Nondestructive characterization of the elastic properties of orthotropic composites with ultrasound

Due to the increasing use of composite materials in critical applications demanding light weight to high strength ratio, reliable evaluation tools are necessary. The field of ultrasound is a well known non-destructive method, in which the classical C-scan has already proven its usefulness in visualizing defects, delaminations, ... Though, because of the limitations for quantitatively characterizing a material using a C-scan, the quest for more sophisticated methods is a big challenge in current research. A polar scan, which makes use of oblique incidence of ultrasound, can serve as a prominent successor of more classical methods. By gathering the reflected (or transmitted) amplitude of the ultrasonic beam, one is able to built a polar plot which covers a certain solid angle. Typically, dark rings are observed in a polar plot which can be linked to the generation of critical bulk waves (pulsed regime) or to the generation of surface waves (harmonic regime). Both types of waves are vigorous entangled with the elastic constants of the material. This implicates that a polar scan is a great candidate tool to investigate anisotropic materials non-destructively, where the mapped amplitudes are a local fingerprint of the investigated material.

Jaar van publicatie:2011

Trefwoorden:anisotropy, NDT, elastic properties, ultrasound, polar scan