Prediction Method for Temporal Change in Fiber Orientation on Cylindrical Braided Preforms

Abstract

An advantage of braided fabrics is that the fiber bundle orientation angle, called the “braiding angle,” can be changed. Because the braiding angle affects the fabric’s mechanical properties, changing the angle is an important means of adjusting the stiffness distribution as required. However, when the braiding angle is changing from an initial braiding angle to a targeted braiding angle designated by the longitudinal velocity of the mandrel, some delay occurs before the actual braiding angle reaches the targeted braiding angle. Previously, several models have been developed in order to predict braiding angles, although a prediction method for a temporal change in braiding angle caused by the mandrel velocity change has not been presented. In order to obtain the temporal change in braiding angle under unsteady-state conditions, this paper presents a step response model in braiding angle on a cylindrical braided fabric. Furthermore, the method is verified with the experimental data. As a consequence, the model has proved effective for predicting fiber orientation on a cylindrical braided preform under unsteady-state conditions.