Elastic-plastic crack-tip-field numerical analysis integrated with moire interferometry

A novel method of integrating displacement field measurements from high-sensitive moire interferometry with the finite element method is introduced for the elastic-plastic fracture mechanics problems. The measured displacements normal to the crack in a fatigue-precracked specimen are input to a finite element model along a near-field boundary. In this paper the analysis is done for a power-law strain hardening material. The near-field region is discretized using 8-noded isoparametric quadrilateral elements. A validation procedure indicates that just the u _y -displacement (normal to the crack) as input is sufficient for an edge-cracked specimen whereas a center-cracked specimen requires both u _x - and u _x -displacement inputs. Results are obtained in the form of J-integral evaluations, HRR fields, and plastic zones. A significant CPU time saving is achieved when compared with the load-input case. Also the results indicate the existence of HRR field under large scale yielding.