13th International Conference on Fracture June 16–21, 2013, Beijing, China -2- impact problems are also available [9–11]. However, there are few studies on the strain rate concentration for notched specimens under various tensile speed. Therefore, in this paper, the finite element method is applied to analyze the notched specimens under various tensile speed. Then, the dynamic stress concentration factor and the strain rate factor will be discussed with varying tensile speed and maximum values of forced displacement. 2. Static stress concentration and specimen geometry In this study, the material analyzed is assumed as polycarbonate, which has especially high impact strength among the polymeric materials. Young's modulus is assumed as E = 2.3GPa, Poisson's ratio ν = 0.37. Figure 1 shows the geometry of the double-edge-notched specimen, with dimensions of notch root radius 0.03mm ρ= and 0.2mm, notch depth t = 5mm, and opening angle 90º. The notch root radius 0.03mm ρ= corresponds to the radius of fillet appearing at polymer products generally. The notch root radius 0.2mm ρ= corresponds to the radius of the notched specimens used in the Izod and Charpy test. When the high-speed tensile test is performed, both ends of the specimen are gripped by rigid chuck, then forced displacement is applied to the end under constant speed. Figure 2 shows FE models for analysis. Here Model 1 has the notch radius 0.03mm ρ= , and Model 2 has 0.2mm ρ= . Figure 2(c) shows the notch root detail in Model 1, and Fig. 2(d) shows the notch root detail in Model 2. Minimum mesh size of the notch root is 243 e ρ = each model. Figure 3 shows the boundary conditions given to the end portion of the analysis models. Figure 3(a) shows boundary conditions in the rigid chucks, and Fig.3(b) shows a tensile stress boundary conditions Figure 1. Geometry of specimen (a) Model 1 (b) Model 2 (c) Notch root detail in Model 2 (d) Notch root detail in Model 1 ρ=0.2mm ρ=0.03mm Figure 2. FE models Unit: mm ρ=0.03，0.2 90 ° l=50 100 t=5 d=10 Grip D=20 Grip
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