Estimation of the axial tensile modulus of a particle-reinforced compositefiber with variable radius

The modulus of a fiber is difficult to measure, especially when the radius of the fiber changes along the length. The use of an arithmetic average rad ius or Volume average radius to calculate fiber modulus leads to an underes timate of the modulus. A model for measuring and calculating the true tensi le modulus of a fiber that has large radius variation is proposed. The mode l has been used to calculate the modulus of a Wollastonite particle-reinfor ced polypropylene fiber. The difference between the modulus calculated from the model and that from either the arithmetic or volume-average radius inc reases linearly as the coefficient of variation (CV) of the fiber radius in creases, especially when CV < 5%. When the evenness of the fiber increases, i.e. CV --> 0, the difference between the three methods for calculating th e axial tensile modulus is negligible. (C) 2000 Elsevier Science Ltd. All r ights reserved.