Possibilities of investigation for ultrasonic method to defects detection in many-layered cylindrical structures

Abstract

Recently the ultrasonic NDT methods are being brought into practice by using it in various investigations of plastics. The aid of an accomplished experimental testing is to ascertain the possibilities of detecting the plastic pipes defects in different depths. The polypropylene (PP) and polyethylene (PE) coupled layer plastic pipe samples were chosen.

The pipe samples were applied with the standard side drilled holes (SDH) and flat bottom holes (FBH). During the investigation process it was found out that such holes were detected in all cases using the two layers PP and PE pipes. However when the three layers plastic pipes, with the internal glass fibred layer were used, the standard holes from the third layer could not be observed. It can be considered that the reason of a poor detection in the third layer was refraction from and an absorption in the intermediate glass fibred layer. The goal of further investigation in this field is to extract the suppressed informative ultrasonic signal from multi refracted background by using mathematical methods.