A hybrid membrane/shell method for calculating springback of anisotropic sheet metals undergoing axisymmetric loading

To reduce the computation cost of finite element analyses aiding die design for sheet metal stamping, a hybrid membrane/shell method was developed to determine the springback of anisotropic sheet metal undergoing axisymmetric loading. The hybrid membrane/shell method uses a membrane model to analyze the stamping operation. The bending/unbending strains and stresses varying through thickness are calculated analytically from the incremental shape d etermined by the membrane analysis. These bending strains and stresses and the final membrane shape are used with a shell finite element model to unlo ad the sheet and calculate springback. The accuracy of the springback predi ction with the hybrid method was verified against the springback of 2036-T4 aluminum and a DQAK steel sheet drawn into a cup. It was found that, in co mparison with a full shell model, a minimum of 50% CPU time saving and a co mparable accuracy was achieved when the hybrid method was used to predict s pringback. (C) 2000 Elsevier Science Ltd. All rights reserved.