13th International Conference on Fracture June 16–21, 2013, Beijing, China -8- 0 4 8 12 16 0 0.2 0.4 0.6 0.8 1 Traction (GPa) Non-dimentional parameter (λ) 300K 473K 673K Figure 10. Traction-separation relationships under different simulate temperatures 5. Simulation of the T-S fracture test In order to model stable crack growth under static loading and analyze cohesive behavior derived from MD towards greater length scales, it is necessary to examine a scenario in which the effective stress intensity factor in the process of crack growth. Thus, we perform a simulation of crack growth for a CT specimen subject to displacement loading via prescribed motion of loading pins. Fracture of a CT specimen can verify whether the cohesive law derived from MD simulations displays behavior consistent with linear elastic fracture mechanics. The geometry and mesh of our CT specimen is shown in Fig.11. The specimen is 384 nm wide by H = 369 nm tall, with an effective width (the distance between the pin holes and the uncracked edge) of W = 307 nm, an initial crack length of a = 155 nm (a/W ≈ 0.5), and pin holes of radius 38.4 nm. Our initial geometry contains a zero-width crack rather than the finite-width crack. Cohesive elements are placed along the predefined crack path, and are 1Å wide. This element size enables the cohesive zone to be resolved over a length of approximately 45Å (45 elements).The parameterized T-S law given was implemented in ABAQUS to simulate the behavior of the CZM. For the FE model of outside of the CZM, two-dimensional continuum plane strain incompatible elements (CPEI4) were used with isotropic material properties to represent the bulk elastic behavior while two-dimensional cohesive elements (COH2D4) were used for the CZM. H W a Figure 11. FEA mesh of CT specimen. The specimen’s height H=369 nm, its effective width W=307 nm, and its initial crack length a=155 nm
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