Study On Vibration Energy Characteristics Of Helicopter Main Transmission System

Helicopter has been widely used in military,public security fire,medical rescue,communications and other areas of the national economy,and the performance of the main reduction transmission system directly affects the performance of the helicopter,safety and reliability.The transmission characteristics of the main transmission system of the helicopter are complex,the coupling factors are many and it is difficult to characterize.Therefore,the research period is long and the cost is huge for accurately estimating the vibration characteristics and optimizing the design of the gear transmission system.In this paper,the coupling dynamics model of a helicopter’s main transmission system is established by using the nodal finite element method and the superelement method in the generalized coordinate system,and the vibration energy transfer characteristics and the proportion of vibration energy are studied.The main research contents are as follows:(1)A gear rotor model considering shafting flexibility and a casing ultrasonic element model considering casing flexibility were established by means of nodal finite element method and super element method respectively.The validity of the casing ultrasonic element model was verified by comparing the modal parameters before and after the casing polycondensation.The coupling relationship between the gear rotor model and the flexible casing model in the generalized coordinate system is derived.The validity of the theoretical model is verified by comparing the experimental data with the theoretical model.(2)Based on a certain type of helicopter main reduction of transmission system coupling dynamics model,through the vibration power flow method to solve the system node energy,vibration analysis under different rotational speed in the shafting system support node energy feature and the coupling vibration of flexible casing for its impact,respectively to study the system level parallel gear and planetary gear train structure for vibration energy transfer characteristics and different structure parameters of the excitation and the influence on transmission characteristics.(3)The contribution ratio of vibration energy of system nodes is measured by single excitation method and interventional excitation method,and the advantages and disadvantages of the two methods are compared.In the case of uncoupled flexible casing,the vibrational energy ratio of the gear rotor system under different operating conditions is studied by the method of intervention excitation,and the influence of the vibrational energy ratio of the coupling flexible casing on each node of the system is also studied.