Calculation and simulation of stratospheric airship capsule stress considering the pressure gradient

The capsule volume of stratospheric airships was usually too huge and the surface curvature of buoyancy capsule was small, so local stress concentration of airship envelope could easily lead to large transformation and cause the capsule to overpressure damage and blast quickly. Basing on the pressure gradient loading condition of the inside and outside of the airship buoyancy capsule, the theoretical calculation method of the hoop and axial stress was developed under the real overpressure load working situation, and the Von Mises stress strength criterion was proposed as well. The finite element (FEM) analysis software ABAQUS was used to simulate the hoop Von Mises stress under the different overpressure loads of 300, 500 and 800 Pa respectively. The contrastive results show the Von Mises values between the simulation and theoretical calculation are in consistent nearly, and the hoop Von Mises stress of airship capsule envelope increases with the increasing of pressure gradient, While the axial Von Mises stress of airship overpressure capsule is determined by the hoop Von Mises stress and envelope local curvature of the warp and weft directions together, moreover, the two kinds of Von Mises stress associated with the overpressure load is positively correlated at different directions, which provides the effective basis research of stress evaluation and strength calculation for the airship envelope overpressure.