Study On Dynamic Characteristics Of Heavy Duty Marine Gearbox With Thermo-elastic Coupling

This project,"Research on common and key technologies of high-speed, heavy-duty, precise mechanical transmission system"(2006BAF01B07-01), belongs to the national science & technology pillar program in the Eleventh Five-year Plan Period of China.Adapting to the needs for the national major equipments and key projects, the gear transmission tends to be high-speed and heavy-duty and bears low noise and high reliability. The high-speed and heavy-duty mechanical transmission system, presented by the marine reducer, gear box of the gas turbine, gear box of the wind power generation, is one of the important basic components of large-scale machineries and equipments. Its quality directly affects the overall performance and longevity.Therefore, it is of great significance for China's economic and social development to carry out the research and development on the common and key technologies of high-speed and heavy-duty gear transmission system, to improve the technology of major equipments, to upgrade the international competitiveness of the industry of mechanical transmission components and related equipments.In the thesis, based on the principles of gear meshing, tooth contact analysis, tribology and heat transfer theory, non-linear system dynamics, by means of theoretical analysis and finite element simulation, the dynamic characteristics of the high-power marine gear box system based on thermo-elastic coupling is studied and verified by tests. The major content is as follows:①A 3-dimensional finite element model of a coupled gear-rotor-bearing-housing system of a heavy duty marine gearbox is developed. The dynamic characteristics is analyzed and the first 20 orders of natural frequency and mode shape of the marine gearbox under constrained condition are obtained②The finite element analysis is performed to explore the tooth contact force and deformation in the case of thermo-elastic coupling. The time-varying gear mesh stiffness under the thermo-elastic coupling conditions is gained.③The dynamic response analysis of the marine gear box system is performed under the influence of the internal excitation, i.e. the time-varying stiffness excitation, transmission error excitation and tooth impact excitation external excitation and the external excitation. The feature of the vibration and noise is obtained. ④Methods of nonlinear dynamics are applied to analyze numerical characteristics of system dynamic response, i.e. time course curves, power spectral density, phase traces and Poincare maps, the maximum Lyapunov exponent, to reveal the principles of non-linear dynamics.⑤The inherent characteristics, structure vibration and noise of the marine gearbox are tested and the results verify the correctness of the theoretical analysis. Methods of analyzing the dynamic characteristics of a large marine gear box are summarized.