Structural performance and failure analysis of balsa and PET core carbon fiber sandwich structures

In this study, carbon fiber-faced balsa-core (Balsa/carbon/sandwich) and carbon fiber-faced PET-core (PET/carbon/sandwich) composites were fabricated. Three-point bending, edge compression, and surface compression tests were performed to comparatively examine the mechanical strengths of both composites. After the experiments, macro- and micro-images of the damage occurring in the surface and core layers were obtained. Image processing was applied to the obtained micro and macro images to better examine the damage behavior of the Balsa/carbon/sandwich and PET/carbon/sandwich composites. Experimental results showed that balsa wood core composites exhibited superior flexural strength at a high maximum load of 3800 N . However, this structure fractured brittlely with sudden load drops. In contrast, PET core composites, despite reaching a lower peak load of 1800 N , exhibited high energy absorption due to their ductile behavior. Numerical measurements were performed using image processing analyses to determine damage propagation. When the numerical measurements were evaluated, damage propagation showed a more widespread distribution in PET core samples, while it was more localized but less severe in balsa wood core samples. These critical differences highlight the importance of core material selection in sandwich structure design. Balsa wood is recommended for areas where high rigidity and strength are required, while PET exhibits better structural integrity and energy dissipation under deformation.