Development of True Stress-Strain Curves of Structural Steel for Fracture Simulations

Abstract

True stress-strain curves are needed for fracture simulation of structural steel using the finite element analysis method. This paper summarizes recent research on development of true stress-strain curves for ASTM A992 structural steel at ambient temperature and at elevated temperatures up to 1000°C. Calibration of true stressstrain curves was based on measured engineering stress-strain curves of ASTM A992 steel obtained from isothermal tests for tension coupons at both ambient and elevated temperatures. Prior to necking, the true stress-strain curve was derived directly from the engineering stress-strain curves using well established equations. After the onset of necking, due to the non-uniform deformation and complex stress state in the necked region, the established equations are no longer valid. Thus, in this research, true stressstrain curves for the post-necking region were developed by calibrating detailed finite element models of the tested tension coupons to match measured engineering stressstrain curves. Comparisons are presented between measured engineering stress-strain curves and simulated results to examine the accuracy of the calibrated true stress-strain curves. Furthermore, generalized true stress-strain curves based on the derived curves are proposed for fracture simulations for ASTM A992 steel.