Control of Nonlinear Behavior - Experiments
Final rept. 10 Jun 93-9 Sep 96
DUKE UNIV DURHAM NC DEPT OF MECHANICAL ENGINEERING AND MATERIALS SCIENCE
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The full effects of the problem of control surface freeplay in an aeroelastic system are examined in the context of a three degree of freedom aeroelastic typical section. A computationally efficient numerical model of the nonlinear system is presented, in which the control surface freeplay is modeled as a system of piecewise linear state space models. The system response is determined by time marching of the governing equations using a standard Runge Kutta algorithm in conjunction with Henons method for integrating a system of equations to a prescribed surface of phase space section. An experimental model which closely approximates the three degree of freedom typical section in two-dimensional, incompressible flow has been created to validate the theoretical model. Consideration is also given to modeling realistically the structural damping present in the experimental system. Limit cycle oscillations are studied numerically and experimentally. The numerical model captures the full range of nonlinear behavior present in the physical system, including decaying oscillations, limit cycles, quasiperiodicity, nonperiodicity, possible chaos and divergent flutter.
- Fluid Mechanics