Effects of Carbon Fiber Misalignment on Composite Strength

Nondestructive Evaluation (NDE) is an effective way for determining material properties. More specifically, ultrasonic waves along with visual measurements from a microscope can be used to systematically determine the elastic modulus of single ply composites that are subject to an altered manufacturing process. In this approach, the magnitude of specific ultrasonic wave velocities are applied to determine the elastic modulus of transversely isotropic composites. On the other hand, fiber misalignment measurements are taken through a microscope camera to satisfy a statistical approach for the determination of the same elastic modulus. The Paper Physics Approach (PPA) and Laminate Analogy Approach (LAA) are utilized to predict the elastic modulus of unidirectional carbon fiber samples. The innovative manufacturing process responsible for the samples under study is a key approach in an effort to decrease the cost of the material, therefore unlocking the application of such a high strength, low weight material. Another challenge in this study is illustrated by the lack of understanding of the behavior of the fiber alignment within the samples. While it is assumed that all of the existing samples have similar fiber alignment properties, the degree of that alignment is unknown. A statistical approach is presumed to assist in the quantitative assessment of these parameters in order to characterize the sample’s elastic modulus. The purpose of this study is to develop a better understanding of whether or not the available samples are retaining structural integrity while being subject to an altered manufacturing process. Sufficient data and theoretical support are required to provide a sound answer through the sole method of nondestructive testing. While the samples will be subject to destructive testing, it is for the purpose of verifying the nondestructive principles that will thus forth provide answers.


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