Hydrostatic load-bearing capacity of porosity-affected filament-wound egg-shaped pressure hulls: RVE-based material characterization and numerical assessment

This study addresses a critical challenge in composite pressure vessels where pore defects, inevitably introduced during manufacturing, significantly compromise structural integrity and safety performance. An investigation is therefore conducted into the failure mechanisms of filament-wound egg-shaped pressure hulls containing such defects. Representative Volume Elements featuring circular, elliptical, and cylindrical pores were developed. Based on homogenization theory, the macroscopic equivalent material properties were predicted utilizing the maximum stress criterion and the maximum principal stress criterion. These derived micro-scale parameters were subsequently incorporated into a macro-scale progressive failure analysis framework for the filament-wound egg-shaped hull. By integrating the 3D Hashin failure criterion with a fracture energy-based damage evolution model, the effects of dominant pore morphology, shape factor, winding layer and liner thickness, and slip coefficient on the ultimate bearing capacity were systematically evaluated. The results indicate that pore morphology significantly affects the transverse tensile and compressive properties of the material. Compared to the model dominated by circular pores, the model dominated by elliptical pores exhibited a 19.28% increase in transverse tensile performance and a 14.34% increase in transverse compressive performance. When the liner thickness increased from 2 to 6 mm, the ultimate bearing capacity of the egg-shaped hull significantly improved by 187.82%.