Wear Mechanism And Life Analysis Of Self-lubricating Spherical Plain Bearing Under Sinusoidal Load

Self-lubricating spherical plain bearings with fabric liners are widely used in aircraft landing gear,helicopter rotor and operating systems due to their advantages of self-lubrication and maintenance-free.The assessment of service performance,life and reliability is of great significance to the healthy operation and safety maintenance of the mechanism.At present,most of the experimental research on the performance and life of spherical plain bearings at home and abroad is based on the condition of constant load.But the load of spherical plain bearings is mostly non-constant load in the process of practical application.Therefore,the research on tribological performance and life of spherical plain bearings under sinusoidal load is of great engineering application value to illuminate the wear failure mechanism under real working conditions,accurately evaluate the life and reliability under complex working conditions,and extend its working life.In this paper,the tribological property and fatigue life experiments of the spherical plain bearings under sinusoidal and load constant load were carried out using the self-made tester.The friction surfaces of spherical plain bearings were analyzed by laser scanning confocal microscope,and the friction and wear mechanism of spherical plain bearings under sinusoidal load were expounded.The wear mechanisms of spherical plain bearing under sinusoidal stress are adhesive wear,abrasive wear and severe fatigue wear.The wear mechanisms spherical plain bearing under constant stress are adhesive wear,abrasive wear and slight fatigue wear.The physical model of friction and wear of spherical plain bearing under sinusoidal load was established,and the nature of the forming process of transfer film of liner was analyzed.The process of film formation under sinusoidal load can be divided into plastic deformation stage,cold flow stage,film forming stage and equilibrium stage.The life and reliability of self-lubricated spherical plain bearings with fabric liners under sinusoidal stress and constant stress were studied by means of maximum likelihood estimation method.The fatigue life of spherical plain bearing under sinusoidal stress is much shorter than that under constant stress.Fatigue wear failure of spherical plain bearing accelerated by repeated interaction of sinusoidal stress.The wear amount of spherical plain bearing was selected as the degradation parameter.The Linear degradation model was selected as the degradation model using the Topsis method,and the failure threshold of wear was determined to be 300 um.The life and reliability of the spherical plain bearing were predicted by the performance degradation model.The test time can be shortened by more than half while ensuring the precision of prediction.Based on the life test,the life formula of spherical plain bearing under sinusoidal stress in the mechanical standard was analyzed and modified.The functional relation between the correction coefficient of characteristic life under sinusoidal load and the loading period was put forward.To sum up,the friction and wear process and mechanism of spherical plain bearing under different loading cycles were expounded,the method of estimating and predicting the life and reliability of spherical plain bearing under sinusoidal stress was given and the life formula of spherical plain bearing under sinusoidal load was modified and supplemented.The research results can provide theoretical reference for the design of spherical plain bearing.