Pulse Echo Ultrasonic Testing of Adhesive Bonded Joints for Automotive Applications

The growing prominence of adhesive bonding technology in automotive manufacture has necessitated the development of reliable and robust quality assurance techniques. Of the different Nondestructive testing technologies available, Ultrasonic testing has shown itself to be the most promising technique to satisfy the requirements in automobile production. The current work attempts to apply two variations of the Ultrasonic Pulse Echo technique namely Contact and Immersion testing for inspecting typical hem bonded automotive joints. The joints have been tested for disbond at the various metal-adhesive interfaces by using an ultrasonic scan comparison method which compares the acquired signals against a reference scan from the unbonded metal sheet. The results for the above tests have been documented. Detection of the absence of adhesive has been possible at the interfaces using the Contact testing variation. In the case of the Immersion testing, suitable distinction between the echoes from the different interfaces has not been achieved. Based on the results obtained, it has been proposed that the testing frequency be increased to obtain a clear distinction between the adherend and adhesive surface echoes.