CONSTITUTIVE MODELLING OF SILICON: PARAMETERS IDENTIFICATION OF CLASSICAL MODELS USING CRYSTAL PLASTICITY

Constitutive models for the yield region of silicon crystals available in the literature are based on results from uniaxial deformation tests of monocrystals oriented for single glide. We analyse in the present work their performance at various temperatures and identify their respective parameters. A crystal plasticity framework is implemented into an explicit Finite Element package in this respect. Analytical laws giving the constitutive parameters as functions of temperature are suggested. They improve significantly the accuracy of the models even beyond the lower yield point. The case of real crystals having dislocation sources on the secondary systems reveals a shortcoming of the classical models. A new one is proposed that corrects the discrepancy.