Investigation on springback behaviours of hexagonal close-packed sheet metals

In this study, a novel analytical method for predicting bending and springback behaviours of hexagonal close-packed (HCP) sheet metals is presented. The proposed analytical approach is developed by using the Cazacu-Barlat 2004 asymmetric yield function and isotropic plastic hardening rule. This model can be used to determine bending momentcurvature relationships and springback of HCP metals under uniaxial and plane strain loading conditions. Furthermore, to capture the nonlinearity in unloading and to improve springback prediction, the variable elastic modulus approach is implemented in the proposed model. The proposed new model reveals that reverse effects of the back force on springback behaviours cannot be found under the plane strain condition, which could not be found by using any existing models. Moreover, the analytical model is implemented into Abaqus via UMAT subroutine for its application in complex cases, and a numerical model is then developed as a showcase. The proposed methods are validated by using those experimental results available in literature. The results show considerable improvements by considering the plane strain condition and nonlinear unloading. (C) 2020 Elsevier Inc. All rights reserved.

Automated summary

This study introduces a novel analytical method for predicting bending and springback behaviors of HCP sheet metals. By utilizing the variable elastic modulus approach, the model is able to capture nonlinearity in unloading and improve springback prediction. Results show significant improvements in prediction by considering the reverse effects of back force on springback behaviors under plane strain conditions.