Crushing behavior of sandwich beams with thermoplastic honeycomb core and composite skins under 3-point bending

The main objective of this work is to investigate the indentation behavior of sandwich structures with circular polypropylene cells as honeycomb core and E-glass fabrics with polyester skins submitted to 3-point bending using numerical models and experimental tests. The methodology involved the manufacturing of sandwich panels via vacuum infusion, followed by a comprehensive experimental characterization, including tensile, compression, and flexural tests according to ASTM standards. The polypropylene honeycomb core was also tested separately to identify its elastoplastic behavior and failure mechanisms, which were incorporated into detailed finite element models developed using Abaqus/Explicit. The developed numerical models were very useful in predicting indentation effects under 3-point bending conditions. The experimental peak loads ranged from 0.19 to 1.11 kN depending on the span and core thickness, while the numerical predictions varied from 0.24 to 1.19 kN, showing good agreement. It was observed that by increasing the span to 167%, the load capacity of the sandwich structure reduced to 42%, mainly due to the post-buckling phenomenon with elastoplastic behavior of the core. This highlighted the importance of precisely predicting indentation in sandwich structures.