Hideo Morimoto

Development of Multi‐Scale Finite Element Analysis Codes for High Formability Sheet Metal Generation

In this study, the dynamic‐ and static‐explicit multi‐scale finite element (F.E.) codes are developed by employing the homogenization method, the crystalplasticity constitutive equation and SEM‐EBSD measurement based polycrystal model. These can predict the crystal morphological change and the hardening evolution at the micro level, and the macroscopic plastic anisotropy evolution. These codes are applied to analyze the asymmetrical rolling process, which is introduced to control the crystal texture of the sheet metal for generating a high formability sheet metal. These codes can predict the yield surface and the sheet formability by analyzing the strain path dependent yield, the simple sheet forming process, such as the limit dome height test and the cylindrical deep drawing problems. It shows that the shear dominant rolling process, such as the asymmetric rolling, generates “high formability” textures and eventually the high formability sheet. The texture evolution and the high formability of the newly ...

Process metallurgy analyses of sheet rolling by multi-scale finite element method based on thermal elastic crystal plasticity theory

In this study, we analysed the final stage of hot rolling process of 6000 series aluminium alloy sheet by introducing the thermal effects, which caused by the plastic deformation induced heat generation. To consider thermal effects, we formulate the critical resolved shear stress, initial hardening ratio, and hardening coefficient in the crystal plasticity model as temperature depend approximation functions at the micro-scale. Simultaneously temperature depend functions are adopted in Norton’s low at the macro-scale. The texture evolution analysis code can apply to control the crystal structure to design a high formability sheet metal in the warm sheet rolling processes. Numerical results of thermal elastic plastic multi-scale finite element analyses have shown the temperature effects on the texture evolutions in the final stage of warm rolling process. It is confirmed that our process metallurgy analysis code can predict the microscopic crystal texture evolution in the industrial warm rolling process.