Research On Integrated Structure-Control Design Of Flexible Linkage Mechanism Based On Noise Attenuation

Various high-speed flexible mechanisms are used popularly in modern industries. Due to their small damp,and the coupling of their large overall displacement and local distortion,they are ready to vibrate under exterior disturbance,which usually leads to intense acoustic radiation,then deteriorate the circumference. Noise pollution has been paid much more attention in modern society,and noise control has become one of the most important tasks in the design of modern mechanisms. It is a challenge project for us to predict the acoustic radiation of high-speed mechanism,and try to depress it effectively,which is also one of the key problems to solve in the design of mechanical products,aeronautics & astronautics products,and martial products. In this study,the analysis of acoustic radiation of flexible linkage mechanism,noise attenuation,and other problems involved in the study of mechanism acoustic radiation are carried out,and some conclusions are obtained.In this dissertation,based on the elasto-dynamic analysis of flexible linkage mechanism,the dynamics equations of the mechanism are obtained. In precondition with the solving of dynamic response of the mechanism,the calculation of acoustic radiation performance index is studied,and the rules of acoustic radiation of flexible linkage mechanism are discussed via several simulation examples. With the wave number analysis of the structural vibration of flexible mechanism,the relationship between structural vibration and structural acoustic radiation are studied. Based on the conclusion of wave number analysis,a new dynamic equation taking the measure of structural acoustic performance is obtained by a set of transformation,which is much convenient for us to discuss the noise attenuation.The structural optimization based on noise attenuation is studied,in which the thickness of each link is taken as the design variable,and the weighting sum of structural mass and measure of the structural acoustic performance is taken as the synthesis performance index. Modified constrained variable metric method is adopted in this optimization,and the application of perturbation method in the re-analysis of the structure is studied.The active structural acoustic control of flexible mechanism is discussed. According to the linear optimal control theory,the optimal control forces are determined,and the design of controller is discussed. At the same time,the application of piezoelectric actuator is studied.The idea of integrated structure and control design is introduced into the structural acoustic control,and two methodologies are discussed on the integrated structure and control design based on noise attenuation. In the first methodology,the active control forces are depended on the structural parameters,and the relationship between them is determined by a matrix Riccati equation. Then the synthesis design variables are kept down to structural design variables. In the second methodology,parameterized matrices are taken as the weighting matrices of the quadratic performance index. Due to the existence of the relationship between parameterized matrices and control forces,the parameterized coefficients of the weighting matrices can be regarded as the control parameters,and they are taken as one part of the synthesis design variables.Since the experimental conditions can not meet the requirement of acoustic measuring,a method based on experiment and simulation analysis is developed. At first,the dynamic response of the mechanism can be measured with the multifunction testing bed,which is designed by ourselves. Then the dynamic response can be taken as the boundary conditions,and the acoustic analysis will becarried out with the help of acoustic analysis software ------ SYSNOISE. Due tothe high-reliability of SYSNOISE,the results can be regarded as the experimental results. After comparison with the results of calculation,the methodology presented is validated.