Mechanical performance of novel curved sandwich structures featuring 3D printed continuous carbon fiber/polyamide 6 composite corrugated core with rail interlocking

Abstract

The integration method of skin and core components in sandwich structures significantly influences their overall performance and functionality. This study introduces an innovative design for curved sandwich structures incorporating a rail interlocking mechanism, which demonstrates superior weight-specific mechanical properties compared to conventional joining techniques. The sandwich skins were fabricated using carbon fiber/epoxy composites prepregs via vacuum bagging, while the rail interlocking core structure was manufactured using 3D printing technology with continuous carbon fiber/polyamide filament. Mechanical performance was evaluated through three-point bending tests and compared with alternative joint configurations, including contact, adhesive, and bolt joints. Theoretical analysis was also conducted to derive failure strengths for various failure modes, and failure maps were constructed based on core and skin thickness. The results indicate that the rail interlocking structure exhibited superior mechanical performance, demonstrating an 18.8 % increase in specific strength and up to 22.9 % higher energy absorption capacity compared to adhesive model. The developed theoretical models accurately predicted failure loads across different failure mechanisms, demonstrating excellent agreement with experimental results, notably achieving a deviation of only 4.7 % for the adhesive model. It was noteworthy that the novel rail interlocking sandwich structure showed effectiveness in achieving lightweight design, superior mechanical performance, and practical advantages for curved and large-scale applications is particularly noteworthy.