NASA 1999 SBIR Phase I

PROPOSAL NUMBER 99-1 01.07-4960 (Chron: 991952 )


Hybrid Thermographic Detection of Kissing Unbond Defects


Fast, portable IR NDE systems capable of automated operation and quantitative defect measurement are now commercially available, and have been credited with significant cost savings in aerospace manufacturing and service sectors. However, despite advantages of speed and wide area, non-contact inspection, IR methods are limited in their ability to detect disbonds in which there is mechanical contact but no adhesive bond. We will investigate the feasibility of a system for detection of these "kissing unbonds" using a novel combination of pulsed thermography and applied vacuum stress. Both vacuum stress and flash heating will be applied to the part, and a differential IR image comparing the post-flash cooling of the stressed and unstressed part will be generated.

The apparatus for acquiring the image and applying the heating and vacuum stress will be housed in a portable hood with a 10" x 10" field of view, and typical acquisition times of 20 seconds. If successful, the fully realized system will extend the capabilities of thermographic NDE systems to allow inspection of skin to core disbonds in honeycomb and foam core structures, and thick composite components used in the space shuttle and X-33, as well as commercial and military aircraft.



The proposed Hybrid Pulsed Thermography (HPT) system will significantly expand the market potential of IR NDI in the aerospace and automotive industries. Aerospace applications include inspections for skin to honeycomb or foam core disbonds, which are relevant for aircraft control structures, propellers, and jet engine casings; and identification of delaminations. The proposed system will be particularly useful for inspection of large scale structures such as the Space Shuttle Orbiter payload bay door, the fixed foam fuel tank insulation for the Delta IV, and commercial aircraft rudders and elevators. At present, inspection of these structures often requires multiple passes using a combination of NDI methods (e.g. shearography and thermography for the payload bay door). The potential for application of the HPT system in automotive manufacturing is enormous, as acceptance of composites as a substitute for steel continues to grow. For example, a consortium of Ford, GM and Chrysler are currently collaborating to develop an all composite truck bed, which will require online inspection. Pulsed Thermography has been identified as the leading candidate for inspection of the bed, with the caveat that kissing unbonds may go undetected. These and many other automotive applications will be better served by the HPT system.



Tasdiq Ahmed, PhD

Thermal Wave Imaging, Inc.

18899 W 12 Mile Road

Lathrup Village , MI 48076 - 2558

NAME AND ADDRESS OF OFFEROR (Firm Name, Mail Address, City/State/Zip)

Thermal Wave Imaging, Inc.

18899 W. 12 Mile Road

Lathrup Village , MI 48076 - 2558