Detecting Changes in Fiber Orientation in a Simulated Chopped Fiber Plate Using Curvature Mode Shapes

The use of chopped fibers in the manufacturing of carbon fiber composite parts is becoming more popular in order to reduce production costs, especially in the automotive, wind, and gas storage industries. The orientation of the fibers in a chopped fiber part is important because the material properties of the part depend upon it. Phenomena such as shear alignment can result in undesired material properties, and therefore, a method for detecting the presence of undesired fiber orientations is needed. In this paper, a metric based on a part's curvature mode shapes is developed to identify the presence and location of fibers whose orientation is different from that of a desired alignment. A proof-of-concept experimental analysis shows the effectiveness of the metric at locating a region in a carbon fiber laminate plate that has been modified by rotating the fibers 90 deg. A finite element model is also developed to validate the experimental results and explore other modification scenarios. In each case, the metric is effective in identifying areas in which fiber alignment changed relative to a baseline model. In one case, a change as small as 3 deg was identified.