Stiffness Active Enhancement Method Research In Thin Cylindrical Shell Structure Based On SMA Actuator

Hypersonic aircraft, which is an important direction of the aircraftdevelopment today, is easy to cause pneumatic thermoelastic problems for thepneumatic thermoelastic coupling affection when flying at high speed. For example,pneumatic effect changes the stiffness characteristic of structure of the aircraft,resulting in a decline in aircraft structure flutter speed and then serious impact onthe control precision of aircraft and even the flight safety.This paper researched the basic strategy and control method of the structurestiffness control from the basic rules and influence factors of the changes of aircraftstructure stiffness under the condition of pneumatic heat load. By using smartmaterial actuator on active control, a design scheme of aircraft structure stiffnessactive control system is proposed to fulfill the functions of smart material and theactive control structure, providing a new idea and solution to the decline ofstructural mechanics performance and improvement of pneumatic thermoelasticitycaused by thermal effect. This paper will research on the active control method ofthe typical aircraft structures stiffness in thermal environment.This paper analyzed the cylindrical shell structure stiffness enhancementmechanism and established the cylindrical shell structure dynamic equation, anddiscussed the relationship between structural stiffness and elastic modulus and thecalculation formula between elastic modulus and temperature, and the dynamicequation of cylindrical shell structure is established based on Love equation undertwo kinds of states of with active control and without active control and worked toutthe vibration frequency formula and these two states and finally calculated theinfluence of different temperature on the structure stiffness.The simulation analysis was carried out on the structure with finite elementsimulation method, which analyzed and calculated corresponding order modalfrequency values of structure under the boundary conditions of theoreticalcalculation. And through the contrast and analysis of simulation and calculationresults, we verify the validity of the theoretical model.This paper analyzed the temperature, stress and the relationship between thestress of shape memory alloy when heating based on one dimensional constitutive model of shape memory alloy, and deduced the temperature response characteristicsof shape memory alloy and then analyzed the influence of heating current, thediameter of the shape memory alloy and the influence of thermal conductivity ontemperature response characteristics by means of the heat transfer and electricalrelated knowledge, and finally complete the relevant design and arrangement of theactuator.Experimental analysis were performed for the proposed control method andground simulation test platform was set up to get relevant experimental data, whichverified the effectiveness of theoretical derivation and simulation calculation andanalysis results of the proposed method, which applied smart material to structurestiffness control.