Study on the failure mode of a sandwich composite structure under the combined actions of explosion shock wave and fragments

To improve the protective performance of structures in terms of explosive shock waves and fragment penetration, a foamed aluminum/UHMWPE fiber sandwich composite structure was designed. A “explosion+fragmentation” penetration experiment was used to study the failure mode of the structure and the failure mechanisms of materials, the effects of the core material combination and explosion distance were discussed, meanwhile, numerical simulation using LS-DYNA was adopted to simulate the timing and distribution law of the shock wave and fragments. The results show that the explosion distance is the main influencing factor for the timing, and the experimental and numerical results have a good consistency. When the structure was perforated completely by fragments, the front aluminum plate was damaged mainly by shear plugging, and the rear aluminum plate was broken largely by cracking and tearing. When the fragments arrived prior to the shock wave, the tearing damage to the rear aluminum plate was more obvious. The foamed aluminum absorbed the explosive energy through its own crushing deformation, and the fiber layer absorbed the kinetic energy of the fragments through its own tensile failure. Of the composite structures prepared herein, the composite structure consisting of foamed aluminum/foamed aluminum/UHMWPE fiber had the best protection performance.