Abstract
With increasing requirements for lower emissions, next generation transport aircraft are poised to have high-aspect-ratio wings. Long lightweight structures become very flexible, and this fact brings new challenges to the aeroelastic analysis. Time-domain aeroelastic simulations of these nonlinear systems are desirable to analyze their behavior over selected points of the flight envelope. Computational aeroelasticity has been traditionally conducted by modeling the structural dynamics behavior based on modal formulation and the aerodynamics using computational fluid dynamics (CFD). While simplified methods exist to model very flexible wings using equivalent geometric-nonlinear beams, essential details can only be captured with built-up finite element models. Unfortunately, these models are expensive and non-robust for extensive dynamic simulations.
This lecture will introduce a nonlinear modal-based formulation to be used in computational aeroelasticity. The creation of such reduced-order model (ROM) involves training that requires the fitting of nonlinear stiffness and displacements from static solutions. A new Enhanced Implicit Condensation and Expansion (EnICE) method will account for the contribution of nonlinear motion to inertia forces during dynamic simulations. The EnICE approach was integrated into the CFD code CFL3D for high-fidelity aeroelastic analyses. To close the talk, we will extend the idea of reducing further the computational cost by introducing an aerodynamic ROM based on convolution corrected by a nonlinear factor obtained from steady solutions. The aeroelastic tool arising from the two reduced-order models simulates large displacements, taking into account structural and aerodynamic nonlinearities.
Bio
Carlos E. S. Cesnik is the Clarence L. “Kelly” Johnson Collegiate Professor of Aerospace Engineering and the founding Director of the Active Aeroelasticity and Structures Research Laboratory. He also directs the Airbus-Michigan Center for Aero-Servo-Elasticity of Very Flexible Aircraft (CASE-VFA). His research interests have focused on computational and experimental aeroservoelasticity of very flexible aircraft; coupled nonlinear aeroelasticity and flight dynamic response in high-altitude long-endurance (HALE) aircraft and advanced jet transport aircraft; aerothermoelastic modeling, analysis and simulation of hypersonic vehicles; and active vibration and noise reductions in helicopters. He has also made seminal contributions in the field of structural health monitoring.
Professor Cesnik is a Fellow of the American Institute of Aeronautics and Astronautics (AIAA) and a Fellow of the Royal Aeronautical Society. He serves as AIAA’s Director for the Aerospace Design and Structures Group and is an elected member of AIAA’s Council of Directors. He has over 300 publications as archival journal and conference papers, and several invited lectures in the areas of aeroelasticity, smart structures, structural mechanics, and structural health monitoring.