FE analysis of springback and secondary yielding effect during forward extrusion

The response of the work-material during forward extrusion and the subsequent unloading process was analysed with a view to examining differences in prediction of component-form errors, when different constitutive models are used. Two types of constitutive models were adopted for the analysis-classical theory of plasticity (CP) with isotropic hardening and non-classical theory of plasticity (NCP). When compared the results of the CP model with the NCP model, the latter shows a slightly smaller maximum punch-force requirement, smaller diameter of the extrudate and larger contraction of the die during unloading. The significant difference in the predicted final dimensions of the extrudate with different constitutive models suggests that more accurate constitutive descriptions on the work-material have to be used for the analysis of component-form errors in precision forming, if more accurate results are to be achieved.