Microbuckling of fiber composites with random initial fiber waviness

Abstract

A fiber microbuckling calculation is presented for the effects of fiber misalignment and material nonlinearity on the compressive strength of fiber composites. The role of fiber bending stiffness is included by using a particular form of couple stress theory. In order to examine the effect of a distribution of fiber waviness, the fiber misalignment angle is assumed to vary along the fiber length but is taken to be uniform in the transverse direction. Thus, the effects of wavelength as well as amplitude of fiber waviness are taken into account. A consideration of sinusoidal initial waviness reveals that short wavelength imperfections are much less deleterious than long wavelengths. A statistical analysis is presented for the effect of random fiber waviness on compressive strength, using a Monte Carlo simulation technique. Compressive strength is found to be particularly sensitive to the area under the spectral density curve and to the minimum fiber wavelength.