Predicting springback in sheet metal forming: an explicit to implicit sequential solution procedure

A layerwise displacement finite element with enhanced strains is used to determine deflections and interface model using the penalty function method is developed to determine interlaminar stresses and strain energy release rates to study delaminations. Since the interface model provides the facility for the closure of a delamination by a small amount, strain energy release rates were evaluated by actual crack closure and virtual crack closure methods. Numerical examples of free edge problems and delamination problems are presented to illustrate the accuracy of the computational approaches developed herein. © 1999 Elsevier Science B.V. All rights reserved.