PSI - Issue 13

Fuhui Shen et al. / Procedia Structural Integrity 13 (2018) 1312–1317 Author name / Structural Integrity Procedia 00 (2018) 000–000

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4. Results and Discussion The results on the plasticity behavior of the material are shown in the following section, while the damage and fracture prediction of various samples are not included due to the space limit. The model described above has been implemented into a user defined VUMAT subroutine in ABAQUS/Explicit. Flow curves along three loading directions have been described using the Swift hardening equation with individually fitted parameters. The calibration procedure of material parameters in the enHill48 model is explained in Lian et al. (2017b). For the simulation of lab scale fracture tests, half-thickness finite element models of corresponding specimens have been constructed to reduce the calculation time. 3D brick elements (C3D8) from the ABAQUS library have been used to ensure the high accuracy. Material orientation has also been defined when the anisotropic model is applied. The simulation results without damage effects of a notched dog bone specimen with notch radius of 10 mm (NDB-R10) are shown in Fig. 4. For comparison reason, the simulation results based on the isotropic Mises plasticity model using their individual flow curves are also provided. The simulation results from the Hill48 model based on stress and r-value are also included.

(a)

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(c) Fig. 4. The experimental and simulated force-displacement curves of the notched dog bone specimens with radius of 10 mm along three loading directions. (a) Rolling direction; (b) Diagonal direction; (c) Transverse direction. The simulated force-displacement curves along three loading angles are in a good agreement with experimental results. It is obvious in the above figure the simulation results of the enHill48 model is more accurate than the isotropic Mises model and anisotropic Hill48 model, especially when the plastic deformation reaches a higher level. This indicates that accuracy of the enHill48 model in the description of evolving anisotropic plasticity features.