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Modeling Ductile Damage of Metallic Materials

Zhai, Jinyuan
http://rave.ohiolink.edu/etdc/view?acc_num=akron1466471348

Abstract Details

2016, Doctor of Philosophy, University of Akron, Mechanical Engineering.
In this dissertation, a comprehensive study of ductile damage of metallic materials is presented, covering constitutive modeling, numerical implementation and model calibration and verification. As the first part of this dissertation, a pressure-insensitive plasticity model, expressed as a function of the second and third invariants of the stress deviator (J2 and J3), is presented. Depending on whether the power of the J3 term is odd or even, the proposed model can capture either the tension-compression strength-differential (S-D) effect or the torsion-tension strength-differential effect of the material. The plasticity model with an odd power to the J3 item has been calibrated and validated using measured experimental data of a ß-treated Zircaloy-4 with a wide range of triaxiality and Lode parameter values. Results show that this model captures the strong strength-differential (S-D) effect in the material. The plasticity model with an even power to the J3 item is able to capture the isotropic plastic behavior of a stainless steel Nitronic 40, under various stress states with good accuracy and computational efficiency. Next, the effect of the material’s plasticity behavior on the ductile damage process is studied by conducting a series of unit cell analyses of a void-containing representative material volume (RMV), where the plastic response of the matrix material is governed by the J2-J3 dependent plasticity model. To simulate the ductile damage process in anisotropic materials, a new constitutive model, which combines the models proposed by Zhou et al. (2014) and Stewart and Cazacu (2011), is developed and employed to study the plasticity and ductile fracture behavior of a commercially pure titanium (CP Ti). In particular, a Gurson-type porous material model is modified by coupling two damage parameters, accounting for the void damage and the shear damage respectively, into the yield function and the flow potential. The plastic anisotropy and tension-compression asymmetry exhibited by CP Ti are accounted for by a plasticity model based on the linear transformation of the stress deviator. The theoretical model is implemented in the general purpose finite element software ABAQUS via a user defined subroutine and calibrated using experimental data. Good comparisons are observed between model predictions and experimental results for a series of specimens in different orientations and experiencing a wide range of stress states. The model is shown to capture the effect of stress state and the change of fracture mechanism. The results also reveal the important effect of the plastic anisotropy and tension-compression asymmetry on the ductile damage process. Literature review indicates that this is the first time to simulate failure under shear dominated conditions in an anisotropic and tension-compression asymmetric material.
Xiaosheng Gao, Dr. (Advisor)
Yalin Dong, Dr. (Committee Member)
Chang Ye, Dr. (Committee Member)
Ernian Pan, Dr. (Committee Member)
Kevin Kreider, Dr. (Committee Member)
147 p.
Mechanical Engineering; Mechanics
Ductile damage; Plasticity; Anisotropic material; Strength differential effect; Void damage; Shear damage; Unit cell analysis; Experiments and finite element analysis

Recommended Citations

Citations

  • Zhai, J. (2016). Modeling Ductile Damage of Metallic Materials [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1466471348

    APA Style (7th edition)

  • Zhai, Jinyuan. Modeling Ductile Damage of Metallic Materials. 2016. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1466471348.

    MLA Style (8th edition)

  • Zhai, Jinyuan. "Modeling Ductile Damage of Metallic Materials." Doctoral dissertation, University of Akron, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=akron1466471348

    Chicago Manual of Style (17th edition)

akron1466471348
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This open access ETD is published by University of Akron and OhioLINK.