Use of wireless strain gauges to detect stress and strain in a structure has been demonstrated with the help of US Naval Air Systems Command, which believes the technology could reduce maintenance labour costs.
Developed by Columbia, South Carolina-based Direct Measurements (DMI), the gauge detected strain induced by cold working of a fastener hole in aluminium. As well as verifying the cold expansion, the gauge measured non-uniform strain - an indicator of fatigue life - near the fastener hole.
DMI's wireless strain gauges can be attached permanently or temporarily to surfaces, and one type can be laser bonded. Once bonded the gauge experiences the same stress and strain as the structure to which is attached.
"The strain field in the vicinity of the gauge is indicated by the gauge's appearance," says DMI, and is detected using a wireless "reading" device that also scans the unique serial number encoded on to the gauge. Custom software analyses and quantifies gauge deformation.
Source: Flight International
