Research on optimization method of compact structure design for composite materials of solid rocket motor nozzle under complex thermal environment

The composite materials nozzle of solid rocket engines faces extreme thermal-mechanical loads requiring optimized thermal protection under compact design constraints. Analysis reveals significant axial temperature gradients in the throat liner (max ΔT ≈ 1800K), while radial distribution remains uniform. The insulation layer shows minimal outer surface temperature rise but steep radial gradients, with high-temperature zones concentrated at the convergent section’s inner wall and throat liner interface. Stress analysis indicates axial stresses peak uniformly at the liner’s inner surface (max 27.74 MPa), while radial/tangential stresses localize at the entrance with limited magnitude. The design demonstrates adequate safety margins in both load-bearing capacity and ablation resistance. Structural optimization achieves 25% mass reduction and 18% volume decrease while maintaining thermal-structural integrity. Radial stress concentration at the throat entrance requires particular attention in compact designs. These findings validate the effectiveness of coupled thermal-mechanical analysis in balancing performance and miniaturization requirements, guiding lightweight nozzle engineering under extreme service conditions.