13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- separation is 0 m . coh G , critical energy release rate, is given by coh max 0 d 0.5 f f m m G T T , where T is an effective traction, an effective separation, and f m a critical crack opening. The damage associated with the cohesive surface separation can be defined [6]. Many researchers assumed that max T and coh G played key roles while the shape of the cohesive law was relatively unimportant. Series of studies indicated that it could lead to unreasonable results [5,7]. Therefore, the shape of the cohesive law should be considered. Dependence of the results on the shape of the cohesive law is closely relevant to the dependence of the results on the mesh. Stress distribution in the cohesive zones must be resolved accurately. Therefore, a minimum number of elements are needed in each cohesive zone and the minimum number has attracted much attention [8]. On the other hand, insertion of cohesive elements introduces fictitious compliance [9]. To alleviate it, Geubelle and Baylor [9] used an adjustable initial slope in the bilinear cohesive law. Figure 1. Bilinear cohesive law The co-rolled SMATed 304SS contains the CGL and the NGIL. A computational configuration with a length 1 mm and a width 0.9 mm is illustrated in Fig. 2. The thickness of the NGIL is taken as 40 μm. Two levels of structured cross-triangular mesh size, namely, 10 by 10 μm and 5 by 5 μm, are used. The cross-triangular meshes with uniform size 10 by 10 μm are illustrated in Fig. 2. Figure 2. Computational configuration and cross-triangular meshes
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