Ultimate state assessment of medium-thick composite cylindrical pressure shells based on progressive damage

The ultimate strength of medium-thick composite pressure shells under hydrostatic pressure was studied by experimental test and finite element method in this paper. The ultimate strength, damage form and strain response of cylindrical shells were obtained by hydrostatic destruction test, which carried out for two T700 carbon fiber/epoxy composite cylindrical pressure shells with different length. Meanwhile, finite element models were built to predict the strength failure pressure based on the progressive damage mechanism of composite materials and its initial defects. The finite element results were in close agreement with the experimental results. A parametric study was carried out to discuss the effect of radius-length ratio and radius-thickness ratio on ultimate strength. Based on the numerical results, an empirical formula was proposed as a function of radius-length ratio and radius-thickness ratio to predict the ultimate strength of medium-thick composite pressure shells.