Behavior of Sandwich Glued Laminated Bamboo Structures with a Core Formed by Bioplastic Fiber Using 3D Printing Technology

This research investigates the behavior of sandwich glued laminated bamboo (Glubam) structures with a core formed by biodegradable plastic fibers, specifically polylactic acid (PLA), fabricated using 3D printing technology. The influence of various fiber printing orientations (0° and 45/135°) on tensile and compressive properties was investigated. The experimental results indicated that polylactic acid with calcium carbonate (PLA+) printed unidirectionally and aligned with the loading direction (0°) exhibits superior tensile and compressive strengths compared to specimens printed bidirectionally at 45/135°. Furthermore, the effect of additives on bioplastics of carbon fiber (PLA-CF) and glass fiber (PLA-GF) additives in PLA-based composites was evaluated in comparison with PLA+ specimens. The finding indicated that PLA+ has a higher strength-to-cost ratio compared to PLA-CF and PLA-GF. Therefore, unidirectionally printed PLA+ was selected as the core material in two geometries: honeycomb and honeycomb lattice. These cores were sandwiched between Glubam panels on the top and bottom surfaces of the structures. Flexural performance was evaluated through four-point bending tests, which revealed that sandwich structures with a honeycomb core achieved a flexural strength-to-weight ratio 56.51% higher than those with a honeycomb lattice core. A parametric study using the finite element model was conducted to evaluate the effect of core scale, cross-sectional depth, Glubam thickness, core depth, and the number of honeycomb elements. The results showed that reducing the Glubam thickness while increasing the 3D-printed core depth significantly improved the flexural performance of honeycomb sandwich structures. Notably, reduced Glubam panel thickness coupled with increased core depth enhanced their flexural performance.