INTERACTION OF FRICTIONAL AND COHESIVE DELAMINATIONS IN LAMINATED STRUCTURES

摘要

Due to poor interlaminar properties, laminated fiber reinforced composites are susceptible to delaminations. In the case of impact, many delaminations are typically formed and occur between layers of different fiber orientation. The presence of the delaminations is often undetectable on the surface and may significantly reduce the stiffness and load carrying capacity of the structure. [1] When a load is applied in such a way that it causes sufficient interlaminar stresses, the delaminations may grow, often catastrophically, separating the structure into several pieces and causing further reduction in stiffness and/or failure. In a previous paper, the authors have studied the elastic interaction of multiple delaminations in laminated structures subject to static out of plane loading [2,3]. The formulated model is based on classical beam theory and accounts for non-frictional contact along the delamination surfaces. The material is assumed to be homogeneous and perfectly brittle. Application of the model to a delaminated cantilever beam has shown strong short and long range interaction effects between the delaminations. In this paper the model will be extended to include nonlinear mechanisms acting along the delamination surfaces, namely friction and cohesive and bridging mechanisms, and to account for different geometric and loading conditions. In addition dynamic loading will be considered. In the next section is a brief discussion of some of the results in [2,3] followed by a description of the current work as well as some preliminary results.