Initiation of Ductile Fracture at Different Stress States of Low Carbon and High-Strength Steel Sheets

摘要

Low-carbon steel (LCS) and high-strength steel (DP600) sheets are widely used in the automotive industry to manufacture lightweight components with complex shapes. In this respect, this study establishes the fracture characteristics of the materials to improve their performance with respect to strength and ductility. For this purpose, standard tensile testson 2 mm-thick sheet metal specimen are performed to establish the constitutive behaviorof each material. Six notched flat specimens with different notch radii are machined from the sheet metal and tested to provide the different stress states (stress triaxiality). Detailed finite element simulation for each test is developed to acquire stress and strain tensor components. The evolution of equivalent plastic strain at various possible fracture localitiesand stress triaxialities is then examined. Results showed that the location ofthe equivalent plastic strain to fracture varies withnotch radii, hence stress triaxiality. The work provides information on appropriate locations in each specimen material for determining the fracture properties.