Dislocation Dynamics Simulation based on Phase-Field Model : Application to Non-Uniform Stress Field

We aim to accelerate the linear equation solver for crack growth simulation based on the phase field model. As a first step, we analyze the properties of the coefficient matrices and prove that they are symmetric positive definite. This justifies the use of the conjugate gradient method with the efficient incomplete Cholesky preconditioner. We then parallelize this preconditioner using so-called block multi-color ordering and evaluate its performance on multicore processors. The experimental results show that our solver scales well and achieves an acceleration of several times over the original solver based on the diagonally scaled CG method.

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Phase Transfomation Stress Field due to Hot Corrosion in the Top Coat of TBC

Volume 1: Advances in Aerodynamics ◽

10.1115/imece2013-63138 ◽

2013 ◽

Author(s):

Abba Abdulhamid Abubakar ◽

Syed Sohail Akhtar ◽

Abul Fazal M. Arif

Keyword(s):

Phase Transformation ◽

Stress Field ◽

Molten Salt ◽

Reaction Zone ◽

Phase Field ◽

Hot Corrosion ◽

Monoclinic Phase ◽

Field Model ◽

Phase Field Model ◽

Premature Failure

Due to the use of low quality fuels in Saudi Arabia, hot corrosion occurs at the top coat of Thermal Barrier Coatings (TBCs) as a result of the formation of a molten salt, V2O5, which penetrates it through either diffusion mechanism or the open porosities in the YSZ. The interaction between this molten salt and the Zirconia stablizer is a dissolution-precipitation type reaction which occurs throughout the Planar Reaction Zone (PRZ) and the Melt-Infiltrated Reaction Zone (MIRZ) leaching a new phase, YVO4, and also causing tetragonal to monoclinic phase transformation of Zirconia. Swelling due to transformation-mismatch plasticity causes the development of localized stresses in the topcoat which subsequently contributes to the premature failure of the coating. In the current work, a 1D-Phase field model was developed that could estimate the kinetics and micro-structural evolution during the isothermal (diffusional) tetragonal-to-monoclinic phase transformation at 900°C in the top coat. The result obtained from the Phase Field Model was sequentially coupled with Finite Element Method, and the resulting stress field in the top coat was predicted.

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Simulation of Facet Dendritic Shape of Isothermal Alloy in a Forced Flow by Phase Field Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.189-193.3874 ◽

2011 ◽

Vol 189-193 ◽

pp. 3874-3879

Author(s):

Zhi Chen ◽

An Qi Chen ◽

Feng Li ◽

Yang Li ◽

Qing Jun Song ◽

...

Keyword(s):

Phase Field ◽

Field Model ◽

Flow Direction ◽

Anisotropy Parameter ◽

Phase Field Model ◽

Field Method ◽

Forced Flow ◽

Phase Field Method ◽

Simulation Based ◽

Steady Velocity

Numerical simulation based on a new regularized phase field model was performed to describe the dendritic growth of an isothermal alloy with a strong anisotropy in the presence of a forced flow. These results indicate that a crystal grow into an equiaxial facet dendritic in the absence of a forced flow and into an asymmetrical facet dendritic in the presence of a forced flow. With increasing a flow velocity, the tip steady velocity of upstream dendritic arm increases, that of the downstream arm decreases, and that of the perpendicular arms increases at first, and then decreases, the perpendicular arms gradually grow toward the incoming flow direction. In the certain range of anisotropy parameter, when γ is larger than 0.14, dendritic tip steady velocities in all direction are expected to reach their own saturation values. In addition, the effect of a compound forced flow on an isothermal facet dendritic is similar to experimental results.

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