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Showing papers on "Ultimate tensile strength published in 1974"


Journal ArticleDOI
TL;DR: In this paper, two related criteria based on stress distribution are presented for predicting the uniaxial tensile strength of laminated composites containing through the thickness discontinuities of a general shape.
Abstract: Two related criteria based on stress distribution are presented for predicting the uniaxial tensile strength of laminated composites containing through the thickness discontinuities of a general shape. The criteria result in two parameter (unnotched tensile strength and a characteristic dimension) models which are capable of predicting observed discontinuity size effects without resorting to classical concepts of linear elastic fracture mechanics. As a direct consequence of the stress criteria, however, a relationship between Mode I fracture toughness and unnotched laminate tensile strength is determined. Limited comparison of theory to experimental data for circular holes and straight cracks yields good results. The simplicity of the analytical approach coupled with its generality make it of practical value to the designer.

1,463 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the mechanisms of plastic fracture in high-purity and commercial 18 Ni, 200 grade maraging steels and quenched and tempered AISI 4340 steels.
Abstract: The mechanisms of plastic fracture (dimpled rupture) in high-purity and commercial 18 Ni, 200 grade maraging steels and quenched and tempered AISI 4340 steels have been studied. Plastic fracture takes place in the maraging alloys through void initiation by fracture of titanium carbo-nitride inclusions and the growth of these voids until impingement results in coalescence and final fracture. The fracture of AISI 4340 steel at a yield strength of 200 ksi (1378 MN/mm2) occurs by nucleation and subsequent growth of voids formed by fracture of the interface between manganese sulfide inclusions and the matrix. The growth of these inclusion-nucleated voids is interrupted long before coalescence by impingement, by the formation of void sheets which connect neighboring sulfide-nucleated voids. These sheets are composed of small voids nucleated by the cementite precipitates in the quenched and tempered structures. The sizes of non-metallic inclusions are an important aspect of the fracture resistance of these alloys since the investigation demonstrates that void nuclea-tion occurs more readily at the larger inclusions and that void growth also proceeds more rapidly from the larger inclusions. Using both notched and smooth round tensile specimens, it was demonstrated that the level of tensile stress triaxiality does not effect the void nu-cleation process in these alloys but that increased levels of triaxial tension do result in greatly increased rates of void growth and a concomitant reduction in the resistance to plastic fracture.

504 citations


Journal ArticleDOI
TL;DR: In this article, the initiation and propagation of microfractures and their contribution to material failure in compression are examined, and the early part of the fracture process, the lateral and the axial yield points of the stress-strain curves, are identified with the onset of micro-fracture, respectively at the tensile and the compressive stress concentrations of the elastic flaw boundary.
Abstract: The initiation and propagation of microfractures and their contribution to material failure in compression are examined. The early part of the fracture process, the lateral and the axial yield points of the stress-strain curves, are identified with the onset of microfracture, respectively at the tensile and the compressive stress concentrations of the elastic flaw boundary. Later stages, including the initiation of inclined shear fractures, the mobilization of total resistance and the reduction of strength to the residual level, are discussed in terms of a modified Coulomb model.

344 citations


Journal ArticleDOI
TL;DR: Nacreous structure, which is very strong but not widely used, apparently evolved earlier than the less strong but widely used crossed-lamellar structure.
Abstract: Pieces of shell from 19 species of molluscs exhibiting various microstructures were tested for tensile strength, modulus of elasticity in bending and modulus of rupture. In tensile strength most shells with cross-foliated, foliated, homogeneous and crossed-lamellar structures did not exceed 60 MNm 2 but prismatic and nacreous structures often exceeded this value. Nacreous structure was generally superior to all others in modulus of rupture tests; that of Turbo being about equal to bone. Values of modulus of elasticity were more uniform between structures. There is a general relation between mechanical properties, microstructure and the life style of each animal. Nacreous structure, which is very strong but not widely used, apparently evolved earlier than the less strong but widely used crossed-lamellar structure.

262 citations


Journal ArticleDOI
TL;DR: In this paper, a theoretical relationship has been developed which relates the ultimate strength of a composite containing spherical fillers to the size, volume fraction, and surface adhesion of the dispersed phase.
Abstract: A theoretical relationship has been developed which relates the ultimate strength of a composite containing spherical fillers to the size, volume fraction, and surface adhesion of the dispersed phase. The theoretical predictions are compared to experimental data using glass beads of known diameters in polyester resin matrix. Results were compared for the case of poor adhesion between the glass beads and the matrix and for the case of good adhesion. The derived relationships should be useful in helping to optimize the strength properties of particulate reinforced systems.

178 citations


Journal ArticleDOI
TL;DR: In this article, the authors developed preliminary conclusions concerning the controls on intrinsic mechanical anisotropy of brittle slate. But their preliminary conclusions were based on the assumption that the cleavage orientation was independent of the principal stress difference in the rock.

168 citations


01 Jan 1974
TL;DR: In this article, a sliding scale of roughness is proposed for estimating the strength of weathered and unweathered joints, and the curvature of the proposed strength envelopes reduces as the roughness coefficient reduces.
Abstract: Direct shear tests performed on model tension fractures have provided a very realistic picture of the behavior of unfilled joints at the roughest end of the joint spectrum. The peak shear strength of rough-undulating joints such as tension surfaces can now be predicted with acceptable accuracy from a knowledge of only one parameter, namely the effective joint wall compressive strength or JCS value. For an unweathered joint this will be simply the unconfined compression strength of the unweathered rock. However in most cases joint walls will be weathered to some degree. Methods of estimating the strength of the weathered rock are discussed. The predicted values of shear strength compare favourably with experimental results reported in the literature, both for weathered and unweathered rough joints. The shear strength of unfilled joints of intermediate roughness presents a problem since at present there is insufficient detailed reporting of test results. In an effort to remedy this situation, a simple roughness classification method has been devised which has a sliding scale of roughness. The curvature of the proposed strength envelopes reduces as the roughness coefficient reduces, and also varies with the strength of the weathered joint wall or unweathered rock, whichever is relevant. Values of the Coulomb parameters c and o fitted to the curves between the commonly used normal stress range of 5-20 kg/sg.km appear to agree quite closely with experimental results. The presence of water is found in practice to reduce the shear strength of rough unfilled joints but hardly to affect the strength of planar surfaces. This result is also predicted by the proposed criterion for peak strength. The shear strength depends on the compressive strength which is itself reduced by the presence of water. The sliding scale of roughness incorporates a reduced contribution from the compressive strength as the joint roughness reduces. Based on the same model, it is possible to draw an interesting analogy between the effects of weathering, saturation, time to failure, and scale, on the shear strength of non-planar joints. Increasing these parameters causes a reduction in the compressive strength of the rock, and hence a reduction in the peak shear strength. Rough-undulating joints are most affected and smooth-nearly planar joints least of all.

144 citations


Journal ArticleDOI
TL;DR: Changes in skin during maturation and ageing as well as after treatment with cortisol acetate were studied in Sprague-Dawley rats, resulting in a decrease in ultimate load and skin thickness and an Increase in tensil...
Abstract: Changes in skin during maturation and ageing as well as after treatment with cortisol acetate were studied in Sprague-Dawley rats. Mechanical parameters (ultimate load and tensile strength) were compared with biochemical parameters, i.e., collagen content and collagen fractions, as well as glycosaminoglycan content and glycosaminoglycan fractions (hyaluronic acid, chondroitin sulfates and heparin sulfate). The values of ultimate load and tensile strength as well as the total collagen and insoluble collagen content showed a biphasic curve during the life span, with a maximum at 4 months or 1 year. Using these parameters, maturation and ageing processes can be distinguished, whereas the other parameters changed only in one direction so that no differentiation between maturation and ageing can be made. Short term treatment with cortisol acetate induced a rise in ultimate load and tensile strength, whereas long term treatment resulted in a decrease in ultimate load and skin thickness and an Increase in tensil...

109 citations


Journal ArticleDOI
TL;DR: In this paper, the influence of microstructure on the strength, fracture toughness and low cycle fatigue behavior of 17-4 PH stainless steel has been examined, and it was shown that fracture toughness increased with increasing strength level and humidity but were not a function of toughness level.
Abstract: The influence of microstructure on the strength, fracture toughness and low cycle fatigue behavior of 17-4 PH stainless steel has been examined. Aging hardening involves initial formation of coherent copper-rich clusters which transform to incoherent fee ∈-copper precipitates upon further aging. The changes in strength level and strain hardening rates observed during aging are consistent with previously suggested models for precipitation hardening based on differing elastic moduli. The fracture toughness and fatigue crack growth rates were shown to be a function of microstructure and environment. At equivalent strength levels overaging resulted in a higher fracture toughness than did underaging. The fatigue crack growth rates increased with increasing strength level and humidity but were not a function of toughness level. Attempts to correlate the fatigue crack growth rates with monotonie tensile properties were unsuccessful. However when final failure obeyed a critical strain criteria, the fracture toughness behavior could be reasonably described and related to preferential void nucleation and growth at δ-ferrite-matrix interfaces.

108 citations


Journal ArticleDOI
01 Apr 1974-Carbon
TL;DR: In this paper, it was shown that the elastic strain energy due to shear stresses in misoriented crystallites is sufficient to fracture the hexagonal planes in such crystallites when the applied tensile stress is in the range of observed ultimate tensile strengths of carbon fibres.

107 citations


Journal ArticleDOI
TL;DR: A new kind of acetal fiber has been discovered which has a tensile strength of 1.7 GPa (250,000 psi) and an elastic modulus of 35 GPa(5 × 106 psi) as mentioned in this paper.
Abstract: A new kind of acetal fiber has been discovered which has a tensile strength of 1.7 GPa (250,000 psi) and an elastic modulus of 35 GPa (5 × 106 psi). This fiber is produced by a special two-stage drawing process in the solid state which requires careful control of deformation rate and temperature. Previously known drawn fibers are reported to consist of folded-chain blocks joined by a limited number of tie-molecules. It is hypothesized that the second stage of the novel drawing process eliminates the lamella (block) surfaces which act as strength-limiting stress concentrators. A new type of fiber is created in which any remaining chain-folds are distributed as defects in a continuous crystal matrix. It is the continuity of the crystal matrix which is believed responsible for the remarkable properties of the fiber.



Journal ArticleDOI
TL;DR: In this paper, a stress-strain relationship includes two basic material constraints: bulk modulus and Poisson's ratio, which are considered functions of invariants of stresses; the appropriate functions are derived from test results.
Abstract: Specimens of paste, mortar, and concrete were tested to failure when subjected to different amounts of lateral confining pressure. Two distinct modes of behavior were observed. Under low confining pressures, failure was accompanied by splitting, by large axial compressive and lateral tensile strains, significant internal microcracking and by a reduction in pulse velocity. For high lateral pressures, the axial strains at failure were smaller, lateral strains were compressive, and very little cracking and reduction in pulse velocity occurred at failure. This transition in behavior is explained in terms of the relative values of maximum deviatoric and hydrostatic components of failure stress, and the strengths of porous matrix and sliding interfaces. A stress-strain relationship includes two basic material constraints: bulk modulus and Poisson’s ratio. These material properties are considered functions of invariants of stresses; the appropriate functions are derived from test results.

Journal ArticleDOI
TL;DR: In this article, stress-strain curves of composites of styrene-acrylonitrile (SAN) and various fillers such as glass beads, carbospheres, CaCO3, asbestos and glass fibers are reported.
Abstract: Stress-strain curves of composites of styrene-acrylonitrile (SAN) and various fillers such as glass beads, carbospheres, CaCO3, asbestos and glass fibers are reported. The influence of the filler shape and the surface treatment on the Young's moduli, ultimate elongation and strength is analysed on the light of the current knowledge of the crazing phenomena. Existing correlations are checked and extended to the fiber composites.

Journal ArticleDOI
TL;DR: In this paper, a theory is presented to predict the flexural tensile strength of concrete reinforced with short, discontinuous steel fibers randomly oriented and uniformly dispersed in a cement-based matrix.

Journal Article
TL;DR: In this article, the double-punch test was used to measure the tensile strength of concrete and the effect of several additional parameters, such as the rate of stressing during the test and the effects of lightweight as well as regular concrete.
Abstract: The tensile strength of concrete is most commonly measured by the indirect split-cylinder test. Recently a new test, the double-punch test, has been proposed. The new test method had undergone preliminary experimental study to determine the testing procedure that would yield the most reliable and consistent results. However, further study was needed. By using the previously recommended procedure, the effect of several additional parameters on the tensile strength was studied. These parameters include the rate of stressing during the test and the effect of lightweight as well as regular concrete. The effects of the molds, machine lubricant, and testing machine are also being studied. Analysis of these results has led to a more thorough understanding and greater applicability of the new tensile test.

Journal ArticleDOI
TL;DR: In this article, the yield-point loads for single-edge notched strips when tensile loading is applied through pins are compared to those for fixed-grip loading, and the percentage drop is larger in plane stress than in plane strain.
Abstract: P lane stress and plane strain yield-point loads have been calculated for single-edge notched strips when tensile loading is applied through pins. These yield-point loads are lower than those for fixed-grip loading, and the percentage drop is larger in plane stress than in plane strain. The calculations were required for assessing various creep and fatigue crack propagation tests. Excellent agreement was found between experimental yield-point loads and the plane stress calculations based on the von Mises yield criterion. However, no such agreement was found when further tests were carried out on doubleedged notched specimens. Possible reasons for this discrepancy are discussed. The plane strain calculations may also be used for the ‘double cantilever bend’ specimen by a simple substitution.

Journal ArticleDOI
TL;DR: In this article, the tensile strength and fracture characteristics of Fe 76 P 16 C 4 Si 2 Al 2, Ni 49 Fe 29 P 14 B 6 Al 2 and Ni 72 P 18 B 7 Al 3 metallic glasses have been investigated from 76 to ∼ 473K.

Journal ArticleDOI
01 Jun 1974-Wear
TL;DR: In this paper, the seizure resistance of several cast aluminium base alloys has been examined using a standard Hohman Wear Tester, and it was shown that a slight increase in the solute content or the hardness of the primary α-phase leads to a considerable increase in seizure resistance.

Journal ArticleDOI
TL;DR: In this article, the ductility and tensile strength of Ni-Fe based alloy glasses prepared by the "roller quenching" technique were investigated and it was suggested that the hot rolling of the alloy during quench is responsible for the brittle behavior.
Abstract: The ductility and tensile strength of NiFe based alloy glasses prepared by the ‘roller quenching’ technique were investigated. These alloy glasses are intrinsically ductile and possess a high tensile strength. However, the mechanical properties of glasses which are predominantly Fe are very susceptible to the quenching conditions, and such glasses tend to be brittle. It is suggested that the hot rolling of the alloy during quenching is responsible for the brittle behavior. Tensile strengths as high as 230 000 psi were obtained for the NiFe based alloy glasses.

Journal Article
TL;DR: In this article, the weakest-link concept has been applied to predict the relationship between specimen volume and load-carrying capacity for Douglas-fir specimens loaded in uniform tension perpendicular-to-grain.
Abstract: The strength of wood in tension perpendicular-to-grain has been studied by several authors and found to depend on specimen geometry In this paper, the weakest-link concept has been applied to predict the relationship between specimen volume and load-carrying capacity for Douglas-fir specimens loaded in uniform tension perpendicular-to-grain The theory allowed the prediction that logarithm of maximum strength should decrease linearly with logarithm of volume Experimental data taken from the literature were used to evaluate the theoretical model and agreement was found to be high (R 2 ≥ 085) Average strength of a unit volume is approximately 460 psi, whereas the predicted strength of a 10- X 10- X 20-inch specimen (2000 inches 3 ) is approximately 100 psi The magnitude of the size effect may depend on the quality of material in the specimens, but certainly any rational development of working stresses for tension perpendicular-to-grain must consider effects of specimen (or structural component) size

Journal ArticleDOI
TL;DR: For idealized true-stress/true-strain curves obeying the Hollomon equation σ=Kpn, where K and n have values typical of real metals, the authors in this paper showed that the true tensile strength is almost independent of n, but the stress at 0·2% plastic strain is strongly dependent on n.
Abstract: Conventional strength and strain-hardening parameters have been derived for idealized true-stress/true-strain curves obeying the Hollomon equation σ=Kpn, where K and n have values typical of real metals. All stress parameters are proportional to the constant K. The true tensile strength is almost independent of n, but the stress at 0·2% plastic strain is strongly dependent on n. The strain-hardening rate dσ/dp is significantly affected by n only when p 0·2. The strain-hardening rate is not easily related to the parameters nσmax, nK or the 0·2% proof-stress/true-tensile-strength ratio. The magnitude of the strain hardening, given by Δσ = (σ2 - σ1), also has a maximum between n=0·1 and 0·3. With these results, assumptions and conclusions in the published literature are discussed and some are shown to be incorrect. It is concluded that for maximum strength and strain hardening in materials obeying the Hollomon equation, large values of K and n values between 0·1 and 0·3 are required.


Journal ArticleDOI
TL;DR: In this paper, the authors investigated the effect of liquids (water, glycerine, ethylene glycol, nitrobenzene, ethyl alcohol, benzaldehyde and n-butyl alcohol) on the tensile strength of Indiana limestone.

Journal ArticleDOI
TL;DR: In this article, the strength reduction factor for glass-, boron-, and graphite-epoxy plates with holes loaded in tension was determined for different layup and stacking sequences.
Abstract: Strain distributions to failure, tensile and compressive strain-concentration factors, and strength-reduction factors were determined for glass-, boron-, and graphite-epoxy plates with holes loaded in tension. Strain gages, photoelastic coatings and moire techniques were used. Ten variations of layup and stacking sequence were studied. The boron-epoxy composite was found to be the stiffest and strongest of the three. The graphite laminate with the highest stress concentration and the most linear strain response exhibited the highest strength-reduction factor. In all cases, the maximum strain at failure on the hole boundary was higher than the ultimate tensile-coupon strain. In general, it was found that, the higher the stress-concentration factor, the higher the strength-reduction factor. Thus, the [0/90/0/90]s layup with a stress-concentration factor of 4.82 had a strength-reduction factor of 3.18. At the other extreme, the most flexible layup [±45/±45]s with the lowest stress-concentration factor of 2.06 had the lowest strength-reduction factor of 1.10. Stacking sequences associated with the tensile interlaminar normal stress or high interlaminar shear stress near the boundary, resulted in laminates 10 to 20 percent weaker than corresponding alternate stacking sequences. Furthermore, it was found that stacking-sequence variations can alter the mode of failure from catastrophic to noncatastrophic.

Journal ArticleDOI
TL;DR: In this article, the fatigue properties of polyamide, polyester, and polyacrylonitrile fibers have been investigated and failure under cyclic loading conditions compared to that caused by simple tensile loading.
Abstract: The fatigue properties of a number of different types of fibers have been investigated and failure under cyclic loading conditions compared to that caused by simple tensile loading. Polyamide, polyester, and polyacrylonitrile fibers have been studied and all have been found to fail by fatigue mechanisms. The loading conditions have been monitored by a fiber fatigue apparatus developed for this purpose and the fracture morphologies inspected by scanning electron microscopy. In all of the cases which are considered in detail, fatigue failure of the fibers has been found to occur when cycling from zero load to a maximum load of about 60% of the tensile strength. Fatigue failure is accompanied by a distinctive fracture morphology, clearly different from the tensile fracture morphology and involving crack propagation along the fiber at a slight angle to its axis, although the mechanism which causes this in the acrylic fiber is probably different from that for the polyamide and polyester fibers.

Journal Article
TL;DR: In this paper, a regular Hveem specimen (4in. diameter by 2 1/2in. height) was water saturated at 122 F (50.0 C) and subjected to repeated pore water pressure.
Abstract: This paper presents the development of new apparatus and procedure for the measurement of stripping susceptibility of asphaltic concrete. In the new method a regular Hveem specimen (4-in. diameter by 2 1/2-in. height (101.6-mm diameter by 63.4-mm height) was water saturated at 122 F (50.0 C.) Then the specimen was subjected to repeated pore water pressure. The effect of the exposure on tensile strength was expressed as retained strength determined with a double punch procedure. The work showed that the method responded to variations in type of aggregate, cleanliness of aggregate, and asphalt content in a direction dictated by experience. Comparative results with the immersion compression test are presented.

Journal ArticleDOI
TL;DR: In this paper, a polyphase alloys based on ordered Zr3Al (Ll2 type) have been deformed in tension at 20 to 600°C and exposed to moist air (300°C), pressurized water and atmospheric pressure steam (400°C).

Journal ArticleDOI
TL;DR: In this article, the effect of fabrication and testing variables on the three point bend testing of glass fiber-reinforced polyester resin composites has been investigated, including the volume fraction of fibres in the composites, the specimen span-to-depth ratio and the overhang of the specimen beyond the outer loading nose.