Experimental and analytical investigation of the bending behaviour of 3D-printed bio-based sandwich structures composites with auxetic core under cyclic fatigue tests

In the present paper, fatigue behaviour of sandwich composites with auxetic core under various stress ratios and for four different core densities is studied. Experimental and analytical analyses are performed on sandwiches subjected to cyclic bending tests in order to determine the influence of stress ratios on their fatigue properties. Experimental and analytical prediction result show good agreement. The analytical method predicts fatigue life as well as damage parameters of the structures and its reliability is verified by experiments. The acoustic emissions method is also used to monitor damage initiation and propagation up to failure. It is found that sandwiches with low core density present the maximum fatigue life.