New Sensors Can Detect Structural Defects

New Sensors Can Detect Structural Defects
A research team from Sandia National Laboratories in the U.S. is developing a family of advanced permanently-mounted sensors that collect data about possible structural defects in support beams, bridges and highway overpasses. These sensors are expected to serve as an improved defect detection mechanism for structural engineers, allowing them to prevent catastrophes.

Dennis Roach with a Comparative Vacuum Monitoring (CVM) device (Credit: Randy Montoya, Sandia)
Dennis Roach with a Comparative
Vacuum Monitoring (CVM) device
(Credit: Randy Montoya, Sandia)

The Sandia research team, led by Dennis Roach, has already tested and proven monitoring sensors for use on aircraft structures. Roach explained the benefits of this technology by comparing the developed sensors to nerve endings in the human body. Both are permanently mounted and constantly sending information. With on-site sensors continually checking for the first signs of wear and tear, engineers can detect cracks early on, perform necessary maintenance at the right time, and possibly prevent massive failures, said Roach. The scientists developed and evaluated several types of inexpensive, reliable sensors that could potentially be mounted on important infrastructure, typically where flaws are expected to form.

One promising structural health monitoring (SHM) sensor developed at Sandia is the Comparative Vacuum Monitoring (CVM) sensor. This is a thin, self-adhesive rubber patch, ranging from dime- to credit-card-sized, that detects cracks in the underlying material. The rubber is laser-etched with rows of tiny, interconnected channels or galleries, to which a stream of air pressure is applied. Any propagating crack under the sensor breaches the galleries and the resulting change in pressure is monitored.

The concept of SHM is continuously developing. The benefit of such systems is both in the immediate data acquisition and in the reduced need for human inspection. Of course, one must make sure that the technology that is used is appropriately reliable. The Hong Kong Highways Department is already using a sophisticated bridge monitoring system to ensure road user comfort and travel safety between Hong Kong and the Hong Kong Airport.

 A Sandia researcher incorporates sensors that monitor stress into a structural beam of a highway overpass (Credit: Sandia National Laboratories)
A Sandia researcher incorporates sensors that monitor
stress into a structural beam of a highway overpass
(Credit: Sandia National Laboratories)

More information on the Sandia project can be found here.

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About the author

Avner Yanai

Avner has a bachelor's degree in Computer Engineering from the Hebrew University in Jerusalem and is currently studying for an M.Sc. in Applied Physics in the Hebrew University.

View all articles by Avner Yanai