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Tensile testing

About: Tensile testing is a(n) research topic. Over the lifetime, 26587 publication(s) have been published within this topic receiving 448948 citation(s). The topic is also known as: tension strength & Tensile testing.

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Abstract: Necking and failure in a round tensile test specimen is analysed numerically, based on a set of elastic-plastic constitutive relations that account for the nucleation and growth of micro-voids. Final material failure by coalescence of voids, at a value of the void volume fraction in accord with experimental and computational results, is incorporated in this constitutive model via the dependence of the yield condition on the void volume fraction. In the analyses the material has no voids initially; but high voidage develops in the centre of the neck where the hydrostatic tension peaks, leading to the formation of a macroscopic crack as the material stress carrying capacity vanishes. The numerically computed crack is approximately plane in the central part of the neck, but closer to the free surface the crack propagates on a zig-zag path, finally forming the cone of the cup-cone fracture. The onset of macroscopic fracture is found to be associated with a sharp “knee” on the load deformation curve, as is also observed experimentally, and at this point the reduction in cross-sectional area stops.

2,645 citations

Journal ArticleDOI
Abstract: This paper is a review on the tensile properties of natural fiber reinforced polymer composites. Natural fibers have recently become attractive to researchers, engineers and scientists as an alternative reinforcement for fiber reinforced polymer (FRP) composites. Due to their low cost, fairly good mechanical properties, high specific strength, non-abrasive, eco-friendly and bio-degradability characteristics, they are exploited as a replacement for the conventional fiber, such as glass, aramid and carbon. The tensile properties of natural fiber reinforce polymers (both thermoplastics and thermosets) are mainly influenced by the interfacial adhesion between the matrix and the fibers. Several chemical modifications are employed to improve the interfacial matrix–fiber bonding resulting in the enhancement of tensile properties of the composites. In general, the tensile strengths of the natural fiber reinforced polymer composites increase with fiber content, up to a maximum or optimum value, the value will then drop. However, the Young’s modulus of the natural fiber reinforced polymer composites increase with increasing fiber loading. Khoathane et al. [1] found that the tensile strength and Young’s modulus of composites reinforced with bleached hemp fibers increased incredibly with increasing fiber loading. Mathematical modelling was also mentioned. It was discovered that the rule of mixture (ROM) predicted and experimental tensile strength of different natural fibers reinforced HDPE composites were very close to each other. Halpin–Tsai equation was found to be the most effective equation in predicting the Young’s modulus of composites containing different types of natural fibers.

1,473 citations

Journal ArticleDOI
Abstract: An equiatomic CoCrFeMnNi high-entropy alloy, which crystallizes in the face-centered cubic (fcc) crystal structure, was produced by arc melting and drop casting. The drop-cast ingots were homogenized, cold rolled and recrystallized to obtain single-phase microstructures with three different grain sizes in the range 4–160 μm. Quasi-static tensile tests at an engineering strain rate of 10−3 s−1 were then performed at temperatures between 77 and 1073 K. Yield strength, ultimate tensile strength and elongation to fracture all increased with decreasing temperature. During the initial stages of plasticity (up to ∼2% strain), deformation occurs by planar dislocation glide on the normal fcc slip system, {1 1 1}〈1 1 0〉, at all the temperatures and grain sizes investigated. Undissociated 1/2〈1 1 0〉 dislocations were observed, as were numerous stacking faults, which imply the dissociation of several of these dislocations into 1/6〈1 1 2〉 Shockley partials. At later stages (∼20% strain), nanoscale deformation twins were observed after interrupted tests at 77 K, but not in specimens tested at room temperature, where plasticity occurred exclusively by the aforementioned dislocations which organized into cells. Deformation twinning, by continually introducing new interfaces and decreasing the mean free path of dislocations during tensile testing (“dynamic Hall–Petch”), produces a high degree of work hardening and a significant increase in the ultimate tensile strength. This increased work hardening prevents the early onset of necking instability and is a reason for the enhanced ductility observed at 77 K. A second reason is that twinning can provide an additional deformation mode to accommodate plasticity. However, twinning cannot explain the increase in yield strength with decreasing temperature in our high-entropy alloy since it was not observed in the early stages of plastic deformation. Since strong temperature dependencies of yield strength are also seen in binary fcc solid solution alloys, it may be an inherent solute effect, which needs further study.

1,449 citations

Journal ArticleDOI
TL;DR: It has been shown that to obtain reproducible results for the strength of tablets prepared at a given compression force, the tablet must break in such a manner that the tensile stress is the major stress.
Abstract: The strength of lactose tablets has been measured by application of the diametral-compression test. The relative value of tensile, compressive, and shear stresses within the tablet varies, depending on the characteristics of the tablets and the surface providing the applied compression. It has been shown that to obtain reproducible results for the strength of tablets prepared at a given compression force, the tablet must break in such a manner that the tensile stress is the major stress. For a given tablet, this may require the placing of suitable padding material between the tablet and the compressing surfaces. Assessment of the type of failure can be made visually and under the correct conditions, the results expressed as a tensile strength. There are, however, a range of conditions which ensure tensile failure resulting in different values for the tensile strength. These values are characteristic of the tablet and test conditions and are not absolute values of tensile strength.

1,163 citations

Journal ArticleDOI
Abstract: Fine-grained alloys of Mg-3Al-1Zn-0.2Mn in wt.% (AZ31B) were obtained by an equal-channel angular extrusion technique and subsequent annealing at elevated temperatures. Tensile tests were performed at room temperature at a strain rate of 1x10-3 s-1. The alloys exhibited an apparent steady-state deformation region and a large tensile elongation of 47%. The deformed microstructure at an elongation of 2% indicated substantial cross-slip to non-basal planes induced by plastic compatibility stress associated with grain boundaries. The non-basal segment of dislocations was found to consist of 40% of the total dislocation density at a yield anisotropy factor of only 1.1 instead of an expected value of 100 obtained from single-crystal experiments. The deformed microstructure at an elongation of 16% indicated recovered regions within twins as well as untwinned matrices. These results indicate that dynamic recovery can occur in Mg alloys at room temperature.

1,057 citations

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