Experimental and Numerical Investigation of the Dynamic Response of a Self-Adhesive Stiffened Polyimide Foam-Based Sandwich Structure Under Blast Loading

Polymer-based sandwich structures have garnered significant interest as energy-absorbing protective materials. However, common damage modes in composite sandwich panels include matrix cracking, delamination, core crushing or core fracture, and debonding between the face sheets and the core. Among these, face–core debonding is one of the most prevalent failure mechanisms. This paper investigates a sandwich configuration designed to enhance blast resistance by incorporating a self-adhesive, stiffened polyimide foam (ASPI) into a steel–foam–steel architecture. The thermogravimetric analysis exhibits that ASPI foam obtained excellent thermal stability, and the residual mass retention at 800 °C was more than 36.2%. Experimental results show that at scaled distances of 1.077 m/kg1/3 and 1.292 m/kg1/3, the ASPI foam-based sandwich panels exhibited mid-span displacements as low as 8.5 mm and 6.7 mm, respectively. Under a scaled distance of 1.077 m/kg1/3, the mid-span displacement of the ASPI foam-based sandwich structure decreased from 15.0 mm to 8.5 mm, representing a 43.3% reduction compared with that of the neat polyimide foam-based sandwich structure. Moreover, compared with neat PI foam, the ASPI foam exhibited superior adhesion to steel face sheets, and no interfacial debonding was observed after blast loading. To further elucidate the underlying damage mechanisms under blast loading, a well-validated finite element model was developed and employed. Complementary scanning electron microscopy (SEM) analyses were conducted to examine the microstructural morphology of the ASPI foam core’s cross-section and surface after blast exposure. This study presents an investigation of a lightweight, self-adhesive, high-thermal stability, blast-resistant polymer-based composite foam.