Effects of strain paths on the fracture forming limit of high strength structural steel sheets

Abstract

The cruciform two-axial tensile specimen was designed and the two-axial tensile test scheme for different strain paths was developed. The effect of strain paths on the forming limit of high strength structural steel plates was obtained by the DIC method. The results show that for the unidirectional alternating loading test scheme, the equivalent strain of the ultimate strain is less than the sum of the equivalent strains from each step. When the main strain direction of the specimen pre-strain is perpendicular to the final strain path, the forming limit decreases with the increase of the pre-strain.