On the initiation and growth of kink bands in fiber composites. Part II: analysis

Motivated by the experimental findings in Part I, the growth of a kink band in a uniaxial composite is investigated using two- and three-dimensional micromechanical models. The models include both a local and a global imperfection and were preloaded in compression and then sheared under displacement control. An inclined kink band initiates from the local imperfection and grows across the specimen. Similar results were obtained for pure compression loading. The simulated kink bands are quite similar to those observed experimentally; though, when J(2) plasticity is used to model the inelastic matrix, their inclination is lower than in experiments. The calculated band inclination is shown to be insensitive to many model parameters including imperfection characteristics, fiber diameter, volume fraction, and matrix yield stress. However, it is quite sensitive to the dilatancy of the matrix as demonstrated by the use of the Drucker-Prager constitutive model for the matrix. It was found that the ability of the matrix to deform in the direction transverse to the fibers plays an important role in allowing larger, more realistic kink band inclinations to be obtained. (C) 2001 Elsevier Science Ltd. All rights reserved.