Analytical Approaches to Model the Stiffness Reduction in Multi-Layered Carbon Fiber Composites with Process-Induced Defects

Abstract

In this paper, we will present analytical models which enable the characterisation of defects in composite materials. First, a study is introduced to determine the reduction of the material stiffness with analytical models. An analytical model based on the Eshelby theory and a three-dimensional laminate theory has been developed to predict the influence of voids on the material properties of a multi-layered fiber composites. Moreover, an efficient analytical approach is presented to account for the influence of fiber waviness on material stiffnesses of multi-layered fiber composites. The fiber waviness is approximated by periodic functions. Effective material stiffnesses are obtained by inserting the functions into transformation equations and integrating over wavelength and height of the laminate. The results of the analytic studies as a basis for future work will be presented.