Ultrasonic inspection of complex geometry component specimen with a smart flexible contact phased array transducer: modeling and application

In many non-destructive testing applications, specimens may exhibit various geometries and state of surface: varying profiles of misaligned specimen, complex and irregular weld shapes. The ultrasonic inspection of such specimens with contact transducer should overcome several major difficulties: degradation of matching contact between the transducer and the specimen leading to a poor sensitivity, disorientation of the transducer resulting in an irrelevant localization of defects, or uncovered scanned area. The French Atomic Energy Commission (CEA) has therefore developed a new concept of transducer, allowing one both to take into account the varying profile of the tested component and to compensate these effects. This transducer is a flexible phased array able to match the surface of the inspected specimen and to efficiently compensate the deformation of its own surface, in order to preserve the ultrasonic beam characteristics in spite of the profile variations encountered during the scanning. The capabilities of this new concept of smart contact probe are described and demonstrated in this paper using modeling and experiments.