Dynamic response and protective efficacy evaluation of Multi-airbag/PU composite structures under external explosion

A three-layer “Multi-airbag” has been designed to be used in conjunction with a polyurethane (PU) panel to mitigate explosive loads. By using an aluminum plate as a witness target, the blast response characteristics and protective effectiveness of the inflated composite structure were investigated through far-field explosion tests and numerical simulations. split hopkinson tension bar (SHTB) tests were conducted on the aluminum plate, and the Johnson-Cook constitutive model was employed for fitting. The P-I damage evaluation model of the aluminum plate was optimized, and the influence of the pressure gradient and the PU/Multi-airbag relative position on the damage to the aluminum plate and the protective capability of the inflated composite structure was studied. The results suggest that when subjected to shock wave loading, the Multi-airbag undergoes a layer-by-layer deformation pattern, with the primary deformation region forming a "V" shape. Regarding the internal pressure gradient inside the airbag, the protective effectiveness follows the order: increasing gradient > uniform pressure > decreasing gradient. When the PU panel is placed above the airbag, the final internal energy of the aluminum plate decreases significantly by 29.0 % compared to GP2(F2). The presence of the inflated composite structure significantly reduces the extent of damage to the aluminum plate. When the aluminum plate is protected by the Multi-airbag, its damage factor (Ds) is reduced by 56.2 %. This study provides a basis for the design of lightweight composite protective structures for key cabins and buildings.