Wind turbine tilting mast: independent structural verification before manufacture

A wind turbine manufacturer had developed a tilting mast in the 15–20 m height range and needed independent structural verification before manufacture.

The commission covered the mast structure and hydraulic lowering arrangement across the relevant operational and maintenance positions. Frugal was engaged to establish the assessment basis, complete the FEA and supporting manual checks, and document the findings in a formal structural substantiation report.

The work extended well beyond checking an upright mast under a single static load case. The structure had to be assessed in its raised, lowered and intermediate maintenance positions, including the behaviour of the hydraulic lowering arrangement.

The verification also needed to address global strength and deflection, support reactions, local structural details, modal behaviour and fatigue. This required an engineering-led assessment strategy that identified the governing cases and presented traceable evidence for design review.

• Client-owned detailed design: Frugal assessed the mast, identified areas requiring revision and advised on practical changes; the client incorporated those changes into the detailed design.

• Multiple analysis scenarios: verification had to cover the raised, lowered and critical-angle positions encountered during operation and maintenance.

• Multiple assessment criteria: strength, deflection, support reactions, utilisation, modal behaviour and fatigue all had to be assessed.

• Hybrid FE modelling: the structure required a mixed shell and solid model, multiple materials and realistic representation of its mass distribution.

• Representative turbine loading: the turbine was outside the detailed FE model, but its mass distribution and representative geometry had to be included for accurate loading and modal results.