Evaluation of fiber orientation in carbon fiber-reinforced polymer composites using simple and low-cost infrared measurement system: Application to unidirectional carbon fiber composites

Carbon fiber-reinforced polymer (CFRP) composites exhibit higher strength in the longitudinal direction than in the transverse direction of the fibers, making their fiber orientation evaluation crucial. In this study, a method for evaluating fiber orientation using halogen spot periodic heating and a non-lock-in type infrared camera is employed and applied to a unidirectional carbon fiber composite—a CFRP composite with unidirectional continuous fibers. Experimental results show that the in-plane thermal diffusivity in the fiber direction is significantly higher than in other directions. Therefore, the employed method successfully evaluates fiber orientation in the unidirectional carbon fiber composite.