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The non-proportionality of local stress paths in engineering applications

By C. Riess, M. Obermayr and M. Vormwald


A scalar measure, which describes the non-proportionality of local stress paths in engineering applications, is\ud introduced. For this purpose the moment of inertia approach by Meggiolaro is modified in a way that the stress time\ud history is evaluated in a tresca-stress-space. This modification makes the non-proportionality factor invariant with respect\ud to the coordinate system. An optimization procedure is implemented to derive a test set-up for new component tests with\ud 2 load channels. The aim of the planned tests is to get a high non-proportionality at the potential crack initiation site. It is\ud not possible to obtain a high non-proportionality factor at the failure location without selective weakening of the\ud component (housing of a rear axle steering). Therefore specific areas of the structure are cut out and the optimization\ud procedure is repeated. As a result of the optimization a test set-up with high local non-proportionality at the potential\ud crack initiation site is achieved for the weakened structure. Another set-up with slightly less non-proportionality but with a\ud very localized damage is derived. This set-up is preferred, because of the robustness in the physical test

Topics: Non-proportional fatigue, Multiaxial testing, Mechanical engineering and machinery, TJ1-1570, Structural engineering (General), TA630-695
Publisher: Gruppo Italiano Frattura
Year: 2016
DOI identifier: 10.3221/IGF-ESIS37.08
OAI identifier:
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