 mm. The composites panels were fabricated using hand lay-out technique. The tensile test was carried out in accordance to ASTM D638. The result showed that pineapple peduncle fiber with 4% fiber volume fraction and fiber length of 30 mm give highest tensile properties. From the overall results, pineapple peduncle fiber shown the higher tensile properties compared to pineapple leaf fiber. It is found that by increasing the fiber volume fraction the tensile properties has significantly decreased but by increasing the fiber length, the tensile properties will be increased proportionally. Minitab software is used to perform the two-way ANOVA analysis to measure the significant. From the analysis done, there is a significant effect of fiber volume fraction and fiber length on the tensile properties.

Juraidi, J. M.; Shuhairul, N.; Syed Azuan, S. A.; Intan Saffinaz Anuar, Noor

2013-12-01

362

The tensile property of commercial Bi2223 tapes: a report on the international round-robin test  

NASA Astrophysics Data System (ADS)

In order to establish the test method of mechanical properties of oxide composite superconductors, an international round-robin test (RRT) has been carried out under the programme of VAMAS activity, for which eight research groups participated. The present RRT made the following guideline clear for assessing the mechanical property of Ag/Bi2223 multifilamentary tapes. Owing to the constitution of the brittle superconductive oxide layer embedded in the ductile metal matrix, the stress-percentage extension (R-A) curve shows a three-stage behaviour, that is, the true elastic region is very narrow and is followed by the quasi-elastic region before reaching the macroscopic plastic region. For assessing the elastic constant, it is recommended to look for the maximum slope carefully by enlarging the initial part of the R-A curve. The following three quantities, elastic constant, yield strength and tensile strength, can be reasonably determined with good accuracy by the procedure reported in this paper. The percentage extension after fracture is, however, excluded from the standard procedure, because it scatters to a great extent owing to the nature of the test sample as well as the experimental limitation.

Osamura, K.; Sugano, M.; Nyilas, A.; Shin, H. S.; Weijers, H.; Hampshire, D. P.; Morley, N.; Morley, K.; Keys, S.; Leghissa, M.; Herkert, W.; Katagiri, K.; Ogata, T.

2002-06-01

363

Re-examination of the Present Stress State of the Atera Fault, Central Japan, Based on the Calibrated Crustal Stress Data of Hydraulic Fracturing Test by Measuring the Tensile Strength of Rocks  

NASA Astrophysics Data System (ADS)

To infer the activity and physical state of intraplate faults in Japan, we re-examined the crustal stress with the hydraulic fracturing test by measuring the tensile strength of rocks. The tensile strength was measured by fracturing hollow cylindrical rock samples (inner and outer radius are 25.0-25.2 mm and 55.1-101.5 mm, respectively, length is 137.0-140.1 mm) which were obtained close to the in situ stress measurement locations by pressurizing the inner hole of the sample. Confining pressure is not applied to the samples in this test. To check the reliability and accuracy of this test, we conducted similar experiments with the standard rock sample (Inada granite) whose physical property is well known. Then, we measured the tensile strength of all available core samples including the Atera fault (at Ueno, Fukuoka, and Hatajiri), the Atotsugawa fault, and the Nojima fault (at Hirabayashi, Iwaya and Kabutoyama), in central Japan, which had been obtained by the National Research Institute for Earth Science and Disaster Prevention (NIED) by the stress measurement with the hydraulic fracturing method. The measured tensile strength data reveals that the in situ re- opening pressure, which is one of the parameters needed for the determination of the maximum in situ horizontal stress, was obviously biased. We re-estimated the re-opening pressure using the measured tensile strength and the in situ breakdown pressure, and re-calculated the in situ stress around the Atera fault. Although the past dislocation of the Atera fault has been considered to be left lateral from the geographical features around the fault, the re-estimated stress suggests that the present dislocation of the Atera fault is right lateral. And the shear stress decreases from the fault. The right lateral dislocation is also supported by the present-day horizontal crustal deformation observed by the triangular and GPS surveys by Geographical Survey Institute in Japan. Therefore, the dislocation direction of the Atera fault seems to change from left lateral to right lateral some time ago. The amount of accumulated right lateral dislocation estimated from the stress data with the dislocation model by Okada (1992) is 2.2-2.6 m. Because the current slip rate from the GPS survey is 2.1-2.3 mm/yr, the accumulation period of the dislocation becomes 960-1240 years if the slip rate is stable. This estimation suggests that during the last 1586 Tensho earthquake the Atera fault dislocated right laterally.

Yamashita, F.; Mizoguchi, K.; Fukuyama, E.; Omura, K.

2008-12-01

364

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

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

365

Effect of Neutron Irradiation on Tensile Properties of Unidirectional Silicon Carbide Composites  

SciTech Connect

Tensile properties of uni-directionally reinforced Hi-Nicalon EType S SiC fiber, chemically vapor-infiltrated (CVI) SiC-matrix composites, with either pyrolytic carbon (PyC) or multilayered PyC/SiC interphase, were characterized following neutron irradiations to the maximum fluence of 7.7x1025 n/m2 at 380 and 800 C. The stress - strain behavior of the multilayered interphase composites remained unmodified after irradiation. The PyC interphase composite increased in ultimate tensile stress and strain to failure following neutron irradiation, whereas the proportional limit stress exhibited a slight decrease. Potential mechanisms for these changes include accommodation of misfit stress through irradiation creep, reduced interfacial friction, and differential swelling among individual composite constituents.

Katoh, Yutai [ORNL; Nozawa, Takashi [ORNL; Snead, Lance Lewis [ORNL; Hinoki, Tatsuya [ORNL

2007-01-01

366

Low-energy electron effects on tensile modulus and infrared transmission properties of a polypyromellitimide film  

NASA Technical Reports Server (NTRS)

Infrared (IR) spectroscopy and tensile modulus testing were used to evaluate the importance of experimental procedure on changes in properties of pyromellitic dianhydride-p,p prime-oxydianiline film exposed to electron radiation. The radiation exposures were accelerated, approximate equivalents to the total dose expected for a 30 year mission in geosynchronous Earth orbit. The change in the tensile modulus depends more on the dose rate and the time interval between exposure and testing than on total dose. The IR data vary with both total dose and dose rate. A threshold dose rate exists below which reversible radiation effects on the IR spectra occur. Above the threshold dose rate, irreversible effects occur with the appearance of a new band. Post-irradiation and in situ IR absorption bands are significantly different. It is suggested that the electron radiation induced metastable, excites molecular states.

Ferl, J. E.; Long, E. R., Jr.

1981-01-01

367

Effects of Long-Term Thermal Exposure on Commercially Pure Titanium Grade 2 Elevated-Temperature Tensile Properties  

NASA Technical Reports Server (NTRS)

Elevated-temperature tensile testing of commercially pure titanium (CP Ti) Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K (531 and 711 F) for times up to 5000 h. The tensile testing revealed some statistical differences between the 11 thermal treatments, but most thermal treatments were statistically equivalent. Previous data from room temperature tensile testing was combined with the new data to allow regression and development of mathematical models relating tensile properties to temperature and thermal exposure. The results indicate that thermal exposure temperature has a very small effect, whereas the thermal exposure duration has no statistically significant effects on the tensile properties. These results indicate that CP Ti Grade 2 will be thermally stable and suitable for long-duration space missions.

Ellis, David L.

2012-01-01

368

Ab initio study of the ideal tensile strength and mechanical stability of transition-metal disilicides M. Friak,1,2  

E-print Network

diamond,26,27 Si,27,28 Ge,27 TiN and HfC,15 iron,29­31 Mo and Nb,32 and -Si3N4.33 Some calculations have­38 and interfaces.39 The calculations of ideal tensile strength for Al,40 AlN,40,41 -Si3N4,42 c-Si3N4

Vitek, Vaclav

369

Hair Regrowth and Increased Hair Tensile Strength Using the HairMax LaserComb for Low-Level Laser Therapy  

Microsoft Academic Search

The authors wished to confirm the efficacy of low level laser therapy (LLLT) using a Hair- Max LaserComb for the stimulation of hair growth and also to determine what effect LLLT with this device had on the tensile strength of hair. Thirty-five patients, 28 males and 7 fe- males, with androgenetic alopecia (AGA) underwent treatment for a six-month period. Both

John L. Satino; Michael Markou

2003-01-01

370

Computer-aided prediction of the Al 2 O 3 nanoparticles’ effects on tensile strength and percentage of water absorption of concrete specimens  

Microsoft Academic Search

In the present paper, two models based on artificial neural networks and genetic programming for predicting split tensile\\u000a strength and percentage of water absorption of concretes containing Al2O3 nanoparticles have been developed at different ages of curing. For purpose of building these models, training and testing\\u000a using experimental results for 144 specimens produced with 16 different mixture proportions were conducted.

Ali Nazari; Shadi Riahi

371

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

PubMed Central

Background and aims. Polymethyl methacrylate, PMMA, is widely used in prosthodontics for fabrication of removable prostheses. This study was undertaken to investigate the effect of adding silver nanoparticles (AgNPs) to PMMA at 2% and 0.2% concentrations on compressive and tensile strengths of PMMA. Materials and methods. The silver nanoparticles were mixed with heat-cured acrylic resin in an amalgamator in two groups at 0.2 and 2 wt% of AgNPs. Eighteen 2×20×200-mm samples were prepared for tensile strength test, 12 samples containing silver nanoparticle and 6 samples for the control group. Another 18 cylindrical 25×38-mm samples were prepared for compressive strength test. Scanning electron microscopy was used to verify homogeneous distribution of particles. The powder was manually mixed with a resin monomer and then the mixture was properly blended. Before curing, the paste was packed into steel molds. After curing, the specimens were removed from the molds. One-way ANOVA was used for statistical analysis, followed by multiple comparison test (Scheffé’s test). Results. This study showed that the mean compressive strength of PMMA reinforced with AgNPs was significantly higher than that of the unmodified PMMA (P<0.05). It was not statistically different between the two groups reinforced with AgNPs. The tensile strength was not significantly different between the 0.2% group and unmodified PMMA and it de-creased significantly after incorporation of 2% AgNPs (P<0.05). Conclusion. Based on the results and the desirable effect of nanoparticles of silver on improvement of compressive strength of PMMA, use of this material with proper concentration in the palatal area of maxillary acrylic resin dentures is recommended. PMID:25587381

Ghaffari, Tahereh; Hamedirad, Fahimeh; Ezzati, Baharak

2014-01-01

372

Influence of Prior Fatigue Damage on Tensile Properties of 316L(N) Stainless Steel and Modified 9Cr-1Mo Steel  

NASA Astrophysics Data System (ADS)

In the current study, the effect of prior low-cycle fatigue (LCF) damage on the tensile properties of 316L(N) stainless steel (SS) and modified 9Cr-1Mo steel were systematically investigated. The LCF tests were interrupted at 5, 10, 30, and 50 pct of the total fatigue life followed by tensile tests on the same specimens at the same strain rate (3 × 10-3 s-1) and temperatures of 300 K, 823 K, and 873 K (27 °C, 550 °C, and 600 °C). Prior strain cycling at elevated temperatures had remarkable effect on the tensile properties of both cyclically hardening and cyclically softening materials. An exponential relationship between the yield stress and the amount of pre-strain cycles is obtained for both the materials. The initial drastic change in the yield strength values up to 10 pct of fatigue life may be due to the microstructural changes that lead to hardening or softening in 316L(N) SS and modified 9Cr-1Mo steel, respectively. Saturation in the yield strength values beyond 10 pct of fatigue life has practical importance for remnant fatigue life assessment. Evolution of fatigue damage in both the 316L(N) SS and modified 9Cr-1Mo steel was analyzed using the surface replica technique.

Mariappan, K.; Shankar, Vani; Sandhya, R.; Mathew, M. D.; Bhaduri, A. K.

2015-02-01

373

????????????????????????????????????????????????? ?????????????????????????????? ????????????????????????????????????????????????????? Effects of carboxymethylcellulose on tensile strength, water vapor transmission rate and oil resistance of mung bean protein-based films  

Microsoft Academic Search

????????: ??????????????????????????????????????????????????????????????????????? ?????????? ????????????????????????????????????????????? ??????????????????????????????????????? ????? (0, 0.1, 0.3 ??? 0.5% ?????????????????????????????) ?????????????????????????? ???????????????????????????????????????????????????????? 30:70 ??????????? (?????????\\/?????? ?????????) ?????????????????????????? 85 ????????????? ???????? 25 ???? ????????????????????? ???? 225 ?????????????? ????????????????????????????? 60 ???????????? ?????????????? 10 ??????? ????????????????????????????????????? ????????????????????????????????????? 480 ??????? ??????????????????????????????????????????????????????? ????????????????????????????????? ??? ?????????????????????????????????????????? Abstract : The objective of this research was to investigate the effects of addition of carboxymethylcellulose on tensile

Nathamol Chindapan; Soonthorn Somsuai

374

Influence of thermo-mechanical treatment on the tensile properties of a modified 14Cr-15Ni stainless steel  

NASA Astrophysics Data System (ADS)

The titanium modified 14Cr-15Ni austenitic stainless steel is used as clad and wrapper material for fast breeder nuclear reactor. Thermo-mechanical treatments consisting of solution annealing at two different temperatures of 1273 and 1373 K followed by cold-work and thermal ageing have been imparted to the steel to tailor its microstructure for enhancing strength. Tensile tests have been carried out on the thermo-mechanically treated steel at nominal strain rate of 1.6 × 10-4 s-1 over a temperature range of 298-1073 K. The yield stress and the ultimate tensile strength of the steel increased with increase in solution treatment temperature and this has been attributed to the fine and higher density of Ti(C,N) precipitate. Tensile flow behaviour of the steel has been analysed using Ludwigson and Voce constitutive equations. The steel heat treated at higher solution temperature exhibited earlier onset of cross slip during tensile deformation. The rate of recovery at higher test temperatures was also influenced by variations in solution heat treatment temperature. In addition, dynamic recrystallization during tensile deformation at higher temperatures was profound for steel solution heat-treated at lower temperature. The differences in flow behaviour and softening mechanisms during tensile testing of the steel after different heat treated conditions have been attributed to the nature of Ti(C,N) precipitation.

Vijayanand, V. D.; Laha, K.; Parameswaran, P.; Nandagopal, M.; Panneer Selvi, S.; Mathew, M. D.

2014-10-01

375

The effect of staining on the monotonic tensile mechanical properties of human cortical bone  

PubMed Central

Microdamage in the form of microcracks has been observed in cortical bone following in vivo and in vitro fatigue loading. It has been suggested that bone has an inherent ability to repair microdamage at physiological activity levels. If the biological remodelling and repair process cannot keep up with the rate of damage accumulation, as in ageing bone and in individuals such as athletes and military recruits, microdamage may accumulate even at physiological activity levels. Such microdamage accumulation is thought to contribute to stress and fragility fractures. It is therefore important to obtain quantitative data on the rate of damage accumulation so as to understand the etiology of skeletal fractures. Sequential labelling of microdamage using fluorochrome stains at different stages of mechanical loading is becoming standard for assessing damage evolution. Although verification of this staining technique is provided in the literature, it has not yet been reported if the stains change the mechanical properties of cortical bone. In this study, monotonic tensile tests were performed to investigate the effect of the staining on the monotonic tensile mechanical properties of cortical bone. Forty-eight specimens were machined from human femora obtained from three male subjects, aged 52–55 years, and all 48 specimens were systematically divided into one control and three treatment groups. Specimens in the first (n = 12) and second treatment groups (n = 12) were stained with alizarin complexone and calcein (0.0005 m), respectively, for 16 h under 50 mmHg vacuum. Specimens in the third treatment group (n = 12) were kept in calcium-supplemented saline solution under the same conditions of the first and second treatment groups. Specimens in the control group (n = 12) were removed from the freezer prior to testing and allowed to thaw at room temperature in saline solution. Differences among the mean values of the mechanical properties for four testing groups were determined by the Mann–Whitney test at a significance level of P < 0.05. The statistical results indicated that the chelating stains and the staining conditions have no significant effect on the mechanical properties of the cortical bone under monotonic tensile loading. This study demonstrated that microcrack labelling with the chelating stains under aforementioned conditions (stain concentration, staining time, etc.) is a reliable method in that staining cortical bone with alizarin complexone and calcein prior to testing does not affect tensile properties. PMID:17894797

Kayacan, Ramazan

2007-01-01

376

Predictions of the Mechanical Properties and Microstructure Evolution of High Strength Steel in Hot Stamping  

NASA Astrophysics Data System (ADS)

Hot stamping is an innovative operation in metal-forming processes which virtually avoids the cracking and wrinkling of high strength steel (HSS) sheets. Examining the phase transformation and mechanical properties of HSS by means of experiments is challenging. In this article, a numerical model of the hot stamping process including forming, quenching, and air cooling was developed to reveal the microstructure evolution and to predict the final mechanical properties of hot-stamped components after multi-process cycles. The effects of the number of process cycles and the holding times on the temperature of HSS were examined using the model. The microstructure evolution of HSS under variable holding times is illustrated. The mechanical properties, particularly hardness and tensile strength, were predicted. It was found that the martensitic content increased with increasing holding time, and the martensitic content of the formed component at the flange and end was higher than for the sidewall, and lowest for the bottom. The hardness trend was consistent with the martensitic content. After six process cycles, the predictive errors of the model for hardness and tensile strength were acceptable for practical applications in engineering. Comparison between the predicted results and the experiment results showed that the developed model was reliable.

Cui, Junjia; Lei, Chengxi; Xing, Zhongwen; Li, Chunfeng; Ma, Shumei

2012-11-01

377

Effects of pulsed Nd:YAG laser on tensile bond strength and caries resistance of human enamel.  

PubMed

This study aims to evaluate the effects of pulsed Nd:YAG laser on the tensile bond strength (TBS) of resin to human enamel and caries resistance of human enamel. A total of 201 human premolars were used in this in vitro study. A flat enamel surface greater than 4 × 4 mm in area was prepared on each specimen using a low-speed cutting machine under a water coolant. Twenty-one specimens were divided into seven groups for morphology observations with no treatment, 35% phosphoric acid etching (30 seconds), and laser irradiation (30 seconds) of pulsed Nd:YAG laser with five different laser-parameter combinations. Another 100 specimens were used for TBS testing. They were embedded in self-cured acrylic resin and randomly divided into 10 groups. After enamel surface pretreatments according to the group design, resin was applied. The TBS values were tested using a universal testing machine. The other 80 specimens were randomly divided into eight groups for acid resistance evaluation. Scanning electron microscope (SEM) results showed that the enamel surfaces treated with 1.5 W/20 Hz and 2.0 W/20 Hz showed more etching-like appearance than those with other laser-parameter combinations. The laser-parameter combinations of 1.5 W/15 Hz and 1.5 W/20 Hz were found to be efficient for the TBS test. The mean TBS value of 14.45 ± 1.67 MPa in the laser irradiated group was significantly higher than that in the untreated group (3.48 ± 0.35 MPa) but lower than that in the 35% phosphoric acid group (21.50 ± 3.02 MPa). The highest mean TBS value of 26.64 ± 5.22 MPa was identified in the combination group (laser irradiation and then acid etching). Acid resistance evaluation showed that the pulsed Nd:YAG laser was efficient in preventing enamel demineralization. The SEM results of the fractured enamel surfaces, resin/enamel interfaces, and demineralization depths were consistent with those of the TBS test and the acid resistance evaluation. Pulsed Nd:YAG laser as an enamel surface pretreatment method presents a potential clinical application, especially for the caries-susceptible population or individuals with recently bleached teeth. PMID:23919623

Wen, X; Zhang, L; Liu, R; Deng, M; Wang, Y; Liu, L; Nie, X

2014-01-01

378

Transverse-Weld Tensile Properties of a New Al-4Cu-2Si Alloy as Filler Metal  

NASA Astrophysics Data System (ADS)

AA2195, an Al-Cu-Li alloy in the T8P4 age-hardened condition, is a candidate aluminum armor for future combat vehicles, as this material offers higher static strength and ballistic protection than current aluminum armor alloys. However, certification of AA2195 alloy for armor applications requires initial qualification based on the ballistic performance of welded panels in the as-welded condition. Currently, combat vehicle manufacturers primarily use gas metal arc welding (GMAW) process to meet their fabrication needs. Unfortunately, a matching GMAW consumable electrode is currently not commercially available to allow effective joining of AA2195 alloy. This initial effort focused on an innovative, low-cost, low-risk approach to identify an alloy composition suitable for effective joining of AA2195 alloy, and evaluated transverse-weld tensile properties of groove butt joints produced using the identified alloy. Selected commercial off-the-shelf (COTS) aluminum alloy filler wires were twisted to form candidate twisted filler rods. Representative test weldments were produced using AA2195 alloy, candidate twisted filler rods and gas tungsten arc welding (GTAW) process. Selected GTA weldments produced using Al-4wt.%Cu-2wt.%Si alloy as filler metal consistently provided transverse-weld tensile properties in excess of 275 MPa (40 ksi) UTS and 8% El (over 25 mm gage length), thereby showing potential for acceptable ballistic performance of as-welded panels. Further developmental work is required to evaluate in detail GMAW consumable wire electrodes based on the Al-Cu-Si system containing 4.2-5.0 wt.% Cu and 1.6-2.0 wt.% Si.

Sampath, K.

2009-12-01

379

Tensile behavior of cortical bone: dependence of organic matrix material properties on bone mineral content.  

PubMed

A porous composite model is developed to analyze the tensile mechanical properties of cortical bone. The effects of microporosity (volksman's canals, osteocyte lacunae) on the mechanical properties of bone tissue are taken into account. A simple shear lag theory, wherein tensile loads are transferred between overlapped mineral platelets by shearing of the organic matrix, is used to model the reinforcement provided by mineral platelets. It is assumed that the organic matrix is elastic in tension and elastic-perfectly plastic in shear until it fails. When organic matrix shear stresses at the ends of mineral platelets reach their yield values, the stress-strain curve of bone tissue starts to deviate from linear behavior. This is referred as the microscopic yield point. At the point where the stress-strain behavior of bone shows a sharp curvature, the organic phase reaches its shear yield stress value over the entire platelet. This is referred as the macroscopic yield point. It is assumed that after macroscopic yield, mineral platelets cannot contribute to the load bearing capacity of bone and that the mechanical behavior of cortical bone tissue is determined by the organic phase only. Bone fails when the principal stress of the organic matrix is reached. By assuming that mechanical properties of the organic matrix are dependent on bone mineral content below the macroscopic yield point, the model is used to predict the entire tensile mechanical behavior of cortical bone for different mineral contents. It is found that decreased shear yield stresses and organic matrix elastic moduli are required to explain the mechanical behavior of bones with lowered mineral contents. Under these conditions, the predicted values (elastic modulus, 0.002 yield stress and strain, and ultimate stress and strain) are within 15% of experimental data. PMID:16434048

Kotha, S P; Guzelsu, N

2007-01-01

380

Effects of heat input on microstructure and tensile properties of laser welded magnesium alloy AZ31  

SciTech Connect

A 3 kW CO{sub 2} laser beam was used to join wrought magnesium alloy AZ31 sheets, and the effects of heat input on the quality of butt welding joints were studied. By macro and microanalysis, it is found that the welding heat input plays an important role in laser welding process for AZ31 wrought sheets. After welding, the grains far from the weld centre present the typical rolled structure. But the microstructure out of the fusion zone gradually changes to complete equiaxed crystals as the distance from the weld centre decreases. Adjacent to the fusion boundary, there is a band region with columnar grains, and its growth direction is obviously perpendicular to the solid/liquid line. The microstructure in fusion centre consists of fine equiaxed grains and the many precipitated particles are brittle phase Mg{sub 17}Al{sub 12} or Mg{sub 17}(Al,Zn){sub 12}. With increasing the heat input, the band width of columnar grains varies, the grains in fusion zone get coarser, and the distribution of precipitates changes from intragranularly scattered particles to intergranularly packed ones. The results of tensile test show that the change trend of ultimate tensile strength (UTS) and elongation of the welded joints is to increase at first and then decrease with the heat input increasing. When the heat input reaches 24 J mm{sup -1}, the maximum value of the UTS is up to 96.8% of the base metal.

Quan, Y.J. [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China)], E-mail: quanyj_2006@yahoo.com.cn; Chen, Z.H.; Gong, X.S.; Yu, Z.H. [School of Materials Science and Engineering, Hunan University, Changsha 410082 (China)

2008-10-15

381

The influence of yarn treatment on the tensile properties of biocomposites  

NASA Astrophysics Data System (ADS)

The aim of this work was to investigate the influence of cotton and linen yarns treatments at different hierarchical levels on the biocomposite tensile properties. The biodegradable poly(lactic acid) (PLA) resin was used as the matrix polymer. The water based mercerization and low pressure plasma treatment were applied for chemical modification of yarns macro- and microfibrils. To improve fiber orientation of fibre bundles and single fibers the pretension of yarn was used. It was obtained that the most efficient is the complex yarns treatment, plasma treatment with subsequent pre-tension, where especially notable was the positive effect of low-pressure plasma.

Širvaitien?, Anne; Jankauskait?, Virginija; Bekampien?, Paul?; Sankauskait?, Audron?

2012-07-01

382

A novel in situ device based on a bionic piezoelectric actuator to study tensile and fatigue properties of bulk materials.  

PubMed

In this work, a miniaturized device based on a bionic piezoelectric actuator was developed to investigate the static tensile and dynamic fatigue properties of bulk materials. The device mainly consists of a bionic stepping piezoelectric actuator based on wedge block clamping, a pair of grippers, and a set of precise signal test system. Tensile and fatigue examinations share a set of driving system and a set of signal test system. In situ tensile and fatigue examinations under scanning electron microscope or metallographic microscope could be carried out due to the miniaturized dimensions of the device. The structure and working principle of the device were discussed and the effects of output difference between two piezoelectric stacks on the device were theoretically analyzed. The tensile and fatigue examinations on ordinary copper were carried out using this device and its feasibility was verified through the comparison tests with a commercial tensile examination instrument. PMID:24985848

Wang, Shupeng; Zhang, Zhihui; Ren, Luquan; Zhao, Hongwei; Liang, Yunhong; Zhu, Bing

2014-06-01

383

A novel in situ device based on a bionic piezoelectric actuator to study tensile and fatigue properties of bulk materials  

SciTech Connect

In this work, a miniaturized device based on a bionic piezoelectric actuator was developed to investigate the static tensile and dynamic fatigue properties of bulk materials. The device mainly consists of a bionic stepping piezoelectric actuator based on wedge block clamping, a pair of grippers, and a set of precise signal test system. Tensile and fatigue examinations share a set of driving system and a set of signal test system. In situ tensile and fatigue examinations under scanning electron microscope or metallographic microscope could be carried out due to the miniaturized dimensions of the device. The structure and working principle of the device were discussed and the effects of output difference between two piezoelectric stacks on the device were theoretically analyzed. The tensile and fatigue examinations on ordinary copper were carried out using this device and its feasibility was verified through the comparison tests with a commercial tensile examination instrument.

Wang, Shupeng; Zhang, Zhihui, E-mail: zhzh@jlu.edu.cn; Ren, Luquan; Liang, Yunhong [The Key Laboratory of Engineering Bionics (Ministry of Education) and the College of Biological and Agricultural Engineering, Jilin University (Nanling Campus), 5988 Renmin Street, Changchun 130025 (China); Zhao, Hongwei [College of Mechanical Science and Engineering, Jilin University (Nanling Campus), 5988 Renmin Street, Changchun 130025 (China); Zhu, Bing [College of Automotive Engineering, Jilin University (Nanling Campus), 5988 Renmin Street, Changchun 130025 (China)

2014-06-15

384

High Strength Stainless Steel Properties that Affect Resistance Welding  

SciTech Connect

This report discusses results of a study on selected high strength stainless steel alloy properties that affect resistance welding. The austenitic alloys A-286, JBK-75 (Modified A-286), 21-6-9, 22-13-5, 316 and 304L were investigated and compared. The former two are age hardenable, and the latter four obtain their strength through work hardening. Properties investigated include corrosion and its relationship to chemical cleaning, the effects of heat treatment on strength and surface condition, and the effect of mechanical properties on strength and weldability.

Kanne, W.R.

2001-08-01

385

The Effect of Artificial Aging on the Tensile Properties of Alclad 24S-T and 24S-T Aluminum Alloy  

NASA Technical Reports Server (NTRS)

An experimental study was made to determine the effect of artificial aging on the tensile properties of alclad 24S-T and 24S-T aluminum-alloy sheet material. The results of the tests show that certain combinations of aging time and temperature cause a marked increase in the yield strength and a small increase in the ultimate strength; these increases are accompanied by a very large decrease in elongation. A curve is presented that shows the maximum yield strengths that can be obtained by aging this material at various combinations of time and temperature. The higher values of yield stress are obtained in material aged at relatively longer times and lower temperatures.

Kotanchik, Joseph N.; Woods, Walter; Zender, George W.

1943-01-01

386

Blends of thermotropic LCP having alkoxy side-groups with PBT: Comparison of their tensile properties with main-chain LCP blends (II)  

SciTech Connect

Two new thermotropic liquid crystalline polymers (TLCPs) were synthesized. One is a dimesogenic TLCP having a flexible hexamethylene spacer in the main chain, the other is a rigid type main chain TLCP having alkoxy side chains on the terephthaloyl group of the polymer. Blends of TLCP with PBT were melt spun at different LCP contents and different draw ratio to produce a monofilament. Maximum enhancement in the ultimate tensile strength was observed for the blends containing 5% LCP at any draw ratio, and decreased with further increase in LCP content. The initial modulus monotonically increased with increasing LCP content. The tensile properties of the rigid type LCP blends were higher than those of the flexible main-chain LCP blends.

Chang, J.H.; Jo, B.W. [Kum-Oh Univ. of Technology, Kumi (Korea, Republic of); Lee, S.M. [Cosun Univ. (Korea, Republic of)

1995-12-01

387

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

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

388

Properties of formable high strength sheet steels for automotive use  

SciTech Connect

Metallurgical factors affecting the press formability of the newly developed high strength sheet steels have been discussed. Dual phase steels, CHLY (cold-rolled sheet steel) and HTP-D (as-hotrolled sheet steel), produced by control of cooling conditions after intercritical annealing or hot-rolling exhibit very low yield to tensile strength ratio and high n-value. Rephosphorized extralow carbon steel, CHRX, produced by continuous annealing with rapid cooling is characterized by its extremely high r-value and low yield strength. CHLY, HTP-D and CHRX have large bake hardenability. Precipitation hardened steel, HTP-F (hot-rolled sheel steel), produced by adjusting carbon equivalent and sulfur content is suitable for manufacturing wheel rims owing to its good formability after flash butt welding.

Satoh, S.; Kato, T.; Nishida, M.; Obara, T.; Shinozaki, M.; Tosaka, A.

1983-11-01

389

In-Situ Observations on the Fracture Mechanism of Diffusion-Alloyed Ni-Containing Powder Metal Steels and a Proposed Method for Tensile Strength Improvement  

Microsoft Academic Search

The mechanical properties of Ni-containing powder metal (PM) steels are usually inferior to those of their wrought counterparts.\\u000a The main problem is attributed to the non-uniform Ni distribution, in addition to the problems caused by porosity. The effects\\u000a of this non-uniform alloying on the mechanical properties were investigated in this study using mini tensile bars that were\\u000a made of diffusion-alloyed

M. W. Wu; K. S. Hwang; H. S. Huang

2007-01-01

390

In-Situ Observations on the Fracture Mechanism of Diffusion-Alloyed Ni-Containing Powder Metal Steels and a Proposed Method for Tensile Strength Improvement  

Microsoft Academic Search

The mechanical properties of Ni-containing powder metal (PM) steels are usually inferior to those of their wrought counterparts. The main problem is attributed to the non-uniform Ni distribution, in addition to the problems caused by porosity. The effects of this non-uniform alloying on the mechanical properties were investigated in this study using mini tensile bars that were made of diffusion-alloyed

M. W. Wu; K. S. Hwang; H. S. Huang

2007-01-01

391

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

PubMed Central

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

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

2013-01-01

392

Solar Effects on Tensile and Optical Properties of Hubble Space Telescope Silver-Teflon(Registered Trademark) Insulation  

NASA Technical Reports Server (NTRS)

A section of the retrieved Hubble Space Telescope (HST) solar array drive arm (SADA) multilayer insulation (MLI), which experienced 8.25 years of space exposure, was analyzed for environmental durability of the top layer of silver-Teflon (DuPont) fluorinated ethylene propylene (Ag-FEP). Because the SADA MLI had solar and anti-solar facing surfaces and was exposed to the space environment for a long duration, it provided a unique opportunity to study solar effects on the environmental degradation of Ag-FEP, a commonly used spacecraft thermal control material. Data obtained included tensile properties, solar absorptance, surface morphology and chemistry. The solar facing surface was found to be extremely embrittled and contained numerous through-thickness cracks. Tensile testing indicated that the solar facing surface lost 60% of its mechanical strength and 90% of its elasticity while the anti-solar facing surface had ductility similar to pristine FEP. The solar absorptance of both the solar facing surface (0.155 plus or minus 0.032) and the anti-solar facing surface (0.208 plus or minus 0.012) were found to be greater than pristine Ag-FEP (0.074). Solar facing and anti-solar facing surfaces were microscopically textured, and locations of isolated contamination were present on the anti-solar surface resulting in increased localized texturing. Yet, the overall texture was significantly more pronounced on the solar facing surface indicating a synergistic effect of combined solar exposure and increased heating with atomic oxygen erosion. The results indicate a very strong dependence of degradation, particularly embrittlement, upon solar exposure with orbital thermal cycling having a significant effect.

deGroh, Kim, K.; Dever, Joyce A.; Snyder, Aaron; Kaminski, Sharon; McCarthy, Catherine E.; Rapoport, Alison L.; Rucker, Rochelle N.

2006-01-01

393

Tensile and fatigue properties of two titanium alloys as candidate materials for fusion reactors  

Microsoft Academic Search

Titanium alloys have been identified as candidate structural materials for the first wall, the blanket and the magnetic coil structures of fusion reactors. Titanium alloys are interesting materials because of their high specific strength and low elastic modulus, their low swelling tendency and their fast induced radioactivity decay. Other attractive properties are an excellent resistance to corrosion and good weldability,

P. Marmy; T. Leguey; I. Belianov; M. Victoria

2000-01-01

394

Data on Material Properties and Panel Compressive Strength of a Plastic-bonded Material of Glass Cloth and Canvas  

NASA Technical Reports Server (NTRS)

Results are presented of tests for determining the tensile, compressive, and bending properties of a material of plastic-bonding glass cloth and canvas layers. In addition, 10 panel specimens were tested in compression. Although the material is not satisfactory for primary structural use in aircraft when compared on a strength-weight basis with other materials in common use, there appears to be potential strength in the material that will require research for development. These points are considered in some detail in the concluding discussion of the report. An appendix shows that a higher tensile strength can be obtained by changes in the type of weave used in the glass-cloth reinforcement.

Zender, George W; Schuette, Evan H; Weinberger, Robert A

1944-01-01

395

Effect of Alloying Elements on Tensile Properties, Microstructure, and Corrosion Resistance of Reinforcing Bar Steel  

NASA Astrophysics Data System (ADS)

The effect of copper, phosphorus, and chromium present in a semikilled reinforcing bar steel produced by in-line quenching [thermomechanical treatment (TMT)] process on the tensile properties, microstructure, and corrosion resistance of steel in simulated chloride environment has been investigated. The results have been compared with that of a semikilled C-Mn reinforcing bar steel without these alloying elements produced by the same process route. Though the amount of phosphorus (0.11 wt.%) was higher than that specified by ASTM A 706 standard, the Cu-P-Cr steel exhibited a composite microstructure, and good balance of yield stress, tensile stress, elongation, and ultimate tensile to yield stress ratio. Two conventional test methods, namely, the salt fog, and potentiodynamic polarization tests, were used for the corrosion test. The rust formed on Cu-P-Cr steel was adherent, and was of multiple colors, while the corrosion products formed on the C-Mn steel were weakly adherent and relatively darker blue. Also, the free corrosion potential of the Cu-P-Cr steel was nobler, and the corrosion current was markedly lower than that of a C-Mn rebar. The Cu-P-Cr steel did not develop any pits/deep grooves on its surface even after the prolonged exposure to salt fog. The improved corrosion resistance of the Cu-P-Cr steel has been attributed to the presence of copper, phosphorus, and small amount of chromium in the dense, adherent rust layer on the surface of reinforcing steel bar. A schematic mechanism of charge transfer has been proposed to explain the improved corrosion resistance of the Cu-P-Cr alloyed TMT rebar.

Panigrahi, B. K.; Srikanth, S.; Sahoo, G.

2009-11-01

396

Studies of Evaluation of Hydrogen Embrittlement Property of High-Strength Steels with Consideration of the Effect of Atmospheric Corrosion  

NASA Astrophysics Data System (ADS)

Hydrogen embrittlement of high-strength steels was investigated by using slow strain rate test (SSRT) of circumferentially notched round bar specimens after hydrogen precharging. On top of that, cyclic corrosion tests (CCT) and outdoor exposure tests were conducted prior to SSRT to take into account the effect of hydrogen uptake under atmospheric corrosion for the evaluation of the susceptibility of high-strength steels. Our studies of hydrogen embrittle properties of high-strength steels with 1100 to 1500 MPa of tensile strength and a prototype ultrahigh-strength steel with 1760 MPa containing hydrogen traps using those methods are reviewed in this article. A power law relationship between notch tensile strength of hydrogen-precharged specimens and diffusible hydrogen content has been found. It has also been found that the local stress and the local hydrogen concentration are controlling factors of fracture. The results obtained by using SSRT after CCT and outdoor exposure test were in good agreement with the hydrogen embrittlement fracture property obtained by means of long-term exposure tests of bolts made of the high-strength steels.

Akiyama, Eiji; Wang, Maoqiu; Li, Songjie; Zhang, Zuogui; Kimura, Yuuji; Uno, Nobuyoshi; Tsuzaki, Kaneaki

2013-03-01

397

Effects of surface treatments and storage times on the tensile bond strength of adhesive cements to noble and base metal alloys.  

PubMed

This work evaluated two resin cements and a glass-ionomer cement and their bond strength to gold-palladium (Au-Pd), silver-palladium (Ag-Pd), and nickel-chromium-beryllium (Ni-Cr-Be) alloys, utilizing three surface treatments over a period of six months. Eight hundred ten pieces were cast (in a button shape flat surfaces) in one of three alloys. Each alloy group was assigned to three other groups, based on the surface treatment utilized. Specimens were fabricated by bonding similar buttons in using one of three adhesive cements. The 405 pairs were thermocycled and stored in saline solution (0.9% NaCl) at 37 degrees C. The tensile bond strengths were measured in a universal testing machine after storage times of 2, 90, or 180 days. The highest mean bond strength value was obtained with the base metal alloy (10.9 +/- 8.6 MPa). In terms of surface treatment, oxidation resulted in the highest mean bond strength (13.7 +/- 7.3 MPa), followed by sandblasting (10.3 +/- 5.5 MPa) and polishing (3.0 +/- 6.4 MPa). Panavia Ex (13.2 +/- 9.3 MPa) showed significantly higher bond strengths than the other two cements, although the storage time reduced all bond strengths significantly. PMID:18348374

Burmann, Paulo Afonso; Santos, Jose Fortunato Ferreira; May, Liliana Gressler; Pereira, Joao Eduardo da Silva; Cardoso, Paulo Eduardo Capel

2008-01-01

398

Tensile, Fatigue, and Creep Properties of Aluminum Heat Exchanger Tube Alloys for Temperatures from 293 K to 573 K (20 °C to 300 °C)  

NASA Astrophysics Data System (ADS)

Since automotive heat exchangers are operated at varying temperatures and under varying pressures, both static and dynamic mechanical properties should be known at different temperatures. Tubes are the most critical part of the most heat exchangers made from aluminum brazing sheet. We present tensile test, stress amplitude-fatigue life, and creep-rupture data of six AA3XXX series tube alloys after simulated brazing for temperatures ranging from 293 K to 573 K (20 °C to 300 °C). While correlations between several mechanical properties are strong, ranking of alloys according to one property cannot be safely deduced from the known ranking according to another property. The relative reduction in creep strength with increasing temperature is very similar for all six alloys, but the general trends are also strong with respect to tensile and fatigue properties; an exception is one alloy that exhibits strong Mg-Si precipitation activity during fatigue testing at elevated temperatures. Interrupted fatigue tests indicated that the crack growth time is negligible compared to the crack initiation time. Fatigue lifetimes are reduced by creep processes for temperatures above approximately 423 K (150 °C). When mechanical properties were measured at several temperatures, interpolation to other temperatures within the same temperature range was possible in most cases, using simple and well-established equations.

Kahl, Sören; Ekström, Hans-Erik; Mendoza, Jesus

2014-02-01

399

Material property correlations for the niobium-1% zirconium alloy  

E-print Network

CORRELATIONS Phase Diagrams Linear Thermal Expansion . Density Lattice Panuneter Melting Point III MESCAL PROPERTY CORRELATIONS Creep Tensile Properties Hardness . Elastic Moduli IV TRANSPORT PROPERTY CORRELATIONS Electrical Resistivity . Thermal... Specimens. . . . . . . . . . . . . , . . 56 Ultimate Tensile Strength Experimental Data: Annealed Specimens. . . 56 Ultimate Tensile Strength Experimental Data: Worked Specimens. . . . 58 Figure 39 Page hradiated Yield Strength Experimenntl Data: Test...

Senor, David James

1989-01-01

400

The Relationships Between Microstructure, Tensile Properties and Fatigue Life in Ti-5Al-5V-5Mo-3Cr-0.4Fe (Ti-5553)  

NASA Astrophysics Data System (ADS)

beta-titanium alloys are being increasingly used in airframes as a way to decrease the weight of the aircraft. As a result of this movement, Ti-5Al-5V-5Mo-3Cr-0.4Fe (Timetal 555), a high-strength beta titanium alloy, is being used on the current generation of landing gear. This alloy features good combinations of strength, ductility, toughness and fatigue life in alpha+beta processed conditions, but little is known about beta-processed conditions. Recent work by the Center for the Accelerated Maturation of Materials (CAMM) research group at The Ohio State University has improved the tensile property knowledge base for beta-processed conditions in this alloy, and this thesis augments the aforementioned development with description of how microstructure affects fatigue life. In this work, beta-processed microstructures have been produced in a Gleeble(TM) thermomechanical simulator and subsequently characterized with a combination of electron and optical microscopy techniques. Four-point bending fatigue tests have been carried out on the material to characterize fatigue life. All the microstructural conditions have been fatigue tested with the maximum test stress equal to 90% of the measured yield strength. The subsequent results from tensile tests, fatigue tests, and microstructural quantification have been analyzed using Bayesian neural networks in an attempt to predict fatigue life using microstructural and tensile inputs. Good correlation has been developed between lifetime predictions and experimental results using microstructure and tensile inputs. Trained Bayesian neural networks have also been used in a predictive fashion to explore functional dependencies between these inputs and fatigue life. In this work, one section discusses the thermal treatments that led to the observed microstructures, and the possible sequence of precipitation that led to these microstructures. The thesis then describes the implications of microstructure on fatigue life and implications of tensile properties on fatigue life. Several additional experiments are then described that highlight possible causes for the observed dependence of microstructure on fatigue life, including fractographic evidence to provide support of microstructural dependencies.

Foltz, John W., IV

401

Tensile, creep, and ABI tests on sn5%sb solder for mechanical property evaluation  

NASA Astrophysics Data System (ADS)

Sn5%Sb is one of the materials considered for replacing lead containing alloys for soldering in electronic packaging. We evaluated the tensile properties of the bulk material at varied strain-rates and temperatures (to 473K) to determine the underlying deformation mechanisms. Stress exponents of about three and seven were observed at low and high stresses, respectively, and very low activation energies for creep (about 16.7 and 37.7 kJ/mole) were noted. A maximum ductility of about 350% was noted at ambient temperature. Creep tests performed in the same temperature regime also showed two distinct regions, albeit with slightly different exponents (three and five) and activation energy (about 54.4 kJ/mole). Ball indentation tests were performed on the shoulder portions of the creep samples (prior to creep tests) using a Stress-Strain Microprobe@ (Advanced Technology Corporation) at varied indentation rates (strain-rates). The automated ball indentation (ABI) data were at relatively high strain-rates; however, they were in excellent agreement with creep data, while both these results deviated from the tensile test data. Work is planned to perform creep at high stresses at ambient and extend ABI tests to elevated temperatures.

Murty, K. Linga; Haggag, Fahmy M.; Mahidhara, Rao K.

1997-07-01

402

Influence of solid-state interfacial reactions on the tensile strength of Cu\\/electroless Ni–P\\/Sn–3.5Ag solder joint  

Microsoft Academic Search

Tensile strength and fracture behavior of Cu\\/electroless Ni–P\\/Sn–3.5Ag (wt.% Ag) solder joint were investigated under high-temperature solid-state aging. The aging results showed that the Ni3Sn4 intermetallic phase grows at the electroless Ni–P\\/Sn–3.5Ag interface, along with the transformation of the underlying electroless Ni–P layer into Ni3P compound. However, after complete consumption of the electroless Ni–P layer, a ternary Ni–Sn–P compound also

Aditya Kumar; Zhong Chen

2006-01-01

403

Effects of cooling speed on microstructure and tensile properties of Sn–Ag–Cu alloys  

Microsoft Academic Search

The microstructures and tensile properties of three typical Sn–Ag–Cu alloys, Sn–3.0wt.%Ag–0.5wt.%Cu, Sn–3.5wt.%Ag–0.7wt.%Cu and Sn–3.9wt.%Ag–0.6wt.%Cu, prepared under three different cooling conditions were evaluated after casting. The microstructures of all rapidly cooled specimens consisted of the eutectic phase of ?-Sn with fine fibrous Ag3Sn dispersion surrounding primary ?-Sn grains. The slowly cooled Sn–3.5Ag–0.7Cu and Sn–3.9Ag–0.6Cu alloys exhibited additional large primary Ag3Sn platelets,

K. S Kim; S. H Huh; K Suganuma

2002-01-01

404

Characterization of the tensile and microstructural properties of an aluminum metal matrix composite  

NASA Technical Reports Server (NTRS)

This study examines a powder metallurgy aluminum alloy in the unreinforced state and with a discontinuous reinforcement of 15 v/o or 30 v/o SiC whisker or 15 v/o SiC particulate. The materials were extruded and then hot-rolled to three plate thicknesses of 6.35, 3.18 and 1.8 mm and were investigated in the as-fabricated and peak aged conditions. The influence of mechanical working on the reinforcement morphology and distribution were examined. A comparison of the mechanical properties was made and the elastic moduli of the reinforced materials were predicted using a micromechanics model. Fractography of tensile specimens revealed that the fracture process was dominated by the presence of microstructural inhomogeneities which were related to both the matrix alloy and to the reinforcement type. An analysis of these microstructural features and a description of the micromechanics model are presented in the paper.

Birt, M. J.; Johnson, W. S.

1990-01-01

405

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

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

406

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

407

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

408

Comparison of strength properties of poly-L/D-lactide (PLDLA) 96/4 and polyglyconate (Maxon) sutures: in vitro, in the subcutis, and in the achilles tendon of rabbits.  

PubMed

Achilles tendon rupture is a common injury. Absorbable sutures are not commonly used because of their limited strength properties. Recently, sutures with prolonged strength retention properties have been developed. The aim of the study is to test the mechanical properties of recently developed poly-L/D-lactide (PLDLA) sutures in comparison with polyglyconate (Maxon) sutures. PLDLA (0.2 mm thick) and Maxon (4.0) sutures were studied in vitro by immersion in a buffered saline solution (pH 7.4). Tensile strength tests were done on sutures retrieved after 1-26 weeks. In vivo, they were implanted in the subcutis of 32 rabbits. Tensile strength tests were done on sutures retrieved after 1-6 weeks. The sutures were also used to repair the Achilles tendon in rabbits. Maximum force before breaking and percentage elongation of tendons were determined. Although PLDLA had a lower initial tensile strength than Maxon, PLDLA showed more prolonged tensile strength retention than Maxon. Tendons repaired with PLDLA, however, had a lower strength than Maxon-repaired tendons at six weeks (insignificant difference). PLDLA has more prolonged tensile strength properties compared with Maxon. Thus, PLDLA offers an alternative to Maxon in repair of the Achilles tendon. PMID:11153008

Kangas, J; Paasimaa, S; Mäkelä, P; Leppilahti, J; Törmälä, P; Waris, T; Ashammakhi, N

2001-01-01

409

Thermal degradation of the tensile properties of undirectionally reinforced FP-AI203/EZ 33 magnesium composites  

NASA Technical Reports Server (NTRS)

The effects of isothermal and cyclic exposure on the room temperature axial and transverse tensile strength and dynamic flexural modulus of 35 volume percent and 55 volume percent FP-Al2O3/EZ 33 magnesium composites were studied. The composite specimens were continuously heated in a sand bath maintained at 350 C for up to 150 hours or thermally cycled between 50 and 250 C or 50 and 350 C for up to 3000 cycles. Each thermal cycle lasted for a total of six minutes with a hold time of two minutes at the maximum temperature. Results indicate to significant loss in the room temperature axial tensile strength and dynamic flexural modulus of composites thermally cycled between 50 and 250 C or of composites isothermally heated at 350 C for up to 150 hours from the strength and modulus data for the untreated, as fabricated composites. In contrast, thermal cycling between 50 and 350 C caused considerable loss in both room temperature strength and modulus. Fractographic analysis and measurement of composite transverse strength and matrix hardness of thermally cycled and isothermally heated composites indicated matrix softening and fiber/matrix debonding due to void growth at the interface and matrix cracking as the likely causes of the strength and modulus loss behavior.

Bhatt, R. T.; Grimes, H. H.

1982-01-01

410

Thermal degradation of the tensile properties of undirectionally reinforced FP-Al2O3/EZ 33 magnesium composites  

NASA Technical Reports Server (NTRS)

The effects of isothermal and cyclic exposure on the room temperature axial and transverse tensile strength and dynamic flexural modulus of 35 volume percent and 55 volume percent FP-Al203/EZ 33 magnesium composites were studied. The composite specimens were continuously heated in a sand bath maintained at 350 C for up to 150 hours or thermally cycled between 50 and 250 C or 50 and 350 C for up to 3000 cycles. Each thermal cycle lasted for a total of six minutes with a hold time of two minutes at the maximum temperature. Results indicate no significant loss in the room temperature axial tensile strength and dynamic flexural modulus of composites thermally cycled between 50 and 250 C or of composites isothermally heated at 350 C for up to 150 hours from the strength and modulus data for the untreated, as-fabricated composites. In contrast, thermal cycling between 50 and 350 C caused considerable loss in both room temperature strength and modulus. Fractographic analysis and measurement of composite transverse strength and matrix hardness of thermally cycled and isothermally heated composites indicated matrix softening and fiber/matrix debonding due to void growth at the interface and matrix cracking as the likely causes of the strength and modulus loss behavior. Previously announced in STAR as N82-21260

Bhatt, R.T.; Grimes, H. H.

1983-01-01

411

Tensile properties of thin Au-Ni brazes between strong base materials  

SciTech Connect

It has long been known that when relatively strong base materials are joined by thin, soft, interlayer metals such as with brazing or various solid state joining processes, the ultimate tensile strength (UTS) of the bond may be several factors higher than the UTS of the bulk, or unconstrained, interlayer metals. However, earlier work reported by the authors confirmed that delayed or ``creep`` failure of the bond may occur at stresses much less than the UTS. It was found that for thin silver interlayers, prepared by brazing and physical vapor deposition (PVD), joining elastically deforming base materials (i.e. no measurable plastic deformation occurs in the base metal at the applied stresses), the ambient (and near-ambient) temperature time to failure is controlled by the creep rate of the silver interlayer which is determined by the effective stress within the interlayer. The plastic deformation within the interlayer causes cavity nucleation which continues until the concentration of nuclei is sufficiently high to lead to instability and eventual failure. The delayed failure may be accelerated by base material creep resulting from the effective stress in the base material. Plastic deformation in the base metal causes corresponding deformation in the interlayer, and cavities nucleate as with elastic base metal case. The delayed failure phenomenon was confirmed by the authors only for silver interlayers; other compositions were not tested. In this study, maraging steel was joined with an Au-Ni braze alloy with 57.5 at. % Au and 42.5 at. % Ni. The microstructure is expected to be a refined two-phase (spinodal) alloy with higher strength than the PVD silver of our previous investigation.

Tolle, M.C.; Kassner, M.E. [Oregon State Univ., Corvallis, OR (United States)

1991-12-01

412

Tensile properties of thin Au-Ni brazes between strong base materials  

SciTech Connect

It has long been known that when relatively strong base materials are joined by thin, soft, interlayer metals such as with brazing or various solid state joining processes, the ultimate tensile strength (UTS) of the bond may be several factors higher than the UTS of the bulk, or unconstrained, interlayer metals. However, earlier work reported by the authors confirmed that delayed or creep'' failure of the bond may occur at stresses much less than the UTS. It was found that for thin silver interlayers, prepared by brazing and physical vapor deposition (PVD), joining elastically deforming base materials (i.e. no measurable plastic deformation occurs in the base metal at the applied stresses), the ambient (and near-ambient) temperature time to failure is controlled by the creep rate of the silver interlayer which is determined by the effective stress within the interlayer. The plastic deformation within the interlayer causes cavity nucleation which continues until the concentration of nuclei is sufficiently high to lead to instability and eventual failure. The delayed failure may be accelerated by base material creep resulting from the effective stress in the base material. Plastic deformation in the base metal causes corresponding deformation in the interlayer, and cavities nucleate as with elastic base metal case. The delayed failure phenomenon was confirmed by the authors only for silver interlayers; other compositions were not tested. In this study, maraging steel was joined with an Au-Ni braze alloy with 57.5 at. % Au and 42.5 at. % Ni. The microstructure is expected to be a refined two-phase (spinodal) alloy with higher strength than the PVD silver of our previous investigation.

Tolle, M.C.; Kassner, M.E. (Oregon State Univ., Corvallis, OR (United States))

1991-12-01

413

Tensile and Creep Property Characterization of Potential Brayton Cycle Impeller and Duct Materials  

NASA Technical Reports Server (NTRS)

This paper represents a status report documenting the work on creep of superalloys performed under Project Prometheus. Cast superalloys have potential applications in space as impellers within closed-loop Brayton cycle nuclear power generation systems. Likewise wrought superalloys are good candidates for ducts and heat exchangers transporting the inert working gas in a Brayton-based power plant. Two cast superalloys, Mar-M247LC and IN792, and a NASA GRC powder metallurgy superalloy, LSHR, are being screened to compare their respective capabilities for impeller applications. Several wrought superalloys including Hastelloy X, (Haynes International, Inc., Kokomo, IN), Inconel 617, Inconel 740, Nimonic 263, and Incoloy MA956 (Special Metals Corporation, Huntington, WV) are also being screened to compare their capabilities for duct applications. These proposed applications would require sufficient strength and creep resistance for long term service at temperatures up to 1200 K, with service times to 100,000 h or more. Conventional tensile and creep tests were performed at temperatures up to 1200 K on specimens extracted from the materials. Initial microstructure evaluations were also undertaken.

Gabb, Timothy P.; Gayda, John

2006-01-01

414