A Study On Vibration Prediction And Calculation Of Vibration Source's Contribution Based On Transfer Path Analysis

Vibration problems and the resulting noise problems are widespread,which have a great harm to people's production and life.To solve the vibration problems,it is necessary to start with vibration analysis.Transfer path analysis methods(TPA)can predict the vibration response and calculate the contribution of the vibration source,so they are widely used in the vibration problems,but they still have some shortcomings.Therefore,the improvement and expansion of TPA methods for vibration prediction and calculation of vibration source' contribution are studied and the researches that have been carried out are as follows:Firstly,Conventional Transfer Path Analysis method(CTPA)is the basis of all the TPA methods and its basic theory are introduced.A cylindrical shell is taken as object of study to study CTPA's application in calculation of vibration source'contribution.The results draws the conclusion that CTPA is very accurate but its process is cumbersome.The work also lays a solid foundation for the later theory and experiment.Then,Operational Transfer Path Analysis method(OTPA)is a simple and efficient TPA method and its basic theory is introduced.An improved OTPA method is put forward to improve its accuracy.The improved method uses the average condition number to optimize the reference points in order to reduce the coupling between vibration sources.To improve the accuracy of the transmission rate matrix's calculation,a normalized calculation method is put forward to alleviate the input matrix's ill-condition.Experiments on the cylindrical shell are carried out to verify the improved method.The results show that OTPA can predict the vibration response very accurately,but when comes to calculation of vibration source'contribution there are still some errors.The results also proves that the improved method can effectively improve the accuracy of OTPA.Finally,to solve the problem that CTPA's excitation force can not accurately characterise the complex vibration source' excitation,a new TPA method is put forwad.The new method introduces equivalent forces to charachterize vibration source in order to improve CTPA and uses the regularization method to solve theill-condition problems when acquiring the equivalent forces.The improved method is called vibration's equivalent force transfer path analysis(equivalent force TPA)and it is proposed that its transfer functions can be obtained by reciprocity principle to improve its application convenience.A motor model platform is seted up and verifying experiments are carried out.The improved method's analyzing results are compared with CTPA's and OTPA's.The results proves the validity of the regularization method,the accuracy of the improved method in predicting the vibration response and calculating the vibarion sources' contribution,the feasibility of using reciprocity principle to obtain its transfer function and its advantages over CTPA and the OTPA when vibation sources' excitation is complex.In order to improve TPA methods' application potential and prospect in solving vibration problems,TPA methods' theory and corresponding vibration experiments are studied.The study has enriched the TPA methods and has some reference significance for using TPA methods to carry out vibration analysis.