A multi-scale damage model and mechanical behavior for novel light-weight C/C honeycomb sandwich structure

The high-resolution spacecraft poses an urgent need for opto-mechanical structure with ultra-high stability and light-weight. Owing to the advantages of both carbon fiber-reinforced carbon-based composites (C/C composites) and honeycomb sandwich structure, a novel C/C honeycomb sandwich structure strategy is proposed in this study. It was fabricated by using weaving fabrics and Chemical Vapor Infiltration (CVI) process, then was tested under out-of-plane compression. Taking the weave structure of honeycomb wall, anisotropy characteristics and damage mechanism of C/C composites, as well as the parameters of core size, a multi-scale damage model is established and validated to investigate mechanical behavior of the novel structure. The effects of influence factors (side length, thickness and height of core) on mechanical properties and damage mode of the novel sandwich structure are investigated. The results demonstrate that the optimal honeycomb core sizes for improving the light-weight and high load-bearing integration performance are l = 5 mm–7.5 mm and t = 0.3 mm–0.4 mm. The matrix damage occurs in the middle region of core, while fiber damage occurs at the end of core when its height reaches 15 mm. This study is helpful for design and optimization for opto-mechanical structure of high-resolution spacecraft.