In-plane and out-of-plane constraint parameters along a three-dimensional crack-front stress field under creep loading

Full-field three-dimensional (3D) numerical analyses was performed to determine in-plane and out-of-plane constraint effect on crack-front stress fields under creep conditions of finite thickness boundary layer models and different specimen geometries. Several parameters are used to characterize constraint effects including the non-singular T-stresses, the local triaxiality parameter, the Tz-factor of the stress-state in a 3D cracked body and the second-order-term amplitude factor. The constraint parameters are determined for centre-cracked plate, three-point bend specimen and compact tension specimen. Discrepancies in constraint parameter distribution on the line of crack extension and along crack front depending on the thickness of the specimens have been observed under different loading conditions of creeping power law hardening material for various configurations of specimens.