Abstract: Aging and creasing damage of the airship envelope materials would affect the air leakage, which is a key factor in determining the duration of a single flight of an airship. In this paper, Uretek3216-LV, a high barrier property envelope material, was used to conduct a flexural durability test across five different aging timelines (0,1, 3, 8, 12 months) under four different flex conditions (20,270,900,2700 cycles) with an air leakage test in all samples. The data was analyzed using the least square method and the principle of the residual sum of squares. The relationship curves and fitted surfaces between the pressure difference, the number of rubbing times, as well as the above two factors and the air leakage rate were obtained. The influence degree of aging and creasing damage on the air leakage rate of the material was analyzed. The deformation process of the material damage was observed by scanning the material with an electron microscope and the failure mechanism was analyzed. The results show that the short-term aging damage has little effect on the air leakage properties of the envelope materials but the creasing damage will seriously affect the air leakage properties. The air leakage is proportional to the pressure difference, and the relationship between the air leakage rate and the number of flex cycles is changed from the nonlinear positive correlation of the initial segment to the linear relationship. The failure process undergoes three stages, which are the stage of loosening and twisting of fiber, the stage of functional layer failure, and the stage of fiber breakage leading to formation of pin hole. The results obtained can provide reference for the analysis and design of the airship envelope structure.

Key words: airship envelope materials; air leakage rate; natural aging; creasing damage; pressure difference