A FINITE-ELEMENT ALTERNATING METHOD FOR EVALUATION OF STRESS INTENSITY FACTORS FOR PART-CIRCULAR CRACKS SUBJECTED TO ARBITRARY LOADINGS

The stress intensity factor solution for embedded circular cracks, semicircular and part-circular surface cracks in plates, quartercircular corner cracks in rods, and semicircular surface cracks at a hole in a plate are evaluated using a finite element alternating method. This method of superposition employs the standard 20-noded solid element solution for the uncracked solid, and the complete analytical solution for an embedded circular crack in an infinite elastic medium, so that arbitrary pressures on the fracture surface can be modelled. The numerical results indicate that the alternating technique is quite cost efficient and effective. Convergence studies based on finite element meshes of 425 to 4499 nodes show that a good estimate of the stress intensity factor variation along the flaw border can be obtained with the coarsest mesh. Also, the natural-basis influence functions for a fixed crack and boundary geometry can be efficiently derived by the alternating process, to extract stress intensity factors for multiple loading problems.