Oldenburg. The timely detection of mechanical damage is crucial for the reliable continuous operation of wind turbines. Scientists at the University of Oldenburg led by physicist Prof Dr Joachim Peinke have now presented a new method for diagnosing even the smallest changes in mechanical properties in "Europhysics News". The article by the Oldenburg team, which the editors of the scientific journal of the European Physical Society (EPS) selected as a research highlight, is also available on the Internet.

The usual methods for monitoring the condition of wind turbines are based on frequency analyses of the turbine structure, which show how often certain vibrations occur in a certain unit of time. However, a shortcoming of these methods is that the smallest turbulent excitation of the structure due to constantly changing wind, vortices and air currents makes the analyses more difficult. This means that the frequency analyses can only reliably detect large changes in the mechanical properties.

The method developed by the Oldenburg researchers delivers more precise results: It analyses the turbulent excitation caused by the effect of the wind using stochastic data analysis methods. This method, developed by Joachim Peinke, Rudolf Friedrich and others in recent decades, makes it possible to separate the deterministic and stochastic parts of the dynamics and thus to analyse the changes in the mechanical structure more precisely.

In an experiment, the researchers exposed undamaged and damaged beam structures to turbulent wind conditions. By analysing the vibrations of the structure, they were able to precisely detect the changes in the mechanical properties. Compared to traditional frequency analyses, the stochastic method proved to be much more sensitive - especially for small changes and still invisible cracks.

In future, the Oldenburg researchers want to apply the new method for damage detection to more complex mechanical structures. They want to prepare it for use in wind turbines, aeroplanes or cars.

The publication

"Stochastic method for in-situ damage analysis", Philip Rinn, Hendrik Heißelmann, Matthias Wächter, Joachim Peinke, European Physical Journal B 86:3 (2013)

Further information: www.europhysicsnews.org/index.php?option=com_content&id=424

[University press release from 8 October 2013]