Damage Detection In Avation Spherical Plain Bearing

The rod end spherical plain bearing on the helicopter's main rotor pitch rod is a key core component of the helicopter,Once its damage fails,it will directly lead to serious flight accidents.Therefore,the helicopter will be regularly shut down and disassembled for maintenance inspections.However,due to production uncertainty and changes in the use environment,regular dismantling and inspection may cause untimely repairs,high inspection costs,and certain safety risks.In view of this problem,I hope to have an online detection technology to perform online detection when the helicopter is stopped to determine whether the rod-end spherical plain bearing fails and is reliable.This theory is based on the theory of vibration mechanics and the main tool of finite element technology.The modal analysis method and the transient dynamics harmonious response method are used to study the pitch rotor rod end spherical bearing of the main rotor of the helicopter,and provide a theoretical research method for the early damage detection of the pitch rotor rod end spherical plain bearing of the helicopter main rotor.It works as follows:First of all,investigate the structural characteristics of the pitch rotor rod end spherical plain bearing of the helicopter main rotor,establish a mathematical model of vibration,and establish a simulation test model based on the mathematical model.Investigate the main failure modes of rod end spherical plain bearings as fatigue cracks and friction wear of the spacer,and study the crack shape,location,and size of the tie rod,and the shape and depth of the friction and wear of the spacer.Friction and wear model of self-lubricating layer.Then,Perform a modal analysis on the model with the failure form established above,obtain the natural frequency,modal shape,and calculate the modal confidence.According to these three sets of modal parameters,research and analysis are performed on cracks of the same size at different positions of the tie rod,cracks of different sizes at the same position,and different forms of friction and wear of the self-lubricating layer,providing a model for early failure detection of rod end spherical plain bearings.Then,Aiming at the fatigue crack of the tie rod,the transient dynamics is used for research and analysis.Apply a transient excitation force on the side of the pull rod to obtain the time-domain acceleration signal of the pull-down rod under the excitation force.Then perform time-domain analysis on the signal when the rod is intact and there are cracks in different positions,and then analyze the time-domain signal statistically.The time-domain analysis and statistical analysis method are used to provide theoretical basis for on-line detection of tie rod cracks on the rod end spherical plain bearing of the helicopter.At last,Aiming at the friction and wear of the self-lubricating layer of the rod-end spherical plain bearing,the harmonic response analysis method is used for research.Through the simple harmonic excitation,the spectrum signal of the self-lubricating layer under this simple harmonic excitation is obtained,and the frequency response results after the self-lubricating layer is intact and different degrees of wear are analyzed.It provides research methods and basis for on-line detection of friction and wear of self-lubricating layers.