Structural-acoustic Coupling Response Analysis Based On Modal Energy Method

Vibration problems existe widely caused by noise environment in the field of aviation,aerospace,machinery,ships and so on.Especially for the typical thin-walled structures,it is easy to form coupling effects between structures and noise,which is necessary to take coupling effect on dynamic response into account during the design stage.In practical engineering problems,uncertainty exists widely in the structural-acoustic coupling system due to mechanical parameters' uncertainty.Accurate structural-acoustic coupling dynamic response prediction method would provide important guidance for the engineering design and testing scheme.Therefore,further study of structural-acoustic coupling analysis method has important theoretical significance and engineering value.In this paper,structural-acoustic coupling dynamic response analysis method has been studied based on MODal ENergy Analysis.The main research work has following four aspects:Firstly,basic theory of MODal ENergy Analysis about coupled two-oscillates and multi modal coupling systems are established based on the energy balance equation.Coupled two-oscillates system and regular plate-cavity coupling system are taken out as the research object to demonstrate the accuracy of MODal ENergy Analysis.Furthermore,influence to the energy response changed by the coupling effect and system parameters are also studied.Results show that:when gyroscopic coupling coefficient is more than that of critical value,energy flows from lower energy subsystem to higher energy subsystem in coupled two-oscillates system.Gyroscopic coupling coefficient is related to the similarity of section lines on the coupling surface and the complexity of vibration mode.The higher of the similarity,the lower of the complexity,the coefficient is larger,and the modal coupling is stronger.MODal ENergy Analysis is an effective means to solve structural-acoustic coupling response problems.Secondly,complex structural-acoustic coupling system that modes information cannot be solved by analytical ways are taken into account.Finite Element-MODal ENergy Analysis theory is built.A stiffened plate-cavity coupling system is studied to verify the correctness and universality.Results show that:Finite Element-MODal ENergy Analysis has precise answers on system energy response.It is a reliable means to analyze complex structural-acoustic coupling system response.For specific frequency response,a fine answer can be obtained within a certain frequency band into consideration.For complex structural-acoustic coupling system,very accurate answer can be given when considering multi point random excitation.Then,Random Perturbation MODal ENergy Analysis theory is built based on Random Factor Method and Random Perturbation Method considering parameter probable uncertainties.Plate-cavity coupling system is taken out to study the effects on energy response of coupled systems with the variation of Young's modulus and density of the plate,where Monte-Carlo Method is used to verify the accuracy.Results show that:Random Perturbation MODal ENergy Analysis is an efficient method to predict energy response with parameter probable uncertainties.Energy response doesn't necessarily obey normal distribution whether the distribution pattern of random parameters,which may be related to analysis frequency.Finally,Interval Perturbation MODal ENergy Analysis theory is built based on Interval Factor Method and Interval Perturbation Method considering parameter interval uncertainties.Plate-cavity coupling system is taken out to study the effects on energy response of coupled systems with the variation of Young's modulus and density of the plate,where Monte-Carlo Method is used to verify the accuracy.Results show that:Interval Perturbation MODal ENergy Analysis is an efficient method to predict energy response with parameter interval uncertainties.