Modeling flat to slant fracture transition using the computational cell methodology

2013 ◽  
Vol 104 ◽  
pp. 80-95 ◽  
Author(s):  
J. Besson ◽  
C.N. McCowan ◽  
E.S. Drexler
Keyword(s):  
Computational Cell ◽  
Fracture Transition ◽  
Slant Fracture

A Fracture Surface Rotation Mechanism for Fatigue Tested 2219-T87 Aluminum Sheet

1979 ◽  
Vol 101 (1) ◽  
pp. 80-85
Author(s):  
G. F. Pittinato
Keyword(s):  
Fracture Surface ◽  
Plastic Zone ◽  
Crack Tip ◽  
Aluminum Sheet ◽  
Surface Rotation ◽  
Fracture Transition ◽  
Slant Fracture ◽  
Crack Movement ◽  
Tension Loading ◽  
Active Slip

Fatigue crack propagation tests were conducted on 2219-T87 aluminum sheet to identify the factors that control the rate of fracture surface rotation. Center-cracked, axial loaded specimens were tested in air at room temperature using tension-tension loading. The log (da/dn) versus (ΔK) curve contained an inflection point that was associated with the flat to slant fracture transition. The size and shape of the plastic zone at the crack tip were determined as a function of the half-crack length by using optical interferometry. It was found that the rate of fracture surface rotation was controlled by the changing size of the crack tip plastic zone. It is proposed that fracture surface rotation in this material occurs by a process of crack movement within active slip zones. A discussion is given on the deformation mechanisms associated with fatigue fracture surface rotation.

Identifying a novel anticancer agent with microtubule-stabilizing effects through computational cell-based bioactivity prediction models and bioassays

2019 ◽  
Vol 17 (6) ◽  
pp. 1519-1530 ◽  
Author(s):  
Yao Luo ◽  
Ranran Zeng ◽  
Qingqing Guo ◽  
Jianrong Xu ◽  
Xiaoou Sun ◽  
...  
Keyword(s):  
Anticancer Agent ◽  
Prediction Models ◽  
Computational Cell ◽  
Bioactivity Prediction

G03 is a novel anticancer agent with unusual microtubule-stabilizing effects.

scholarly journals A Revisit to CMFD Schemes: Fourier Analysis and Enhancement

Energies ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 424
Author(s):  
Dean Wang ◽  
Zuolong Zhu
Keyword(s):  
Fourier Analysis ◽  
Eigenvalue Problems ◽  
Neutron Transport ◽  
Coarse Mesh ◽  
Successive Overrelaxation ◽  
Computational Cell ◽  
Artificial Diffusion ◽  
Acceleration Method ◽  
The Stability ◽  
Partial Current

The coarse-mesh finite difference (CMFD) scheme is a very effective nonlinear diffusion acceleration method for neutron transport calculations. CMFD can become unstable and fail to converge when the computational cell optical thickness is relatively large in k-eigenvalue problems or diffusive fixed-source problems. Some variants and fixups have been developed to enhance the stability of CMFD, including the partial current-based CMFD (pCMFD), optimally diffusive CMFD (odCMFD), and linear prolongation-based CMFD (lpCMFD). Linearized Fourier analysis has proven to be a very reliable and accurate tool to investigate the convergence rate and stability of such coupled high-order transport/low-order diffusion iterative schemes. It is shown in this paper that the use of different transport solvers in Fourier analysis may have some potential implications on the development of stabilizing techniques, which is exemplified by the odCMFD scheme. A modification to the artificial diffusion coefficients of odCMFD is proposed to improve its stability. In addition, two explicit expressions are presented to calculate local optimal successive overrelaxation (SOR) factors for lpCMFD to further enhance its acceleration performance for fixed-source problems and k-eigenvalue problems, respectively.

Theoretical Analysis of CFD-DEM Mathematical Model Solution Change With Varying Computational Cell Size

2018 ◽  
Author(s):  
Annette Volk ◽  
Urmila Ghia
Keyword(s):  
Mathematical Model ◽  
Standard Deviation ◽  
Cell Size ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Independent Solution ◽  
Model Verification ◽  
Computational Cell ◽  
Drag Laws ◽  
Fraction Method

Successful verification and validation is crucial to build confidence in the application of coupled Computational Fluid Dynamics - Discrete Element Method (CFD-DEM). Model verification includes ensuring a mesh-independent solution, which poses a major difficulty in CFD-DEM due to the complicated solution relationship with computational cell size. In this paper, we investigate the theoretical relationship between the solution and computational cell size by tracing the effects of a change in cell size through the mathematical model. The porosity profile for simulations of fixed-particle beds is determined to be Gaussian, and the average and standard deviation of the representative distribution are reported against cell size. We find the standard deviation of bed porosity increases exponentially as the cell size is reduced, and the drag calculations are very sensitive to changes in the porosity standard deviation, resulting in an exponential change in expected drag when the cell size is small relative to the particle diameter. The divided volume fraction method of porosity calculation is shown to be superior to the centred volume fraction method, as it reduces the porosity standard deviation. The sensitivity of five popular drag laws to changes in the porosity profile is presented, and the Ergun and Beetstra drag laws are shown to be the least sensitive to changes in the cell size.

scholarly journals SIMULATION TESTS OF EXTINGUISHING PROCESS USING MIST NOZZLES WITH APPLICATION OF HYBRID FIRE MODEL

2016 ◽  
Vol 22 (4) ◽  
pp. 573-583 ◽  
Author(s):  
Jerzy GAŁAJ ◽  
Marek KONECKI ◽  
Ritoldas ŠUKYS
Keyword(s):  
Heat Flux ◽  
Computer Model ◽  
Input Data ◽  
Elementary Cell ◽  
Characteristic Parameters ◽  
Computational Cell ◽  
Fire Model ◽  
Fire Extinguishing ◽  
Unique Approach

The article presents a computer model of the fire extinguishing process using mist nozzles. A previously developed hybrid fire model was used for this purpose. Assumptions and relationships were given to represent a math­ematical model of extinguishing process, which comprises a unique approach to the determination of sprinkling area in an elementary cell of field fire model. A description of simulation tests of the model was given for several different input data, differing by mean diameters of droplets. This enabled a study of their effects on such output parameters as received heat flux, temperature and rate of its growth. For one selected computational cell located on the axis of the nozzle at floor level having the coordinates [10, 10, 1], the obtained results were presented in the form of heat flux and temperature. To simplify the analysis, characteristic parameters of particular curves were listed in the table. Conclusions formulated on the basis of results obtained during tests were specified at the end of work. They confirmed the expected regularity assuming that the extinguishing process was more effective in the case of droplets of a smaller diameter and greater sprinkling intensity. This allows assessing the degree, to which these stream parameters affect the extinguishing effectiveness.

Comparisons of Diesel PCCI Combustion Simulations Using a Representative Interactive Flamelet Model and Direct Integration of CFD With Detailed Chemistry

2006 ◽  
Vol 129 (1) ◽  
pp. 252-260 ◽  
Author(s):  
Song-Charng Kong ◽  
Hoojoong Kim ◽  
Rolf D. Reitz ◽  
Yongmo Kim
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Direct Integration ◽  
Computational Cell ◽  
Flamelet Model ◽  
Detailed Chemistry ◽  
Engine Simulation ◽  
Integration Approach ◽  
Simulation Results ◽  
Release Data

Diesel engine simulation results using two different combustion models are presented in this study, namely the representative interactive flamelet (RIF) model and the direct integration of computational fluid dynamics and CHEMKIN. Both models have been implemented into an improved version of the KIVA code. The KIVA/RIF model uses a single flamelet approach and also considers the effects of vaporization on turbulence-chemistry interactions. The KIVA/CHEMKIN model uses a direct integration approach that solves for the chemical reactions in each computational cell. The above two models are applied to simulate combustion and emissions in diesel engines with comparable results. Detailed comparisons of predicted heat release data and in-cylinder flows also indicate that both models predict very similar combustion characteristics. This is likely due to the fact that after ignition, combustion rates are mixing controlled rather than chemistry controlled under the diesel conditions studied.

scholarly journals Computational Cell-Barcoding for High-Throughput Robotic Microscopy

2017 ◽  
Vol 112 (3) ◽  
pp. 303a-304a
Author(s):  
Mariya Barch ◽  
Gaia Skibinski ◽  
Alicia Lee ◽  
Steven Finkbeiner
Keyword(s):  
High Throughput ◽  
Computational Cell

Prediction of the Absence of Brittle Failure Risk for Ferritic Steel Piping Components in the Brittle-Ductile Region

2011 ◽  
Author(s):  
S. Marie ◽  
J. Schwab ◽  
S. Vidard
Keyword(s):  
Brittle Fracture ◽  
Fracture Risk ◽  
Brittle Failure ◽  
Risk Evaluation ◽  
Critical Stress ◽  
Ferritic Steel ◽  
Loading Condition ◽  
Maximum Principal Stress ◽  
Fracture Transition ◽  
Secondary Loop

This paper deals with the brittle fracture risk evaluation for a C-Mn piping component in the upper shelf of the brittle to ductile fracture transition temperature range, with the main objective to validate a predictive criteria, able to demonstrate the complete absence of brittle fracture risk. The criteria is based one a critical stress and the volume around the crack were the maximum principal stress exceed this critical stress. The model is calibrated on notched tensile specimens and CT specimens. A four-points bending pipe test has then been designed using this criterion to insure that no brittle fracture will occurs at a temperature that all CT specimens failed by cleavage. The material is a French secondary loop Tu42C ferritic steel and the pipe dimensions for the test are the same than the size of the principal secondary loop pipes. The results of the pipe test confirm the prediction with the model and the interpretation lead to define an equivalence between the loading conditions (based on the J parameter) of the pipe and the loading condition of a CT specimen.

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