Anticlastic Stability Modeling for Cross-ply Composites

A viable aspect of fiber-reinforced composites is their elastic tailoring ability. Anticlastic curvature is one example of elastic tailoring that occurs with an unsymmetric cross-ply layup. Residual stresses resulting from differences in coefficients of thermal expansion and elastic properties in each lamina can cause large out-of-plane deformations. In the case of thin unsymmetric cross-ply laminates under thermal curing load, a cylindrical shape is observed because of this inherent geometrical nonlinearity as opposed to the saddle shape that classical lamination theory predicts. In this article, a finite element approach, using ABAQUS ^™ , is implemented in order to predict the unsymmetric cross-ply laminate shapes under thermal curing stresses and understand the underlying limit point instability. Numerical results for curvatures of the predicted shapes are in agreement with published experimental and analytical data. The stability of the cylindrical laminates is also investigated. Depending on the aspect ratio of the rectangular laminate, a cylindrical shape may snap-through from its current stable configuration to another stable cylindrical shape with a different curvature. In particular, both the critical aspect ratio where snap-through will cease to occur and the buckling load are reported.