Experimental Research on Local Fiber Stress Distribution Resulted from Fiber Waviness in Unidirectional Reinforced Composites

Abstract

Because mechanical properties of composites reinforced by fiber significantly owe to fiber orientation, fiber waviness plays an important role. In this study detailed measurement of fiber stress along fiber in unidirectional composites was carried out by using micro-Raman spectroscopy. Micro-Raman measurement was done along waved fiber in mm spatial resolution to clarify local load-shearing. As the result, fiber stresses on longitudinal and transverse plain are almost uniform in case of without waviness. On the other hand, in a specimen with waviness fiber stresses along fiber are smaller in a waved fiber than in a straight fiber. They show almost uniform distribution in low tensile load but become un-uniform with increase in loading.