Testing large aerospace CFRP components by ultrasonic multichannel conventional and phased array pulse-echo techniques

Abstract

The inspection of large aerospace CFRP components with ultrasonic techniques is subject to very challenging requirements in terms of ensuring a reliable and time-efficient non-destructive examination. The different approaches such as squirter immersion and contact techniques are discussed under these aspects, which for achieving an optimised solution seem to be contradictory at first view. Assessing the advantages and the weak points of each of these methodologies, the conclusion resulted in a contact technique combining high-frequency conventional and low-frequency phased array probes. This system facilitates pulse-echo technique and backwall monitoring - even in the non-parallel sections - as two complementary sources of information about the structural integrity of the component. The development of this technique and its optimisation performed have helped to determine the optimised parameters of such techniques and the optimum number of channels between 'very high' associated with high cost, but fast examination, and 'low' as a low-cost version, which in turn requires a considerable time for the examination. Most of this work leading to the implementation of such system was performed in the framework of the German research project MaTech, partly sponsored by the Federal Ministry for Education and Research. Project partners are Airbus in Bremen, Ingenieurburo Dr Hillger in Braunschweig and intelligeNDT Systems & Services in Erlangen. The experience achieved with this system has proven its compliance with the performance criteria as planned under the aspect of reliability and time-efficiency.