A continuous structural health monitoring system that uses ultrasonic signals with sensors placed throughout an aircraft is being developed under the EU's sixth-framework programme.

Information on the state of the fuselage and wings and even helicopter rotors would be presented on a cockpit display and could be transmitted to a maintenance centre. Micro-cracks, composite structure delamination, the weakening of adhesive bonds and thermal and chemical damage could be detected and imaged. The technology, to be developed over the next five to 10 years, uses non-linear elastic wave spectroscopy. This involves active and passive sensors transmitting and detecting ultrasonic signals that pass throughout the aircraft.

"The sensitivity of this method is superior to existing methods," says Professor Josef Maes, aerospace division head for project participant Asco, the Belgian aircraft component supplier. "It will use novel actuators and sensors with tunable properties that can be integrated into the aircraft. Research will focus on sensor integration into structures."

Sensors with tunable properties will be developed because different types of damage are detected and imaged using different ultrasonic frequencies.

Source: Flight International