13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- normalized IFs 0 / I I K K , 0 / IV IV K K and 0 / V V K K are all increase monotonously for the crack in the equivalent homogeneous MEE plate while none of them varies monotonously for the crack in the particulate MEE plate. Besides, for the same geometry configuration, the EDIF (MIIF) for the particulate plate is quite larger (smaller) than that for the equivalent homogeneous plate. The reason may be that both of the crack tips are located in the PE phase. Next, a crack of fixed length ( / 0.4 a W= ) is considered and the angle θ varies from 0° to 90°. As shown in Fig. 5, both of the crack tips are located in the matrix for (0 ,90 ) θ= ° ° and in the particles for 18 ~72 θ= ° °. Fig. 6(a) and (b) show the normalized IFs obtained at the right crack tip varying with the crack angle. The results show that although obvious differences can be noted between the IFs for the particulate plate and those for the equivalent homogeneous plate, the varying trends of the SIFs are very similar for these two plates, while both the EDIF and MIIF vary distinctly with the increasing of the angle θ. The above phenomena imply that the actual PE/PM microstructures and the relative position between the crack and particles have great effects on the fracture performance of MEE composites. Figure 5. Crack locations for different angle θ. 0 18 36 54 72 90 0.0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 0 18 36 54 72 90 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Normalized EDIF and MIIF θ(deg) (b) KIV/K 0 IV, particulate KV/K 0 V, particulate KIV/K 0 IV, effective KV/K 0 V, effective Normalized SIFs θ(deg) (a) KI/K 0 I , particulate KII/K 0 II, particulate KI/K 0 I , effective KII/K 0 II, effective Figure 6. Normalized IFs vs angle θ for / 0.4 a W= : (a) SIFs; (b) EDIF and MIIF. 5. Summary MEE composites contain PE and PM phases and the interfaces between these constituent phases may reduce the reliability of MEE composites since the interfaces generally act as sources of failures in service. The complex interface environment brings a great difficulty to the fracture analysis of these MEE composites. This paper first introduces a domain form of the
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