Elastic–plastic constraint parameter A for test specimens with thickness variation

Abstract

AbstractThree‐dimensional elastic–plastic problems for a power‐law hardening material are solved using the finite element method. Distributions of the J‐integral in terms of the normalized elastic–plastic stress intensity factor and constraint parameter A along the crack front for varying the strain hardening exponent, specimen thickness and crack length are determined for edge cracked plate, centre cracked plate, three‐point bend and compact tension specimens. The second parameter A in three‐term elastic–plastic asymptotic expansion of the crack tip stress field is a measure of stress field deviation from the Hutchinson‐Rice‐Rosengren field and can be considered as a constraint parameter in elastic–plastic fracture. The loading levels cover conditions from small‐scale to large‐scale yielding. Results of finite element analyses show that the constraint parameter A significantly decreases when specimen thickness changes from 0.1 to 0.5 of the specimen width. Then, it has more or less stable value. Among four specimens, the highest constraint is demonstrated by the compact tension specimen that has the constraint parameter A lower than its small‐scale yielding value.