scholarly journals Numerical Simulation and Experimental Verification of Dry Pressed MgTiO3 Ceramic Body during Pressureless Sintering

2021 ◽  
Author(s):  
Jiang Wang ◽  
Yu Ni ◽  
Kai Liu ◽  
Yanying Du ◽  
Wei Liu ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Relative Density ◽  
Ceramic Body ◽  
Simulation Method ◽  
Shrinkage Rate ◽  
Pressureless Sintering ◽  
Numerical Simulation Method ◽  
Average Grain Size ◽  
Simulation Results

Abstract To clarify the densification law of dry pressed MgTiO3 ceramic body during pressureless sintering, SOVS model modified with creep characteristics was embedded into finite element software Abaqus. The selected model can effectively express the grain boundary characteristics and densification mechanism. The change law of relative density, shrinkage rate, sintering stress and grain size of MgTiO3 cylindrical specimens were investigated by the above numerical simulation method. It showed that the average relative density of ceramic body rose from 60% to 97% and the shrinkage rate resepectively reached 17.28% and 11.99% in axial and radial direction. The average grain size increased from 1μm to 6 μm. In order to verify the accuracy of the simulation results, corresponding sintering experiments on cylindrical specimens were carried out to obtain actual sintering densities and shrinkage rates. It showed that the errors of relative density and shrinkage is below 5% and 2%. Grain growth trend was also basically consistent with the simulation results. After that, the above numerical simulation method was applied into the prediction of fabricating MgTiO3 filter with complex structure. Therefore, the present work provided a reliable numerical simulation method to predict the densification behavior of MgTiO3 ceramics during the pressureless sintering process, which was helpful to design and fabricate microwave dielectric products.

scholarly journals Numerical simulation for the effects of waves and grain size on deltaic processes and morphologies

2020 ◽  
Vol 12 (1) ◽  
pp. 1286-1301
Author(s):  
Yang Liu ◽  
Hongde Chen ◽  
Jun Wang ◽  
Shuai Yang ◽  
Anqing Chen
Keyword(s):  
Numerical Simulation ◽  
Grain Size ◽  
Numerical Simulations ◽  
Morphological Changes ◽  
Morphological Characteristics ◽  
Simulation Method ◽  
River Channels ◽  
Grain Sizes ◽  
Average Grain Size ◽  
Simulation Results

AbstractCurrently, the sedimentation process concerning the formation of the morphological changes of deltas under the action of waves has received little attention. Two numerical simulations were carried out in this study to explore the sedimentary morphological changes of deltas under wave action. In the first experiment, the morphological characteristics of river-dominated deltas and wave-dominated deltas were compared. Results showed that a wave-dominated delta was more likely to produce slender and stable rivers relative to a river-dominated delta. In the second experiment, the morphologies of wave-dominated deltas with sediments of different grain sizes were compared. Results indicated that delta morphology was not significantly correlated with the median grain size ({\phi }_{50}) of the sediment, and the average grain size of the coarser sediments ({\phi }_{25}) was an important factor affecting delta morphology. Moreover, a delta with a larger {\phi }_{25} value of the input sediment, a smaller topset gradient, and a smaller number of active river channels had a more arcuate shape. The results showed that the hydrodynamic numerical simulation method has the ability to reveal the evolution of deltas under the action of waves. The final simulation results were consistent with the actual delta data.

Effect of Plenum Chamber Configuration on Airflow Uniformity in Unidirectional Flow Cleanrooms

1994 ◽  
Vol 37 (4) ◽  
pp. 21-27
Author(s):  
Guoping Xie ◽  
Yoshihide Suwa
Keyword(s):  
Numerical Simulation ◽  
Numerical Method ◽  
Pressure Loss ◽  
Simulation Method ◽  
Calculation Domain ◽  
Plenum Chamber ◽  
Unidirectional Flow ◽  
Numerical Simulation Method ◽  
Airflow Distribution ◽  
Simulation Results

Uniformity of airflow distribution in a unidirectional flow cleanroom has been studied experimentally and numerically. The influence of the height of the plenum chamber and the velocity of airflow introduced into the chamber on the airflow uniformity are investigated experimentally. In addition, a numerical simulation method to predict airflow uniformity is proposed, taking into account the characteristics of the pressure loss of the filter. The calculation domain in this study includes not only the cleanroom but also the plenum chamber and the exhaust chamber. The validity of the numerical method is also verified by comparing the simulation results with the experiments. Finally, the numerical method is used to obtain an appropriate height for the plenum chamber.

A Study on the Numerical Simulation Method for the NC Incremental Sectional Forming

2014 ◽  
Vol 988 ◽  
pp. 241-244
Author(s):  
Hu Zhu ◽  
Wen Wen Lin ◽  
Jin Lan Bai
Keyword(s):  
Numerical Simulation ◽  
Digital Simulation ◽  
Simulation Method ◽  
Forming Quality ◽  
Numerical Simulation Method ◽  
Simulation Results ◽  
The Difference

The digital simulation method for NC incremental sectional forming is studied and the forming effect of NC incremental integral forming and sectional forming is analyzed through the digital simulation method in this paper. Digital simulation results show that the proposed simulation method for NC incremental sectional forming is reasonable and achievable. The difference of the forming quality between NC incremental sectional forming and integral forming is small. The sectional forming method has feasibility.

Preparation of γ-AlON Transparent Ceramics by Pressureless Sintering

2014 ◽  
Vol 602-603 ◽  
pp. 226-229 ◽  
Author(s):  
Feng Chen ◽  
Fang Zhang ◽  
Jun Wang ◽  
Run Tian ◽  
Jian Zhang ◽  
...  
Keyword(s):  
Grain Size ◽  
Flexural Strength ◽  
Relative Density ◽  
Carbothermal Reduction ◽  
High Strength ◽  
Nitrogen Atmosphere ◽  
Pressureless Sintering ◽  
Transparent Ceramics ◽  
Average Grain Size

In this paper, AlON powders were prepared by carbothermal reduction and nitridation method. By adding a mixture of Y2O3, La2O3 and MgO as sintering agent, transparent AlON ceramics with high strength were fabricated by pressureless sintering at 1950°C for 8h under nitrogen atmosphere. The obtained ceramic had a relative density of 99.9% and average grain size of 150μm. The transmittance of the 2mm thick ceramics was 82.4% at 1100nm and flexural strength was 300 MPa.

Numerical Simulation Method of Track Irregularities Based on Secondary Filtering

2014 ◽  
Vol 1008-1009 ◽  
pp. 1525-1529
Author(s):  
Bao Shan Xiang ◽  
Xing Han ◽  
Xue Wei Wang
Keyword(s):  
Numerical Simulation ◽  
Vibration Analysis ◽  
Simulation Method ◽  
External Excitation ◽  
Coupling Vibration ◽  
Filtering Method ◽  
Numerical Simulation Method ◽  
Simulation Results ◽  
The U.S ◽  
Track Irregularities

Track irregularities are the only external excitation in vehicle-bridge coupling vibration analysis and therefore the numerical simulation method of track irregularities is very important. The U.S. frequency spectrum is usually employed to simulate the track irregularities in China. In this paper, the secondary filtering method is introduced to the simulation of track irregularities and MATLAB programing is employed to simulate an example. Based on the comparison of the simulation results and the objective function, it is indicated that the simulation result is reliable and the method is feasible.

A Simulation Method for Memristor Based Dopant Drift Model

2012 ◽  
Vol 239-240 ◽  
pp. 915-920
Author(s):  
Jie Tao Diao ◽  
Xiao Bo Tian
Keyword(s):  
Numerical Simulation ◽  
Physical Model ◽  
Model Simulation ◽  
Simulation Method ◽  
Circuit Element ◽  
Nano Scale ◽  
Drift Model ◽  
Numerical Simulation Method ◽  
Simulation Results

Memristor is a kind of circuit element with nano scale, its appearance may radically change the traditional circuit. Recently, dopant drift model is a hot issue in research works connected to memristor. However, because of lack of transparency in the process of simulation, simulation method on dopant drift model of memristor needs to be strengthened. Dopant drift model was analyzed, circuit characteristics and relations between different circuit variables were studied. Based on those works above, a kind of numerical simulation method was designed to simulate and validate the memristor model. Simulation results show that the method designed accurately expresses conducting behaviour of memristor physical model, which provides a new feasible way for simulations of memristor model.

Numerical Simulation of Air-Deck Slotted Charge Blasting

2010 ◽  
Vol 143-144 ◽  
pp. 787-791 ◽  
Author(s):  
Guo Liang Yang ◽  
Ren Shu Yang ◽  
Chuan Huo ◽  
Y.L. Che
Keyword(s):  
Numerical Simulation ◽  
Stress Distribution ◽  
Theoretical Analysis ◽  
Physical Process ◽  
Laboratory Tests ◽  
Decisive Role ◽  
Simulation Method ◽  
Numerical Simulation Method ◽  
Simulation Results ◽  
Air Deck

Air-deck ratio plays a decisive role in blasting engineering. Researchers have conducted extensive work to study the optimal air-deck ratio. But consensus has not been achieved. Especially slotted charge blasting, the study on it just starts. For its complicated physical process in blasting, it is difficult to perform theoretical analysis to obtain the law between blasting result and air-deck ratio. The numerical simulation method is adopted to study the effect of different air-deck ratio on stress distribution at first. And then laboratory tests are carried out to validate the simulation results. The conclusion may be drawn that good directional fracture could be obtained with air-deck ratio 33.3% ~ 50%. The achievement could provide reference for blasting engineering.

Numerical Simulation of Wave Propagation in Variable Cross-Section Bars

2011 ◽  
Vol 378-379 ◽  
pp. 72-76 ◽  
Author(s):  
Hong Bin Jin
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Cross Section ◽  
Analytical Solutions ◽  
Simulation Method ◽  
Variable Cross Section ◽  
Variable Cross ◽  
Numerical Simulation Method ◽  
Simulation Results

A model for wave propagation in variable cross-section bars is developed. Then a numerical simulation method based on CSPM is introduced. Furthermore the wave propagations in stepped bars and conical bars are simulated. The simulation results agree well with the analytical solutions, which demonstrate that the model can describe the wave propagation in variable cross-section bars precisely.

scholarly journals Experimental and Numerical Study on PDMS Collapse for Fabrication of Micro/Nanochannels

2016 ◽  
Vol 67 (6) ◽  
pp. 414-420
Author(s):  
Zhifu Yin ◽  
Helin Zou
Keyword(s):  
Numerical Simulation ◽  
Numerical Study ◽  
Low Cost ◽  
Local Stress ◽  
Simulation Method ◽  
Bonding Pressure ◽  
Cost Approach ◽  
Numerical Simulation Method ◽  
Simulation Results

Abstract PDMS (polydimethylsiloxane) collapse method is a simple and low cost approach for micronanochannel fabrication. However, the bonding pressure which influences the size of the final PDMS micro/nanochannels has not yet been studied. In this study, the effect of the bonding pressure on the size and maximum local stress of the PDMS micronanochannels was investigated by both experimental and numerical simulation method. The results show that when the bonding pressure is lower than 0.15 MPa the experiment results can agree well with the simulation results. The fluorescent images demonstrate that there is no blocking or leakage over the entire micro/nanochannels.

Effects of the Complex Strengthening Process on Microstructureand Properties of Low Carbon Steel

2015 ◽  
Vol 833 ◽  
pp. 169-172
Author(s):  
Jian Gang Wang ◽  
Jian Wen Hu ◽  
Lei Mao ◽  
Yong Juan Dai ◽  
Dong Ying Ju
Keyword(s):  
Numerical Simulation ◽  
Depth Distribution ◽  
Low Carbon Steel ◽  
Induction Hardening ◽  
Simulation Method ◽  
Low Carbon ◽  
Tempered Martensite ◽  
Steel Microstructure ◽  
Numerical Simulation Method ◽  
Simulation Results

A numerical simulation method is used to predict the depth distribution of martensite and hardness in the case layer of carburizing (carbonitriding)-quenched 20CrMnTi steel. Microstructure and mechanical properties of 20CrMnTi steel after carbonitriding and subsequent induction hardening is investigated. The results show that the microstructure after nitriding and subsequent induction hardening is main tempered martensite and nitrides; after carbonitriding and subsequent induction hardening is main martensite and a small amount nitrides. The simulation results were a little different from experimental results. According to the results, the factors of reducing the accuracy of the numerical simulation method have been discussed.

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