Identifying alternative methods for non-destructive testing of aeroplane structures (AMEND)

Important results from the project

Tests have been performed on reference materials with built in defects, where the results showed great difficulties in detecting these defects. How the artificial defects with paper in the adhesive joint relate to a more real defect consisting of air cavities. The outcome shows that the signal level increases by 2-3 times to the advantage of the air cavity. A concept for how an automation of the method might look has been described which shows possible cost and cycle time savings compared to ultrasound NDT, provided that the thermography method can be implemented.

Expected long term effects

The result has shown that it is difficult to detect if there are defects inside metal structure and at what depth they exist. The IR NDT method has also been tested against a composite panel with built in defects. Since composite has a lower thermal conductivity than aluminium, excitation needs to be carried out with a halogen lamp for a longer excitation period. The results from the composite panel show good conditions for detecting defects. A continuation of these preliminary tests should be able to give quantitative results on detection performance in composite materials.

Approach and implementation

The project started with a workshop where the project group got acquainted with the selected test product and the thermography method. Reference materials with built in defects were developed and appropriate parameters for testing were derived. When the preliminary test results for metal structure showed difficulties, tests on composite structure was also carried out. The project was concluded with a presentation of the results that together with a demonstration of the test method. The test results and evaluation of the test method have been compiled in a confidential report.