Innovative foam-based laminated composite panels with embedded SMA strip for low-impact shock absorption

Sandwich structures with Carbon Fiber Reinforced Polymer (CFRP) skins are being utilized in construction applications where impact loading is a critical concern. Incorporating foam into the core layer is a promising strategy to enhance structural stability and integrity under impact conditions. However, the geometry, material properties, and assembly of the foam layer significantly affect the energy absorption capacity of such structures. In conventional foam-based sandwich structures, while the inclusion of foam reduces the risk of catastrophic failure under impact, it often results in partial permanent deformation. To address this limitation, this study introduces an innovative Foam-Based Sandwich Panel (FBSP) with laminated layers made of CFRP as the skins, and Shape Memory Alloy (SMA) strips, termed SMA-FBSP. The SMA-FBSP integrates high-density foam in the core for enhanced energy absorption and embeds SMA strips to enable shape recovery after the structure being deformed due to impact load. Low-velocity impact and repetitive impact testing were conducted to simulate real-world scenarios and evaluate the performance of the SMA-FBSP. A proof-of-concept prototype was fabricated, demonstrating the capacity of the structure in shape recovery under low-velocity impact loading. The presence of SMA strips enable the sandwich panel to regain its original shape for low strain. However, at high strain, (~10%), the SMA-FBSP regained approximately 80% upon releasing the applied load. The induced strain is measured by an array of surface bounded Fiber Bragg Grating (FBG) sensor. This advancement highlights the potential of SMA-FBSP in applications requiring both high impact resistance and structural recovery.