| To solve the problem of stiffness decrease induced by aerodynamic heating, stiffness controlusing shape memory alloys was investigated based on its active strain energy tuning (ASET).Firstly, the influence of missile structure natural frequency due to aerodynamic heating wasresearched using FEM simulation, and based on properties of shape memory alloys, the stiffnesscontrol strategy was presented.Secondly, the one-dimension constitutive model of SMA which can apply to recovery stresscalculation was discussed and a device for SMA pre-stretching and recovery stress measurements wasdesigned. By using Brinson one-dimension constitutive model, the recovery stress vs. temperatureunder different pre-strain was researched and compared with experiment results.Thirdly, due to limitation in MSC.NASTRAN to simulate SMA material, combined withpractical engineering, the one-dimension shape memory alloys system was created and integrated inPATRAN based on its function of pre and post processing and secondary development. By this, it waseasy to define shape memory alloys’ properties and directly model and analyze the composites andactuators embedded with SMA wires. And to solve the problem of stiffness decrease induced byaerodynamic heating, the application of shape memory alloy fibers embedded in the structure ispresented. A composite aluminum plate with embedded SMA fibers was considered and the influenceof temperature, volume ratio of SMA and pre-strain in the SMA fibers on the plate stiffness wereinvestigated numerically.Finally, stiffness control of plate structure using shape memory alloys was investigated and thelayout optimization of actuators on the plate is presented. A FEM model was established to analyzethe active control effect and the simulation results were validated by experimental results.Furthermore, the layout of SMA actuators was optimized by using a genetic algorithm. The resultsshowed that the optimized layout is more effective in stiffness control than the original layout. |
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