7. Cracks

Linear elastic fracture mechanics is established based upon the knowledge of stress field in the vicinity of a crack. Since cracks are special cases of wedges, the near tip solutions for the general cases of cracks can be derived from the eigenfunctions presented in Chap. 5 for the multi-material wedges. A straight crack is also a special case of an elliptical hole with zero minor axis, and hence the full field solutions of crack problems can be obtained from their associated hole problems. Therefore, in the first two sections of this chapter, most of the computer codes are designed based upon the related functions of the previous two chapters. Sections 7.3 and 7.4 provide the solutions and computer codes for the problems of collinear cracks and collinear interface cracks. Most of the codes include the calculation of fracture parameters such as stress intensity factors, crack opening displacements and energy release rates. Examples using the designed computer codes for crack problems are then presented at the last section of this chapter.