PSI - Issue 2_A

Dong-Jun Kim et al. / Procedia Structural Integrity 2 (2016) 832–839 Dong-Jun Kim et al. / Structural Integrity Procedia 00 (2016) 000–000

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4.4. Determination of elastic-follow-up factor, Z In this work, elastic-follow-up factor should be determined for characterization of stress field under displacement control condition. This factor was determined from comparing eqn. (12) with FE results. Fig. 3 show that elastic follow-up factor depends on creep exponent. Elastic-follow-up factor was determined as 2.0 and 2.5 when creep exponent, n is 5 and 10, respectively. 4.5. Results The proposed equations in Section 3 are compared with results of FE analysis. Fig. 4 shows comparison of FE results on normalized crack opening stresses by reference stress under load control condition with Eqn. (17). The stress fields are calculated at r/a = 0.005 and show the characteristics for the time of primary loading. Eqn. (17) is a good prediction for the crack-tip stress fields under transient creep.

Fig. 1. Schematic single-edge crack bend specimen considered in this work.

(a) (b) Fig. 2. (a) Typical FE mesh to simulate (b) Validation for C(t)-integral value with creep exponent, n = 3 and 5.

(a) (b) Fig. 3. Validation for C(t)-integral value with creep exponent (a) n = 5, (b) n = 10.