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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, the statistical pore size characterization by metallography in the framework of Extreme Value Statistics (EVS) is presented and applied to different sets of cast AlSi7Mg specimens.
121 citations
TL;DR: It was concluded that a fatigue mechanism in a pulsatile cardiovascular pressure environment reconciles clinical evidence of acute plaque rupture at seemingly low stress levels, and it could provide a framework for developing strategies to create a biomechanically benign environment which is least conducive to plaque rupture.
120 citations
TL;DR: In this paper, the authors investigated the tensile strain relaxation in AlxGa1−xN layers of different compositions epitaxially grown on GaN/sapphire.
Abstract: Relaxation of tensile strain in AlxGa1−xN layers of different compositions epitaxially grown on GaN/sapphire is investigated. Extended crack channels along 〈211¯0〉 directions are formed if the aluminum content exceeds a critical value, which decreases with increasing layer thickness. This process is found to limit the average strain energy density to a maximum value of 4 J/m2. By calculating the stress distribution between cracks and the strain energy release rate for crack propagation, the relaxed strain as measured by x-ray diffraction is correlated to the crack density, and the onsets of crack channeling and layer decohesion are fitted to a fracture toughness of 9 J/m2. Moreover, the crack opening at the surface is found to linearly increase with the stress. Annealing of samples above the growth temperature introduces additional tensile stress due to the mismatch in thermal expansion coefficients between the layer and substrate. This stress is shown to relieve not only by the formation of additional cr...
120 citations
TL;DR: Testing the hypothesis that the radius of curvature at the gingival embrasure of the FPD connector significantly affects the fracture resistance of three-unit FPDs found a good correlation between the experimentally measured failure loads and those predicted by FEM simulation analyses.
Abstract: Fracture of ceramic fixed-partial dentures (FPDs) tends to occur in the connector area because of stress concentrations. The objective of this study was to test the hypothesis that the radius of curvature at the gingival embrasure of the FPD connector significantly affects the fracture resistance of three-unit FPDs. Two three-dimensional finite element models (FEMs), representing two FPD connector designs, were created in a manner corresponding to that described in a previous experimental study (Oh, 2002). We performed fractographic analysis and FEM analyses based on CARES (NASA) post-processing software to determine the crack initiation site as well as to predict the characteristic strength, the location of peak stress concentrations, and the risk-of-rupture intensities. A good correlation was found between the experimentally measured failure loads and those predicted by FEM simulation analyses. Fractography revealed fracture initiation at the gingival embrasure, which confirms the numerically predicted fracture initiation site. For the designs tested, the radius of curvature at the gingival embrasure strongly affects the fracture resistance of FPDs.
120 citations
TL;DR: Based on the complex-valued "stress concentration vector" introduced by Willis, a new definition of real-valued stress intensity factors is introduced in this article, where tractions ahead of the crack and the relative crack face displacements given by Willis are rewritten into real-form expressions.
Abstract: Based on the complex-valued «stress concentration vector» introduced by Willis, a new definition of real-valued stress intensity factors is introduced. In terms of the new stress intensity factors, tractions ahead of the crack and the relative crack face displacements given by Willis are rewritten into real-form expressions. The energy release rate obtained by Willis is also expressed into a real form in terms of the stress intensity factors
120 citations