Theoretical Modeling and Analysis of Fiber-pull-out Behaviour from a Bonded Fibrous Matrix: The Elastic-bond Case

A theory to characterize the single-fibre-pull-out behaviour of bonded fibrous systems is presented. Based on the shear-lag mechanism and the statistical-mean microstructural elements in the systems, the theory is developed for structures in which fibers are bonded with each other at contact points, and, as a result, the fiber-bonding with the matrix (the other fibers) is effected through the discrete points instead of a continuous interface. A theory aimed at one single bond is first derived, and it is then extended to the whole fiber by adding up the contributions from all bonds on this fiber into the result so as to predict a stepwise curve of the pull-out force and the embedded fiber length. This theory can also be used, combined with experimental results, to estimate the important bond properties, such as the bond shear strength Tband the shear modulus Gb. A parametric study is carried out and illustrated in this study to reveal the effects of the important factors involved during the fiber-pull-out process.