Showing papers on "Ultimate tensile strength published in 1973"
TL;DR: In this paper, a sliding scale of roughness is proposed for estimating the shear strength of rough joints, and 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.
1,168 citations
TL;DR: Theories of the biaxial tensile properties of yarns and the shear-deformation properties of plain-weave fabrics are presented in a general form, a simplified stereo-model of the structure of plain weave fabrics being used throughout these theories as discussed by the authors.
Abstract: Theories of the biaxial tensile properties, the uniaxial tensile properties, and the shear-deformation properties of plain-weave fabrics are presented in a general form, a simplified stereo-model of the structure of plain-weave fabrics being used throughout these theories. In the first part of this series, the biaxial tensile-deformation theory is presented with the aid of the model, and the forces required to stretch the fabric along the warp and weft directions at the same time are theoretically calculated from the properties of yarns and from the structure of the fabrics. In this biaxial theory, both warp and weft yarns are assumed to be perfectly flexible, and the forces caused by yarn-bending are ignored. The compressibility of the yarn under the action of a lateral compressive force is also introduced into the theory, and it is shown that the compressive properties of yarns have a great influence on the tensile properties of the fabrics.
387 citations
TL;DR: In this article, the authors investigated the compression yield behavior of PMMA over a wide range of experimental conditions which cannot be reached in tensile tests owing to the brittle nature of the material.
Abstract: The compression yield behaviour of PMMA has been investigated, here, over a wide range of experimental conditions which cannot be reached in tensile tests owing to the brittle nature of the material. The plot of the ratio of the compression yield stress to absolute temperature, as a function of the logarithm of the strain-rate, gives a set of parallel curves which can be accurately superimposed by shifting along a slanting straight line. A master curve is built from which the yield behaviour may be predicted for any state of stress, or value of temperature and strain-rate in the glassy range, using Bauwens' yield criterion.
219 citations
TL;DR: In this article, aqueous solutions of poly(vinyl alcohol) were submitted to varying doses of electron beam irradiation and the molecular weight between crosslinks, Mc, was calculated as a function of radiation dose, initial polymer concentration, and temperature.
Abstract: Aqueous solutions of poly(vinyl alcohol) were submitted to varying doses of electron beam irradiation. By modification of the classical Flory-Huggins equations appropriate to the initial state of solution of the polymer, the molecular weight between crosslinks, Mc, was calculated as a function of radiation dose, initial polymer concentration, and temperature. Following crosslinking in the solution state, crystallization was induced by dehydrating the network at temperatures above 90°C. Following dehydration, the polymer network was reequilibrated with water and its tensile properties compared with identically prepared hydrogels not subjected to crystallization by dehydration. Greatly enhanced values of ultimate tensile strength and resistance to tear result from the treatment producing crystallization, compared with those of the crosslinked but not previously dehydrated gels.
147 citations
01 Mar 1973
TL;DR: In this article, the coupled tensile and compressive volume expansion predictions of elementary perfect plasticity and more complex forms of workhardening plasticity theory, including a possible key role of the theoretical strength under triaxial tension, are described briefly and pictorially.
Abstract: Appreciable differences have been reported recently between tensile and compressive yield strengths (SD or strength-differential effect) in martensitic steels and other alloys, as well as in plastics. Data on plastic volume changes are not yet available for the steels, but a volumeexpansion in both tensile and compressive deformation accompanies the SD effect in plastics and in granular media. In this paper, the coupled SD-volume expansion predictions of elementary perfect plasticity and more complex forms of work-hardening plasticity theory, including a possible key role of the theoretical strength under triaxial tension, are described briefly and pictorially. They then are compared with available data to provide some estimates of the likely successes and failures of the approach. An attempt is made to sharpen the distinction between true and apparent SD, and to suggest several critical experiments.
130 citations
TL;DR: The effects of stress and strain history on the mechanical properties of highimpact polystyrene and PPOR resin have been studied in a number of different tests, including repeated creep testing of individual specimens and repeated tensile tests at constant strain-rate upon individual specimens as discussed by the authors.
Abstract: The effects of stress-and strain-history upon the mechanical properties of HIPS (highimpact polystyrene) and of blends containing HIPS and PPOR resin have been studied in a number of different tests, including repeated creep testing of individual specimens and repeated tensile tests at constant strain-rate upon individual specimens The results show that craze formation increases volume and lowers Young's modulus in specimens subjected to tensile strain, and that strained specimens recover only slowly towards the properties of the unstrained material Recovery is accelerated by heating, or by immersion in alcohols A given initial strain produces a greater reduction in modulus in HIPS, which deforms almost entirely by crazing, than in HIPS/PPO blends, which deform by a combination of crazing and shear band formation The properties of strained specimens are dominated by the distinctive non-linear mechanical behaviour of crazes, and the problems of constructing models to represent this behaviour are discussed
129 citations
TL;DR: In this paper, the substructure developed during the slow tensile deformation of Type 316 stainless steel at temperatures between 21° and 816°C has been investigated by transmission electron microscopy.
128 citations
TL;DR: In this paper, the authors investigated the effect of porosity on the strength of portland cement pastes and found that porosity was the most important factor in the strength and porosity is the linear relation between strength and log porosity.
Abstract: The goal of the present investigation was (1) to achieve very high strengths in materials which are basically cement pastes and (2) to contribute to an understanding of the factors involved in generating strength in such materials. Unusually high strength materials were produced by simultaneous heating and pressing, and intermediate strengths were achieved by applying high pressures at room temperature to portland cement pastes. The strengths of materials prepared by these relatively mild hot-pressing conditions, approximately 250 deg C and 50,000 psi, were as high as 95,000 psi (compressive) and 9,250 psi (indirect tensile). The strengths obtained are higher than those characteristic of most dense microcrystalline rocks and higher by more than an order of magnitude than the strengths obtained on reference simples of the same cements prepared as normal pastes. The linear relation observed between strength and log porosity is consistent with observations of others for ceramic materials, which, however, have not been described specifically by the equation presented in this report. On the basis of the present results, of the factors affecting strength, porosity appears to be by far the most important.
116 citations
TL;DR: It would appear that the physical properties of the nonprecious alloys, Jel-Span and Ultratek, represent a significant improvement which could be of potential clinical importance to the success of porcelain-fused-to-metal restorations.
Abstract: The physical properties of two representative nonprecious alloys, Jel-Span and Ultratek, were determined and compared to those of a control gold-based alloy Ceramco "O". The values for hardness, rigidity, resistance to permanent deformation, sag resistance, and bond strength to porcelain of the nonprecious alloys were significantly greater than those of the gold-based alloy. The nonpercious alloys differed from each other in that Jel-Span (a nickel-chromium-cobalt-palladium alloy) had higher hardness and yield strength values, while Ultratek (a nickelchromium alloy) had a higher ultimate tensile strength, modulus of elasticity, and per cent elongation. In general, it would appear that the physical properties of the nonprecious alloys, Jel-Span and Ultratek, represent a significant improvement which could be of potential clinical importance to the success of porcelain-fused-to-metal restorations.
115 citations
TL;DR: In this article, the tensile strength of dry Douglas-fir was measured through rapid constant deformation rate tests at temperatures from 25 to 288°C, at initial thermoequilibrium and after 2 h of heating.
Abstract: Compressive and tensile strength of dry Douglas-fir was measured through rapid constant deformation rate tests at temperatures from 25 to 288°C, at initial thermoequilibrium and after 2 h of heating. The tensile strength decreased slowly with increasing temperatures to 175°C. Above 175°C, the tensile strength reduces rapidly. This is attributed to alteration of the cellulosic fraction of wood. The compressive strength decreases more uniformly with temperatures increasing to 288°C due to changes occurring in all three basic wood components with change in temperature. A first-order reaction equation for bond rupture/formation was adopted to describe the response. Including only terms for bond rupture resulted in good correlation to the observed strength response at reaching thermoequilibrium.
104 citations
TL;DR: In this article, the yield tensile strength, elongation at break, and modulus of melt blends of low-density polyethylene, high density polyethylenes, and polypropylene have been studied over the entire ternary composition range.
Abstract: As part of a study on reuse of plastics as blends, the yield tensile strength, elongation at break, and the modulus of melt blends of low-density polyethylene, high-density polyethylene, and polypropylene have been studied over the entire ternary composition range. The modulus and strength are nearly monotonic functions of blend composition. The contribution of the pure components to these properties is roughly additive. The elongation at break is a more complex function of composition in that minima are observed near the center of the triangular composition diagram and on each of the three binary legs. The response is nearly symmetrical along two of the binary legs but is skewed toward high-density polyethylene for blends of high- and low-density polyethylene. The deterioration of elongation produced by blending is much less severe for polyolefins than observed for other blend systems. This, combined with the observed additivity of strength, make polyolefin blends mechanically superior to blends of other plastics found in wastes. This fact is interpreted in terms of compatibility and amorphous phase interactions which are likely for polyolefins. Modification of polyolefin blends by addition of a rubbery copolymer of ethylene and propylene produced large improvements in elongation at break for some compositions.
Patent•
17 Oct 1973TL;DR: In this article, a sodium-sulfur storage battery having as part of its sulfur electrode a porous current collector formed of knitted or woven carbon or graphite yarn of high elastic modulus and tensile strength is described.
Abstract: A sodium-sulfur storage battery having as part of its sulfur electrode a porous current collector formed of knitted or woven carbon or graphite yarn of high elastic modulus and tensile strength so as to yield greater mobility of sodium polysulfide (Na2Sx) within the current collector Also, highly improved current collecting function is attained by virtue of use of knitted or woven yarn, and excellent corrosion resistance and high mechanical strength is attained by virtue of the use of carbon yarn of high elastic modulus and tensile strength, resulting in a storage battery having excellent discharge performance and durability
TL;DR: In this paper, it was shown that the hard-segment domains undergo continuous "restructuration" under stress, especially at elevated temperatures, leading, in some cases, to extensive stress relaxation but results in highly oriented samples which have extremely high maximum tensile strengths.
Abstract: Wide- and small-angle X-ray diffraction and differential scanning calorimetry have been used to gain some understanding of the extent of domain formation in polyurethans of varying urethan content. The process by which these hard domains and the rubbery polyester (or polyether) chains orient or crystallize upon stretching has been examined. It is shown that the hard-segment domains undergo continuous “restructuration” under stress, especially at elevated temperatures. This leads, in some cases, to extensive stress relaxation but results in highly oriented samples which have extremely high maximum tensile strengths.
TL;DR: In this paper, the authors investigated the mechanical properties of glass-fiber-reinforced epoxy plates subjected to high rates of strain on a specially designed impact-loading machine propelled by explosives.
Abstract: The object of this investigation is to establish experimentally the mechanical properties, and the mode of failure of glass-fiber-reinforced epoxy plates subjected to high rates of strain (30,000 in./in./min), in the direction of the fibers, on a specially designed impact-loading machine propelled by explosives. The results are correlated with those obtained by testing glass-fiber-reinforced epoxy plates subjected to various low rates of strain (0.0265 in./in./min, 0.66 in./in./min and 26.5 in./in./min).
01 Dec 1973
TL;DR: In this paper, the tensile strength of isotropic rocks is measured by loading discs and rings along their diameter, and the finite element method is used to correlate tensile stress, for which tensile failure is assumed to occur in each test, with the orientation of the axes of anisotropy.
Abstract: The tensile strength of rock materials is a parameter relevant to many rock mechanics applications. Rocks are often anisotropic in nature. Therefore, it is of interest to investigate suitable experimental methods for tensile testing to be used with these rocks. An attempt is made in this paper to see if the indirect methods adopted for testing isotropic rocks can be applied. Two rock types with transversely isotropic behavior are tested by loading discs and rings along their diameter. The finite element method is used in order to correlate the tensile stress, for which tensile failure is assumed to occur in each test, with the orientation of the axes of anisotropy. It is shown that the experimental results can be appropriately explained by this method and a parameter be defined which allows one to describe the law of variation of tensile strength with the anisotropy of deformability.
01 Jul 1973
TL;DR: In this article, the authors compared tensile strain hold and compressive strain hold periods for cast Rene 80 at 1600°F and found that the predictive equations for high-temperature fatigue give good agreement with experiments in which the hold times are equal.
Abstract: Strain-time programs involving continuous cycling, equal hold times in tension and compression, tensile strain hold periods, and compressive strain hold periods are compared for cast Rene 80 at 1600°F. It was found that the predictive equations for high-temperature fatigue give good agreement with experiments in which the hold times are equal. Contrary to expectation, however, tensile strain hold experiments gave longer liver than predicted, wile compressive strain hold period experiments were shorter than the predictions. Concurrently, the hysteresis loops from these two sets of experiments exhibited pronounced and opposite mean stresses, the tensile strain hold tests showing a compressive mean stress shift. These shifts were explainable in terms of the times spent in tensile and compressive loading, and could account qualitatively for the observed life behavior.
TL;DR: In this paper, two postulates on the strength of notched laminated composites are compared to experimental data, and the first concerns the use of the fracture strength of angle ply composites to estimate the fractur...
Abstract: Two postulates on the strength of notched laminated composites are compared to experimental data. The first concerns the use of the fracture strength of angle ply composites to estimate the fractur...
01 Apr 1973
TL;DR: In this paper, an investigation was carried out to determine the metallurgical properties of Al-Zn-Mg and AlZnMg-Cu alloy products processed according to newly developed Final Thermomechanical Treatments (FTMT) of T-AHA type.
Abstract: An investigation was carried out to determine the metallurgical properties of Al-Zn-Mg and Al-Zn-Mg-Cu alloy products processed according to newly developed Final Thermomechanical Treatments (FTMT) of T-AHA type. The results show that these cycles can be utilized to produce wrought products of high purity Al-Zn-Mg(-Cu) alloys characterized by equivalent toughness and ductility and much higher strength than conventionally processed commercial purity materials. Based on transmission electron microscopy studies, it was found that such improved behavior of FTMT material is attributable to the superposition of hardening effects, from aging precipitation and from dislocations. Preliminary stress-corrosion and fatigue tests indicate that these properties are not substantially influenced by T-AHA thermomechanical process. Further work is needed in this area, in order to better understand the directions to follow for developing better alloys.
TL;DR: In this paper, the results of an investigation which analytically relates the fiber/matrix nonlinearities to the post yielding behavior of symmetric laminates made from unidirectional plies are presented.
Abstract: This paper and a subsequent one will present the results of an investiga tion which analytically relates the fiber/matrix nonlinearities to the post- yielding behavior of symmetric laminates made from unidirectional plies. This first paper is primarily concerned with the behavior of the single ply and the means for anticipating its response within a laminate. Boron and carbon/epoxies are considered along with a metal matrix composite. The qualitative features of the response of these unidirectional materials to normal, shear, and combined loads are discussed. The analysis (based on triangular finite element idealizations of regularly-spaced inclusion arrays) anticipates the level of nonlinearity that has been observed in composite shear and transverse tensile tests. Also, it reveals a nonlinear coupling that may exist between the combined shear and normal stress response.
TL;DR: In this article, the effect of microstructure and porosity on the performance of hot-pressing in portland cement pastes is discussed, and high pressure techniques are compared with other methods of strength generation.
TL;DR: In this article, a mathematical solution is derived which permits the computation of critical load, deflection and stresses for eccentrically loaded slender prismatic compression members made of materials that have compressive strength but no tensile strength.
Abstract: A mathematical solution is derived which permits the computation of critical load, deflection and stresses for eccentrically loaded slender prismatic compression members made of materials that have compressive strength but no tensile strength. A graphical presentation of the solution facilitates its applicaiton. In an example of application, the solution is used to compute the strength of masonry walls which were tested by the Structural Clay Products Institute. Even though there are limitations to our ability of predicting the behavior of a complex material such as masonry by a mathematical solution based on a simplified model, there is good agreement between computed and measured strength.
TL;DR: In this paper, the authors present a method for measuring the maximum and minimum strength of a sand at different densities in a laboratory environment, by performing a pose test on the sand at relative densities aBOVE zero.
Abstract: THE PEAK STRENGTHS OF SAND IN SYMMETRIC STRAIN(FOR EXAMPLE, TRIAXIAL COMPRESSION) AND PLANE STRAIN CONVERGE AT VERY LOOSE DENSITIES TOWARDS THE COMMON ULTIMATE STRENGTH.BY DIVIDING THE PEAK STRENGTHS BY THE CONSTANT ULTIMATE STRENGTH, A SET OF DIMENSIONLESS CURVES IS OBTAINED WHICH REPRESENT THE EXTRA STRENGTH THAT CAN BE MOBILIZED IN SAND AT RELATIVE DENSITIES ABOVE ZERO.FOR THE RANGE OF ULTIMATE STRENGTHS NORMALLY ENCOUNTERED IN NATURAL SANDS (AVERAGE ULTIMATE STRENGTH EQUALS 28 TO 36 DEG), COMPUTATIONS SHOW THESE EXTRA STRENGTHS CAN BE REPRESENTED BY SINGLE CURVES OF DENSITY COMPONENTS (IN DEGREES), WHICH CAN BE ADDED TO THE ULTIMATE STRENGTH TO GIVE THE TOTAL DRAINED STRENGTH. THE ULTIMATE STRENGTH CAN BE RELIABLY ESTIMATED BY PERFORMING A STATIC ANGLE OF REPOSE TEST ON THE SAND.THE RECOMMENDED TECHNIQUES FOR MEASURING THE ANGLE OF REPOSE AND THE MAXIMUM/MINIMUM DENSITY OF SAND IN THE LABORATORY ARE DESCRIBED.THE METHOD OF PREDICTING STRENGTHS HAS BEEN COMPARED WITH ACTUAL STRENGTH TESTS PERFORMED ON SEVERAL SANDS OF DIVERSE ORIGINS,AND THE COMPARISONS GENERALLY AGREE TO WITHIN 1 DEG ON THE AVERAGE. FINALLY, TYPICAL COMPUTATIONS ARE PRESENTED TO AID THE PRACTICING ENGINEER IN THE USE OF THE METHOD. /AUTHOR/
TL;DR: In this paper, an axial growth of en-echelon cleavage cracks, inclined at angles smaller than 45°, was observed in feldspar during deformation of a pegmatite having a mineralogy and texture similar to granite.
TL;DR: In this article, it is argued that large, nonlinear shear strains occur at the interfaces for fiber orientations leading to near maximum shear coupling compliances, which allow the initiation of matrix cracks at the free edge, which are ultimately responsible for the premature rupture of the coupon.
Abstract: Strength characterization of the fiber-reinforced laminated composite materials is quite often accomplished through the utilization of the finite-width tension coupon specimen. Recent analytical studies have shown that the state of stress in the vicinity of the free edge of such a laminate is fully three dimensional in nature and may not be predicted by laminated plate theory. Furthermore, experimental results have revealed that while the strength of angle-ply tensile coupons of certain fiber orientations are predicted adequately by laminate strength theories, coupons of other fiber orientations are not. As an explanation of this result, it is argued that large, nonlinear shear strains occur at the interfaces for fiber orientations leading to near maximum shear coupling compliances. Further, these strains allow the initiation of matrix cracks at the free edge, which are ultimately responsible for the premature rupture of the coupon. Experimental evidence which supports these arguments is presented.
Journal Article•
TL;DR: In summary, it can be stated that injection-molded reinforced polyethylene has much superior properties to the nonreinforced P.E. which can be further improved if better adhesion between P. E. matrix and reinforcing fibers can be secured.
Abstract: Properties of injection-molded high-density polyethylene reinforced with carbon fibers were investgiated. With 20% by weight carbon fibers tensile strength of polyethylene was almost doubled. Further increase of volume fraction of fibers did not produce as dramatic results. With 40% by weight carbon fibers, elastic modulus increased one order of magnitude: from 0.225 × 106 psi to 2.48 × 106 psi. This value is close to the value of the elastic modulus of bone, hence the material may substitute for bone where the same stiffness is required. The total strain at fracture was reduced two orders of magnitude, but still stayed comparable to total strain at in bone failures (1–2%).
No appreciable changes were noted in shear strength, impact strength and wear resistance. The work to fracture increased from 0.9 to 2.9 kg cm/cm2 with 40% of carbon fibers.
The most significant improvement of polyethylene with addition of carbon fibers was demonstrated in measurements of viscoelastic properties of the material. Creep characteristics were dramatically improved.
In summary, it can be stated that injection-molded reinforced polyethylene has much superior properties to the nonreinforced P.E. which can be further improved if better adhesion between P.E. matrix and reinforcing fibers can be secured.
TL;DR: In this article, a finite element elastic analysis is made of a skull and the skull is idealized with a doubly curved and arbitrary triangular shell element and the importance of using a composite material through the thickness of the shell was established.
Abstract: : A finite element elastic analysis is made of a skull. Measurements were made of the geometry and thickness of a skull. The skull was then idealized with a doubly curved and arbitrary triangular shell element. Results suggest that the skull is well built for resistance to front loads. The importance of using a composite material through the thickness of the shell was established. On the basis of tensile cracking at maximum elastic stress, loads of 3,500 lbs. and 1,400 lbs. were predicted for the first cracking of the skull due to front and side loading respectively.
01 Mar 1973
TL;DR: In this paper, a theory describing the strain, ultimate strength, and work during uniform strain to ultimate loading of metal-matrix composites deformed in tension parallel to the reinforcement is presented.
Abstract: A theory describing the strain, ultimate strength, and work during uniform strain to ultimate loading of metal-matrix composites deformed in tension parallel to the reinforcement is presented. These quantities may be calculated for composites of arbitrary volume fraction using only the component stress-strain curves. The theory is based on the systematic application of a macroscopic principle commonly used to predict the ultimate strength of ductile monolithic materials—namely, that necking occurs when the load borne by the material is maximized. For brittle reinforcing elements, the results are identical to those of previous workers. For ductile reinforcing elements, necking strains intermediate between those of the components and ultimate strengths increasing smoothly with volume fraction from that of the matrix to that of the reinforcement are predicted. The theory can be used to predict the variation of composite ultimate properties with any parameter of interest. In this paper the variation with volume fraction and yield strength of the matrix are studied, with both exact solutions and useful approximations being derived.
TL;DR: Tensile strength testing after varying periods of implantation showed that of the materials studied, only Dacron maintained its initial knot security and tensile strength, and polyglycolic acid sutures were superior in Tensile strength and markedly superior in knot security as compared to catgut.
Abstract: Changes in tensile strength and knot security of commonly used surgical suture materials during the postoperative period were evaluated by implanting sterile suture loops in the subcutaneous tissue of rats and rabbits. Tensile strength testing after varying periods of implantation showed that of the materials studied, only Dacron maintained its initial knot security and tensile strength. Silk and cotton showed moderate loss of strength even in two weeks. Of the absorbable sutures, polyglycolic acid sutures were superior in tensile strength and markedly superior in knot security as compared to catgut. Both materials showed progressive loss of strength reaching minimal values at about three weeks.