Modelling the flexural behaviour of sandwich composite materials under cyclic fatigue

In this work the fatigue behaviour of the sandwich composite materials in three point bending has been studied. A stiffness reduction approach was adopted which was further based on the interpolation by the empirical functions of our test results, whose coefficients depends on the material properties and loading conditions. This approach permitted to predict the fatigue life of the sandwich composite materials while avoiding the large number of experiments that would normally required in fatigue testing. Wöhler curves were utilised in order to obtain a comparison of experimental results with analytical results. In addition, a simple approach based on the analogy between the mechanical behaviour and the fatigue damage evolution of sandwich composites during fatigue was employed. Damage accumulation models were proposed to check the experimentally observed stiffness degradation. The developed models were applied to analyse the fatigue life and damage of sandwich composites under fatigue. A good agreement was found between the experimental and analytical results.