Regularization in 3D for Anisotropic Elastodynamic Crack and Obstacle Problems
The problems of wave scattering by obstacles or cracks appear very often in geophysics and in mechanics. In particular the linearized theory of elastodynamics for 3 dimensional elastic material is used frequently, because this theory keeps the analysis relatively simple. Even with this theory, however, a practical analysis is possible only with the use of some numerical methods. This has been the raison d’être of many numerical experiments carried out in the engineering community. Among those numerical methods tested so far, the boundary integral equation (BIE) method has been accepted favourably by engineers, presumably because it can deal with scattered waves effectively in external problems. In particular the double layer potential representation is considered to be an efficient tool of numerical analysis for wave problems including cracks. The only inconvenience of the double layer potential approach, however, is the hypersingularity of the kernel, which does not permit the use of conventional numerical integration techniques. Hence we can take advantage of this approach only after weakening the hypersingularity of the kernel, or only after ‘regularizing’ it. As a matter of fact, some of such attemps can be found in the articles by Sladek & Sladek , Bui , Bonnet , Polch et.al , Nishimura & Kobayashi ,  who used the collocation method and in Nedelec , Bamberger  where the variational method has been used.
KeywordsCollocation Method Stress Function Boundary Integral Equation Inverse Fourier Transform Crack Problem
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