Iowa State engineers test a model of a cable in the department of aerospace engineering's Aerodynamic/Atmospheric Boundary Layer wind tunnel. They're working to understand and prevent out-of-control cable galloping in wind storms. Photo courtesy of Partha Sarkar

Researchers at Iowa State University are testing how high wind affects power lines and bridge suspension cables in hopes of helping engineers better predict at what wind speeds those cables begin to bounce wildly around, or gallop.

With a
 $338,000 grant from the National Science Foundation, Partha Sarkar, a professor of aerospace engineering at ISU, is using the university’s Wind Simulation Testing Laboratory to test various cables, some grooved like power lines, and some smooth like bridge cables, to better understand why the cables gallop at different speeds. 

Sarkar has spent the last five years collecting data on cable vibration in the high winds generated by hurricanes and other windstorms in hopes of finding a solution that will dampen the galloping wires and reduce the risk of fires, transmission tower collapse, power outages and other accidents. 

“Structural or fatigue failure of a cable, due to these vibrations, pose a significant threat to the safety and serviceability of these structures,” Sarkar and a co-worker wrote in the journal 
Engineering Structures

The researchers have found that factors such as whether the cables are wet or dry, single or bundled, or horizontal or angled, can affect how they react in high wind. The steeper the angle, the lower the wind speed needs to be to cause galloping, Sarkar said. The research, he said, could one day make it less likely for cables to gallop dangerously and catastrophically fail in high wind.