Studies On Vibration Active/Passive Control Methods Of Satellite Adapter Structure

Since 1990's, the structures had become larger and more flexible with the development of aeronautic, aerospace, mechanical, architecture and marine. Then, the problems which caused by the vibration and resonance such as destroy, disable and disturb can't be neglected during engineering design process. Investigation on vibration control of structures becomes an important and challenge issue for academia and engineering.At present, many satellite adapter used in aerospace engineering over the world were made up with the metal truncated conical shell structures with small damping ratios. So, it can not control the vibration effect during the launch by the adapte itself. In addition, the truncated conical shell structures, as a special thin walled braced structure, are wildly used in some other engineering fields. Nozzles, joint elements, adapters and fairings can be seen as conical shell structures. Then, the investigations on vibration control of this structure have important practical significance. Then, the investigation subject of this paper is a conical shell satellite adapter model in aerospace application. Theoretical derivations and experiment on active and passive vibration control for the conical shell model have been performed.There are two types of structures vibration control method: active control and passive control. The passive control needs no control energy input and has a simply form with good stability. The inefficient for low frequencies vibration control is the main shortage of passive control method. The active control method can supply the gap of the passive control. Low frequencies vibration can be controlled effective by using active control method and the controller design becomes more flexible.The main contents of the paper are as follows:The passive control of structure vibration research in this paper includes three aspects. Firstly, the parameter variations affect for vibration isolation system is analyzed by a simplified model with two degree of freedoms. Secondly, composite honeycomb structures were applied for structural modifications of the truncated conical shell satellite adapter model. The mathematical modeling of the structure above is based on equivalence method. Thirdly, an aluminum conical shell model with constrained damping layer was simulated by using modal strain energy method. The calculation results of the second and third part above were compared with the relevant data of untreated aluminum conical shell model. Comparison results proved that the adoption of composite and honeycomb structure could improve the effect of vibration isolations and reductions.Based on the piezoelectric equations and Hamilton principle, four nodes Mindlin plate element is applied for finite element modeling. But it is difficult for the modeling of complex piezoelectric structures by the method above. Then, in this paper, an equivalent modeling method based on the universal finite element software is present. Commercial softwares Patran/Nastran are used for derivations of structural dynamic equations. The control force of piezoelectric actuator is considered as boundary conditions in dynamic equations. The actuating equations are derived from piezoelectric equations and electrodynamics. Numerical examples show that this method is efficient and accurate.Active control of vibration for the truncated conical shell satellite adapter model is simulated with the independent modal space control method base on the finite element model and dynamic equations. The method has an extensive application in structure vibration control and the controller design is simplified with it. Two control laws are used for the simulations and comparisons. One is the proportional feedback control and the other is LQR optimal control. Vibration control results prove the availability of actice control method and the LQR control has a high performance.Optimal placement of actuators is investigated with the optimization criterion of modal damping ratios maximization. Accumulation method is used for optimization calculations. Numerical results show that actuators located at the optimal place can control the vibtaion effectively.Several relevant experiments were performed to validate the results of theoretical analysis and simulations. Firstly, modal test was accomplished for the composite honeycomb conical shell adapter model by using LMS system. The experiment results were in good agreement with the calculations. Secondly, vibration table experiment was conducted to test the vibration transmissibility of the model above. The results show that the model has favorable vibration isolation effect. Finally, based on the xPC real-time control platform in MATLAB, active vibration control experiment for conical shell adapter model was developed by using piezoelectric actuators. Feasibility and effectiveness of the active method were verified by control results comparisions.