Bio-inspired hybrid Aluminum/CFRP sandwich structure: A ductile Containment Strategy for energy absorption

This study introduces a novel bio-inspired hybrid design, mimicking a crab claw, to address instability issues in lightweight composite energy absorbers. The design combines ductile aluminum 6061-T6 with high-strength Carbon Fiber Reinforced Polymer (CFRP) in a sinusoidal thin-walled structure. The crashworthiness of three configurations: CFRP bonded internally (IN), externally (OUT), and as a sandwich panel (SP) was evaluated through quasi-static lateral crushing tests and numerical simulations in LS-DYNA. Furthermore, a theoretical relationship was developed, and the accuracy of the results was validated. To analyze the failure mechanisms, the microstructure of the composite was investigated using Scanning Electron Microscopy (SEM). A key mechanism, termed “Ductile Containment,” was identified where the outer aluminum shell contains the inner composite, leading to stable crushing. The optimized design (AHC-4LR geometry, [0/0] layup) achieved the Specific Energy Absorption (SEA) of 12.85 kJ/kg. These findings underscore that the strategic placement of the composite is a critical parameter for enhancing crashworthiness.