Stress-sensing cables

Anyone who has rigged up a satellite antenna will know that the slightest kink in a coaxial cable can kill the connection. This is because the signal will bounce off the kink and corrupt the link.But this effect could soon provide structural engineers with an ingenious new way to spot faults buried deep inside buildings and bridges. The University of Missouri, US, is patenting a way to embed weakened cables inside concrete and use signal disruption to pinpoint structural weaknesses.The cable would be clad in a thin layer of spun copper. Any untoward stress or strain should easily crack the cover open to expose the cable inside.A timing signal would be continually fed into each cable and checked for reflections caused by cracks. The strength of any reflection and the time it takes to arrive back should give engineers an accurate fix on the position and extent of any damage deep inside a structure.