Summary
<xml></xml>Wind energy plants are becoming larger and more powerful with each successive generation. This is accompanied by optimisation of their components and their interaction. The intention of this research project is to develop an operational stability verification that makes better use of the information from simulated and measured loads than was previously the case and also takes account of innovations such as lightweight design.
The project partners are comparing calculations with measured loads to ultimately derive usable simplifications for the operational stability calculation method.
This results in a cost-effective method for forecasting component service life, which improves plant reliability and cost optimisation, while ensuring maintenance activities are more targeted than previously.
The authors of the individual reports are concentrating on specific critical components and recording the following results:
Screw connections:
- The load on screws rises sharply due to imperfections when welding. Gaps that cannot be entirely closed are unacceptable and should be sealed with filler plates during assembly.
Screwed flange connections, machine:
- A calculation for screw connections can often be carried out using finite element models (FEMs) at comparable cost to methods specified in directive VDI2230 but with more accurate results.
Screwed flange connections, tower:
- Verification of L flange connections is being supplemented with calculation of imperfections on steel tube towers.
Cast structures:
- For operational stability verification on semi-ductile cast structures, there is a good correspondence between normal stress theory and the cutting plant algorithm.
- Methods using the ASME code achieve unrealistic results.
- Grooves result in stress concentrations being channelled in one direction and thus reduce multi-axiality.
Welded connections:
- The IIW verification concept appears to be more suitable than the local reference stress concept in Eurocode 3.
