Prediction of strength mis-match welded joints failure by using of crack driving force curve and crack tip opening displacement (CTOD) resistance curve

Prediction of failure of fracture toughness specimen is possible to estimat e by using crack driving force and delta (5)(CTOD)-R resistance curve of ma terial. Accuracy of numerically determinated points on the curve of crack d riving force depends on numerical model and description of mechanical prope rties of material. The appropriation of numerical model can be determined b y comparison between numerical and experimental results for characteristic displacements. Initiation of stable crack propagation can be determined by deviation between numerically and experimentally obtained fracture behavior curves. The intersection point between curve of crack driving force and de lta (5)(CTOD)-R resistance curve provides the critical values of delta (5)( CTOD) and crack extension, where the instability can be expected. The unsta ble fracture behavior depends on hardening ability of weld metal and its vo lume in the weld joint.