Modelling of laminates using a layerwise element with enhanced strains

A layerwise nite element with enhanced strains is developed for the analysis of laminates with special emphasis on determination of interlaminar forces and study of delaminations. An interface model using the penalty function method is developed to calculate strain energy release rates. Since the interface model provides the facility for the closure of delamination by a small amount, strain energy release rates were evaluated by actual crack closure and by virtual crack closure methods for a comparative study. Numerical examples of delamination are presented to illustrate the accuracy of the computational approaches developed herein.