Infrared image of a defective rotor blade. The yellow areas are air inclusions.
Infrared image of a defective rotor blade. The yellow areas are air inclusions.
Mobile testing unit.
Mobile testing unit.

“Infrared thermography is well suited to this task, as it is fast, relatively cheap and doesn’t cause any damage,” according to WKI project manager Dr Hiltrud Brocke.

“The surface is briefly heated with an infrared radiator," Brocke explains. "A special camera shows how the heat front spreads inside the material. If the front hits on any air inclusions or delaminated areas, it accumulates because heat spreads less in air than in solid laminate.”

In this way, the researchers can 'see' several centimeters into the material.

“Because the equipment – the infrared radiator, a camera and a computer – is mobile, we can carry out measurements during production, at the end of the transport route, and also on fully assembled wind energy plants,” says Brocke.

The researchers demonstrated their technology on a rotor blade section incorporating several typical faults at the Hannover-Messe exhibition earlier this year.

 

Further information: Thermographic Testing of Rotor Blades in Wind Turbine Generators.