WIT Press

Usefulness Of Non-linear Crack Mechanics Under Plane Strain Conditions


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WIT Press


H Nisitani & T Kawamura


Recently, non-linear crack mechanics was proposed by one of the authors and its usefulness under plane stress conditions was confirmed in the case of plate specimens with a center crack. Non-linear crack mechanics assures that if the y-directional plastic strain 6PyO at a crack tip obtained by FEM are equal to each other in a specimen (1) and a real object (2), the crack opening displacements and the elastic-plastic stress fields in both are equal to each other respectively, and therefore the same phenomena occur in the specimen and the real object, where the y-direction is the direction normal to the crack. Originally, linear fracture mechanics should be called linear crack mechanics. The non-linear crack mechanics is a direct extension of linear crack mechanics [1]. 1 Introduction In the non-linear crack mechanics, the plastic strain at a crack tip obtained by the finite element method (FEM) is used as the severity of a cracked body [2]. The effectiveness of non-linear crack mechanics (NLCM) has been confirmed under plane stress conditions, through a few results of FEM analysis and the experimental data obtained by the other researchers [2,3]. However, in order to apply the NLCM to practical problems, it is necessary to evaluate the severity of the crack tip in the plate of finite thickness rationally. For the evaluation, it is useful to know the phenomena under both plane stress conditions and plane strain conditions. In this paper, the concept of non-linear crack mechanics is extended to the case of plane strain conditions and the usefulness of the concept under plane strain