Ductile damage model calibration for high-strength structural steels

Abstract

Numerical analyses incorporating appropriate damage models provide an opportunity to predict the strength and deformation capacity of steel structures. This paper presents a practical calibration for the ductile damage model of S355 and high-strength steel S690Q, S700MC, S960Q based on tensile coupon test results. A combined linear and power expression is adopted to calibrate the post-necking damaged stress–strain relations of the investigated steels, upon which the undamaged stress–strain relations are estimated further. Damage initiation criterion is based on the Rice-Tracey model and damage evolution law is related to the calibrated damaged stress and the estimated undamaged stress. Fracture of the tensile coupons is modelled using a critical damage variable. Tensile coupon tests on the investigated steels are modelled in ABAQUS with the explicit solver. Results show that combining the proposed post-necking stress–strain relations and ductile damage model generates very good predictions for strain localization and final fracture of the tensile coupons. Numerical engineering stress–strain curves agree well with the experimental results. It also indicates that high-strength steels are more susceptible to damage than S355. The damage variable of S960Q is about 2 times as large as that of S355 from the onset of necking to the final fracture.