The National Renewable Energy Laboratory’s (NREL) National Wind Technology Center (NWTC) has embarked on the task of determining the causes and loading conditions that result in the premature failure of wind turbine gearboxes. The NWTC approaches this challenge by bringing together the parties involved in the gearbox-design process to achieve the common goal of the improving the lifetime of gearboxes. This is being accomplished through the Gearbox Reliability Collaborative (GRC). In addition to this collaborative effort, the GRC seeks to achieve its goal by exploring three avenues of research: drivetrain numerical analysis and modeling, full-scale dynamometer testing, and field testing. These different avenues are correlated and iterated to obtain the closest representation of actual load behavior in a controlled environment. The numerical analysis plays a key role in the design process of the gearbox; thus, the “Gearbox Reliability Collaborative, Analysis Round Robin” presented here seeks to examine various analytical approaches to gain insight in the validity and level of fidelity required to satisfy the design practice. The analysis is based on modeling techniques that range from simple torsional models to models that account for gear tooth contact and gear tooth load distribution, as well as bearing compliances and roller load distribution. The results from the GRC Analysis Round Robin will be validated with experimental data, and eventually will be a valuable data set that can be used for the validation of analysis tools. Industry designers typically have used different design approaches, but there is some consensus based on AGMA 6006 [1]. It would be useful to establish a definition of this consensus as a baseline and then compare it against a broad range of analytical approaches. The GRC Round Robin could provide an objective database of analytical results as well as experimental validation to aid the evaluation of the consensus. The main focus of this document is the analytical approaches overseen by the Round Robin. It also gives a brief overview of the GRC and describes the gearbox redesigns, instrumentation, and testing, as well as the GRC Round Robin. Next is a description of the different analytical approaches presented by the participants, and discussion of the levels of fidelity implemented. The load cases and the parameters provided to the participants are presented along with the results obtained.
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