抄録
Plant-based natural fibers have a large variation in cross-sectional area. Even in a single fiber the cross-sectional area varies along the fiber-axis. In addition, the shape of the cross-section is not circle, but rather close to an ellipse. Therefore the fiber strength often results in under- or over-estimation. It was observed from cross-sectional micrographs of a curaua fiber green composite that real fiber cross-sectional areas indicated a strong correlation with fiber cross-sectional areas assumed as an ellipse. Based on such correlation, therefore, the present study proposes a new method of determining approximately fiber cross-sectional areas. The validity of the proposed method is shown through elliptical areas calculated from two projection widths, which are measured from two orthogonal directions of single curaua fibers. Moreover, a new probabilistic distribution function based on Weibull theory was created to explain the effect of variation in cross-sectional area along the fiber axis on fiber strength. This function is characterized to decide the statistical properties of fiber strength through a parameter, R, of variation in cross-sectional area.
