Investigations of pitch-catch angled-beam ultrasonic NDE for characterization of hidden regions of impact damage in composites

Abstract

This study explores the use of angled-beam ultrasonic NDE for the potential characterization of hidden regions of impact damage in composites. While simulations of an angled-beam pulse-echo inspections have shown the potential to detect both direct and full-skip indications from edge delaminations, recent experimental testing has encountered considerable difficulty in detecting diffracted signals from delamination fields. To overcome this challenge, several alternative pitch-catch configurations were studied for characterizing the hidden delamination fields. Simulated studies were performed for both back-scatter and through pitch-catch configurations. Clear differences between the signals on the far side of the impact site were observed between columnar and diamond-shaped damage. When including steps in delaminations with connecting matrix cracks, pitch-catch measurements were still found to provide sensitivity to the shape of the hidden profile. Experimental studies were also performed, supporting the feasibility of a through pitch-catch inspection of the hidden damage region. However, care must be taken to precisely control the source beam and measure the through-transmission receive fields.