25 August 2006
25 August 2006
John Mandell and Dan Samborsky from Montana State University have built one of the largest open-access databases on wind turbine materials in the US.
Modern blades reach lengths of up to 200 feet and weights of up to 50,000 pounds, manufactured from materials including fibreglass and carbon fibre. They may spin half a billion times or more in their hoped-for 20-plus-year life spans.
But no one is willing to wait 20 years to see if a particular composite material for a blade holds up or not. That's where Mandell and his team come in. In 1989, Sandia National Laboratories, the huge Department of Energy facility in Albuquerque, New Mexico, offered to fund Mandell in assessing these materials, and he’s been at it ever since.
A professor of materials science in MSU's department of chemical and biological engineering, Mandell's work is essentially to predict how a particular composite material will hold up over years or decades from the tug of gravity and the stress of wind.
""A lot of effort has gone into these tests so that the data mean something,"" Mandell said. ""We've had to invent methods ourselves. It has been a great deal of work."" Current materials last much longer in the tests and are stronger compared with the more primitive materials in early years of the study. A fibreglass or carbon fibre sample can spend weeks or months - 24 hours a day - being fatigued in the grip of the laboratory's machines.
In 17 years, Mandell and Samborsky, a research specialist, have accumulated 10,000 results on about 150 different composite materials. The research has been gathered up on Sandia's Web site as the ""MSU/DOE Fatigue Database for Composite Materials."" It is one of the world's largest open-access libraries on wind turbine materials and the largest in the United States, according to Sandia, and is used by researchers around the globe.
""Within in the U.S., we are still doing the bulk of the testing that's open literature,"" Mandell said.
Mandell works closely with fellow MSU engineering professor Doug Cairns. Cairns' program is in the manufacture of composite materials, understanding how to resin-infuse and cure layers of fibreglass and carbon fibre on a 150-foot-long blade.
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