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Methodologies to compute fracture mechanics parameters (A revisit and some applications to large strain elastic-plastic problems)
Hiroshi Okada

Last modified: 2020-07-26


In this presentation, methodologies for computing fracture mechanics parameters such as the stress intensity factor and the energy release rate will be discussed. Although the use of the finite element method (FEM) to analyze fracture mechanics has a long history, it is still considered to be difficult. This is because it is necessary to create a good (optimized) mesh consisting of a regular arrangement of hexahedral finite elements in the vicinity of the crack front. However, fracture analysis becomes far easier if a bad (non-optimized) mesh is insteadused. Here, methodologies for computing the stress intensity factor and the energy release rate in linear and elastic-plastic solids using such a bad mesh are discussed.The domain integral method and the virtual crack closure-integral method (VCCM, also known as the virtual crack closure technique, VCCT) are often used to compute fractureparameters, and they generally require a good mesh to obtain accurate results. This is why fracture mechanics analysis is considered to be so troublesome.It should also be pointed out that finite-element model generation for a three-dimensional crack problem becomes less difficult if tetrahedral finite elements are used even in the vicinity of the crack front. This is because automatic mesh generation methods can be customized for crack problems. However, it is still not easy to generate a good mesh. Thus, methodologies for computing fracture parameters even using bad meshes need to be developed.In this presentation, the VCCM [1], J-integral method [2], and interaction integral method [3] are considered for automatically generated meshes. Finally, applications to problems of nonhomogeneous materials [4] and of large stain cyclic loads [5] are discussed.

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