engleski

Anisotropic plasticity models with shear constraint

In the present study, anisotropic plasticity constitutive models based on associated or non- associated flow rule that utilize Hill48 or Karafillis-Boyce stress function with numerically determined parameters are considered. In the model calibration, the constraint is imposed on the plastic potential function to ensure equal and opposite principal strains for shear loading states. For stress functions with or without shear constraint anisotropy parameters are calculated using genetic algorithm. For the selected AA2090- T3 sheet, contours of yield function/plastic potential and predictions of orientational dependences of yield stresses/Lankford coefficients are analysed. Also, principal strains ratio and stress triaxiality are considered for the selected stress states satisfying the yield condition. The developed formulations result in improved predictions of uniaxial tensile tests data and physically acceptable shear loading states. The influence of the included shear constraint on the model predictions is more pronounced for the models based on Hill48 stress function.

anisotropic material, constitutive modelling, model calibration, shear constraint, non-associated flow rule

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