Structural Repair of Composite Structural Armor

Abstract

Composite structural armor (CSA) is a multifunctional material that provides ballistic protection, stiffness, and strength at minimum weight. It consists of a multilayered architecture of polymer composites, rubber and ceramic tiles, stacked in a precise manner to obtain optimal performance. During its lifetime, CSA will experience manufacturing defects and be subjected from low to high velocity impact threats that will reduce the performance of the structure. The ability to repair a CSA is consequently an important factor in the future deployment of the CSA. The present study addresses the problem of the repair of CSA in a minimum number of steps. Several potential repair methods are introduced, and an adhesively bonded plug repair scheme is then further analyzed. Virgin (control) and repaired CSA beams are manufactured and their static behaviors are compared in a four-point bend test. The performance of a scarf patch repair is assessed. The effect of three scarf angles and two repair adhesive systems, one being low-temperature cure and the other room-temperature cure, are compared. The room-temperature cure repair system offers only a limited ability to bond to the different material layers, thereby limiting the performance of the repaired CSA. On the other hand, it is found that the low-temperature cure repair system provides sufficient interfacial strength to allow the repair to recover an appreciable amount of the original structural performance of the beams. Furthermore, it is found that the repair efficiency increases as the scarf angle decreases. This study clearly demonstrates that it is possible to repair the through-thickness section of CSA, in a single-step operation, and renew structural performance.