Paris, France--At the JEC Composites Show 2008 held in Paris last week, scientists from the Fraunhofer Institute for Structural Durability and System Reliability demonstrated a structural health monitoring system based on the use of piezoelectric materials. Six Fraunhofer Institutes are part of a European consortium called the "Clean Sky" Joint Technology Initiative (JTI), which aims minimize the amount of air pollution caused by aircraft.
"We demonstrated an aircraft wing made of a fiber composite material incorporating a number of piezoelectric sensors and actuators," says Dr. Ursula Eul, strategic manager of Fraunhofer LBF. "This system enables damage to the material, caused by impact for instance, to be detected at a very early stage—practically as it arises."
Piezoelectric actuators in the structure emit acoustic signals which generate a specific pattern of structure-borne noise on the wing. The resulting vibrations are recorded by piezoelectric sensors. Any incipient damage to the material, such as the first signs of delamination, causes changes in the wave pattern of the structure-borne noise. A major challenge here is that the sensors integrated in the structure must not have any negative effect on the fatigue strength of the component or, worse still, on the normal performance of the wing. Reliable structural health monitoring systems that can operate continuously without affecting structural durability are one of the thematic areas of the Clean Sky Joint Technology Initiative.