Showing papers on "Tensile testing published in 1981"
Journal Article•
TL;DR: In this paper, the applicability of linear elastic fracture mechanics to concrete and similar materials is analysed by use of the Fictitious Crack Model, where the fracture zone in front of a crack is represented by a fictitious crack able to transfer stress.
Abstract: A calculation model (the Fictitious Crack Model), based on fracture mechanics and the finite element method, 1s presented. In the model the fracture zone in front of a crack is represented by a fictitious crack that 1s able to transfer stress. The stress transferring capability of the fictitious crack normally decreases when the crack width increases. The applicability of linear elastic fracture mechanics to concrete and similar materials is analysed by use of the Fictitious Crack Model. It" Is found that linear elastic fracture mechanics 1s too dependent on, among other things, specimen dimensions to be useful as a fracture approach, unless the dimensions, for concrete structures, are in order of meters. The usefulness of the J-integral, the COD-approach and the R-curve analysis is also found to be very limited where cementitious materials are concerned. The complete tensile stress-strain curve is introduced as a fracture mechanical parameter. The curve can be approximatively determined if the tensile strength, the Young's modius and the fracture energy are known. Su1table~lest methods Tor determining" TRise~~/'Voerties are presented and test results are reported for a number of concrete qua! » a. A new tyr * very stiff tensile testing machine Is presented by which it is possible to carry r . itable tensile tests on concrete. The complete tensile stress-strain curves h •«• feen determined for a number of concrete qualities. The thesi' overs a complete system for analysing crack propagation in concrete as it Include* -ealistic material model, a functional calculation model and methods for determiv" «/ the material properties necessary for the calculations. Therefore this work oi r t to be of use as a base for further studies of the fracture process of concrete < i similar materials.
897 citations
TL;DR: A tension version of the split Hopkinson bar or Kolsky apparatus was developed for conducting tests in tension at high rates of strain up to 103 s−1 as discussed by the authors, which is the highest rate of strain sensitivity known.
Abstract: A tension version of the split Hopkinson bar or Kolsky apparatus is developed for conducting tests in tension at high rates of strain up to 103 s−1. A number of aluminum, titanium, and steel alloys tested in tension show increasing degrees of rate sensitivity above 10 to 102 s−1. Tests on 6061-T651 and 7075-T6 aluminum show measurable strain-rate sensitivity in tension at the highest strain rates, although similar tests in compression in the literature show essentially no strain-rate sensitivity. Details of the apparatus and instrumentation and guidelines for its use are presented.
357 citations
TL;DR: In this paper, the deformations in a plane strain tensile test are analyzed numerically, both for a solid characterized by a phenomenological corner theory of plasticity and for a nonlinear elastic solid.
Abstract: The deformations in a plane strain tensile test are analyzed numerically, both for a solid characterized by a phenomenological corner theory of plasticity and for a nonlinear elastic solid As opposed to the simplest flow theory of plasticity with a smooth yield surface, both these material models exhibit shear band instabilities at a realistic level of strain Initial imperfections are specified in the form of thickness inhomogeneities A long-wavelength imperfection grows into the well-known necking mode and subsequently, at a sufficiently high local strain level, bands of intense shear deformations develop in the necking region The location of these shear bands is strongly influenced by the location of small strain concentrations near the surface, induced by various short-wave patterns of initial thickness imperfections In accord with the non-uniform straining in the neck it is found that the intensity of the localized deformations varies along the bands, and some of the shear bands end inside the material
306 citations
TL;DR: In this article, the effects of strain rate, temperature, and sample size on the compressive and tensile properties of frozen silica sand have been determined experimentally using uniaxial compression and split cylinder tests.
96 citations
TL;DR: In this article, it was concluded that the fairly high bond strength of a Al2O3-Nb interface might be attributed to the formation of a thin NbOx layer, which had grown epitaxially on the surface.
Abstract: Diffusion couples of Al2O3 single-crystal, sapphire, and Nb polycrystal were heat-treated in the temperature range 1873 to 2073 K under pressure in the range 3 to 15.2 MN m−2 for various times up to 3.6×103 sec. Tensile testing at various temperatures up to 1873 K in a vacuum of about 10−3 Pa, Knoop hardness testing at room temperature, optical microscopy, scanning electron microscopy, transmission electron microscopy, and electron-probe X-ray microanalysis studies were carried out on the specimens. From the results, it was concluded that the fairly high bond strength of a Al2O3-Nb interface might be attributed to the formation of a thin NbOx layer, which had grown epitaxially on the Al2O3 surface. Lattice matching between Al2O3 and NbOx phases was also considered.
91 citations
TL;DR: In this article, a study was made of serrated yielding in two commercial Al-Zn-Mg alloys in the as-quenched condition, and an estimate of 19.7 kJ/mole for the activation energy for exchange of a solute atom and a vacancy in Al-6.2 wt% Zn, 2.5wt% Mg was made.
68 citations
TL;DR: In this paper, the long-term ageing characteristics of Ni-Mo-Cr alloys (the high-temperature HASTELLOY alloy S and the corrosion resistant hasselloy alloys C-4 and C-276) at 810 K were investigated.
Abstract: The long-term ageing characteristics of some commercial Ni-Mo-Cr alloys (the high-temperature HASTELLOY alloy S and the corrosion resistant HASTELLOY alloys C-4 and C-276) at 810 K were investigated. It was found that the three alloys undergo the following long-range ordering reaction: disordered f c c lattice → ordered orthorhombic, Pt2Mo-type superlattice. Ordering was found to cause considerable strengthening without severe loss of tensile elongation. Deformation in the ordered state occurred predominantly by twinning. The corrosion rates of alloys C-4 and C-276 in boiling sulphuric-ferric sulphate solution did not seem to be greatly affected by the long-range ordering reaction. In addition to ordering, the three alloys were also found to undergo grain boundary reactions. The resulting phase in alloys S and C-4 assumed a dispersed morphology and was identified as carbide, probably of the Type M12C. In alloy C-276, however, which contains higher amounts of iron and tungsten, the boundary precipitate was in the form of a continuous layer consisting of M12C and Mu-phase. This could account for the reduced tensile elongation of alloy C-276 relative to alloys S and C-4 and also to its high corrosion rate.
59 citations
DSM1
TL;DR: A submitted manuscript is the version of the article upon submission and before peer-review as mentioned in this paper, while a published version is the final layout of the paper including the volume, issue and page numbers.
Abstract: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers.
52 citations
TL;DR: In this article, a new method using zone drawing and zone annealing has been studied to prepare high-modulus and high-strength PET fiber, and the experimental procedure consists of two stages: Zone drawing and Zone Annealing, where the zone drawing was done on the original as-spun fiber to produce a fiber with as high an orientation and as low a crystallinity as possible.
Abstract: To prepare high-modulus and high-strength PET fiber, a new method using zone drawing and zone annealing has been studied. The apparatus used for this method is the usual tensile tester equipped with a band heater 2 mm wide and a sample holder which can apply a high tension to the fiber. The experimental procedure consists of two stages: zone drawing and zone annealing. The zone drawing was done on the original as-spun fiber in order to produce a fiber with as high an orientation and as low a crystallinity as possible. The zone-drawn fiber was subsequently zone annealed under high tension by moving the band heater from one end to the other of the fiber at a temperature above the crystallization temperature at a considerably low moving speed. In spite of the simple apparatus and procedure, Young's modulus of the fiber obtained was 19.4 × 1010 dyn/cm2, which is comparable to the maximum value of the high-tenacity PET filament commercially available. In order to elucidate the change in the superstructure with zone drawing or zone annealing, optical, x-ray, IR, DSC, and dynamic mechanical measurements were performed. It is suggested that the zone-annealed fiber consists of almost perfectly oriented crystallites and fully extended amorphous chains.
50 citations
TL;DR: In this paper, the effect of the heat treating parameters on the properties and structure of molybdenum and vanadium bearing dual-phase steels was studied and the relationship between strength and ductility was independent of alloy addition.
Abstract: A systematic study was made of the effect of the heat treating parameters,(i.e., temperature, time, and cooling rate) on the properties and structure of molybdenum and vanadium bearing dual-phase steels. The volume percent martensite was found to be the major structural factor that controls the strength and ductility of these steels. The relationship between strength and ductility was independent of alloy addition for the alloys studied. Annealing temperature was shown to be very important in these alloys, especially at high quench rates. The molybdenum alloy exhibited better hardenability than the vanadium alloy for equivalent heat treating conditions. Therefore, for a given set of annealing conditions the molybdenum alloy generally had the highest tensile strength and lowest total elongation. A minimum in the 0.2 pct yield strength was found at a specific volume fraction martensite. The increase in yield strength at the lowest volume fraction studied can be related to a jog or discontinuity in the stress-strain curve during tensile testing. This jog was found to be the result of the lack of a sufficient amount of free dislocations. The causes of this deficiency of the dislocations may be: 1) an insufficient amount of transformed martensite, 2) a large martensite interparticle spacing, 3) dynamic recovery of dislocations during cooling, and 4) pinning of dislocations by precipitates during cooling.
44 citations
TL;DR: The modes of strain localization in the tensile testing of a sheet sample are diffuse necking, localized necking and localization in an unstable shear band as mentioned in this paper, and it is shown that the materials have similarH vs strain curves in the range of uniform tensile straining, but the curves diverge widely at higher strains whereH falls below 1.
Abstract: The modes of strain localization in the tensile testing of a sheet sample are diffuse necking, localized necking and, in some materials, localization in an unstable shear band. In a tensile test of a rate insensitive material, the normalized strain hardening parameter,H = (1/σ)(dσ/de) has the values ofH = 1 for diffuse necking andH = 0.5 for localized necking. Curves ofH vs strain were obtained up to large values of plastic strain using the hydraulic bulge test. The materials selected were commercially important sheet alloys in the condition normally used for forming. It is shown that the materials have similarH vs strain curves in the range of uniform tensile straining, but the curves diverge widely at higher strains whereH falls below 1. This has important consequences on strain localization behavior. The limit strains of the alloys in simple tension and punch stretching show reasonable correlation with their values ofH and those alloys which are susceptible to catastrophic shear failure have low values ofH at high strains. Strain rate sensitivity adds to or subtracts from theH values obtained in this study and has an additional influence on strain localization.
TL;DR: In this article, an injection-molded tensile bars of unstabilized polypropylene were oven aged at 90°C and showed that after an induction period, tensile elongation decreased catastrophically.
Abstract: Injection-molded tensile bars of unstabilized polypropylene were oven aged at 90°C. After an induction period, tensile elongation decreased catastrophically. During the induction period no evidence of oxidation was observed by infrared reflectance; however, a definite surface etching was noted by electron microscopy. Differential scanning calorimetry measurements indicated that, for samples aged beyond the induction time, oxidative degradation caused a decrease in the melting temperature of polypropylene. Toluene immersion was used to remove selectively material from the surface of tensile bars aged for various times. Using this technique, changes in melting behavior were observed for partially aged polypropylene even prior to the catastrophic decrease in tensile elongation. Similarly, oxidation products and a reduction in molecular weight were detected for the dissolved surface layer during the apparent induction time. Results indicate that molecular weight measurement is the most sensitive indicator of oxidative degradation during the induction period.
TL;DR: In this paper, the authors describe the factors affecting the test procedures and methods for preparation of test specimens for determination of tensile strength of soils by unconfined-penetration (UP) method.
Abstract: This paper describes the factors affecting the test procedures and methods for preparation of test specimens for determination of tensile strength of soils by unconfined-penetration (UP) method. Correlation of tensile strength with other soil constants and strength parameters, such as Atterberg limits, activity, toughness index, unconfined compressive strength, cohesion, and friction angle, are presented. Theoretical explanations of this method and the conventional split-tension test by use of the limit analysis concept are discussed.
TL;DR: In this article, a method for measuring strain-rate sensitivity with a single tensile test and without repeated rate changes is presented, which is applicable to a limited class of alloys, requires only a fixed crosshead-speed tensile testing machine, and uses a strain recording method based on photo-printed grids on the specimen.
Abstract: A rapid technique for measuring strain-rate sensitivity with a single tensile test and without repeated rate changes is presented. This test is applicable to a limited class of alloys, requires only a fixed crosshead-speed tensile testing machine, and uses a strain recording method based on photo-printed grids on the specimen. The strain and strain-rate hardening properties are deconvoluted by computer analysis. Results of tests performed on a zinc-based sheet alloy show that both effects can be consistently characterized for the rolling, transverse, and 45 deg directions. The strain-rate sensitivities in these directions are found to be 0.070, 0.065 and 0.095 respectively.
TL;DR: In this paper, the microplastic model of plastic flow described by Nabarro, Basinski and Holt is extended to the tensile data of nominally pure polycrystalline aluminum at elevated temperatures.
TL;DR: In this article, a fixture is presented for a fixture to test concentric-ring loaded disks and four-point loaded plates at high temperatures, where the loading plunger is guided by flexure plates to determine the load path with accuracy.
Abstract: A design is presented for a fixture to test concentric-ring loaded disks and four-point loaded plates at high temperatures. In this fixture the loading plunger is guided by flexure plates to determine the load path with accuracy. The uniaxial and equibiaxial tensile strengths of a brittle material were measured at 982°C with this fixture. For lapped surfaces, the equibiaxial tensile strength of dense, isostatically pressed, sintered alumina was 16.0% lower than the uniaxial tensile strength. The uniaxial strength at 982°C was 42.3% lower than the previously reported value for comparable tests at room temperature. The effect of frictional forces and lateral constraint, of specimen and loading geometry, and of local stresses on the nominal stress are discussed.
TL;DR: In this article, the authors show that the behavior described by Hu of sharply decreasing r-value as the strain increased in a tensile test has been confirmed in two strongly textured steels, but only for conditions of discontinuous yielding.
Abstract: The behavior described by Hu of a sharply decreasingr-value as the strain increased in a tensile test has been confirmed in two strongly textured steels, but only for conditions of discontinuous yielding. It does not occur in the absence of interstitial elements when yielding is homogeneous. The present work shows that two distinct anisotropies exist, one in the Luders range and one in subsequent uniform deformation. Possible reasons for this behavior are discussed. The enhanced anisotropy due to discontinuous yielding does not confer benefits in terms of improved drawability and it is recommended that prestrained or temper rolled material should be used when determingr-values.
TL;DR: The rheological behavior of polybutadiene on sudden application of finite strain was examined in this paper, where the shear stress σ, two components of birefringence, and the extinction angle were measured in shear (magnitude of shear γ ≤ 3.5) and tensile stress and the bire fringence were measured by uniaxial elongation (elongation ratio ≥ 3.8) with a tensile tester equipped with appropriate sample holders.
Abstract: The rheological behavior of an uncrosslinked polybutadiene on sudden application of finite strain was examined. The shear stress σ, two components of birefringence, and the extinction angle were measured in shear (magnitude of shear γ ≤ 3.5) and tensile stress and the birefringence were measured in uniaxial elongation (elongation ratio λ ≤ 3.8). Measurements were performed at 30°C with a tensile tester equipped with appropriate sample holders. The stress-optical coefficient was 3.01 × 10−9Pa−1. The first and second normal-stress differences v1 and v2 were separately evaluated with the use of stress-optical law. The Lodge—Meissner relation v1 = γσ held good. The ratio v2/v1 was independent of time and varied from about −0.3 to −0.2 with increasing γ in the range of measurements. Each of the stress components was factored into a function of strain and one of time, and the latter was common to all the stress components. Simple formulas were proposed to represent stress components in step deformations.
TL;DR: In this article, the effects of a particular strain path change, tensile-tensile, on the mechanical properties of an aluminum-killed steel was examined, where large tensile specimens were prestrained various amounts in one direction followed by machining smaller tensile samples at 0, 45, and/or 90 deg to the prestrain direction.
Abstract: Multiple forming operations are often needed to stamp complex shapes out of sheet metal. Large changes in strain path can occur from such operations. This study examined the effects of a particular strain path change, tensile-tensile, on the mechanical properties of an aluminum-killed steel. Large tensile specimens were prestrained various amounts in one direction followed by machining smaller tensile specimens at 0, 45, and/or 90 deg to the prestrain direction. The smaller samples were then pulled to failure. For samples pulled in the same direction as the prestrain, the residual strength and ductility were equivalent to those obtained from an interrupted tensile test. In contrast, both the 45 and the 90 deg prestrained specimens showed a larger than expected flow stress and an abrupt change in the nature of the residual ductility at prestrains of 7.5 pct and larger. At 7.5 pct prestrain, the uniform strain, as measured by the maximum-load point on the load
vs elongation tensile curve, decreased abruptly. The decrease was accompanied by a corresponding increase in the post-uniform strain. This unusual behavior is explained in terms of a rapid increase in strain-hardening with strain.
TL;DR: In this paper, a miniature tensile specimen technology has been developed in support of high energy neutron irradiated material testing, including miniature specimen design and fabrication technique development, as well as both baseline and irradiated tensile testing.
TL;DR: In this paper, the low pressure plasma spray process was used to deposit coatings of a Co- 29Cr-6A1-1Y alloy onto IN-738 test specimens and to make free-standing deposits from which specimens were machined.
TL;DR: Tensile testing fails to provide the profession with a thorough understanding of the wrought wires used as clasp materials in dentistry, and it is imperative that the test methods approach the conditions present during clinical function as much as possible.
Abstract: 1 h d 1 l’t t e enta I era ure fails to provide the profession with a thorough understanding of the wrought wires used as clasp materials in dentistry. All information currently available has largely been obtained through the use of tensile testing. In tensile testing, the atoms within the alloy are subjected to tensile stresses at a constant rate of loading. This is not representative of the type of stress present in clasp arms during clinical use. Since clasp arms are required to undergo repeated bending, both tensile and compressive stresses are developed within the material. The extent and rate of any clasp deflection vary. To provide data which can be analyzed to obtain results which can be applied to clinical situations, it is imperative that the test methods approach the conditions present during clinical function as much as possible. During stress-relaxation testing, the test specimen is deflected by the instrument and released. The resiliency of the material returns the test specimen to its original position in the same manner as a clasp arm, after it has passed beyond the curvature of the tooth. As the clasp is deflected, both the tensile and compressive stresses
TL;DR: In this article, the dynamic mechanical properties of polyblends of a polyurethane (PU) elastomer and polyvinylchloride (PVC) at five compositions were studied at 110 Hz, between −120 and 120°C.
Abstract: The dynamic mechanical properties of polyblends of a polyurethane (PU) elastomer and poly(vinylchloride) (PVC) at five compositions were studied at 110 Hz, between −120 and 120°C. The study also included tensile testing at 25°C, and examination of polyblend morphology and fire-retardant properties. The results were analyzed using suitable two-phase mechanics models valid for such systems. This analysis, together with the morphological evidence and the thermomechanical spectra, indicate that these polymer alloys are essentially heterogeneous and their useful mechanical properties are due to good adhesion between the two phases. This conclusion is also corroborated by the tensile properties study. Fire retardancy is significant only above ∼60% by weight of PVC.
TL;DR: The results of the tensile tests show that the room temperature yield and ultimate strength were not much affected by sensitization, whilst significant reduction in the ductility was observed depending on the heat treatment and the method of charging as mentioned in this paper.
Abstract: Thin tensile specimens of 316L-type austenitic stainless steel were tested either at room temperature after cathodic charging or whilst undergoing cathodic charging. Throughout this study we have compared solution-annealed samples with samples given the additional sensitization treatment. The results of the tensile tests show that the room temperature yield and ultimate strengths were not much affected by sensitization, whilst significant reduction in the ductility was observed depending on the heat treatment and the method of charging. The specimens tested while undergoing cathodic charging showed 21% reduction of elongation at-fracture for the annealed specimens and 49% reduction of elongation for the sensitized specimens. The fracture surfaces of the specimens tested while cathodically charged show considerable differences between the annealed and the sensitized specimens. The sensitized specimens were predominantly intergranular, while the fracture of annealed specimens showed massive regions of microvoid coalescence producing ductile rupture. The results were correlated with the presence or absence of the martensite phases determined by means of a ferrite detector and transmission electron microscopy studies.
TL;DR: An alloy of type 316 stainless steel with the addition of 0.23% Ti (316 + Ti) has been irradiated in the 20% cold-worked condition in the HFIR (a mixed fast and thermal neutron spectrum reactor) and tested near the irradiation temperature in the range of 300-600°C as discussed by the authors.
TL;DR: An analysis of the diametral compression test was carried out by means of the finite element method and below a limit value for the width of the contact surface tensile stresses appeared peripherically outside the contact area, peripheral fracture initiation must be regarded as a possibility.
Abstract: In an attempt to find an explanation for an experimentally found strong connection between the extension of the loaded area and the load required for fracture, an analysis of the diametral compression test was carried out by means of the finite element method. The distribution of the stresses in a quadrant of a circular specimen section was studied for varying contact surface but at a given load distribution within this surface. Below a limit value for the width of the contact surface tensile stresses appeared peripherically outside the contact area, which had a magnitude exceeding those stresses which are centrally located and should normally initiate fracture. For that reason, peripherical fracture initiation must be regarded as a possibility. Only marginal importance could be attached to changes in the extension and magnitude of the central tensile stresses, as compared with the potential impact of the peripherical tensile stresses.
TL;DR: In this article, the change in the strength of the joints tensile test samples are discussed in terms of the relative importance of physical and chemical changes on the mechanical properties of lap joints.
Abstract: Mechanical test data are reported on lap joints and tensile test specimens which have been subjected to a defined post cure cycle. The mechanical properties exhibited an apparently systematic variation with temperature. Inspection of the resins indicated that chemical modification does not appear to occur to a significant extent below 433K. The change in the strength of the joints tensile test samples are discussed in terms of the relative importance of physical and chemical changes on the mechanical properties. It is evident that in the presence of oxygen considerable chemical modification can occur and this is observed both in terms of a change in colour of the resin and the appearance of voids.
TL;DR: In this article, the tensile properties of carbon fibers in a form of strand were studied and the three-plates aluminum tab and loaded through pins were clamped with the strand specimens.
Abstract: Clamping methods for evaluating tensile properties of carbon fibers in a form of strand were studied. When clamped with the three-plates aluminum tab and loaded through pins, the strand specimens i...
TL;DR: In this paper, a method for the detection of thermal oxidation in polyethylene pipes is proposed, which can be interpreted according to basic principles of fracture mechanics, such as the shift of unstable/stable necking transition to lower stresses and longer times.
TL;DR: In this paper, the tensile strength of four types of coated fabric material specimens with cracks were measured, and the anisotropy of tensile strengths along warp and filling was investigated.
Abstract: Tensile strength of specimens of coated fabric which had a crack, a bias crack and a circular defect respectively was measured using a uniaxial and using a biaxial tensile tester. Then, uniaxial and biaxial tensile strength figures were compared, and strengths for the three types of defect condition were compared. Further, uniaxial strengths of four types of coated fabric material specimens with cracks were measured, and the anisotropy of tensile strength along warp and filling was investigated. And, relations between crack opening ratio under deformation and stress were measured on the specimen.