Nonlinear aeroelastic analysis for a wrinkling aeroshell/ballute system

Nonlinear aeroelastic analyses have been performed for a modeled ballute system with wrinkling phenomena considered. Specifically, the explicit nonlinear finite element code, DYNA3D, is extended to include the modified Newtonian flow theory for providing hypersonic aerodynamic loading; and a higher fidelity CFD approach, gaskinetic Bhatnagar-Gross-Krook-Xu (BGKX) method, is currently under development and will be integrated with DYNA3D to render a tightly-coupled nonlinear aeroelastic analysis system. BGKX has broad applicability of wide range of Knudsen number from continuum to transition flow, and accurate solutions for real gas flow, crisp shocks resolutions and shock-shock interactions, thus an ideal aerodynamic tool for hypersonic re-entry applications. DYNA3D's feasibility on wrinkling modeling is carefully investigated through a rectangular membrane under simple shear and Buck's experimental cone configuration under CF4 wind tunnel test. Thereafter, nonlinear aeroelastic analyses for the modeled ballute system (MBS) reveal that, at lower altitudes, the MBS has larger overall displacements due to the larger dynamic pressure. As the altitude gets lower, the wrinkling becomes more pronounced, and some secondary (smaller amplitude) wrinkles appear along with the primary ones. At higher altitude, the wrinkling is comparatively less evident. Dynamic characteristics around the statically deformed MBS configurations are studied from the restarting transient analysis after the nonlinear aeroelastic static analysis.