Wind energy is not very efficient and activists have turned on it because 300,000 out of 10,000,000,000 birds are killed by wind turbines each year. Without subsidies it would not exist but exist it does, only now manufacturers have had to discover physics they did not anticipate.
Wind turbine failures primarily happen because components are weakened under turbulent air flow conditions and then need to be replaced, at significant cost.
A team writing in European Physical Journal B set out to find a method for detecting fatigue in wind turbines parts without having to remove each of the components and while the turbine is in operation. Spectral analysis, which looks at different frequency responses, are distorted by the turbulent working conditions so it often only detects really major damage, like a crack that covers more than 50 percent of a blade.
A simple experimental set-up of undamaged and damaged beam structures exposed to excitations containing an element of interfering vibrations, or noise, made by different turbulent wind conditions, allowed them to distinguish between dynamics attributed to mechanical properties such as stiffness of the blade, and those attributed to interfering noise, such as turbulences.
The authors demonstrated that they were able to precisely detect the changing mechanical properties of the beam material based on an analysis of the mechanical vibrations.
Ultimately, when the method is further refined, this could be used to identify material fatigue or untightened screws, for example, and be applied to more complex structures such as automotive or airplane parts.
Citation: P. Rinn, H. Heiβelmann, M. Wächter, and J. Peinke (2013), Stochastic method for in-situ damage analysis, European Physical Journal B 86: 3, DOI: 10.1140/epjb/e2012-30472-8