ULTRASONIC METHOD FOR DETERMINING PLY ORIENTATION IN UNIDIRECTIONAL CARBON FIBER COMPOSITES

摘要

Carbon fiber composites are heavily used in a wide variety of industries from aerospace to automotive to marine to athletic equipment. In many industries, destructive testing is not a preferred option to obtain material properties as the desire to keep the part in service is quite high due to individual part costs. This research uses an ultrasound technique to scan unidirectional carbon fiber laminated composites. The data collected from the scan is analyzed in MATLAB and C-scans are created to visually determine the ply-orientation for each layer within the stack. In the presented instance, the technique for determining the ply orientation is based on detecting the weft fiber that is used to maintain the integrity of the unidirectional ply during fabrication that remains within the part after fabrication; the weft fiber runs perpendicular to the carbon fibers [1]. Thus, once the weft fiber orientation is identified by post-processing the collected data the ply orientation is obtained. The results presented in this work demonstrate the ability to nondestructively identify the ply orientation for most of the lamina in the two laminate stacks presented. With the technique presented in this work it would not be possible to determine ply orientation - after the first layer - if there is no artifact in the fabric that may be correlated to the direction of unidirectional alignment, such as the weft fiber.