Uncertain-but-nonrandom dynamic optimization of composites flexible membrane structure

In the past few years, owing to the vital role in maritime safety monitoring and marinehazard warning, stratospheric airship has become a research hotspot around the world. The structureof stratospheric airship is a typical aerated flexible membrane one. It is geometrical nonlinear inessence and it bears a distinct mechanical nature of large deformation. Therefore it makes optimizingthe structure more difficult. The current studies of air-supported flexible membrane structuraloptimization ignore the uncertainty influence which is resulted from the loading environments,material properties and structural parameters. According to the Lagrangian Coordinate method, thedeformed configuration is used as a reference in order to build accurate strain/displacement geometry.The Equilibrium equation is created by using the principle of virtual work. Meanwhile, the accuracyand stability of the solution is ensured by using the Updated Lagrangian Formulation. The uncertainparameters which are introduced during the analysis and optimization of the aerated flexiblemembrane structure are portrayed by interval mathematical theory. With respect to engineeringapplication, the factors of uncertainty are considered. Maximizing the structural fundamentalfrequency(or first-order natural frequency) is taken as the objective, while structural integrity is takenas the constraint. Then the dynamic optimization is carried out under interval uncertainty. In this waythe reliability of the membrane structure in complex conditions is improved and the probability offailure is reduced.