Initial Configuration and Nonlinear Mechanical Analysis of Stratospheric Nonrigid Airship Envelope

Abstract

A stratospheric airship (SSA) is a cost-effective platform for telecommunications and science missions in near space 20 km above the Earth’s surface. However, an accurate model of the structural behavior of the large envelope of a SSA composed of a series of identical gores welded together has not been developed to date owing to the complex mechanical properties of the multilayer laminated envelope materials, complicated manufacturing procedures, stringent operational conditions, and variation of the loading. In this work, biaxial tensile experiments on a typical SSA envelope fabric are first performed to describe the nonlinear mechanical properties based on the response surface method, and a nonlinear material model for numerical analysis is developed. Next, patterning effects and creep influences of a reduced-scale model of the SSA envelope are thoroughly analyzed and discussed. The initial configuration of the scale model is presented and compared to the ideal model generated by the revolution of the design shape profile. Finally, experiments and numerical analyses on the scale model under the inflation process are performed and discussed in detail. Compared to the ideal model, the numerical results of the model considering the initial configuration are in better agreement with the experimental results. This finding demonstrates that patterning effects and creep influences must be considered in the numerical analysis of a SSA envelope.