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Stress concentration
About: Stress concentration is a research topic. Over the lifetime, 23250 publications have been published within this topic receiving 422911 citations.
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TL;DR: In this paper, a series of large-scale true triaxial experiments with acoustic emission (AE) monitoring were conducted to characterize the fracture initiation and propagation in a selected deep shale formation.
97 citations
TL;DR: In this article, pre-cracked double torsion specimens of Arkansas Novaculite were deformed at a fast cross-head speed using an Instron deformation machine to obtain stress intensity factor (K I )-crack velocity ( v ) data for stress corrosion in liquid water.
97 citations
TL;DR: In this paper, a continuum theory for non-Newtonian flow of a two-phase composite containing rigid inclusions is presented, which predicts flow suppression by a factor of (1 - V)q, where V is the volume fraction of the rigid inclusion and q depends on the stress exponent and the inclusion shape.
Abstract: A continuum theory for non-Newtonian flow of a two-phase composite containing rigid inclusions is presented. It predicts flow suppression by a factor of (1 - V)q, where V is the volume fraction of the rigid inclusion and q depends on the stress exponent and the inclusion shape. Stress concentrations in the rigid inclusion have also been evaluated. As the stress exponent increases, flow suppression is more pronounced even though stress concentration is less severe. To test this theory, superplastic flow of zirconia/mullite composites, in which zirconia is a soft, non-Newtonian superplastic matrix and mullite is a rigid phase of various size, shape, and amount, is studied. The continuum theory is found to describe the two-phase superplastic flow reasonably well.
96 citations
TL;DR: In this paper, the authors investigated the superplasticity of SiO{sub 2}-doped tetragonal zirconia polycrystal (2.5Y-TZP) by means of tensile testing in a temperature range 1,200--1,500 C.
Abstract: Superplasticity in SiO{sub 2}-doped tetragonal zirconia polycrystal (2.5Y-TZP) is investigated by means of tensile testing in a temperature range 1,200--1,500 C. The grain boundary SiO{sub 2} phase reduces the flow stress and greatly enhances the tensile ductility in TZP. The stress and grain size exponents take a value close to 2 and 3, respectively, in this temperature range, but there is an abrupt change in activation energy at 1,380 C in SiO{sub 2}-doped TZP. The activation energy for superplastic flow above and below this temperature is estimated to be 182 kJ/mol and 635 kJ/mol. The enhancement of superplasticity due to SiO{sub 2}-doping is explained in terms of the accelerated plastic flow in the grain boundary SiO{sub 2} phase to accommodate the stress concentration generated by grain boundary sliding. The elongation to failure in the SiO{sub 2}-doped TZP is phenomenologically described as a function of the Zener-Hollomon parameter. At high temperatures and low strain rates, the cavities tend to align and interlink parallel to the tensile axis, and the huge elongation in excess of several hundred percent is obtained.
96 citations
TL;DR: In this paper, a concept of fracture was developed from experimental data, and the mechanism is one of crack propagation which begins when the local stress at the crack exceeds a minimum value.
Abstract: A concept of fracture is developed from experimental data. Fractures are found to originate at flaws or cracks of finite size, most of which are at the surface. The mechanism is one of crack propagation which begins when the local stress at the crack exceeds a minimum value. The rate of propagation increases with crack growth until a critical stress is reached at the crack tip which coincides with a limiting crack velocity. This limiting condition is identified with the boundary of the mirror surface of the fracture. From calculations to be presented in Part 11, the critical stress is estimated to be several million pounds per square inch.
96 citations