Influence of the fiber volume fraction and the fiber Weibull modul on the behavior of 2D woven SiC/SiC - a finite element simulation

The behavior of two-dimensional woven SiC/SiC ceramic matrix composite (CMC) is studied by numerical simulations based on the finite element method (FEM). Starting point of the investigations is a micromechanical model regarding a three-dimensional unit cell, which takes damage and fracture of the single components - fiber bundles and inter yarn matrix - into account. The scattering of the strength values which is characteristic for ceramic material is involved using Weibull distribution. In a first step the unit cell regarded within the simulations is cooled down to consider the residual thermal stresses resulting from the fabrication process. In a second step the unit cell is subjected to tensile loading and its behavior - especially the influence of the scattering of the strength values - is studied. To be able to estimate the influence of important parameters on the behavior of the composite a macrostructure is built up using the results obtained for a large number of unit cell. Thus an averaging effect is reached and the behavior obtained for the macrostructure should be characteristic for the composite. Doing so, the influence of the fiber volume fraction v sub f and the fiber Weibull modul M sub f on the composite behavior can be studied.