Study On Mechanical Response Characteristics Of Aviation Self-lubricating Joint Bearings Under Complex Load Conditions

Aviation self-lubricating joint bearings are widely used in aircraft such as helicopters due to their excellent tribological and mechanical properties.The self-lubricating joint bearing at the rod end of the pitch-variable tie rod is an important force transmission part between the main rotor and the control system of the helicopter.It is often seriously damaged due to the complexity of the service environment of the helicopter and the load on the transmission path,which will not only affect the work of the helicopter Efficiency,but also has an impact on the performance safety of the helicopter.Therefore,this paper studies the mechanical response characteristics of the self-lubricating joint bearing under the main rotor of the Robinson R44 helicopter under the condition of complex load(radial load + rotational load),and uses the finite element simulation method to simulate the service condition of the self-lubricating joint bearing,so as to obtain the mechanical response characteristics of the aviation self-lubricating joint bearings under this load condition.The main work and conclusions of this paper are as follows:The modal analysis of the aviation self-lubricating joint bearing is carried out,and its first ten natural frequencies and the mode shapes at the corresponding frequencies are obtained,and the natural frequency of the aviation self-lubricating joint bearing is compared with the natural frequency of the helicopter as a whole,so as to judge the relationship between the local vibration of the aviation self-lubricating joint bearing on the helicopter and the overall vibration of the helicopter.The results show that the first-order to sixth-order vibration frequencies of the bearing are 0 Hz,and the seventh-order to tenth-order vibration frequencies are 58983 Hz,58984 Hz,73746 Hz,and 73746 Hz,which are much higher than the first order of a certain helicopter hovering in the air.The eighth order natural frequency is 16 Hz.Therefore,the local vibration of the aviation self-lubricating joint bearing will not resonate with the helicopter.Static simulation analysis of aviation self-lubricating joint bearings under the action of radial sine loads is carried out,so as to obtain the distribution law of the mechanical response characteristics of the bearings;the mechanical cloud diagram of the bearing liner is compared with the damage characteristics of the actual service bearing liner,In order to find out which force caused the damage of the failed bearing pad and the cloud diagram of the force distribution.The results show that the upper part of the liner is dominated by fatigue damage caused by contact stress;the lower part is dominated by transfer film formed under shear stress.The frictional heat simulation analysis of the aviation self-lubricating joint bearing under the measured load history curve is carried out,so as to explore the temperature change of the self-lubricating joint bearing and the distribution law of the temperature cloud map.The results show that the highest temperature of the liner and the inner ring appear at the top and bottom of each,the highest temperature of the inner ring is 22.3 ℃,the temperature rise is 0.3 ℃,the highest temperature of the liner is 23.347 ℃,the temperature rise is 1.347 ℃,the liner The maximum temperature and temperature rise of the pad are higher than the maximum temperature and temperature rise of the inner ring;the generation of frictional heat will increase the contact stress,equivalent stress and deformation of the bearing.