Fibre and ply orientation measurement in carbon fibre composites from ultrasonic data

Nelson, Luke; University of Bristol; United Kingdom

Nelson, L.J.; University of Bristol; United Kingdom
Smith, R.A.; University of Bristol; United Kingdom

ID: ECNDT-0406-2018
Download: PDF
Session: Composite Material - UT 1
Room: G1
Date: 2018-06-14
Time: 11:50 - 12:10

The complex geometrical nature of fibre-waviness and ply-wrinkling defects in carbon fibre composite components makes defining acceptance criteria for manufactured parts a difficult task. A solution which is gaining in popularity is to use finite element models to predict the mechanical performance of each manufactured part. The success of this approach relies on robust inversion techniques that can be applied to non-destructive inspections to provide location and orientation information for the plies and fibres. This paper presents a solution using pulse-echo immersion ultrasonic inspections. An understanding of the interaction of ultrasonic pulse with the ply layers and fibre tows allows acquisition of three-dimensional (3D) datasets that have sensitivity to these features. Signal processing and image processing techniques, specifically structure tensor and Radon transform methods, have been applied to ultrasound data acquired from a number of test samples. The resulting 3D maps of ply location, ply orientation and fibre orientation are compared to actual profiles of these features obtained from X-ray CT and optical micrographs. This analysis shows the proposed ultrasonic approach can assist in the generation of finite element models of as-manufactured components featuring ply-wrinkling and fibre waviness defects.