Viscoplastic BEM fracture analysis of creeping metallic cracked structures in plane stress using complex variable techniques

This paper extends a boundary element approach developed earlier by the present author to the solution of viscoplastic fracture problems arising in creeping cracked metallic structural components undergoing plane stress deformation conditions. By using a plane stress viscoplastic formulation this work adopts the procedure of Lyness and Moler to express the derivative of displacement rate as the ratio of the imaginary part of the displacement rate to the imaginary part of a complex variable representing the coordinates of a collocation point. In this manner the evaluation of creep stresses at internal points is greatly simplified. The results thus obtained are highly accurate in comparison with conventional BEM. The application of the present BEM approach is illustrated by obtaining creep stress and strain distribution for center cracked and standard CT fracture specimens subjected to remote tensile and shear stress loading under plane stress deformation conditions.