PSI - Issue 2_B

N.A. Alang et al. / Procedia Structural Integrity 2 (2016) 3177–3184 Author name / Structural Integrity Procedia 00 (2016) 000 – 000

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Fig. 6. Hysteresis loops: (a) SR = 2.4x10 -3 s -1 (first cycle); (b) SR = 2.4x10 -3 s -1 (half-life cycle)

Fig. 7. Hysteresis loops: (a) SR = 2.4x10 -5 s -1 (first cycle); (b) SR = 2.4x10 -5 s -1 (half-life cycle)

Fig. 8. Relationship between strain rate and lifetime: (a) number of cycles to failure; (b) time to failure

3. Comparison between finite element results and experimental data

The hysteresis loops and stress response of the ex-service P92 steel under LCF loading were simulated using the commercial finite element software ABAQUS v6.13. The material was modelled as an elastic-plastic material with nonlinear isotropic/kinematic hardening rules. The elastic properties of the material were determined from the first cycle of hysteresis loop where the modulus of elasticity was calculated from an average value of the linear lines during loading and unloading. For each strain rate, the kinematic hardening parameters were determined from the hysteresis loop at half of the fatigue life and the plastic isotropic hardening parameters were obtained from a set of hysteresis loops at the highest strain amplitude. Detailed procedures to determine the hardening parameters can be