MONITORING ROB COPPINGER / LONDON

Germany's Fraunhofer Institute has developed an oscillating piezo­electric
actuator system to detect damaged aircraft parts for struc­tural health
monitoring.


The response of aircraft struc­tures to vibrations from a network of
actuators is detected by another set of piezoceramic sensors, ena­bling the
damage to be located.


A team at the Fraunhofer Institute for Structural Durability and System
Reliability in Darmstadt has already performed laboratory tests on a hull
compo­nent and is now implementing the system with standardised piezo and
electronic components.


"We investigated the oscillation behaviour of damaged struts and rivets in
an aircraft body and compared it with that of intact parts," says project
manager Dirk Mayer. "If a component is defective, it oscillates at a
different frequency from one that is intact when stimulated by the
piezoceramics."


The US University of Missouri-Columbia is also working on struc­tural
health monitoring using pie­zoceramic actuators. That team's system detects
cracks in composite structures using a laser to measure the vibration
generated by the actuators (Flight International, 20-26 February).