Video ultrasonics by pulsed TV holography : a new capability for non-destructive testing of shell structures

Abstract

We present a novel capability of the TV holography technique applied to the non-destructive testing of mechanical parts or structures with the form of a plate or a shell, which consists of the recording of high quality synthetic movies of the spatio-temporal evolution of instantaneous ultrasonic displacement fields of the surface under inspection. Moreover, in the case of narrowband acoustic excitation, movies of the spatio-temporal evolution of the acoustic amplitude and of the total acoustic phase can also be generated. Some examples of the application of the technique to flaw detection in aluminium plates using surface waves are presented. As a previous step for evaluating the context and the advantages of the new capability presented, a description of the state of the art with a comparative analysis about non-destructive testing techniques based on optical probing of ultrasound, focused on shell structures, is included in the first part of this article.