Mechanical Performance of Bio-Based Additively Manufactured Honeycomb Sandwich Panels: Experimental and Numerical Investigation

Honeycomb-core sandwich structures offer excellent strength-to-weight performance, making them well-suited for lightweight and sustainable engineering applications. This study investigates the mechanical behavior of bio-based, three-dimensional printed honeycomb sandwich panels using numerical analysis. A finite element (FE) model was developed to simulate three-point bending tests on hexagonal honeycomb cores fabricated from bioepoxy materials with plywood face sheets. The numerical predictions were validated against experimental data from mechanical testing of the printed specimens. The effects of key geometric parameters, including core height, panel width, cell size, and face sheet thickness, on structural stiffness and load-bearing capacity were systematically assessed. A progressive damage model predicted the peak load within 0.6% and captured the postpeak failure behavior. Increasing the core height from three to four printed layers proportionally improved bending stiffness. Similarly, the 2.3 mm face sheet configuration reached a maximum load of 1526 N, more than twice the 705 N of the 1.0 mm sheet. Smaller 15 mm cells exhibited higher absolute stiffness (75.2 N/mm) than 45 mm cells (63.1 N/mm), though the coarser cells showed 78% higher specific stiffness and were the more mass-efficient design, while increasing panel width from 32 mm to 40 mm enhanced stiffness by around 25%. These findings demonstrate the potential of combining additive manufacturing with bio-based materials to produce sustainable sandwich structures with tunable mechanical properties.