Design, Analysis and Comparison of Biomimetic Hierarchical Honeycomb Sandwich Composites for Aerospace Applications

This study explores the performance of a geometrically modified honeycomb structure in terms of crashworthiness, energy absorption capacity, and structural stiffness, through a comparative analysis with a conventional honeycomb core design. To evaluate the influence of hierarchical geometry on these parameters, three distinct honeycomb core models were developed, each representing an ascending level of hierarchical complexity. The hierarchical architecture, inspired by spider web morphology, integrates smaller hexagonal infill patterns concentrically within the primary honeycomb cells. These nested hexagons are connected via radial spoke-like beams, mimicking the concentric and radial organization characteristic of natural spider webs. The geometric models for all configurations were developed using SolidWorks. A standard hexagonal honeycomb core was also created to serve as a baseline for comparison. All core models were subjected to identical boundary conditions and loading scenarios to ensure consistency and accuracy across simulations. Finite element simulations were conducted using ANSYS Mechanical Workbench and ANSYS Mechanical LS-DYNA 2023 R1. For crashworthiness evaluation, an out-of-plane impact loading scenario was simulated. For stiffness evaluation, Aluminium 7075-T6 (Al 7075-T6) honeycomb cores were sandwiched in between two Carbon Fibre Reinforced - Polyether Ether Ketone (CFR-PEEK) face sheets and the assembled specimens were subjected to three-point bending tests to evaluate their specific stiffness and flexural rigidity. These sandwich composite specimens were developed due to their widespread adoption in the aerospace industry, where high stiffness-to-weight ratios are essential. Additionally, low-velocity drop-weight impact tests were carried out to assess the structures' energy absorption characteristics. The simulation results indicate that hierarchical honeycomb cores offer significantly improved mechanical performance compared to the conventional design-particularly in terms of energy absorption and stiffness. This enhancement is attributed to the added geometric complexity of the hierarchical structuring, which plays a key role in optimizing structural response under both quasi-static and dynamic loading. These findings underscore the promise of biomimetic hierarchical designs in advancing lightweight structural systems for high-performance aerospace applications.