Toru Takase

Evaluation of Accuracy for 2D Elastic–Plastic Analysis by Embedded Force Doublet Model Combined with Automated Delaunay Tessellation

An embedded force doublet (EFD) model is proposed to express the presence of permanent strain in body force method (BFM). BFM is known as a boundary type method for elastic stress analysis based on the principle of superposition. In EFD model, the permanent strain is replaced by distributed force doublets. In an actual elastic–plastic analysis, the plastic region whose shape is not clear a priori, have to be discretized into elements where the magnitude of embedded force doublets is unknown to be determined numerically. In general, the determination process of magnitude of EFD is considerably difficult due to nonlinear nature of yield criterion and plastic constitutive relations. In this study, by introducing the automated Delaunay tessellation scheme for discretizing the prospective plastic region, appreciable reduction in input data was realized. Adding to this, in order to improve the computational efficiency, influence coefficients used for determining the magnitude of EFD are stored in a database. Th...

Accurate SIF Analysis of a Partially Cylindrical Side Crack Opened by Far-Field Tension

In recent years, due to a remarkable progress of qualified mesh generation algorithms combinedwith computational image processing technologies, a complex shaped 3D crack analysis has been carried out more and more easily by finite element method. Generally speaking, in order to assess thereliability of numerical solution, existence of a closed-form solution or a practically exact numericalsolution is important and thank-worthy. In contrast with 2D problems, however, there are very fewnumber of closed form solutions regarding to 3D crack problems. In the present analysis, we examineda highly accurate body force method (BFM) analysis for a partially cylindrical 3D surface crackin which a suitable basic density function can be supposed reasonably by taking account the crackgeometry. The present SIF solution could be used effectively for the purpose of benchmark the finiteelement solution for general non-planar crack problems.