Totally wired components to monitor stress in planes and cars

Tiny magnetic wires embedded within composite materials could allow better assessments of internal damage in aircraft parts, ship hulls or pipelines.

Composites are now ubiquitous across aerospace, automotive and other engineering sectors, but researchers from the National University of Science and Technology in Russia said internal stress assessments have always been an issue. 

Assessment is key as stress on critical components made of polymer composites often reaches 95% of tensile strength after fabrication, said researcher Andrey Stepashkin. Carbon plastics, glass fibre and hybrid composites also face stress from operation and external conditions, leading to damage and reduced load bearing. Changes affect operational safety and must be identified quickly, said Stepashkin.

Existing non-contact methods such as shearography, ultrasonic or acoustic flaw detection identify defects that have already happened, but the team said they do not provide information about stress within the material or distribution within the structure. Contact methods involve film sensors being stuck to structures.

Instead, the team created “amorphous soft magnetic circuits” of wires with diameters of 10-60 microns. During composite manufacture, the wires could be inserted between layers to form stress-sensitive grids that react to external magnetic fields.

The researchers said the technology could simplify, speed up and reduce the cost of assessments. They now hope to develop a field prototype and test their system in the laboratory.

The work was published in the Journal of Alloys and Compounds.