03/26/2009
Germany - German institute develops wind turbine blade testing technology
At first glance, the rotor blade appears to be flawless, but the expert knows that outward appearances cannot be trusted. He taps the surface and listens. A full, deep sound tells him that the laminate is homogeneous, while a more flat, hollow tone indicates irregularities in the material.
Delaminated and hollow sections of a certain size near the surface can also be detected by running an expert hand over the surface material. But even an experienced inspector cannot find all hidden faults in this way.
Rotor blades consist mainly of glass fibers which are processed to form mats or meshes. In order to make a 60-meter rotor blade, hundreds of these mats have to be laid flat inside a mold and impregnated with special resins in a vacuum. Even minor irregularities can cause air bubbles or other faults to form, often leading to mechanical stresses in the material when the blade is subjected to everyday loads. As a consequence, the laminate can rip and cause the rotor blades to fail prematurely.
Researchers at a one of the foremost research institutes in Germany are now able to make such faults visible. “Infrared thermography is well suited to this task, as it is fast, relatively cheap and doesn’t cause any damage,” explains a WKI project manager. “The surface is briefly heated with an infrared radiator. 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 peer 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, even on fully assembled wind energy plants,” a WKI project manager said.
The researchers will be demonstrating their technology on a rotor blade section incorporating several typical faults at the Hannover-Messe from April 20 to 24.
For more information please contact Trevor Sievert at ts@windfair.net
Delaminated and hollow sections of a certain size near the surface can also be detected by running an expert hand over the surface material. But even an experienced inspector cannot find all hidden faults in this way.
Rotor blades consist mainly of glass fibers which are processed to form mats or meshes. In order to make a 60-meter rotor blade, hundreds of these mats have to be laid flat inside a mold and impregnated with special resins in a vacuum. Even minor irregularities can cause air bubbles or other faults to form, often leading to mechanical stresses in the material when the blade is subjected to everyday loads. As a consequence, the laminate can rip and cause the rotor blades to fail prematurely.
Researchers at a one of the foremost research institutes in Germany are now able to make such faults visible. “Infrared thermography is well suited to this task, as it is fast, relatively cheap and doesn’t cause any damage,” explains a WKI project manager. “The surface is briefly heated with an infrared radiator. 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 peer 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, even on fully assembled wind energy plants,” a WKI project manager said.
The researchers will be demonstrating their technology on a rotor blade section incorporating several typical faults at the Hannover-Messe from April 20 to 24.
For more information please contact Trevor Sievert at ts@windfair.net
- Source:
- Online editorial www.windfair.net
- Author:
- Posted by Trevor Sievert, Online Editorial Journaist
- Email:
- ts@windfair.net
- Link:
- www.windfair.net/...
- Keywords:
- wind energy, renewable energy, wind turbine, wind power, wind farm, rotorblade, onshore, offshore, Principle Power
