scholarly journals Study of the Fracture Behavior of Tetragonal Zirconia Polycrystal with a Modified Phase Field Model

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4430 ◽  
Author(s):  
Jingming Zhu ◽  
Jun Luo ◽  
Yuanzun Sun
Keyword(s):  
Phase Transformation ◽  
Crack Propagation ◽  
Phase Field ◽  
Fracture Behavior ◽  
Tetragonal Zirconia ◽  
Finite Size ◽  
Phase Field Model ◽  
Crack Tip ◽  
Propagation Mode ◽  
Tetragonal Zirconia Polycrystal

The superior fracture toughness of zirconia is closely correlated with stress-induced martensitic phase transformation around a crack tip. In this study, a modified phase field (PF) model coupling phase transformation and fracture is proposed to study the fracture behavior and toughening effect of tetragonal zirconia polycrystal (TZP). The stress-induced tetragonal to monoclinic (t–m) phase transformation around a static or propagating crack is characterized with PF simulations. It is shown that the finite size and shape of the transformation zone under different loads and ambient temperatures can be well predicted with the proposed PF model. The phase transformation may decrease the stress level around the crack tip, which implies the toughening effect. After that, crack propagation in TZP is studied. As the stress field is perturbed by the phase transformation patterns, the crack may experience deflection and branching in the propagation process. It is found that the toughness of the grain boundaries (GBs) has important influences on the crack propagation mode. For TZP with strong GBs, the crack is more likely to propagate transgranularly while, for TZP with weak GBs, intergranular crack propagation is prevalent. Besides that, the crystal orientation and the external load can also influence the topology of crack propagation.

Transformation behavior of yttria stabilized tetragonal zirconia polycrystal–TiB2 composites

2001 ◽  
Vol 16 (7) ◽  
pp. 2158-2169 ◽  
Author(s):  
B. Basu ◽  
J. Vleugels ◽  
O. Van Der Biest
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Low Temperature ◽  
Tetragonal Zirconia ◽  
Mechanical Analysis ◽  
Transformation Behavior ◽  
Thermal Expansion Data ◽  
Thermally Induced ◽  
First Time ◽  
Tetragonal Zirconia Polycrystal

The objective of the present article is to study the influence of TiB2 addition on the transformation behavior of yttria stabilized tetragonal zirconia polycrystals (Y-TZP). A range of TZP(Y)–TiB2 composites with different zirconia starting powder grades and TiB2 phase contents (up to 50 vol%) were processed by the hot-pressing route. Thermal expansion data, as obtained by thermo-mechanical analysis were used to assess the ZrO2 phase transformation in the composites. The thermal expansion hysteresis of the transformable ceramics provides information concerning the transformation behavior in the temperature range of the martensitic transformation and the low-temperature degradation. Furthermore, the transformation behavior and susceptibility to low-temperature degradation during thermal cycling were characterized in terms of the overall amount and distribution of the yttria stabilizer, zirconia grain size, possible dissolution of TiB2 phase, and the amount of residual stress generated in the Y-TZP matrix due to the addition of titanium diboride particles. For the first time, it is demonstrated in the present work that the thermally induced phase transformation of tetragonal zirconia in the Y-TZP composites can be controlled by the intentional addition of the monoclinic zirconia particles into the 3Y-TZP matrix.

scholarly journals Phase-field modeling of fracture in heterogeneous materials: jump conditions, convergence and crack propagation

2020 ◽  
Author(s):  
Arne Claus Hansen-Dörr ◽  
Jörg Brummund ◽  
Markus Kästner
Keyword(s):  
Crack Propagation ◽  
Phase Field ◽  
Strain Energy ◽  
Heterogeneous Media ◽  
Phase Field Model ◽  
Diffuse Interface ◽  
Jump Conditions ◽  
Modeling Framework ◽  
Material Interfaces ◽  
Mechanical Jump Conditions

Abstract In this contribution, a variational diffuse modeling framework for cracks in heterogeneous media is presented. A static order parameter smoothly bridges the discontinuity at material interfaces, while an evolving phase-field captures the regularized crack. The key novelty is the combination of a strain energy split with a partial rank-I relaxation in the vicinity of the diffuse interface. The former is necessary to account for physically meaningful crack kinematics like crack closure, the latter ensures the mechanical jump conditions throughout the diffuse region. The model is verified by a convergence study, where a circular bi-material disc with and without a crack is subjected to radial loads. For the uncracked case, analytical solutions are taken as reference. In a second step, the model is applied to crack propagation, where a meaningful influence on crack branching is observed, that underlines the necessity of a reasonable homogenization scheme. The presented model is particularly relevant for the combination of any variational strain energy split in the fracture phase-field model with a diffuse modeling approach for material heterogeneities.

An Approach for Modeling Transformation Plasticity Using a Phase Field Model

2011 ◽  
Vol 320 ◽  
pp. 285-290 ◽  
Author(s):  
Takuya Uehara
Keyword(s):  
Thermal Expansion ◽  
Phase Transformation ◽  
Phase Field ◽  
Transformation Temperature ◽  
Field Model ◽  
Volume Fraction ◽  
Phase Field Model ◽  
Field Variable ◽  
Transformation Plasticity ◽  
Temperature Strain

In this paper, an approach for modeling transformation plasticity using a phase field model is presented. A conventional formula is utilized to represent the strain due to transformation plasticity as well as thermal expansion and transformation dilatation. A phase-field variable is introduced to express the state of phase in material instead of volume fraction, and numerical simulations under simplified conditions are demonstrated. As a result, the strain induced by phase transformation is suitably regenerated, and qualitatively appropriate temperature-strain curves are obtained. In addition, the effect of each parameter is investigated, and various dependencies, such as transformation temperature and stress, on the induced strain are demonstrated. It is then concluded that the results indicate the applicability of the presented model for practical use by adjusting the parameters.

A phase field model for phase transformation in an elastically stressed binary alloy

2005 ◽  
Vol 13 (3) ◽  
pp. 299-319 ◽  
Author(s):  
Dong-Hee Yeon ◽  
Pil-Ryung Cha ◽  
Ji-Hee Kim ◽  
Martin Grant ◽  
Jong-Kyu Yoon
Keyword(s):  
Phase Transformation ◽  
Binary Alloy ◽  
Phase Field ◽  
Field Model ◽  
Phase Field Model

Experimental and FEM Analysis of the Fracture Behavior in NiTi Shape Memory Alloys

2006 ◽  
Vol 324-325 ◽  
pp. 919-922 ◽  
Author(s):  
Xin Mei Wang ◽  
Zhu Feng Yue
Keyword(s):  
Fracture Toughness ◽  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Fracture Behavior ◽  
Micromechanical Model ◽  
Crack Tip ◽  
Fem Analysis ◽  
Transformation Behavior ◽  
Niti Shape Memory Alloys

In the present work, the fracture toughness of a NiTi pseudoelastic alloy has been obtained by experiments on CT specimens, which is KIC =39.38MPa·m1/2. Then the stress induced phase transformation behavior in front of the crack tip of the CT specimen is simulated by a micromechanical model considering the different elastic properties between martensite and austenite. The results show that the pre-crack promotes phase transformation at the crack tip. And the phase transformation is localised near the crack tip. It is also shown that phase transformation reduces the Mises stress around the crack tip.

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