On Feasibility of Ply-Layup Orientation in CF/Epoxy Composite Laminates Using Rayleigh Probes

Abstract

A nondestructive technique would be very beneficial, which could be used to test the CF/Epoxy composite laminates. A new method for nondestructively determining the ply layup in a composite laminate is presented. A one-sided pitch-catch setup was used in the detection and evaluation of flaws and material anomalies in the composite laminates. Two Rayleigh wave transducers were joined head-to-head and used in the pitch-catch mode on the surface of the composites. The pitch-catch signal was found to be more sensitive than normal incidence backwall echo of longitudinal wave to subtle flaw conditions in the composite. Also the other method employs a normal-incidence longitudinal ultrasound to perform C-scan of ply interfaces of the laminate, and extracts fiber orientation information from the ultrasonic reflection in the laminate. Using two-dimensional spatial Fourier transform, interface C-scan images were transformed into quantitatively angular distribution plots to show the fiber orientation information therein and to determine the orientation of the ply. Therefore, it is found that the efficiency of developed system shows between the one-sided pitch-catch testing and C-scan images in characterizing ply-layup orientation of the laminates.