| As a new energy industry,wind power generation is favored by all countries in the world.Wind turbine is an important part of power generation system,and its performance problems seriously affect the efficiency of power generation.As the core component of wind turbine,gearbox often fails,which leads to the unit shutdown and affects the normal operation of the generator.The failure of gearbox components is the main reason affecting the reliability of the unit,and the gear tooth fracture caused by fatigue crack propagation is the most serious failure mode.Therefore,the damage tolerance design of wind turbine gear has important theoretical significance and guiding value to ensure the efficient operation of the unit.In this paper,based on the actual working conditions of wind turbine,taking the planetary-sun gear pair of 1.5 MW wind turbine transmission system as the research object,the numerical simulation of tooth root crack propagation was established to accurately predict the fatigue crack propagation path and residual fatigue life,so as to provide theoretical support for the formulation of reasonable maintenance scheme and ensure the reliable operation of wind turbine in the whole life cycle.Firstly,the parametric design of the finite element model of gear pair with different meshing positions was realized by using MATLAB and ABAQUS software.Through the static analysis of the gear pair,the crack initiation position was determined to prefabricate the initial crack.The ABAQUS script file was written in Python language to simulate the fatigue crack growth process of wind turbine gear,and the NASGRO equation was used to predict the fatigue crack growth life of gear.Then,considering the dynamic process of gear meshing,a quasi-static numerical simulation method was proposed,which decomposes the gear meshing process into multiple positions for analysis,and the multi meshing position model of wind turbine gear was established.The analysis results were compared with the simulation results of the model loaded at the highest point of the single tooth contact(HPSTC)to study the influence of gear meshing process on crack propagation characteristics.In order to verify the validity of the multi meshing position model,the numerical simulation results were compared with the experimental results of fatigue crack growth under the same working conditions.The results show that the crack growth life calculated by the multi meshing position model is larger than that calculated by the HPSTC loading model;Compared with the HPSTC loading model,the curvature of the fatigue crack growth path obtained by the model is larger and more inclined to the direction of the gear teeth,and the results are in good agreement with the results of the experiment,and the model has better calculation accuracy.At the same time,the effects of initial crack length and load size on the crack growth characteristics were studied by using the model,the results show that the load amplitude will change the law of crack propagation under different meshing conditions,and the crack length and propagation life will decrease with the increase of load.Finally,according to the distribution of input torque of gear pair under random wind speed,the fatigue crack growth characteristics of wind turbine gear under random load were studied,and the fatigue crack growth life of wind turbine gear under actual wind farms was evaluated.Considering the interference of load duration on crack growth behavior under variable amplitude load,the effect of load sequence on crack growth behavior was discussed.The results show that the crack growth rate varies irregularly with the fluctuation of instantaneous load.The average level of wind speed and the order of loads affect the fatigue crack growth life,and the crack growth rate is obviously delayed from high amplitude load to low amplitude load;from low amplitude load to high amplitude load,the crack growth rate increases with the change of load. |
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