A feasible methodology for engineering applications in damage tolerance of composite sandwich structures

In this paper, a feasible methodology is proposed for the damage-tolerant design of composite sandwich structures and the residual safety evaluation of low-velocity impacted composite sandwich structures. This methodology is based upon the implementation of an event-driven failure criterion called Damage Propagation Criterion. In this criterion, the impact-damaged composite sandwich structure is considered to be unsafe if the damage will propagate to a specified characteristic location near the damage zone under the desired compressive load. The critical far field stress corresponding to the initiation of damage propagation at the specified characteristic location is used as the only characteristic value in this criterion. For a sandwich structure with low-velocity impact damage, this critical far field stress can be determined through either Sandwich Compression After Impact (SCAI) test or numerical analysis by using a modified analytical model or a nonlinear finite element model. Both the experimental and numerical approaches are briefly introduced with examples in this paper. At the end of this paper, the feasible methodology is introduced for the engineering applications in damage-tolerant design of composite sandwich structures and the residual safety evaluation of impact-damaged composite sandwich panels.