Prediction of fracture in IS2062 grade steel coupons under action of monotonic tensile loads based on a void growth model

Abstract

Earthquakes induce large reverse cyclic plastic strains causing rapid loss of strength of materials leading to collapse of structures in a few cycles. Development of earthquake resilient steel structural systems to ensure community resilience requires accurate prediction of fracture initiation. In this work, the behaviour of tensile coupons made of mild steel (IS2062 grade) is studied. Fracture initiation under the action of monotonic tensile load is predicted by employing a triaxiality dependent uncoupled damage model based on void growth and coalescence. von Mises yield surface is considered with two different isotropic hardening models: one based on the conventional true stress-true strain relation obtained directly from the experiments, and another mixed linear-power law hardening model including the effect of necking. Fracture index of the void growth model is evaluated based on these two hardening models. The model parameters for mild steel IS2062 grade are calibrated based on experimental tests and complementary Finite Element (FE) simulations on tensile coupons of three different thickness by comparing the fracture index. The proposed model parameters will be useful for estimation of fracture initiation in mild steel components.