Hysteresis Modeling And Deflection Control Of Shape Memory Alloy Bump

With the development of aviation technology and intelligent material science,new requirements for the flight efficiency,flight cost,safety and stability of aircraft are put forward.When the aircraft reaches the critical Mach,the shock resistance will increase sharply,and with the increase of flight speed,it will even become the main component of the flight resistance.Therefore,it is of great significance to reduce the wave resistance.Shock control bump is a passive method of shock wave drag reduction.In recent years,the concept of self-adaptive bump has been proposed.In this paper,the twodimensional and three-dimensional adaptive shape memory alloy bumps are proposed for adaptive shock wave control.The main contents and innovations of this paper include:(1)Two-dimensional and three-dimensional bumps were trained using the phase change cycle method under constant stress.The deflection-temperature curve was used to evaluate the merits of the bumps.By comparing the deflection-temperature curve of three different thicknesses(0.25 mm,0.35 mm,and 0.55mm)bumps,it is found that the bumps with 0.55 mm thickness has superior performance.(2)A PXI-based measurement and control system was designed,as well as a Labview-based measurement&control program and a graphical display interface.In order to overcome the difficulty of the algorithm design with Labview graphical programming language,Matlab's calculation module is called by Labview to implement the programming of the algorithm,which has a high stability.(3)The hysteresis relationship between the temperature and deflection of the three-dimensional shape memory alloy bump was obtained through experimental tests.A discrete model identification method based on the Preisach theory was proposed,and the hysteresis model of the three-dimensional shape memory alloy bump was established.In order to solve the problem that thermal expansion can interfere with phase transition hysteresis,a method of fitting the deflection component of thermal expansion with experimental data was proposed,and the phase transition deflection and thermal expansion deflection were separated.The accuracy of the model is verified by comparing the experimental value with the theoretical value(4)Model-free control experiments were performed on two-dimensional and three-dimensional bumps,and model-controlled experiments were performed on three-dimensional bumps.The results show that the deflection of two-dimensional bump can be control well by using model-free control.For three-dimensional bump,the effect of model control is better than that of model-free control.