Fatigue Assessment of Casting Hub in a ۲.۵ MW Wind Turbine

One of the main important parts of wind turbine is rotor hub, which experiences the loads from blades. All the blade loads due to wind and extreme conditions should be transferred to hub. In this work, at first, by applying finite element analysis in ANSYS workbench and considering the extreme loads, static strength of horizontal-axis hub is investigated. In addition, since the hub is subjected to time-varying cyclic forces and moments due to external wind load and aeroelastic effects on blades, fatigue analysis of hub is performed. The popular way to find the fatigue damage for structures in high-cycle situations is using of material SN curves (fatigue life curves based on applied stress in logarithmic scale). To fatigue analysis, the S-N curve is synthesized for the hub material EN-GJS-۴۰۰U-۱۸LT using appropriate formula. After that, by applying nCode Designlife tool using load-time series and damage accumulation, fatigue assessment of hub is carried out and the fatigue life and accumulated damage are obtained. It is found that the hub is able to withstand the extreme loads as well as is safe for ۲۰ years of wind turbine lifetime.

Keywords:

fatigue , casting hub , wind turbine , EN-GJS- ۴۰۰U-۱۸LT material