J.E. Ortiz

Boundary element analysis of fatigue crack propagation micromechanisms in austempered ductile iron

Abstract The Dual Boundary Element Method (DBEM) is used in this work to model the micro mechanics of fatigue crack propagation in austempered ductile iron (ADI). Emphasis is put in devising accurate procedures for the evaluation of the interaction effects between very close crack–microcrack arrays. Fracture parameters are computed via the so-called one-point displacement formula using special crack-tip elements. Crack propagation is modelled using an incremental crack extension analysis; with crack extensions calculated using a propagation law that accounts for the near-threshold regime. Obtained results are in agreement with experimental observations, providing evidence to fracture mechanics models proposed in the literature.

A Parallel Domain Decomposition BEM Algorithm for Three-Dimensional Exponentially Graded Elasticity

A parallel domain decomposition boundary integral algorithm for three-dimensional exponentially graded elasticity has been developed. As this subdomain algorithm allows the grading direction to vary in the structure, geometries arising from practical functionally graded material applications can be handled. Moreover, the boundary integral algorithm scales well with the number of processors, also helping to alleviate the high computational cost of evaluating the Greens functions. For axisymmetric plane strain states in a radially graded material, the numerical results for cylindrical geometries are in excellent agreement with the analytical solution deduced herein.

Boundary Element Analysis of Three-Dimensional Interface Cracks in Transversely Isotropic Bimaterials Using the Energy Domain Integral

It is presented in this paper a three-dimensional Boundary Element Method (BEM) implementation of the Energy Domain Integral for the fracture mechanical analysis of three-dimensional interface cracks in transversely isotropic bimaterials. The J-integral is evaluated using a domain representation naturally compatible with the BEM, in which the stresses, strains and derivatives of displacements at internal points are evaluated using their appropriate boundary integral equations. Several examples are solved and the results compared with those available in the literature to demonstrate the efficiency and accuracy of the implementation to solve straight and curved crack-front problems.

Boundary Element Assessment Of Three-dimensional Bimaterial Interface Cracks

A general numerical tool for the analysis of three-dimensional bimaterial interface cracks is presented in this chapter. The proposed tool is based on a multidomain formulation of the boundary element method (BEM), with the crack located at the interface of the domain. Mixed mode stress intensity factors are computed along the three-dimensional crack fronts using the energy domain integral (EDI) methodology and decoupled via the interaction integral. The capability of the procedure is demonstrated by solving a number of examples. The presentation of an application example, namely the three-dimensional analysis of a fiber/matrix debond interface crack under transverse loading closes the chapter.