To automate that procedure, researchers at the Fraunhofer Institute for Silicate Research (ISC) in Wurzburg have developed a system that can detect microfissures of 5mm in length in the glass, and indicate when repairs are needed long before the glass actually breaks.
The system comprises several piezoelectric sensors and an actuator that are attached to a window panel. In operation, the actuator generates an ultrasound wave that is then picked up by the sensors.
If the acoustic signal remains constant, then the pane is not defective. If it changes, this indicates a fissure has occurred. The sensors are linked to a building control system by a cable. There, the data received from the sensors is analysed automatically and if a fissure occurs, an alarm goes off.
The researchers say that the sensors, which measure 15 x 15 x 0.5mm can be placed between both sheets of laminated glass during the glass manufacturing process.