Research On Aeroelastic Response Of All-movable Control Surface With Freeplay Nonlinearity

At present,more and more aircraft adopts the all-movable control surface,and the transmission structure of the all-movable control surface often has a variety of structural nonlinearities,which often produce more complex dynamic phenomena and are difficult to predict.Freeplay nonlinearity is one of the most common structural nonlinearities in aircraft structure.The system with freeplay nonlinearity will generate limit cycle oscillation,bifurcation,chaotic motion and so on,which will affect the safety and stability of the system.In this paper,we take the all-movable control surface as the object of study,the aeroelastic response theories and wind tunnel tests are carried out for the nonlinear system of the all-movable control surface in regard to its freeplay nonlinearity problem.The main contents are as follows:The nonlinear structural model of the all-movable control surface is established.Virtual mass is applied to the freeplay degrees of freedom of the structure by virtual mass method to produce virtual mass mode.Modal analysis and flutter analysis for linear and nonlinear structural models verify that the virtual mass method does not affect the natural characteristics and flutter characteristics of the structure.A time domain integral method is developed to solve the nonlinear system of the all-movable control surface.By analyzing the transient dynamic response of the nonlinear system about all-movable control surface,the nonlinear parameters are calculated at each time step,then the time domain state equation of the current time step is obtained by interpolation for calculating the transient response of the nonlinear system in the current time step,and the effects of different gap sizes and wind speed on nonlinear system response are also researched.A device for simulating bending and torsion support stiffness of the all-movable control surface model and realizing the two-dimensional clearance of bending and torsion was designed for wind tunnel flutter test,and the effectiveness of the device was proved by ground test.The wind tunnel test of the all-movable control surface was carried out,implementing the linear wind tunnel test and the nonlinear wind tunnel test respectively.The nonlinear response with different clearance size,wind speed,nonlinear parameters and preloading with angle of attack was obtained,and observed a good limit cycle oscillation,The wind tunnel test provides a basis for theoretical calculation and aircraft design.