| The Frequency synthesizer is an important part of electronic equipment,and it is very important to monitor its running state.However,the working environment of the frequency synthesizer is complex,and it is easy to be subjected to the stress of various environmental loads such as heat,vibration and electricity.Moreover,multi-physical fields such as heat and vibration have the characteristics of mutual coupling,which makes the internal components of the frequency synthesizer highly likely to have parameter failure,mechanical failure,corrosion and other failures,and finally cause the failure of the frequency synthesizer,which poses a challenge to the reliability of the frequency synthesizer.Therefore,in order to explore the reliability and comprehensive evaluation of frequency synthesizer,this paper takes the 13 th Five-Year national defense technology research project "XXXX Radar Antenna Reliability and Testability Collaborative Modeling and Design Technology Research" and Chongqing Technology Innovation and application special development key project "Data-driven Quality Intelligent Control Technology for complex electromechanical Products" as support.Based on the fault mechanism and environmental load of the frequency synthesizer,the multi-field coupling model of the frequency synthesizer is established,and the thermal analysis and vibration analysis are carried out,and the comprehensive reliability evaluation of the frequency synthesizer is systematically studied from the point of view of fault physics.The main work and innovation points are as follows:1)A fault mechanism analysis method of frequency synthesizer based on failure mode effects and criticality analysis(FMECA)and fault tree analysis(FTA)is proposed.Because of the problem that the failure of any function module of the frequency synthesizer directly affects the system reliability,based on the traditional FMECA method,FTA was introduced to construct the fault mechanism tree of the frequency synthesizer,and the critical fault modes were obtained according to the critical importance degree.Then,the critical fault mechanism of the critical fault modes was studied based on FMECA.The analysis results show that the critical fault mechanism of the frequency synthesizer is closely related to thermal stress and vibration stress.2)A frequency synthesizer multi-field coupling method based on finite element method and boundary element method(FEM-BEM)is proposed.Considering that the frequency synthesizer is affected by various environmental loads and coupled with multiple physical field effects such as heat and vibration,the computational fluid dynamics(CFD)and finite element analysis(FEA)digital prototype models of the frequency synthesizer are established respectively.On the one hand,the CFD digital prototype model of the frequency synthesizer is analyzed.On this basis,the temperature prediction of the frequency synthesizer under different working conditions is carried out by using the method of grey relation analysis and stochastic configuration network(GRA＿SCN).The rationality and superiority of the proposed algorithm are verified by comparing it with the numerical simulation results under different working conditions and other algorithms.On the other hand,the modal analysis and random vibration analysis of the FEA digital prototype model of the frequency synthesizer are carried out.Finally,based on the FEM-BEM theory,the coupling analysis of thermal vibration is carried out for the frequency synthesizer,and the results of the thermal analysis are taken as the load conditions for vibration analysis.The simulation results show that the existence of thermal stress will increase the natural frequency of the frequency synthesizer.3)The reliability comprehensive evaluation method of frequency synthesizer based on entropy weight TOPSIS and the reliability comprehensive evaluation method based on environmental reduction coefficient are proposed.In view of the complex working environment and the difficulty to predict the life of the frequency synthesizer,a fault physical model based on temperature stress,vibration stress and thermal vibration coupling stress was established on the basis of multi-field coupling analysis of the frequency synthesizer.Then,combined with the fault physical model and Monte Carlo sampling(MCS),the reliability of frequency synthesizer components is predicted.Finally,on the one hand,reliability prediction results of frequency synthesizer components under different environmental loads were taken as evaluation indexes.On the basis of the traditional TOPSIS method,the information entropy weight method was introduced to assign weights to indicators,and the entropy weight TOPSIS algorithm was proposed to conduct a reliability comprehensive evaluation of the frequency synthesizer.On the other hand,the reliability of the frequency synthesizer is evaluated by using the environmental reduction coefficient.The two algorithms show that the lifetime of the frequency synthesizer is less than that of the uncoupled condition.In this study,the frequency synthesizer was taken as the research object,and the frequency synthesizer was studied according to the steps of fault mechanism analysis,thermal and vibration coupling analysis under a complex environment,and reliability comprehensive evaluation considering multi-field coupling.The effectiveness of multifield coupling analysis was verified by comparing experimental simulation with engineering-measured data.Combined with the fault physical model,the reliability comprehensive evaluation of the frequency synthesizer is realized. |
PDF Full Text Request