Haruyuki Konishi

Localized Deformation on Silicon Iron Sheet. Numerical Simulation of bcc Crystal Based on Crystal Plasticity Theory.

FEM simulation of the strain localization in sheet metals is performed using crystal plasticity theory. The constitutive relations formulated by Asaro et al. are used, in which the rate-dependent property is included so as to determine active slip systems uniquely for a strain increment. The strain localization which appears in a silicon iron sheet under uniaxial tension is calculated. All 48 slip systems of the bcc crystal are considered, and isotropic hardening for the relationship between resolved shear stress and strain is assumed. Strain localization is affected by the combination of the activated slip systems. The analytical results are compared with those of experiments. The dependence of localized deformation mode on initial lattice orientation is predicted well by numerical results.

Analysis of Localized Deformation in Sheet Metal Based on Crystal Plasticity Theory

Estimation of deformation limit is an important problem for design of the sheet forming process. Metallurgical factors such as crystal lattice structure, texture, solution or precipitation, dislocation kinematics, and so on, have a strong effect on the nature of ductile fracture. There have been many theoretical studies concerning localized necking by using phenomenological constitutive expression of plasticity. However, explicit examination of the effects of the texture development or microstructural factors in the crystal is impossible by these approach. In this paper, strain localization of the sheet metals is analyzed using a crystal plasticity theory[1].