Delamination Phenomenon in Composite Laminated Plates and Beams

Failure analysis of laminated composite decks structures has attracted a great deal of interest in recent years due to the increased application of composite materials in a wide range of high-performance structures. Intensive experimental and theoretical studies of failure analysis and prediction are being reviewed. Delamination, the separation of two adjacent plies in composite laminates, represents one of the most critical failure modes in composite laminates. In fact, it is an essential issue in the evaluation of composite laminates for durability and damage tolerance. Thus, broken fibers, delaminated regions, cracks in the matrix material, as well as holes, foreign inclusions and small voids constitute material and structural imperfections that can exist in composite structures. Imperfections have always existed and their effect on the structural response of a system has been very significant in many cases. These imperfections can be classified into two broad categories: initial geometrical imperfections and material or constructional imperfections. Delamination is a critical failure mode in fiber-reinforced composite decks plates and beams. It may lead directly to through-thickness failure owing to interlaminar stresses caused by out of plane loading, curved or tapered geometry, or discontinuities owing to cracks, ply drops or free edges. Impact loading causes multiple delaminations, which can propagate in conjunction with sub laminate buckling, greatly reducing the residual compressive strength.