Modeling the Flexural Behavior of Synthetic and Bio-Based Sandwich Composite Materials Under Cyclic Fatigue

This study investigates the fatigue behaviour of sandwich composite materials under three-point bending. A stiffness reduction approach was adopted to model the damage evolution as a function of fatigue cycles. However, existing studies often rely on extensive experimental campaigns or focus on isolated damage indicators, without providing a unified and efficient framework for predicting fatigue life under displacement-controlled bending. Empirical functions, fitted to experimental data, allowed the prediction of fatigue life while minimizing the need for extensive testing. Wöhler curves were constructed to compare experimental results with analytical predictions. Damage accumulation models were developed to describe stiffness degradation and damage kinetics. These models were experimentally validated and applied to simulate load evolution, fatigue life, energy release rate, and damage progression in sandwich composites. A good agreement was achieved between experimental data and model predictions, confirming the reliability of the proposed approach.