Specimen thickness effect on elastic-plastic constraint parameter A

Three-dimensional elastic-plastic problems for a power-law hardening material are solved using thefinite element method. Distributions of the J-integral and constraint parameter A along the crack front forvarying specimen thickness and crack depth are determined for edge cracked plate, center cracked plate, threepoint bend and compact tension specimens. The constraint parameter A is a measure of stress field deviationfrom the HRR field. Higher A values signify lower specimen constraint. Results of finite element analyses showthat the constraint parameter A significantly decreases when specimen thickness changes from 0.1 to 0.5 of thespecimen width. Then it has more or less stable value. Among four specimen the highest constraint is demonstrated by the compact tension specimen which has the constraint parameter A lower than its small scale yielding value