Showing papers on "Ultimate tensile strength published in 1989"
TL;DR: In this article, the deformation characteristics of ceramic whisker- and particulate-reinforced metal-matrix composites were studied experimentally and numerically with the objective of investigating the dependence of tensile properties on the matrix microstructure and on the size, shape, and distribution of the reinforcement phase.
721 citations
TL;DR: It is shown that tensile and shear bond strengths are highly dependent on the geometry of the test arrangement and the materials involved, and there is a need for the standardization of test procedures for the measurement of bond strengths so that a universally valid comparison between different bonding agents can be performed.
535 citations
TL;DR: It is suggested it is feasible to develop better empirical formulae for the prediction of cortical bone strength than are currently available if a variety of variables is introduced.
341 citations
TL;DR: In this paper, the authors measured the tensile fracture strength of a thin film of the ceramic on a ductile, metal substrate and found that the fracture strength was in the range 3.4-6.7 GPa.
337 citations
01 Jan 1989-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the results of a study on the effects of matrix microstructure and particle distribution on the fracture of an aluminum alloy metal matrix composite containing 20% by volume SiC particulate were presented.
Abstract: This paper presents the results of a study on the effects of matrix microstructure and particle distribution on the fracture of an aluminum alloy metal matrix composite containing 20% by volume SiC particulate. The matrix microstructure was systematically varied by heat treating to either an under- or over-aged condition of equivalent strength, and was characterized using a combination of techniques. Quantitative metallographic techniques were utilized to characterize the material with respect to size, size distribution, and particle clustering, while transmission electron microscopy was utilized to characterize the details of the matrix microstructure in addition to the effects of aging on the character of the particle/matrix interfaces. Fracture experiments were conducted on smooth tensile, notched bend, shortrod toughness, and on specimens designed to permit controlled crack propagation, in an attempt to determine the effects of matrix microstructure and clustered regions on the details of damage accumulation. Large effects of microstructure on the notched properties were obtained with little effect of microstructure on tensile ductility. It is shown that the micromechanisms of fracture are significantly affected by the details of the matrix microstructure, interface character, and degree of clustering in the material. Fracture of the SiC was predominant in the underaged materials, with a preference for failure in the matrix and near the interface in the overaged material. Metallographic and fractographic analyses revealed that clustered regions were preferred sites for damage initiation in both the aging conditions tested, while preliminary results additionally indicate that damage accumulation ahead of a propagating crack also tended to occur in clustered regions.
332 citations
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TL;DR: In this paper, Caprolactam was polymerized in the interlayer spacing of montmorillonite, a clay mineral, yielding a nylon 6-clay hybrid (NCH) 1).
Abstract: ζ-Caprolactam was polymerized in the interlayer spacing of montmorillonite, a clay mineral, yielding a nylon 6-clay hybrid (NCH) 1). X-ray and TEM measurements revealed that each template of the silicate, which is 10 A thick, was dispersed in the nylon 6 matrix and that the repeat unit increased from 12 A in unintercalated material to 21 A in the intercalated material. Thus NCH, is a “polymer based molecular composite” or “nanometer composite”. NCH, when injection-molded, shows excellent properties as compared to nylon 6 in terms of tensile strength, tensile modulus and heat resistance. Heat distortion temperature increased from 65 °c for nylon 6 to 152 °c for NCH, containing 4 wt% (1.6 vol%) of clay mineral.
314 citations
TL;DR: In this article, the influence of different coupling agents, such as poly[methylene(polyphenyl isocyanate)], silanes, and grating on the mechanical properties of composites is discussed.
Abstract: Wood fibers of aspen in the form of chemithermomechanical pulp (CTMP) and Tembec 6816 have been used as reinforcing fillers in different varieties of polystyrene. The tensile strength, elongation, and energy at maximum point, as well as tensile modulus at 0.1% strain is reported. Also revealed is the optimum condition of compression molding. The influence of different coupling agents, such as poly[methylene(polyphenyl isocyanate)], silanes (A-172, A-174, A-1100), and grating on the mechanical properties of composites is discussed. The extent of increase in mechanical properties depends on the weight percentage of fibers, the concentration of coupling agents, and the grafting level (add-on %). Coating followed by an isocyanate treatment appears to be the best treatment. In addition, the isocyanate treatment and grafting are superior to the silane treatment. Experimental results are explained on the basis of possible interactions among cellulose fiber-coupling agent-polymer in the interfacial area.
275 citations
TL;DR: Results show that setting occurs after dissolution of MCPM, as a result of the precipitation of dicalcium phosphate dihydrate (DCPD) in the paste, and the ultimate tensile strength of the hardened cement is proportional to the amount of DCPD formed.
274 citations
TL;DR: Data for load histories involving both tensile and compressive loading indicate lower time to failure than predicted by a simple summation of time-dependent and cycle-dependent damage.
259 citations
TL;DR: In this article, linear low density polyethylene (LLDPE) was reinforced with different wood fibers, aspen chemithermomechanical pulp (bleached and unbleached), and other commerical wood pulps.
Abstract: Linear low density polyethylene (LLDPE) was reinforced with different wood fibers, aspen chemithermomechanical pulp (bleached and unbleached), and other commerical wood pulps. Silane coupling agents A-172, A-174, A-1100, and polymethylene polyphenyl isocyanate were used to improve the bonding between the fiber and matrix. LLDPE filled with pretreated wood fiber produced a significant improvement in tensile strength and modulus. Comparison of tensile and impact properties of wood fiber composites with mica and glass fiber composites shows the potential advantage (in terms of material cost and specific properties) of wood fiber as a reinforcement.
250 citations
TL;DR: Etude sur un polyethylene lineaire et un copolymere ethylene-butene-1, entre 175 o K et 260 o K as discussed by the authors, entre 170 o K and 260 O K
Abstract: Etude sur un polyethylene lineaire et un copolymere ethylene-butene-1, entre 175 o K et 260 o K
TL;DR: Laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased Tensile strength on the opposite side as well.
Abstract: We examined the biostimulating effects of helium-neon laser radiation (HeNe; 632.8 nm), pulsed infrared laser radiation (IR; 904 nm), and the two combined on skin wound healing in New Zealand white rabbits. Seventy-two rabbits received either (1) no exposure, (2) 1.65 J/cm2 HeNe, (3) 8.25 J/cm2 pulsed IR, or (4) both HeNe and IR together to one of two dorsal full-thickness skin wounds, daily, for 21 days. Wound areas were measured photographically at periodic intervals. Tissue samples were analyzed for tensile strength, and histology was done to measure epidermal thickness and cross-sectional collagen area. Significant differences were found in the tensile strength of all laser-treated groups (both the irradiated and nonirradiated lesion) compared to group 1. No differences were found in the rate of wound healing or collagen area. Epidermal growth was greater in the HeNe-lased area compared to unexposed tissue, but the difference was not significant. Thus, laser irradiation at 632.8 nm and 904 nm alone or in combination increased tensile strength during wound healing and may have released tissue factors into the systemic circulation that increased tensile strength on the opposite side as well.
TL;DR: A brief review of early lightguide work can be found in this article, where the authors assess advances since the mid-1970s and note important work on strength distributions and procedures for improving strength.
Abstract: After a brief review of early lightguide work, the authors assess advances since the mid-1970s. They note important work on strength distributions and procedures for improving strength. This is followed by a discussion of long-length strength, prooftesting and splicing. Flaw character is studied along with strength degradation, fatigue limits, aging and fatigue, and hermetic coatings. >
TL;DR: In this paper, the effect of modifiers of polypropylene (PP) on the properties of the composites was evaluated and MPP was also evaluated as a compatibilizer for the PP-RGP composites, and a tremendous improvement of tensile strength was achieved with MPP addition of only 2.5%.
Abstract: Composites of polypropylene (PP) or maleic-anhydride-modified polypropylene (MPP) with refiner ground pulp (RGP) were prepared under various kneading conditions (mixing temperature, rate of rotation, and mixing time) and evaluated for their tensile strength (σmax), break elongation (ϵmax), and Young's modulus (E). Particularly, for the rate of rotation, fiber length distribution and its fibrillation were investigated in connection with mechanical properties of the composites. Also evaluated in this study was the effect of modifiers of PP on the properties. Modified PP that can be grafted or can have affinity to RGP was proved to improve the tensile strength of the molded composites as the RGP content increases, while the strength was decreased for PP–RGP composite without a modifier. MPP was also evaluated as a compatibilizer for the PP–RGP composites, and a tremendous improvement of tensile strength was achieved with MPP addition of only 2.5%, indicating that MPP can act as a compatibilizer in its system. These lines of evidence is interpreted to be caused from the improvement of the adhesion between RGP and PP through localizing MPP at the interface of these two components.
TL;DR: The results suggest that the early (one-hour) mechanical properties of the hybrid material exceed those of glass ionomer, and surface crazing, a documented problem with some glass ionomers when they become desiccated, is alleviated with this hybrid formulation.
TL;DR: In this paper, the effect of phosphorus and silicon on the formation of retained austenite has been investigated in a low-carbon steel cold rolled, intercritically annealed, and isothermally held in a temperature range of bainitic transformation followed by air cooling.
Abstract: The effect of phosphorus and silicon on the formation of retained austenite has been investigated in a low-carbon steel cold rolled, intercritically annealed, and isothermally held in a temperature range of bainitic transformation followed by air cooling. The steel sheet containing phosphorus after final heat-treatment consisted of ferrite, retained austenite, and bainite or martensite. Phosphorus, especially in the presence of silicon, in steel was useful to assist the formation of retained austenite. Mechanical properties, such as tensile strength, uniform elongation, and the combination of tensile strength/ductility, were improved when phosphorus was increased up to 0.07 pct in 0.5 pct Si steel. This could be attributed to the strain-induced transformation of retained austenite during tensile deformation. Furthermore, two types of retained austenite were observed in P-containing steel. One is larger than about 1 μm in size and usually exists adjacent to bainite; the other one is of submicron size and usually exists in a ferrite matrix. High phosphorus content promotes the formation of stable (small size) austenites which are considered to be stabilized mainly by their small size effect and have a different formation mechanism from the coarser retained austenite in the lower P steels. The retained austenites of submicron size showed mechanical stability even after 10 pct deformation, suggesting that these small austenites have little effect on ductility. The 0.07 pct P-0.5 pct Si-1.5 pct Mn-0.12 pct C steel showed a high strength of 730 MPa and a total elongation of 36 pct.
TL;DR: In this paper, the influence of shape and size distribution of defects on material strength is investigated and a very general analytical expression for the tensile strength decrease with size is obtained and then confirmed by experimental evidence.
TL;DR: In this paper, Young's moduli were estimated for two SiC-based and three oxide ceramic fibers for temperatures from 25° to 1400°C, and they were found to be stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures.
Abstract: Tensile strengths were measured and Young's moduli were estimated for two SiC-based and three oxide ceramic fibers for temperatures from 25° to 1400°C. The SiC-based fibers were stronger but less stiff than the oxide fibers at room temperature and retained more of both strength and stiffness to high temperatures. High-temperature strengths of the SiC-based fibers were limited by internal void formation and oxidation; those of the oxide fibers were limited by softening of an intergranular glassy phase.
TL;DR: In this paper, the mechanical properties of polypropylene (PP) filled with wood flour were studied and different surface treatments of the fiber were carried out to improve adhesion at the interface.
Abstract: Mechanical properties of polypropylene (PP) filled with wood flour was studied. To improve adhesion at the interface, different surface treatments of the fiber were carried out. Polymethylene polyphenylisocyanate (PMPPIC) and silane coupling agents (silane A-172, A-174, and A-1100) were used to pretreat the fiber before it was introduced into the polymer. Increase in tensile strength, with fiber concentration, was found in PP filled with PMPPIC pretreated wood flour. Elastic modulus was unaffected by fiber treatment. Izod-impact strength decreased with increased filler level in the composite.
TL;DR: In this paper, the Weibull model was used to determine the tensile strength of high strength carbon fibres and their gauge length dependence by means of a linear logarithmic dependence on gauge length.
Abstract: Generally, to determine the fibre-matrix interfacial properties in fibre reinforced plastics, it is necessary to know the tensile strength of the fibre at very short lengths, for which direct measurements are not possible. Accordingly, in this study, the determination of the tensile strength of high strength carbon fibres and their gauge length dependence are analysed by means of the Weibull model. The influence of the estimator chosen and of the sample size on the calculated value of the tensile strength of the fibre are first determined. Secondly, the accuracy of the three- and the two-parameter Weibull distributions is examined. Finally, it is shown that the most appropriate extrapolation at short length is performed by means of a linear logarithmic dependence on gauge length of the tensile strength. This method seems to be valid for untreated as well as for surface-treated high strength carbon fibres.
15 Nov 1989-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the role of thermal stresses on the mechanical integrity of oxide layers is discussed, and it is shown that the processes of cracking and spalling of oxides differ depending on the stress state (tensile or compressive) and on the relative strengths of oxide and oxide-metal interface.
Abstract: This paper discusses the role of thermal stresses on the mechanical integrity of oxide layers. It is shown that the processes of cracking and spalling of oxides differ depending on the stress state (tensile or compressive) and on the relative strengths of oxide and oxide-metal interface. Under tensile conditions, through-thickness cracks develop from pre-existing defects in the oxide layer and these generate shear stresses along the interface which may result in decohesion. Under compressive conditions, spallation may result either from the growth of a tensile, wedge crack along the interface or by buckling and cracking of the oxide layer. Initial results of a finite element analysis are provided for both mechanisms.
TL;DR: In this paper, a new class of injection molded long fiber composites based on PP and PBT matrices were analyzed and it was concluded that higher mechanical performances of the long fiber reinforced thermoplastics will be attained by the injection molding process to further reduce fiber breakage.
Abstract: This paper deals with the mechanical performances of a new class of injection molded long fiber composites based on PP and PBT matrices. Effects of material parameters such as fiber concentration, breakage, orientation, and matrix composition are analyzed. The critical fiber length, l, of the PP long fiber composite, evaluated from the pull-out length of the tensile fracture surface, was found to be much higher than those previously reported. Tensile strength calculated from the measured ll and fiber length distribution in the molded samples was found to be in agreement with the measured values. From this work it is concluded that higher mechanical performances of the long fiber reinforced thermoplastics will be attained by the injection molding process to further reduce fiber breakage.
TL;DR: The ultimate tensile failure load, stiffness, and energy-absorbing capacity at failure were found to increase with increasing loading rates for both the AL and LF, and the distractions at failure did not indicate this tendency.
Abstract: This study was undertaken to investigate the dynamic response of human cervical spine ligaments. Uniaxial tensile failure tests were conducted on anterior longitudinal ligament (AL) and ligamentum flavum (LF) structures. These ligaments were tested under in situ conditions by transecting all the elements except the one (AL or LF) under study. A fixture was designed to properly align the specimen to induce a uniaxial mode of loading. A six-axis load cell was placed at the distal end of the specimen. The proximal end of the specimen was attached to the piston of a specially designed electrohydraulic testing device. The biomechanical properties of the ligaments were determined at four different loading rates of 8.89, 25.0, 250.0 and 2500 mm/sec. The mechanical response indicated nonlinear and sigmoidal characteristics. The ultimate tensile failure load, stiffness, and energy-absorbing capacity at failure were found to increase with increasing loading rates for both the AL and LF. However, the distractions at failure did not indicate this tendency. While the ultimate tensile force and ultimate energy-absorbing capacity varied nonlinearly with the logarithm of the loading rate, the stiffness varied linearly.
TL;DR: In this article, it was found that the major controlling factors in the peel strength are the thickness, Young's modulus, the yield strength, the strain hardening coefficient of the film, and the compliance of the substrate as well as the interface adhesion strength.
Abstract: —Mechanical effects in the peel strength of a thin film have been studied both experimentally and theoretically. It has been found that the adhesion strength measured by the peel test is a practical adhesion (an engineering strength per unit width) and does not represent the true interface adhesion strength. The measured value may represent a multiplication of the true interface adhesion and other work expended in the plastic deformation of the thin film. The contribution of the latter to the peel strength is found to be, sometimes, of the order of 100 times higher than the former. It is found that the major controlling factors in the peel strength are the thickness, Young's modulus, the yield strength, the strain hardening coefficient of the film, and the compliance of the substrate as well as the interface adhesion strength. Even though the true interface adhesion strength is the same, a higher peel strength is obtained if the film is thinner or more ductile under the test conditions reported in this pa...
TL;DR: In this article, the first time synthesis of high density and high mechanical strength polyacetylene films has been reported, which is comparable to those of well-known engineering plastics such as Kevlar (132 and 3.9 GPa, respectively).
TL;DR: In this article, an experimental study of unidirectional bamboo-epoxy laminates of varying laminae number was performed, in which tensile, compressive, flexural and interlaminar shear properties were evaluated.
Abstract: Bamboo reinforced epoxy possesses reasonably good properties to waarrant its use as a structural material, and is fabricated by utilizing bamboo, an abundant material resource, in the technology of fibre composites. Literature on bamboo-plastics composites is rare. This work is an experimental study of unidirectional bamboo-epoxy laminates of varying laminae number, in which tensile, compressive, flexural and interlaminar shear properties are evaluated. Further, the disposition of bamboo fibre, the parenchymatous tissue, and the resin matrix under different loading conditions are examined. Our results show that the specific strength and specific modulus of bamboo-epoxy laminates are adequate, the former being 3 to 4 times that of mild steel. Its mechanical properties are generally comparable to those of ordinary glass-fibre composites. The fracture behaviour of bamboo-epoxy under different loading conditions were observed using both acoustic emission techniques and scanning electron microscopy. The fracture mode varied with load, the fracture mechanism being similar to glass and carbon reinforced composites. Microstructural analyses revealed that natural bamboo is eligibly a fibre composite in itself; its inclusion in a plastic matrix will help solve the problems of cracking due to desiccation and bioerosion caused by insect pests. Furthermore, the thickness and shape of the composite can be tailored during fabrication to meet specific requirements, thereby enabling a wide spectrum of applications.
TL;DR: In this article, the authors studied the in-plane tensile and compressive stresses of symmetrical multilayer films and found that the film that is stressed in tension in the early stage of sintering is most susceptible to fracture.
Abstract: Sintering of symmetrical multilayer films has been studied theoretically and experimentally. Experiments were conducted on ceramic/metal/ceramic and glass/metal/glass films. The sintering rate of free films was compared to the sintering rate of multilayers. The origin of processing flaws was examined. The following results were obtained: (1) Differential sintering rates of the components in the multilayer give rise to in-plane tensile and compressive stresses. The film that is stressed in tension in the early stage of sintering is most susceptible to fracture. Experiments with ceramic/metal/ceramic multilayer are in agreement with this prediction. (2) A theoretical prediction that the glass/metal/glass multilayer will not develop defects because of a high value of the shear relaxation factor in glass is confirmed by experiments. (3) The likelihood of developing a tensile stress in the multilayer depends only on geometry, the green density, and the ratio of the intrinsic sintering pressures. (4) The in-plane shrinkage of the multilayer depends on the difference in the free-sintering rates and the shear relaxation factors, and is reasonably well predicted by the analysis. (5) We have evidence that the metal layer deforms plastically when it is placed in tension by differential sintering.
TL;DR: In this article, the authors used transmisssion electron microscopy to detect and analyse the nature and evolution of interfacial compounds as a function of copper oxidation and bonding time Chemical reactions lead to the formation of the binary oxide CuAlO2 and the reversibility of chemical reactions appear to be very dependent on the amount of oxygen present in the system.
Abstract: Bonding between copper and alumina can be obtained by the “solid state bonding” process and the “liquid phase bonding” process The strength of interfaces has been tested mechanically using shear tests, tensile tests and fracture toughness tests The effects of bonding parameters on bond strength have been studied Observations by transmisssion electron microscopy have been performed to detect and analyse the nature and evolution of interfacial compounds as a function of copper oxidation and bonding time Chemical reactions lead to the formation of the binary oxide CuAlO2 The stability of this compound and the reversibility of chemical reactions appear to be very dependent on the amount of oxygen present in the system
TL;DR: In this article, a cohesive crack model is proposed to describe the size effects of fracture mechanics, i.e. the transition from ductile to brittle structure behaviour, by increasing the size scale and keeping the geometric shape unchanged.