Development Of A Smart Flexible Transducer To Inspect Component Of Complex Geometry: Modeling And Experiment

In many industrial sectors, as nuclear and aircraft, the main part of ultrasonic non destructive testing is carried out using contact transducers. Among others, the cooling piping of French pressurized water reactor comprises many welding components with complex geometry which lead to degraded inspection performances; loss of sensitivity due to unmatched contact on irregular surface, beam distortions, uncovered area. To improve the performances of such inspections, the French Atomic Energy Commission (CEA), supported by the safety authorities (IPSN), has developed a new concept of contact phased array transducer. Its radiating surface is flexible to optimise the contact, while the characteristics of the transmitted beam (orientation and focal depth) are preserved thanks to a delay law optimising algorithm. This computation requires the actual positions of the elements, so an instrumentation is coupled to the transducer to measure its radiating surface distortions. Thus, this smart flexible transducer becomes self-adaptive. Recent studies have been made to obtain further performances improvements of this system, including instrumentation development and a new phased array design allowing to generate both longitudinal and shear waves beams. Inspections have been performed on a specimen containing artificial defects under a realistic profile, with an adaptive mode to compensate the effect of the irregular profile. Experimental results show the ability of this system to detect and characterize defects under irregular profiles, using longitudinal or shear waves.