GL Garrad Hassan (GH) has a long track record in designing structural components for large wind turbines (eg nacelle machine frame, bearing housing, hub). The designs have evolved over several years, but can be optimised further. GH believes that the method of numeric topology optimisation may be an alternative option to further optimise structural components. Reducing tower head mass also leads to reduced tower and support structure weight. GH plans to evaluate Topology optimisation software (Tosca) on an existing 7MW offshore wind turbine design. Based on the layout of this turbine an 'optimised' nacelle machine frame and bearing housing(s) are generated using numeric topology optimisation. The 'traditional' design and 'optimised' will be compared. Relevant criteria are: fatigue and ultimate strength, but also load distribution on for instance the yaw bearing will be evaluated.