Additively manufactured bio-inspired energy absorbers based on avian bone structure for enhanced crashworthiness

This study introduces an Avian Bone-Inspired Structure (ABIS), a bio-inspired energy absorber fabricated via Fused Deposition Modeling (FDM) using carbon-fiber-reinforced polylactic acid (PLA-CF) to enhance the crashworthiness of lightweight energy absorbers. Motivated by the limitations of conventional manufacturing in realizing complex biologically inspired geometries and the need to achieve high energy absorption at minimal mass, the novel ABIS concept emulates the hollow and internally reinforced morphology of avian bones, integrating a gyroid infill pattern and a tapered outer geometry to achieve efficient energy dissipation under axial loading. The primary objective of this work is to experimentally evaluate and optimize the crashworthiness performance of this bio-inspired architecture in terms of Specific Energy Absorption ( S E A ) and Crush Force Efficiency ( C F E ) using a surrogate-based optimization framework. Quasi-static compression tests were performed on the nominal ABIS design (N) and a simple tube (ST) baseline design to evaluate S E A and C F E . The N design exhibited a 124% increase in S E A and a 65% improvement in C F E compared to the ST design. Specifically, the S E A increased from approximately 10.3 kJ/kg for the ST design to 23.1 kJ/kg for the nominal ABIS, with a corresponding increase in C F E from 0.44 to 0.72. Design exploration using Latin Hypercube Sampling (LHS) was employed to analyze the effects of infill density, number of walls, and taper angle on crashworthiness indicators. Surrogate-based optimization using Polynomial Response Surface (PRS) and Gaussian Process Regression (GPR) models identified two optimal candidates. The optimal configuration, characterized by 19% infill density, five walls, and a 6.3° taper angle, achieved a 27% increase in S E A relative to the N design without a significant change in C F E , and improvements of 185% in S E A and 64% in C F E compared to the ST design, resulting in an S E A of approximately 29.3 kJ/kg while maintaining a C F E of about 0.72. Experimental validation confirmed excellent agreement between surrogate model-predicted and observed results, with errors below 1%. The results confirm that the proposed bio-inspired ABIS design, coupled with surrogate-based optimization, provides a robust framework for developing geometrically efficient, additively manufactured crashworthy structures with enhanced energy absorption performance.