Elastic fracture mechanics analysis by the boundary integral equation method

Abstract

The boundary integral equation (b. i. e.) method of stress analysis is shown to be a powerful numerical technique for solving three-dimensional fracture mechanics problems. Comparison with established solutions for an embedded penny-shaped crack and a semicircular surface crack in a rectangular prism show that accurate values of stress intensity factor along the front of a crack can be obtained by this method. Stress intensity factors are also presented for semi-elliptical surface cracks is internally pressurized cylinders. Computed hoop strains for such cracked cylinders show very good agreement with experimental measurements. The high accuracy of the b. i. e. method makes it possible to study numerically the nature of the stress (strain) singularity at the intersection between a crack front and a free surface. Results obtained for both straight and curved crack fronts show that stresses (strains) at and very near the free surface are somewhat less singular that the inverse square root form normally assumed, an effect which becomes more pronounced with increasing Poisson ratio.