摘要: Lightweight composite cryogenic tanks are critical components of some of the next-generation reusable space launch systems. Composites offer several benefits over industry-standard metallic tanks such as reduced weight through inc... 展开 Lightweight composite cryogenic tanks are critical components of some of the next-generation reusable space launch systems. Composites offer several benefits over industry-standard metallic tanks such as reduced weight through increased specific strength, relatively low coefficient of thermal expansion, and high tailorability. However, thermal fatigue involving cryogenic temperatures and nonvisible or barely visible impact damage in composites may develop areas of microcracking, which can lead to cryogenic fuel leakage into the atmosphere. Therefore, the objective of the present study is to evaluate the gas permeability of impacted and thermally cycled composite specimens and correlate it to their absorbed energies and post-impact flexural properties. Cross-ply carbon/epoxy composites ([0/90]4s) were subjected to twenty cryogenic cycles from ambient to cryogenic temperatures (-196 ℃). Barely visible impact damage at two different impact velocities (～75 m/s and ～60 m/s) was imparted to the specimens at room and cryogenic temperatures before and after thermal cycling. The gas permeability and flexural strength of the test specimens were measured and correlated. Composite specimens subjected to impact at room temperature had higher gas permeability and absorbed energy with lower residual flexural strength. A linear relationship was observed for gas permeability with absorbed energy and post-impact flexural strength. Two linear models to predict the permeability of impacted specimens have been presented in terms of absorbed energy and flexural strength irrespective of the test temperature or impact velocity. 收起