13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- 4.1. The mesh sensibility and validation Firstly, in order to get accurate results, the mesh sensibility was studied with mesh size 10um, 30um and 50um in the quarter model. The result of the overall force-displacement response and the mises contour are shown in Fig.6. The overall force-displacement response shows very small difference. The mises contour pictures corresponding to the loading of 1.12×10-3mm for 10um, 30um and 50um are listed from left to right(white means 0Mpa, and black grey means 200Mpa, and black means exceeding 200Mpa), the maximum stress in matrix is between 203.3Mpa and 208.7Mpa, while it is 250.8Mpa and 273.1Mpa for the yarns, which shows little difference. So, 50um was accepted for its time-efficiency. (a) Overall force-displacement (b) The mises contour Figure 6. The effect of mesh size The prediction of the elastic modulus is about 75Gpa. And the elastic modulus from experiments is almost between 70Gpa[10,11] and 81.2Gpa[3]. Furthermore, the damage in RVE initiates at the stress about 53Mpa in the matrix, which agrees well with the initial proportional limit of the composites[3], around 50Mpa. 4.2. The damage prediction White-Black 0-200Mpa 0-150Mpa 0-800Mpa Figure 7. The mises contour of matrix(5th step)/interface/fibers(37th step) From the elastic RVE model, the matrix is probably damaged first at the thinnest region that close to the yarns, the damage of the yarns will initiate at the woven point, and the interface is easy to get damaged at the region of woven edge, shown in black in Fig. 7. When the stress in matrix reaches the strength, the average stress in the RVE is about 53Mpa. When the stress in the yarns reaches the strength, the average stress in the RVE is about 330Mpa,
RkJQdWJsaXNoZXIy MjM0NDE=