13th International Conference on Fracture June 16–21, 2013, Beijing, China -4- Figure 2. A model of polycrystalline structure The expectation value of the only positive values of AFD* gbθ is obtained, and it represents the parameter governing EM damage, AFD* gen, concerning void formation in a polycrystalline line as It means the number of atoms decreasing per unit time and unit volume. At line ends, boundary condition with respect to atomic flow has to be given for the formulation of the parameter at line ends. Namely, there is no coming-in at cathode end of the line and no going-out at anode one. The boundary condition can be expressed by possible zero flux within the microstructure unit being assigned to each θ-range as listed in Table 1 [7]. Table 1. Boundary condition concerning atomic flux Range-I Range-II Range-III −2π/3+Δ ϕ+ β< θ≤−π/3−Δ ϕ+ β −π/3−Δ ϕ+ β< θ≤ β β< θ≤π/3+Δ ϕ+ β JII=JIII=0 JII=0 JI=JII=0 Range-IV Range-V Range-VI π/3+Δ ϕ+ β< θ≤2π/3−Δ ϕ+ β 2π/3−Δϕ+ β< θ≤π+ β π+ β< θ≤4π/3+Δ ϕ+ β JI=0 JI=JIII=0 JIII=0 ( ) θ π π d AFD AFD AFD ∫ + = 2 0 * * * gen gbθ gbθ 4 1 (3)
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