Stress Intensity Factor Computations for Corner Cracks Using The Boundary Element Method

The determination of the stress intensity factor for crack problems in the three dimensional linear elastic body has been an important and interesting subject iu investigations involving fatigue life predictions. A multi-domain boundary element approach for calculating the stress intensity factor is proposed. The nine-­node quadrilateral elements arc employed to represent the √r displacement and 1/√r traction variations in the vicinity of the crack-front in the three dimensional geometrics; these are used in the form of singular crack elements. The numerical procedure suggested for evaluating the singular integrals extending over these singular elements is described, esptecially the elimination of singularities arising from the 1/ √r term combined with Kelvin's kernel for displacement in the integrals. Stress intensity factors of modes I, II and III can be obtained directly from crack-front nodal values, without any extrapolation. By using this method, stress intensity factors for corner-cracks in th() three dimensional linear elastic finite body under far field uniform tension can be determined. The method is outlined and numerical results are currently being generated.