Weld bushings are an economical solution for attachment of tower internals to the tower shell. However, the weld bushings usually have a negative impact on the fatigue strength of the tower shell because of the poor design category, in turn making higher shell thicknesses necessary. Even worse: in reality, the design categories are even poorer than assumed in the recognized standards.
We have designed an innovative but simple solution to design weld bushings in a manner that they affect the tower shell as little as possible. Out patented solution PE-90 is named after its main advantage: we achieve Design Category 90 or better for the tower shell. This saves many tons of material in the tower compared with conventional weld bushings.
- reduced cross section of the weld bushing at the interface to the tower shell
- locally reduced stiffness increases the fatigue strength of the tower shell
- Design Category 90 can be demonstrated for different geometries
- we find the optimal arrangement of weld bushings to sustain large static loads without impairing the design category
- the stress analysis to verify Design Category 90 is certifiable