Abstract: The lightweight design of the wind turbine gearbox house is of great significance to reduce the cost of wind turbines,improve the power density of wind turbines and the mechanical properties of wind turbine structure.Affected by extreme wind conditions and climatic conditions,the housing has been subjected to the impact of irregular loads from the transmission system for a long time,which leads to the problems of incomplete load cases coverage,unreasonable model simplification and low material utilization rate in the optimization design process. Therefore,based on considering multiple extreme service load cases and reasonable equivalence of models,the lightweight design of the housing was carried out.Based on the premise of verifying the accuracy of the model through modal testing,with the minimum mass of the housing as the optimization goal,and with the maximum stress of the housing under different extreme load cases as the constraint condition,multi-condition optimization design was carried out on the main shell,transition plate and rear shell in the components of the housing,and a comparison of the performance of the housing before and after improvement was made.The results show that after optimization,the mass of the housing was reduced by 4.7 %(549.8 kg),and under different load cases,both maximum displacement and stress were significantly reduced. The lightweight design has also improved the strength and stiffness of the housing,which provides a reference for the design improvement of wind turbine gearboxes.

Key words: extreme service load cases, multiple load cases, lightweight, wind turbine gearbox house, modal test