NDE Studies on Spacecraft Structural Components Using Aircoupled Ultrasonic and Thermography Techniques

The two Non-Destructive Evaluation [ NDE ] techniques viz., Air Coupled Ultrasonic [ACU ] and Pulsed Thermography [PT ] find many applications in aerospace industry . These NDE techniques can be used for debond detection in spacecraft structural components like honeycomb sandwich deck plates, shear web panels and central cylinder made of aluminum core and composite face sheets. The Air coupled ultrasonic NDE techniques, because of its non contact and non couplant nature and thermography because of it’s non contact and whole field nature are very much useful for NDE of honeycomb sandwich components especially made of carbon fiber reinforced composite [CFRP] face sheets which are hygroscopic in nature for couplants . Air coupled ultrasonic and pulsed thermography were used for the calibration studies and actual application of honeycomb sandwich panels made of aluminum core and CFRP face sheets . Different debonds were simulated by adhesive missing in the honeycomb panels between the face sheets and the honeycomb core. Also the debonds were simulated for some test coupons by inserting the Teflon sheet between the layers in the CFRP composite face sheet. These two techniques were also used for the actual testing of few spacecraft structural components for the NDE purpose.