Tonality predictions in wind turbine gearboxes: a comparison between analytical and finite element methods
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Insinööritieteiden korkeakoulu |
Master's thesis
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Date
2020-06-15
Department
Major/Subject
Mcode
Degree programme
Master's Programme in Mechanical Engineering (MEC)
Language
en
Pages
115
Series
Abstract
The gear whine is a noise problem that widely occurs in wind power transmission and characterizes by one or more high amplitude acoustic signals. This noise originates from the excitation of gear pair in mesh caused by transmission error. Transmission error is a vital excitation source of gearbox sound and vibration. Thus, Moventas Gears OY needs to define the range of applicability of their tools to have a reliable and predictable method for tonality risk assessment. This thesis work is a part of a long-term development task to minimize the tonality risk in the early phase of the design process with advanced and calibrated simulation methods. This thesis aims to identify a range of applicability of the analytical method implemented in KISSsoft AG software in comparison with the finite element method and recommend virtual testing of transmission error for conceptual wind gearboxes design use. Power transmission and contact mechanics were modeled using the finite element method. Evaluation study cases were established for comparison of selected methods in terms of developed assessment criteria. The developed finite element model manages to define the transmission error defined as the leading cause of the gear whine noise and account effect of geometry, cross-influence and provides the opportunity for modal and acoustic assessment resulted from bearing excitation. KISSsoft is a suitable tool to find the optimized shape that delivers the lowest static transmission error amplitude. KISSsoft is able to estimate tooth deflection while considering the influence of tooth profile modifications, misalignments caused by system configurations. The findings from both approaches depict that there is a strong correlation between transmission error profile results from the FEM and KISSsoft. The peak to peak amplitude is formed by corresponding local minimum and maximum mesh stiffness values at LPSTC and HPSTC coordinates of the contact pattern. Finally, it is concluded that both tools can be used together in optimization studies of powertrain by defining the optimum combination of macro and micro gear modifications to minimize tonality amplitudes and corresponding gear casing geometry to reduce generated whine noise to a satisfactory level.Description
Supervisor
St-Pierre, LucThesis advisor
Kleemola, JukkaKeywords
whine noise, static transmission error, mesh stiffness, cylindrical gear, finite element contact mechanics