SBIR-STTR Award

The aerodynamic performance of aircraft is significantly impacted by the aero-elastic dynamics of its control surfaces. In particular, the dynamics of flutter - an unstable self-excitation of structure due to undesirable coupling of structural flexibility and aerodynamics - has critical impact on the stability and performance of aircraft. The control surface flutter characteristics are affected by the unavoidable free-play which is inherent in the control surface due to manufacturing imperfections. There are no systematic methods to predict free-play effect on flutter. The proposed research will develop a comprehensive tool-suite which will: (a) provide state-of-the-art capability for stability and performance analysis of any generic control surface configuration, (b) allow modeling of control surface dynamics with varying degrees of fidelity using combination of analytical, computational, and experimental identification methods, (c) provide new analysis techniques to enable accurate prediction of stability/performance boundaries for existing platforms, and (d) provide optimal design capability for design of control surfaces for new platforms. The Phase 1 of the project will develope essential elements of the proposed tool-suite to prove the feasibility of the approach and demonstrate the capabilities by using 1950's WADC test data for all-movable un-swept horizontal tail.

Benefit:
The proposed development of modeling, analysis, and design tool suite will provide state-of-the-art capability for stability and performance analysis of any generic control surface configuration. The tool suite will also provide optimal design capability for design of control surfaces for new platforms. The modular design of tool suite allows building of control surface dynamic models with varying degrees of fidelity using any combination of analytical, computational, and experimental identification methods. The nonlinear dynamic analysis tools provided will include newly developed techniques which will enable optimization of design space for control surfaces as well as accurate prediction of stability and performance boundaries for existing platforms.

Keywords:
Free play, Free play, stability, airfoil, Control Surface, Flutter, dynamics, All-movable tail, Simulation

This STTR is aimed at developing methods and tools to characterize the impact of free-play on control surface flutter and overall stability and performance of the system. A successful completion of this two-phased STTR effort will lead to a modeling, analysis, design, and simulation tool that will provide a state-of-the-art capability for stability and performance analysis for any generic control surface configuration with free-play. It will also provide an optimal design capability for the design of control surfaces for new platforms. The modularity of the tool will allow model generation with varying degrees of fidelity using a combination of analytical, computational, and experimental identification methods. The nonlinear dynamic analysis capabilities in the tool will include newly developed nonlinear analysis techniques which will enable optimization of the design space for control surfaces as well as accurate predictions of stability and performance boundaries for existing platforms. The final product is envisioned to be a software that can: Model, simulate, and analyze the existing control surface geometries with free play and provide stability and performance assessment through useful metric. Optimally design new control surfaces for a specified stability and performance robustness with least restrictive free-play specifications.

Benefit:
The successful completion of this research will result in a commercial software tool with wide-spread applications. The tool will be useful for modeling, analysis, simulation, and design of aeroelastic structures. The modular architecture of the tool will have a core set of routines (the base package) which will be common to all potential applications and then for each discipline-specific application there will be add-on packages available for purchase. Such a modular design will allow expansion of customer base with minimal increase in development costs. The market segment for the resulting software tool can be broadly classified into three categories: (1) Government Agencies (primarily federal labs); (2) Industry; (3) Academia. The target applications of the software will include aeroelastic analysis and design of aerostructures, wind turbines, tall terrestrial structures, and bridges.

Keywords:
Free-play, Limit Cycles, LCO, Flutter, optimal design, Modeling and Simulation, multidisciplinary design