Research On Structure And Dynamics Of A Helicopter Drive Rotor System

The transmission system is the important part of helicopter, it’s vibration characteristics directly affect the performance of the helicopter. The helicopter transmission system increasingly to high efficiency, high speed, high precision, high bearing capacity, especially the drive shaft, on designing time,it need to consider the influence of structure parameters on the vibration characteristics of the system, general speaking, the need to study the dynamics characteristics of the drive shaft in the work, control the vibration of the drive shaft in the work, to ensure the safety and reliability of the helicopter.Diaphragm coupling is a key component in the helicopter tail drive shaft structure, which is connected with the main driven shaft, which has a direct effect on the vibration characteristics of the helicopter transmission shaft. Firstly based on Hertz contact theory and the GW contact model theory, the diaphragm surface contact stiffness model is deduced, won the stiffness model of the surface to surface contact; Established diaphragm coupling solid model and surface to surface contact stiffness model of computing results is introduced to consider the contact of the diaphragm in the group model, by comparing the calculation results of considering the contact patch group model calculation of diaphragm coupling stiffness of superiority and accuracy, and using this model, the stiffness of the diaphragm coupling of the helicopter transmission system is calculated, which provides the basis for the calculation and analysis of the dynamic characteristics of the shaft.The selection of materials, structure design of the transmission shaft is related to whether the strength of the driving shaft to meet the needs of the work. Based on the materials theory and third strength theory, according to the structural parameters of the helicopter tail transmission shafting,established three-dimensional solid model of the helicopter transmission shaft; and combining the basic principles of finite element, and establishing a professional finite element model, the strength check of each transmission shaft is carried out by using the finite element method, and the strength of each drive shaft of the helicopter transmission shaft is determined.Due to the secrecy, the actual helicopter tail drive shaft can not be directly carried out on the test bench, so the common parts of the transmission system are considered, the transmission shaft, the diaphragm coupling and the supporting component are considered,a dynamic model of rotor-diaphragm coupling-support system is established, and carrying out numerical analysis by using of less degree of freedom finite element method, obtaining the static characteristics(natural frequency, static vibration characteristics, etc.) of the system and dynamic characteristics(critical speed, unbalance response, etc.), providing basement for the establishment of the test bench for the rotor- diaphragm coupling- elastic support system ahd the comparison of experimental results,and for the research on the basic characteristics of the dynamic characteristics of the helicopter transmission shaft.The dynamic characteristics of the helicopter tail rotor drive system directly affects the safety of the helicopter’s operation, so it is very important to study the dynamic characteristics of the transmission shaft.\Through multi degree of freedom finite element method(with the help of ANSYS software) and less degree of freedom finite element method(node partition, preparation of rotor dynamics program) carring out the dynamics simulation analysis to the main drive shaft of the helicopter to obtain the natural frequencies, mode shapes and critical speed calculation results from the helicopter transmission system, and contrasting analysis results fot the two calculation methods results, and determining the effectiveness and accuracy of the two methods. And then use this two methods simulation the helicopter drive shaft dynamics characteristics, intuitive display designing and working reliability of the helicopter transmission shaft, which provide the reference and basis for the helicopter transmission shaft design and dynamic characteristics of prediction.Finally, the rotor-diaphragm coupling-system was builted, which was equipped with high-precision eddy current displacement sensor and data acquisition and the integrated experimental system is constructed, which is a set of testing, collecting and analyzing function.Carried out the static and dynamic analysis of experiment,and the dynamic characteristic of the system experiments were carried out at different speeds,and the result compired with the numerical analysis results of the rotor-diaphragm coupling-support of the fourth chapter, the correctness of the numerical analysis method is proved. Providing a good reference and basis to the dynamic characteristics prediction of the helicopter transmission system, and providing a necessary theoretical basis and experimental basis for the future optimization of helicopter transmission system mechanism and the dynamic characteristics improvement of helicopter.