Conventional methods for designing rolling bearings against fatigue assume that a bearing ring is fully rotating and that the load is ideally distributed over the rolling elements. Blade bearings in wind turbines, are operated under oscillating motions and dynamic loads. The load distribution is strongly dependent on the stiffness of the bearing rings and the surrounding structural components. This has been shown in numerous studies using FEM simulations for static load cases. In this paper a method is presented that reduces the calculation effort of the deformation of the bearing rings, so that a flexible integration into an aeroelastic mbs model of a wind turbine is possible. Thereby an average accuracy of 6.5% between FEM and mbs could be achieved. The model allows the determination of time series of the global load distribution of each raceway. By data processing of the simulation results, the number of load cycles and the maximum contact pressure for individual segments of the raceways could be determined and their fatigue probability could be estimated using the linear damage hypothesis according to Palmgren-Miner.
相似文献Wind energy is an essential source of renewable energy. However, to compete with conventional energy sources, energy needs to be produced at low costs. An ideal situation would be to have no costly, unscheduled maintenance, preferably. Currently, O&M are half of the yearly expenses. The O&M costs are kept low by scheduled and reactive maintenance. An alternative is predictive maintenance. This method aims to act before any critical and costly repair is required. Additionally, the component is used to its full potential. However, such a strategy requires a damage indication, similar to one provided by a condition monitoring system (CMS). This paper investigates if Supervisory Control and Data Acquisition (SCADA) can be used as a damage indicator and CMS. Since 2006, every wind turbine is obliged to use such a SCADA-system. SCADA records a 10-minute average, maximum, minimum, and standard deviation of multiple technical information channels. Analytics can use those data to determine the normal behavior and a prediction model of the wind turbine. The authors investigated statistical and data mining methods to predict main bearing faults. The methods indicated a defect of up to 6 months before its maintenance.
相似文献Using large components made of nodular cast iron (GJS) in wind turbines enables the application of lightweight construction through the high degree of design freedom. Besides the sand-casting process, casting into a permanent metal mould, i.e. chill casting, leads to a finer microstructure and higher quasi-static mechanical properties as well as higher fatigue strength. Unfortunately, in present design methodologies specific fatigue data is only available for sand cast and not for chilled cast GJS. Thus, lightweight design strategies for large, chilled cast components are not achievable, which led to the publicly funded project “Gusswelle”. Based on material investigations of EN-GJS-400-18-LT chill cast, an optimized hollow rotor shaft is developed. The design process and the resulting shaft design are presented. The optimized hollow rotor shaft prototype will be tested on a full-scale test bench to validate the design methodology. The intended validation plan as well as the test bench setup is shown in this paper. Furthermore, the decreasing wall thickness influences the interference fit between main bearing and hollow rotor shaft. Thus, through the applied bending moment, inner ring creep is more probable to occur in the main bearing seat. The creeping behaviour is investigated with finite element simulations and a measuring method is presented.
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