Effect of Element Size and Pre-deformation on Unsafe Zone Structural Finite Element Analyses

Structural finite element analyses (FEA) are usually performed in two zones - safe zone and unsafe zone related to the status of a structure after loading. Safe zone structural FEA focus on the deformation behavior prediction of a component or a structural system. While unsafe zone structural FEA do not only focus on their deformation behavior but also their failure behavior prediction. As a fatal disaster or a high cost often results from the premature rapture of critical parts, it is very important to predict the catastrophic failure possibility and process of a component or a structural system. Unsafe zone structural FEA is one of the feasible methods making such a prediction possible. In this paper, the deformation behavior and necking process of automotive steels were discussed based on their stress-strain curves obtained from standard tension tests. New material model was developed for high strength (HS) steel through simulating a standard tension test. The effect of element size and pre-deformation was investigated on unsafe zone structural FEA of typical automotive parts. Residual ductility was highlighted for pre-deformed materials. It was found that not only internal energy and reaction force but also failure behavior of a structural component was significantly influenced by element size and pre-deformation.