Yukitane Kimoto

Evaluation of measurement method for carbon fiber length using an optical image scanner

Fiber length and its distribution are important factors to determine the mechanical properties of discontinuous carbon fiber-reinforced composites. For the efficient and easy measurement of fiber length, an optical image scanner was introduced into the measurement procedure. The scan image allowed to measure approximately 25,000 carbon fibers. The measured values ( ) and mean value of these (< >) were evaluated by comparison with reference values ( ) obtained using an optical microscope. were dependent on the angle between fiber and sub-scanning direction. Furthermore, the relative errors between < > and were less than 2.5% in case that were 0.226 mm or more. The sample standard deviations of were approximately constant and their values were ca. 0.010 mm. Therefore, it was found that the relative error of measurement value derived from the scan image was dependent on the measured fiber length.