| The rotating scissors of swashplate is an important device for ensuring that the rotating ring and the paddle rotate synchronously to realize the torque change of the paddle.Therefore,the fatigue life of the rotating scissors will inevitably affect the service life of the swashplate,thus affecting the flight performance of the helicopter,it is particularly important to make performance tests on key parts of the rotating scissors.However,domestic research and development of mechanical equipment for detecting key parts in rotating scissors is still not perfect.Therefore,a test machine designed to detect the fatigue life of key components in a specific model of rotating scissors is designed and the dynamic performance of the test machine is analyzed.According to the test requirements of the key parts of the rotating scissors,the overall structure of the test machine is determined.According to the requirements of the swing angle,the test machine uses the crank rocker mechanism without the quick-return feature to achieve the relative swing of the inner and outer rings of the joint bearing,and according to the given conditions.The length of each rod is calculated for the four-bar linkage mechanism;according to the requirements of the phase synchronous movement of the oscillating system and the loading system during the test,this tester uses a differential to divide the output power of the motor equally between the oscillating system and the loading system for achieving synchronous movement,and through the calculation to determine the type of motor,and according to the detection parameters requirement to complete the measurement and control system-related sensor selection.Considering that the inertia force generated by the pendulum rod and the Z-shaped bracket may cause the resonance of the testing machine,the dynamic analysis of the oscillating mechanism can get the angular velocity and angular acceleration curve of the pendulum,and the complex vector method in the analytic methods is used to analyse the kinetic characteristic of the oscillating mechanism.The results of the theoretical analysis are used to verify the accuracy of the simulation results.According to the results obtained by the simulation,the change curve of the inertial force of the two are obtained through further calculation.Then the MATLAB software is used to fit the sinusoidal curve to obtain the general formula of inertial force.The modal analysis of the oscillating mechanism obtains the natural frequency and mode shape of the system.The sinusoidal force of the loading system is external to the oscillating system and may also cause resonance.Therefore,the three types of stimuli are respectively applied to the oscillating mechanism.The ANSYS software was used to analyze the harmonic response of the oscillating mechanism.It was concluded that when the external excitation frequency reaches the natural frequency of the oscillating mechanism,three external loads will cause the oscillating system to have different degrees of resonance,and at the same time,the resonance frequency is given range.The frequency analysis method is used to test the oscillating mechanism,and the low-order natural frequency of the oscillating mechanism is identified by the single-point excitation and multi-point measurement excitation modes.The modal test results are compared with the simulation results to verify the the accuracy of the establishment of three-dimensional models of institutions. |
