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Description
The use of Advanced High Strength Steel (AHSS) allows for lightweighting of sheet steel components, with maintained structural integrity of the part. This has enabled a wide-spread use of the materials and an ever increasing development of new, even stronger AHSS grades. However, with increased strength comes limited formability. Thus, the use of conventional cold forming processes is not always possible. Edge-cracking is a manufacturing defect common in cold forming of AHSS. It arises from damage introduced to the cut edge during the shear cutting process, prior to the cold forming steps. The edge-cracking phenomena cannot be predicted using conventional forming limit diagram. Consequently, new predictive tools are required.
Numerical modelling of the shear cutting process can aid the understanding of the sheared edge damage, thus avoiding unforeseen edge failure in the subsequent cold forming. However, the extreme deformations and rapid failure of the blank during the shear cutting process are likely to cause numerical instabilities and divergence using conventional Finite Element modelling. To overcome these challenges, this work presents the use of a particle-based numerical modelling method called the Particle Finite Element Method (PFEM). PFEM was developed for accurate handling of some of the challenges encountered in shear cutting with the standard Finite Element method, such as large deformation, angular distortions, generation of new boundaries and an efficient way of transfer historical information from the old to the new mesh, minimising the diffusion. It has in previous research also been proven suitable for orthogonal cutting with chip formation and granular material flows.
The present work shows prediction of the cut edge morphology of AHSS using a PFEM modelling scheme, where the numerical results are verified against experiments. Additionally, the work shows the benefit of using particle based numerical methods over the conventional Finite Element Method. With these results, the authors show new possibilities to obtain accurate numerical prediction of the shear cutting process, which promotes further advances in prediction of edge damaged related to shear cutting of AHSS.