Ductile fracture model for structural steel under cyclic large strain loading

• A cyclic ductile fracture model based the concept of void growth and coalescence proposed.
• Experimental study on ductile fracture of structural steel under cyclic large strain loading conducted
• Ductile cracking simulation of structural steel under cyclic large strain loading carried out
• The parameters of the plasticity models and fracture model can be obtained from a smooth coupon under tension.

This paper aims to predict ductile fracture of mild steel under cyclic large strain loading (CLSL) using only tensile coupon test results. A micromechanics-based fracture model which adopts void growth model and Miner's rule in incremental form is proposed, where fracture is assumed to occur when a damage index reaches unit. Damage is postulated not to accumulate when stress triaxiality is less than a threshold. To calibrate the fracture model, cyclic experimental and numerical studies on hourglass-type coupons are conducted under various loading histories. Since cyclic plasticity models play an important role on the simulation results, two cyclic plasticity models are employed to carry out the simulation, in which the proposed fracture model is employed. The predicted fracture displacements using either of the plasticity models compare with the experimental results with acceptable accuracy.