As impressive as the ready gearboxes, or the completed wind turbines are, they are a symphony of their parts. Some components are large, some are small, but they are all important in bringing clean renewable wind energy closer to everyone.
One such component are the castings used in gearboxes. These play a vital role, as they need to house the internal gearings as well as be capable of handling the operational loads, starts and stops of the wind turbine. Reaching towards optimized casting solutions via validated simulation(s) enables both material savings, as well as facilitates drivetrain logistics – to mention just a few benefits.
Vili Ryynänen, Metallurgist at Moventas, completed his Master’s thesis on the optimization of cast iron components. In Vili’s own words:
The task of this white paper and of the original M.Sc. thesis was to find correlation between the capabilities of casting simulation programs, and the reality of large spheroidal graphite cast iron castings. The thesis spearheaded one of Moventas’ brand-new research projects from start to finish, with the help of Moventas team of top experts of the field. Cast optimization by manufacturing Simulation Tools (COST) was proposed to answer the growing need in gearbox design to get more out of the material.
This topic is of great importance due to the growing need in gearbox design(s) to optimize material usage. At its core, the mechanical properties data used for the finite element method (FEM) analysis is based on values provided in the respective standard. This value is often a safe value, referring to lowest expected properties in the casting. Using simulation software to predict local mechanical properties in the casting could allow for higher design stresses for cast components, thus allowing optimized design.
Correlations were found in mechanical properties and simulation, but values need to be adjusted to fully correspond. The effect of pearlitizing in SGI (spheroidal graphite cast iron) was also evaluated. Correlation between nodule count and mechanical properties was also found. Similar procedure as presented in this thesis can be implemented with other foundries, where cast simulations are compared to real-life mechanical testing results of castings.