Sensing skin monitors structural health of wind turbine blades, giving insight into needed repairs
An inexpensive polymer that can detect damage on large-scale surfaces could be pivotal in making wind energy a more affordable alternative energy option.
The material, which is made into 3-inch square pieces, is a nanocomposite elastomeric capacitor fabricated from a dielectric layer sandwiched between two painted conductive layers. When the skin is placed on a surface, engineers can measure its capacitance, or stored electrical charge, to make inferences about any changes in geometry taking place on that surface.
Simon Laflamme says using this material on large-scale structures, such as wind turbines, could mean making less expensive, condition-based repairs when small cracks and other deformities appear instead of incurring the high cost of maintenance on a fixed time interval or after a breakdown, which may necessitate the replacement of huge components, like an entire turbine blade.
Laflamme, assistant professor of civil, construction and environmental engineering, has been developing the sensing skin since he was a student at MIT. While he didn’t originally plan on the skin being used on wind turbines, he says it’s a great application.
That’s because current structural health monitoring of wind turbine blades can’t be done in real-time on a continuous basis. “The turbines have to be physically inspected, and this usually happens only once or twice a year. By the time inspectors get to a blade, it could have sustained too much significant damage to do minor repairs,” Laflamme explains.
Once it’s adhered to a surface, the sensing skin would act as an indicator, automatically telling engineers to inspect a blade if something unusual happens. Over time, a pattern of how blades deteriorate emerges, providing insight into better maintenance plans for wind turbines, which could extend the life of the blades, as well as provide new ideas for future blade designs.
All of these factors come together in what is called an automated condition assessment. “The sensing skin is integral in capturing the entire lifecycle of blades as changes happen rather than through the reverse inspection that is used today,” Laflamme adds.
His research has become truly multidisciplinary. The skin itself is produced in collaboration with the materials science and engineering department, but it also has ties with electrical and computer engineering for designing cost-effective data acquisition systems. Additionally, various efforts have been undertaken with aerospace engineering and several centers on Iowa State’s Campus, including the Center for Nondestructive Evaluation and the Bridge Engineering Center.
Laflamme says an approach that brings in different ideas is absolutely necessary. “It’s the way modern problems are going to have to be solved. We have to share insight to create the best solution,” he explains.
He adds that he appreciates being able to bring this perspective to the undergraduate and graduate students working on the research project. “We have at least 12 students who are getting a sense of how valuable multidisciplinary engineering is, and they are truly enjoying the experience,” Laflamme says. “Integrating the concept into their education means it becomes a natural way of thinking for the next wave of engineers in industry, and that’s going
to mean big things for what’s to come.”