Experimental and numerical study of the effects of defect orientation on the crushing behavior and energy absorption of irregular aluminum honeycombs in the L and W directions

Aluminum honeycomb structures are widely used in the aerospace, automotive, marine, and defense sectors due to their excellent energy absorption capabilities and exceptional strength-to-weight ratio. However, manufacturing processes can introduce geometric defects, whose orientation and morphology may vary depending on the manufacturing method, that can compromise their mechanical performance. This study analyzes the effect of vertical (DV) and horizontal (DH) defects on the crushing of irregular aluminum honeycomb structures (77 kg/m³) under quasi-static compression in the longitudinal and transverse directions. A coupled experimental-numerical approach was adopted, combining explicit finite element simulations in Abaqus/Explicit validated by comparison to compression tests with real-time monitoring of deformation modes. Six configurations were studied: defect-free (LIR-ND, WIR-ND), vertical defect (LIR-DV, WIR-DV), and horizontal defect (LIR-DH, WIR-DH). The results reveal marked anisotropy, with SEA values ranging from approximately 0.33 to 0.43 kJ/kg in the L direction versus 0.24 to 0.28 kJ/kg in the W direction, depending on the displacement range considered. Both vertical and horizontal defects were found to consistently increase SEA relative to the defect-free configuration in both loading directions, with gains ranging from 15% to 18% in the W direction and from 19% to 28% in the L direction, depending on the defect orientation and the comparison window (e.g. LIR-DV: CFE = 0.943, SEA ≈ 0.43 kJ/kg). This counterintuitive behavior demonstrates that the controlled introduction of defects can be used to optimize energy absorption characteristics.