On the analysis of plasticity induced crack closure in welded specimens: A mechanism controlled by the stress intensity factor resulting from residual stresses

The aim of this paper is to clarify how and to what extent varied welding residual stresses (WRSes) affect the plane stress plasticity induced crack closure (PICC) simulation. A well-characterized, representative WRS field with tensile and compressive reversals was imported and the predicted PICC results were evaluated against the relevant WRS-free ones. It turned out that instead of WRS typically reported in the literature, there is actually a K-res (stress intensity factor resulting from residual stresses) controlled crack closure mechanism when investigating the PICC behavior in the presence of a WRS field, i.e., WRS influences PICC in the form of K-res. Four major categories where the crack tip was located in different K-res zones were defined using MT (middle tension) and SENT (single edge notch tension) specimens to investigate the mechanism in detail. In summary, the K-res value determined the general steady-state PICC level in the WRS field, i.e., a diminished steady-state opening stress level was predicted in the WRS field with a positive K-res regardless of whether the crack is located in a tensile or a compressive WRS zone, and an elevated value was estimated when the K-res was negative. Besides, the initial transient period was scrutinized that occurred in some WRS scenarios and the concept of primary and secondary plastic wake evolution was proposed to explain its formation. It was found that the transient behavior could be eradicated by tailoring the secondary plastic wake employing appropriate constitutive models and mesh refinement levels. The results attained in the present work provide some guidelines for the WRS-PICC modeling and simulation in the fracture mechanics community.