An analytical and experimental study of the nonlinear behaviour of a carbon/epoxy under a three-point bending test

In order to ensure structural integrity in such applications of composites materials, it is important to understand the material behaviour under mechanical loadings and predict correctly its responses. In this paper, the authors perform several three-point bending tests on a typical stacking sequences used in composite structures. Inspection techniques involving a digital microscope are used to study the successive failures and the effect of the thickness ratio (l h(-1)) on nonlinear behaviour. It was found that successive failures depend on the stacking sequence where the orthogonal sequences have a significant effect on the delamination between the plies. To describe the nonlinear behaviour observed, Von-Karman's large deflection theory and classical plate theory (CPT) are employed in the formulation of analytical modelling used in this work. The Riccati equation obtained leads to predict the experimental nonlinear curves with good accuracy. However, a slight dispersion between the experimental and analytical curves less than 11% was observed at large deflection.

Automated summary

The authors conducted three-point bending tests on a typical stacking sequence of composite materials to study their behavior under mechanical loadings and the effect of thickness ratio on nonlinear behavior. It was found that orthogonal stacking sequences had a significant impact on delamination between plies. The experimental and analytical curves showed a slight dispersion of less than 11% at large deflection.