NUMERICAL STUDY ON MIXED-MODE FRACTURE MECHANICS PARAMETERS OF SURFACE CRACKS IN AN HFMI-TREATED WELDED JOINT

Kurzfassung

To elucidate the mechanism of fatigue strength improvement by High-Frequency Mechanical Impact (HFMI), it is necessary to analyze fatigue crack propagation (FCP) considering the change of the weld toe profile and compressive residual stress (RS) field induced by HFMI treatment. In this study, mixed-mode (MM-) influence coefficient (IC) database (ICDB) for surface cracks in as-welded (AW) and HFMI-treated T-joints are developed using the automatic MM-ICDB generation system developed by Kyaw et al. (2020). The crack face tractions (CFT) are calculated by thermal-elastic-plastic welding and explicit dynamic elastic-plastic peening finite element (FE) analyses. The MM stress intensity factors (MM-SIFs) for cracks in both AW and HFMI-treated conditions are evaluated using the influence factor method (IFM). The accuracy of the constructed ICDB is verified by comparing MM-SIFs obtained from external loading with those evaluated using IFM. The relationship between the MM-SIF distribution along the crack front and the HFMI-induced RS distribution is discussed.