A numerical study on compressive behavior of composite plates with multiple circular delaminations considering delamination propagation

The compressive behavior of multiply delaminated composite plates was numerically evaluated considering both structural instability and delamination growth in order to clarify the reason for the significant reduction in the compressive strength of composite laminates that results from an impact. Embedded circular delaminations were placed at regular intervals in the thickness direction at the plate center. A three-dimensional block element was used to discretize the laminates, and a cohesive element was placed at the same planes as the delaminations. The cohesive element had a bilinear relationship between traction and relative displacement, and the element failed when the energy stored in it exceeded a threshold, that is, the critical energy release rate of the interface. Through the present numerical study we found that the applied load dropped after slight increase of the load when the delaminations started growing, and the delamination growth in the buckled laminate governed the compressive strength of the damaged composite laminates.