A Generalized Methodology for a Highly Parallelizable Uncoupled Method for Static Aeroelastic Analysis in Support of Design Optimization

Abstract

Incorporation of static equilibrium aereoelastic deformations into the design phase of a vehicle platform would result in a final design that is holistically closer to optimal from a weight and performance perspective than neglecting these effects and potentially correcting problems with a patchwork of solutions. Today, accurate analysis of fluid structure interaction (FSI) is readily achieved by coupling computational fluid dynamics (CFD) solvers to finite element analysis (FEA) tools. Unfortunately, due to the high computational cost associated with CFD-based FSI analysis, the consideration of aeroelastic solutions in trade studies and design optimizations are typically infeasible. The desire to account for these aeroelastic effects in the design phase has led researchers to develop alternative means of obtaining the equilibrium aeroelastic solution. One such scheme, known as the uncoupled static aeroelastic analysis (SAA) method, removes the standard iterative approach of exchanging field information between the structure and fluid domains across a model interface, and instead replaces it with independently generated fluid and structural databases. Generation of these databases is trivially parallelizable and obtained by performing many separate structure and fluid analyses. By generating response surfaces from these solution databases, the equilibrium solution between the structure and fluid domains can be analytically obtained without additional assumptions. Previous work has shown this scheme is capable of significantly reducing computational expense as compared to traditional coupled FSI analyses when many static solutions are required. However, prior work has been limited to 2D and simple 3D problems with easily parameterized geometry. This work extends the approach to arbitrarily complex 3D geometries by utilizing mode shapes and corresponding generalized forces as fitting parameters. Application of this new approach is demonstrated on a high-altitude long endurance (HALE) wing utilizing both linear and nonlinear finite element models. The uncoupled approach is shown to accurately reproduce the equilibrium solution obtained by classic coupled approaches. Furthermore, the incremental computational costs associated with obtaining subsequent aeroelastic solutions is substantially reduced as compared to the traditional coupled FSI scheme.