Three-Dimensional-Printed Natural Fiber-Reinforced Composite Honeycomb Sandwich Structures Inspired by Beetle Forewings for Circular Economy Applications

Introduction:
In the context of a circular economy, the integration of renewable materials into structural components is a key pursuit in mechanical engineering. Honeycomb sandwich structures are widely used in energy absorption and impact mitigation due to their high strength-to-weight ratio. This study explores the use of wood-fiber-reinforced poly (lactic acid) (PLA/WF) in 3D-printed sandwich panels inspired by the end-trabecular structure of beetle elytra.

Methods:
Two structural configurations—a traditional honeycomb plate (HP) and a beetle elytron-inspired plate (EBEP)—were fabricated using fused filament fabrication with both pure PLA and PLA/WF materials. Out-of-plane compression tests were conducted alongside finite element analysis (FEA) to evaluate mechanical performance. Additionally, microstructural characterization using SEM and a cost analysis of the materials were performed.

Results:
PLA/WF-based structures exhibited a 10–17% increase in specific compressive strength and a 26–44% improvement in energy absorption compared to PLA counterparts. The EBEP design demonstrated over 90% higher structural efficiency than HP. FEA results closely matched experimental data, confirming model validity. SEM revealed multiple reinforcement mechanisms in PLA/WF, including improved stress transfer, interfacial bonding, and energy dissipation through micro-voids and crystalline domains.

Conclusion:
The synergistic effect of biomimetic geometry and natural fiber reinforcement significantly improves the compressive performance and sustainability of 3D-printed sandwich panels. The PLA/WF-based EBEP offers a lightweight, cost-effective, and eco-friendly solution for mechanical components requiring energy absorption, such as crashworthy modules or protective layers in mechanical systems.