3D stress analysis of composite laminate based on a kind of interfacial element

An interfacial element derived from the combination of two rigid elements and three spring elements was developed to analyze the interfacial properties of composite laminates. The 3D stress distribution of a laminate was determined by means of a quasi-3D finite element mesh，in which each layer of the laminate is modeled by Mindlin plate elements，and the cohesion among the neighborhood layers is simulated by the interfacial elements，for which none of the additional nodes and degrees of freedom are needed. The in-plane stress can be determined from the plate elements，and the interlaminar stress can be confirmed from the spring force in interfacial elements. As an example，a rectangular multidirectional laminate under tension was analyzed. The 3D stress determined correlates well with that of a 3D solid element model. With the recommended interfacial elements, the delamination damage and its evolution can be easily simulated by the degradation of the corresponding spring stiffness.