Integrated experimental and numerical modeling study of compressive behaviors of needled C/C composite rings at room and high temperatures

This paper presents a novel approach combining numerical simulations and experiments to evaluate the mechanical behaviors of ring-shaped throat backups reinforced with needled C/C composites in solid rocket motors under room and high temperatures. First, the fracture pattern of the ring is examined experimentally. On this basis, a multiscale homogenization method is used to integrate microstructural features into a macroscale model by passing homogenized temperature-dependent material properties. The macroscale model is established according to the experimental condition, and combines the Tsai–Wu failure criterion for initiation and an instantaneous stiffness reduction method for evolution. Meanwhile, zero-thickness cohesive elements are employed to obtain fracture behaviors within the ring. Validation against experimental results demonstrates the predicted relative errors are both below 12.22 % for the critical load and displacement. Furthermore, investigations into the effects of the wall thickness and aspect ratio (β) indicate that the peak load and compressive stiffness go up as the wall thickness or β rises at 1200 °C. The results show that the ultimate load increases nearly 25-fold as the wall thickness grows from 1 mm to 5 mm, while it increases by 34.69 % as the β rises from 0.86 to 1.2. Additionally, the ring length has little significant influence on the critical displacement. These findings provide theoretical guidance for the design and optimization of needled C/C composite ring-shaped parts.