13th International Conference on Fracture June 16–21, 2013, Beijing, China -5- biaxial loading reported in the literature. 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 A б/б0 SECP,a/W=0.7 λ=0.5 ◆ FEM,n=3 ◇ FEM,n=4 ■ FEM,n=5 □ FEM,n=7 ▲ FEM,n=10 Figure 5. . FEA solutions of constraint parameter A for SECP, a/W=0.7, λ=0.5 0.0 0.2 0.4 0.6 0.8 1.0 0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 A б/б0 SECP,a/W=0.3 λ=1.0 ◆ FEM,n=3 ◇ FEM,n=4 ■ FEM,n=5 □ FEM,n=7 ▲ FEM,n=10 Figure 6. . FEA solutions of constraint parameter A for SECP, a/W=0.3, λ=1.0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 A б/б0 SECP,a/W=0.7 λ=1.0 ◆ FEM,n=3 ◇ FEM,n=4 ■ FEM,n=5 □ FEM,n=7 ▲ FEM,n=10 Figure 7. . FEA solutions of constraint parameter A for SECP, a/W=0.7, λ=1.0 For the purpose of comparison, finite element analysis for CCP specimen is carried out with hardening exponent n=10 for biaxial loading ratio λ=0.5 and geometry ratio a/W=0.1, 0.5. The values for J-integral from finite element analysis are compared with those obtained from EPRI estimation formulas of J [19]. Figure 3 shows the comparison results for a/W=0.1 and 0.5. It can be found that the J-integral values from FEA are very close to those from the estimation formulas. Based on the results of finite element analysis, constraint parameter A can also be obtained by using the fitting method proposed by Nikishkov et al. [12]. Through relationship between A and Q presented in authors’ previous paper [13], the obtained solutions for A are converted to values of Q. Then determined Q values are compared with those reported by O’Dowd et al. [19]. It is found that, for both relative crack length a/W=0.1 and 0.5, Q solutions from the preset FEA results are close to those obtained by O’Dowd et al. [19]. As a numerical example, data comparison between Q values from FEA as well as A-Q relationship and those presented by O’Dowd et al [19] for the CCP under n=10 with a/W=0.5 and λ=0.5 is shown in Table 1.
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