Harnessing predictable failure: a bio-inspired adhesively bonded Al/CFRP hybrid structure with guided crushing for enhanced crashworthiness under oblique loading

The pursuit of lightweight and crashworthy structures in transportation is often limited by the unpredictable and brittle failure of composites. This study introduces a novel bio-inspired hybrid structure, the Adhesively bonded Hybrid Euplectella -Inspired Structure (AHEIS), that overcomes this limitation by harnessing a “guided crushing” mechanism. Inspired by the Euplectella aspergillum sponge, the design uses an adhesively bonded aluminum framework to guide the progressive crushing of corner-reinforced Carbon Fiber Reinforced Polymer (CFRP) laminates, ensuring stable and predictable energy absorption. Crashworthiness was investigated experimentally and numerically under quasistatic oblique loading angles (10°–30°). A validated finite element model, with less than 10% deviation from experiments, captured complex damage, including delamination, petalling, and matrix cracking. Parametric studies showed that the [90/0] layup maintained exceptional crushing stability up to 25°, resisting global buckling. Optimized CFRP reinforcement increased specific energy absorption (SEA) by 79% and reduced load fluctuations by 93% compared to conventional aluminum tubes. Additionally, AHEIS outperformed six alternative bio-inspired geometries in both energy absorption and crushing stability. This guided crushing strategy establishes a new design paradigm for developing reliable, damage-tolerant, and lightweight energy absorbers for next-generation automotive applications.