  The fracture behavior of fiber-ceramics like C/C-SiC strongly depends on the
initial damage arising during the production process. We study the transverse
cracking of the 90{\deg} ply in [0/90]S cross-ply laminates due to the
thermochemical degradation of the matrix material during the carbonization
process by means of a discrete element method. The crack morphology strongly
depends on the fiber-matrix interface properties, the transverse ply thickness
as well as on the carbonization process itself. To model the 90{\deg} ply a
two-dimensional triangular lattice of springs is constructed where nodes of the
lattice represent fibers. Springs with random breaking thresholds model the
disordered matrix material and interfaces. The spring-lattice is coupled by
interface springs to two rigid bars which capture the two 0{\deg} plies or
adjacent sublaminates in the model. Molecular dynamics simulation is used to
follow the time evolution of the model system. It was found that under gradual
heating of the specimen, after some distributed cracking, segmentation cracks
occur in the 90{\deg} ply which then develop into a saturated state where the
ply cannot support additional load. The dependence of the micro-structure of
damage on the ply thickness and on the disorder in spring properties is also
studied. Crack density and porosity of the system are monitored as a function
of the temperature and compared to an analytic approach and experiments.
