Numerical prediction of tensile properties and damage evolution of three dimensional-four directional braided CMCs

A numerical method was developed to simulate the effective elastic properties, strength and progressive damage evolution of three dimensional-four braided ceramic matrix composites(3D-B-CMCs). Firstly, the elastic properties of yarns were predicted using the composite cylinder assemblage (CCA) model and the strength were predicted by the global load sharing (GLS) model considering the strength distribution of fibers. Then a three dimensional unit-cell finite element model was constructed based on the geometric data from micro-CT images. After that, anisotropic damage model has been adopted in the fiber tows with Hashin failure criteria and damage evolution law based on the characteristic length of element. The model was coded as the ABAQUS/UMAT subroutine program and implemented into monotonic tension simulation of 3D-B-CMCs. The stress-strain curve was predicted and correlated well with the experimental curve, which verified the rationality of the method and the validity of the UMAT subroutine program. At the same time, more insights of the influence of different damage process on material mechanical behavior were concluded from the simulation, which provide information for the progressive damage evolution of the material fatigue and creep.