Simulation of progressive damage of 3D braided compositesusing domain superposition technique

Domain superposition technique (DST) has been implemented for simulation of the progressive damage of braided composites in this paper. To establish the tow finite element mesh used for the DST analysis model, first of all, regular parametric geometric model for the tows were easily constructed using ANSYS parametric design language (APDL), and then a programmed automatic mesh trimming process has been carried out to trim the tow meshes established in the first step to establish new tow meshes which can fit exactly the space of the unit cell (UC) model used for the DST analysis. The element edges crossing the UC boundaries were cut by the UC boundaries to create new nodes. Some new elements were constructed using these newly created nodes and some original nodes to fit the boundary regions. Hashin and Von Mises damage criterions were used to predict damage initiations in tow phase and matrix respectively. Blackketter's degradation scheme for the elastic properties of the composites was adopted. A stiffness matching scheme suitable for damage analysis for DST implementation has been applied. A domain mapping method to ease the post-processing of the damage results of the matrix/resin-rich regions has been implemented. The numerical results predicted using the DST model correlate well with the traditional FEM predictions. And also, the strength and failure strain predictions are in good agreement with experimental results.