Unified constitutive models for deformation of thin-walled structures

Abstract

Sheet metals are widely used as body panels and trims in automotive body structures. In the event of a crash, these panels will likely to experience impact loads in the range where the strain rate effect is significant. The behaviour of sheet metals differs as the strain rate increases. Thus, Abaqus FE software was employed as an aid to predict the behaviour of the sheet metals. The Johnson–Cook (JC) model was used in the FE simulation. Low carbon steel (SGACD, SPCC and SHS) and high strength steel (DP600) were employed to study the effect of loading rate onto sheet metals. Metallurgical study was carried out to identify the element composition and orientation of the microstructure since the materials had undergone several processes during manufacturing. Tension tests were conducted at strain rate 0.001/s to 0.1/s to study the stress-strain relation of the material. Parameters of the JC model (A, B, C, m and n) were extracted using results from the tension tests. These parameters were incorporated into the JC model and used in FE simulation. FE simulation of tension test was performed in order to validate the JC model parameters. Experiment and FE simulation of axial compression test on thin-walled tube and drop weight impact test on steel plate were conducted. Results from the experiment were compared with FE simulation for validation where the large deviation of the compressive load-displacement curve occurred in the axial compression test. Whereas, in the drop weight impact test, the dynamic acceleration and deceleration were accurately predicted by FE model and served to validate the model.