Compression and bending performance of thermoplastic corrugated sandwich panels with recycled PET foam

The core topology of sandwich panels plays a pivotal role in determining their mechanical performance, weight efficiency, and multifunctional capabilities. This paper experimentally and numerically investigates the mechanical performance of corrugated core sandwich panels with varied core geometries, including triangular, trapezoidal, rectangular, and circular, under compression and bending loads. Panels were fabricated using polylactic acid (PLA) and tested both with and without the addition of recycled polyethylene terephthalate (R-PET) foam inserts. R-PET foam, a sustainable material, offers benefits in strength-to-weight ratio, moisture, thermal, and acoustic insulation. The results indicate that core geometry significantly impacts load-bearing capacity, with rectangular cores exhibiting superior compression strength while triangular cores excel under bending loads. The foam inserts, placed within the core channels, notably improved compressive and flexural load capacity by, on average, 270 and 220% across all geometries with only a 30% increase in weight. Failure modes were also observed, with initial mode 1 buckling of the core walls and localized deformation leading to subsequent failure mechanisms such as delamination and core debonding. ABAQUS was used to develop finite element models for flatwise compression and three-point bending tests for all core geometries. The numerical simulations closely aligned with the experimental results, providing insights into stress distribution, the influence of cell wall thickness, and the impact of corrugation angles on panel performance. These findings highlight the critical role of core geometry and the impact of foam inserts in enhancing structural integrity in sandwich panels.