Inexpensive simulation of delamination growth in composite plates by using FEM with two- dimensional elements

Abstract

Recently, integrated large composite structures have been administered to many different vehicle structures. To improve the cost performance and reliability, it is necessary to judge the structural integrity of the composite structures with defects. To enable this, we need fracture simulation techniques. Much research on the fracture simulation method using FEM has been carried out by now. Most of the research involved only matrix cracking and fiber breaking simulations, and did not simulate delamination growth. Several papers have reported the delamination simulation, but all of these reports require three-dimensional elements or quasi three-dimensional elements for FEM analysis. These analyses are expensive and time-consuming. It is known that initiation and propagation of delamination are dominated by the strain-energy release rate. In the present study, an approach to estimate the total strain-energy release rate by using FEM with plane stress elements was investigated. The approach regards delamination as the stiffness degradation of composite laminates. By using CF/epoxy laminates with an open hole, the approach was investigated in comparison with experimental results. As a result, it is shown that the proposed simulation method can roughly predict the delamination growth and stiffness degradation, and that the analysis can be carried out easily and inexpensively.