Analyses of shearing mechanism during shear-cutting of 980 MPa dual-phase steel sheets using ductile fracture modeling and simulation

摘要

In this work, the effects of various process input parameters in the sheared edge characteristics are studied during shear-cutting of DP980 sheet material. A virtual experimental approach, based on finite element (FE) modeling of the trimming process, is used to investigate the shearing mechanism precisely. In this context, the Hosford-Coulomb (HC) fracture model is used to predict the fracture initiation, and a hybrid experimental-numerical technique is adopted to calibrate HC parameters. Furthermore, the calibrated HC model is incorporated into FE simulation of the shear-cutting process. Experimental sheet trimming setup is also developed to conduct the experiments, and subsequently validate the developed FE models. It is found that the sheared edge quality and trimming load are varied by the process parameters including trimming angle, trimming clearance and punch radius. Therefore, regression models are proposed to understand the effect on the sheared edge profile and trimming load while varying the input parameters simultaneously. Subsequently, these regression models are represented in the 3D space as a function of the input parameters to visualize the tendency of variations of process parameters on outputs over the operating range. The mathematical models are useful to predict and subsequently improve sheared edge quality by varying the process parameters. Furthermore, a comparison between the open-cut and close-cut processes has also been studied. Two different crack propagation mechanisms are observed due to difference in the boundary conditions regarding rotation of the scrap. For this reason, a strong variation in the stress triaxiality evolution is observed between two processes.