Prediction and mitigation of behind armor blunt trauma in composite plate armor using rubber backing or air gaps

Ballistic impact induced behind armor blunt trauma (BABT) could be caused in a person wearing a personnel armor inspite of the projectile getting arrested. Backing materials like rubber and/or air gaps could prevent energy transmission to the human body thus reducing BABT. Two different injury scores such as the Viscous Tolerance Criteria (VCmax) and the Stored Energy Criteria (SEC) are used to predict the BABT in the present work. An analytical model has been developed to predict the BABT during a ballistic impact on a plain weave glass fiber reinforced polymer (GFRP) composite plate with a rubber backing material. The model was used to predict the BABT for the cases of no backing material, a rubber backing material and an air gap. Finite Element models have also been developed to compare and validate the analytical model results for the GFRP and the GFRP-Rubber composite. BABT was estimated using VCmax and SEC criteria for different rubber thicknesses or air gap widths varying from 1 mm to 4 mm and compared with the case of no backing or air gap. The study indicated that both rubber backing or air gap can significantly mitigate BABT in comparison to the impact scenario where no backing or gap is used. Rubber backings however proved to be more beneficial in comparison to air gaps in BABT reduction and higher energy absorption.