Dynamic Analysis Of Helicopter Tail Drive Shaft System

The tail drive shaft system is an important part of helicopter transmission system,generally by the coupling of diaphragm coupling and multi section thin-walled slender shaft.In the working process,the tail drive shaft system is subjected to different kinds of driving force.At the same time,the dynamics of the tail drive shaft system is more complicated due to the existence of the diaphragm coupling.Therefore,it is necessary to deeply analysis the dynamic characteristics of the helicopter tail drive shaft system,to fully reveal the vibration characteristics of the shaft system,which provide the necessary theoretical bases for the dynamic design and fault diagnosis of the helicopter tail drive shaft system.Firstly,a hierarchical analysis method is used to analyze the components from the components to the system in this paper.Dynamic models for thin-walled slender shaft,diaphragm coupling and other key components of the torsional vibration,bending vibration and bending-torsional coupling vibration were established.According to the composition of the structure of the tail drive shaft system,the various parts of the model match and the system integration,the paper deduces the tail drive shaft system overall torsional vibration,bending vibration and bending-torsional coupling vibration dynamic differential equation.Secondly,based on the finite element method,the dynamic model of the tail drive shaft system is established,and the inherent characteristics of the tail drive shaft system are calculated and analyzed.The critical speed of torsional vibration and corresponding vibration mode of the tail drive shaft system are calculated.In consideration of the gyroscopic effect to calculate the tail drive shaft system bending vibration and bending-torsional coupling vibration and the Campbell diagram,critical speeds and corresponding vibration modes are obtained.At the same time,the influences of the diaphragm coupling and bearing the kinetic parameters of the tail drive shaft system torsional vibration,bending vibration and bending-torsional coupling vibration.Finally,based on the analysis of the dynamic model and the inherent characteristics of the tail drive shaft system.Application of Newmark-? numerical integral method,respectively,to the tail transmission shafting torsional vibration,bending vibration and bending-torsional coupling vibration in the unbalanced amount under the action of dynamic response characteristics numerical calculation and analysis,get the shaft unbalance response graph in time domain,frequency spectrum,orbit and the amplitude frequency characteristic curve.Nonlinear dynamic characteristics of interaction bending and torsional vibration of the tail drive shaft system to focus on and analysis of the value of unbalance(eccentricity),speed effect of unbalance response of the tail drive shaft system.