Abstract

Carbon-fiber reinforced plastics (CFRP) are widely used for aircraft structure manufacturing due to their efficient stiffness to mass ratio. Numerous failure modes can occur in these materials; therefore, inspections are required both in production and in the field. The increased use of CRFPs has also raised requirements for fast and reliable NDT techniques capable of inspecting large components within a short time. Recent developments in the field of laser-ultrasound (LU) lead to fast all-optical systems providing detailed images with sub-ply resolution. However, manual analysis of such images can be time-consuming and infeasible in the case of large components inspection. Therefore, automatic signal processing methods of these scans are required. The main challenge in the implementation of such methods is multi-modal nature of laser ultrasound generation. Surface and shear waves create artifacts in B-scans and can hinder defects detection through simple signal gating. In this paper, we present a short-time correlation techniqe that analyzes similarities between a reference obtained for a pristine structure and the inspected signal. Any differences between the signals are observed as a drop in local correlation coefficient which can be acquired and presented in the form of a time-of-flight C-scan.

How to Cite:

Mrowka, J., Spytek, J. & Ambrozinski, L., (2019) “3D reconstruction of barely visible impact damages shape from local coherence difference between laser ultrasound signals”, Review of Progress in Quantitative Nondestructive Evaluation .