Smarter, safer bridges with Sandia sensors

through a Sandia-sponsored Laboratory Directed Research and Development project. The project explored using mounted sensors and wireless data transfer to continuously monitor a wide array of civil structures ranging from heavy mining equipment to railway systems and bridges. These sensors can monitor the health of structures and mechanical devices by detecting the presence of corrosion and cracks and even the condition of critical moving parts.

Roach and his team also use piezoelectric sensors, fiber optics and printed eddy current sensors for structural health monitoring. Printed eddy current sensors, a Sandia-patented technology, can be installed on curved surfaces and use changes in a magnetic field to detect cracks. On the other hand, a network of piezoelectric sensors can monitor a wide area instead of just a few patches. Each sensor takes turns sending out a vibration through the underlying material that the other sensors receive. Cracks or other damage within the sensor network change the “pitch” of these vibrations. However, these pitch changes are more complex than the “yes” or “no” results from the vacuum monitors. Comparative Vacuum Monitoring is ready and certified for commercial use, the other technologies are still in different stages of lab and field testing.

Tom Rice, the mechanical test engineer in charge of testing various structural health monitoring systems, said “In 15 years of testing Comparative Vacuum Monitoring sensors, they have achieved a tremendous track record for producing dependable structural health monitoring. Once they get incorporated into more systems, in areas of concern, it’s just going to make aircraft, trains and bridges safer as time goes on.”

Structural health monitoring is especially good for hard-to-reach or remote areas, but it’s not a panacea for all inspection needs, Roach said. “There’s still plenty of times when you want a human in there with a flashlight or other inspection equipment, reasoning it out.” With that caveat, he added “Structural health monitoring is only beginning to scratch the surface of the varied types of infrastructure it could be used for.”

Railcars and rail lines, ships, wind turbines, power plants, remote pipelines, storage tanks, vehicles, even buildings could benefit from real-time, remote structural health monitoring. “The civil infrastructure industry is becoming more aware of the benefits structural health monitoring can provide and is now interested in using them,” said Roach.