Modeling the Behavior of Impact Induced Multiple Delaminations under Compressive Load

摘要

A two-part study is presented focusing on post-impact behavior prediction ofrncompression after impact (CAI) specimens.rnThe first part is dedicated to the study of cohesive zone model (CZM) and meshrndensity parameters as well as to the evaluation of their influence on resultingrnsimulation accuracy and computational costs. For that purpose, two different tests arernreplicated by numerical simulations: double cantilever beam (DCB) and end-notchedrnflexure (ENF) tests. The parameters under investigation are: element edge length,rncohesive stiffness and strength for mode Ⅰ and mode Ⅱ loading. By comparingrnanalytical with numerical results from the parametric study, an adequate parameter setrnis found and finally applied to the CAI model.rnIn the second part, a procedure for predicting the behavior of impacted carbonrnfiber reinforced plastics (CFRP) structures under uniaxial compressive loading isrnpresented by the example of a CAI test simulation. For that purpose, a model is usedrnto represent realistic impact damages with multiple delaminations of elliptical shape asrnwell as varying sizes and orientations distributed throughout the laminate thickness.rnNon-self-similar delamination propagation in the resin-rich zone and sublaminate andrnglobal buckling phenomena are considered in a nonlinear simulation based on thernfinite element method (FEM). The sublaminate buckling modes are calculated in arnpreceding buckling analysis and applied simultaneously onto each sublaminate asrninitial geometrical imperfections. Peel and transversal shear tractions emerge asrnsublaminate and global buckling develops, leading to delamination propagation. Thernpredicted behavior is in line with numerical and experimental findings reported in thernliterature.