| The herringbone star gearing transmission system has the characteristics of large transmission power,low noise,reliable operation,and is widely used in aviation,navigation,aerospace and other fields;it is used as an important reduction transmission in a geard turbofan(GTF)engine.The device operates in a harsh environment,which puts more stringent requirements on the dynamic performance and supporting components of the GTF herringbone star gearing transmission system(GTF gear transmission system).The sliding bearing supporting the star gear of the GTF gear transmission system(GTF sliding bearing)adopts a special structure of rotating bearing bush and fixed journal in order to cope with high working conditions and strict space design requirements.In this paper,the GTF gear transmission system using GTF sliding bearing as the supporting part of the star gear is taken as the research object,considering the coupling relationship between the sliding bearing radial clearance and the backlash,the time-varying support characteristics of the bearing and other nonlinear excitations,and the system dynamics modeling,Dynamic characteristics analysis and other research.The main research contents of this paper are as follows:(1)Based on the traditional gear pair backlash model,the coupling relationship between the backlash of each gear pair and the radial clearance of GTF sliding bearing under dynamic condition is analyzed.Through the analysis of the geometric structure and meshing characteristics of the system,the mathematical model of the dynamic coupling backlash of the system is formed.(2)In view of the special structure of GTF sliding bearing,the support characteristic analysis is carried out based on the hydrodynamic lubrication theory,and the support characteristic simulation model is constructed using computational fluid dynamics technology.On this basis,it is based on the mixed level uniform test design and genetic algorithm(GA),BP neural network and other technologies establish the mapping relationship between the dynamic meshing force of the gear pair,the instantaneous axis position parameter and the bearing support characteristics to form the GA-BP neural network for the rapid calculation of the GTF sliding bearing support characteristics.(3)The lumped parameter method is used to establish a bending-torsion nonlinear dynamic model of the GTF gear transmission system including dynamic coupling backlash,sliding bearing time-varying support characteristics,time-varying meshing stiffness,comprehensive meshing error,tooth surface friction characteristics,and through certain mathematics Processing to ensure the solvability of the model;compare the established dynamic model with related theories to verify the accuracy of the model.(4)On the basis of the above work,the dynamic characteristics analysis of the GTF gear transmission system is carried out.Under different working conditions(input speed,power),the system displacement,speed,acceleration is considered when the dynamic coupling backlash or sliding bearing time-varying support characteristics are considered.Analysis and comparison of iso-vibration response,discuss the influence of dynamic coupling backlash and sliding bearing time-varying support characteristics on system dynamic behavior.The research results of this paper show that:in terms of vibration response,the vibration response amplitude of the comprehensive excitation dynamic model that takes into account the dynamic coupling backlash and the time-varying support characteristics of sliding bearings is larger than other models;in terms of frequency components,the comprehensive excitation after two excitations is considered The vibration response of the dynamic model shows richer frequency components;therefore,the dynamic coupling backlash and the time-varying support characteristics of the GTF sliding bearing have an important influence on the system dynamics.The system dynamics model considering the two is closer to engineering reality.The research work in this paper has created the dynamic characteristics analysis of the GTF gear transmission system from the dynamic meshing force of the gear pair→the instantaneous axis position parameter of the GTF sliding bearing→the dynamic coupling backlash model→the time-varying support characteristics of the GTF sliding bearing→the dynamic model of the gear transmission system The technical approach and related research results provide a certain theoretical and technical reference for the analysis and design of the GTF gear transmission system. |
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