Damage Propagation in a Composite Sandwich Panel Subjected to Increasing Uniaxial Compression after Low-velocity Impact

This paper is focused on an analytical model to simulate the damage propagation behavior and to predict the onset of damage propagation of a low-velocity impacted composite sandwich panel subjected to increasing uniaxial compressive load. Major damage modes due to impact, such as the residual indentation and the locally crushed core, are included into this model. Composite sandwich panels with unsymmetrical angle-plied facesheets are studied. A consequential core-crushing mechanism is incorporated into the analysis. Good correlations between the numerical results and the experimental data have been obtained. The far-field stress corresponding to the onset of damage propagation at a characteristic location near the damage zone has been captured accurately. This quantity can be used to represent the residual load-bearing capacity of an impact-damaged sandwich panel under compression. It serves as a characteristic value in a newly proposed event-driven failure criterion named damage propagation criterion. This criterion can be used in both the damage tolerant design and the safety evaluation of composite sandwich structures.