Stress intensity factors and weight functions for surface cracked plates and welded joints

Abstract

Weight function and stress intensity factor solutions for semi-elliptical surface cracks in flat plates and welded joints are developed, which account for the effect of two-dimensional stress distributions and load shedding.

Two methods are proposed to develop weight functions for the calculation of stress intensity factors for two-dimensional cracks under two-dimensional stress distributions: a general point load weight function and a Fourier series approach. In order to accommodate the effects of fixed boundary conditions into the weight functions, a compliance analysis method to obtain stress intensity factor solutions for fixed displacement boundary conditions from the available solutions for the same geometry with traction boundary conditions is developed for surface cracks. These methods are used to develop stress intensity factors and weight function solutions for embedded elliptical cracks, surface cracks in flat plates, T-plate, pipe-plate and tubular weld joints.

The solutions developed are suitable for fatigue life prediction or fracture assessment of these structures. The present approach is more efficient (in terms of computing and cost) than three-dimensional finite element analyses, yet more accurate and widely applicable than available empirical solutions.