A machine vision system for the braid angle measurement of tubular braided structures

Two-dimensional braided composite materials consist of an impregnated and cured braided fiber structure. The braid angle, which describes the orientation of fibers on the mandrel, affects the material properties of the composite part. Furthermore, braid production is often inaccurate, requiring quality assurance measurements of the fiber orientation. In this study, a frequency domain machine vision algorithm was applied to tubular braided preforms to measure fiber alignment during production. Several approaches to compensate for the tubular mandrel shape were tested and the fiber distribution in both the spatial and frequency domains was compared. The developed machine vision system allowed braid angle measurements to be made in real-time and in-line during the braiding process. The integration of such a system eliminates the need to make manual quality assurance measurements of the braided fiber structure, it further automates the braiding process, and it decreases production error