Fracture Analysis of Delaminated Composite Panels in Compression Using Numerically Integrated MVCCI

Delamination tolerance is one of the key issues in laminated composites used in high technology structures. Delamination in these structures could grow due to repeated in-plane compressive loading during operation and the delamination tolerance levels are obtained by comparing mode-I SERR component with the corresponding fatigue threshold values. The Modified Virtual Crack Closure Integral (MVCCI) is used to estimate individual mode SERR components in a mixed-mode situation, which occurs at an embedded delamination. The present work proposed a numerical integration for the first time to evaluate the MVCCI for Hexa20 elements used in three-dimensional finite element analysis. Extensive numerical results are presented including a parametric study on a typical laminate.