scholarly journals Modelling of the cylindrical geometry cooling process based on the solution of the inverse problem

2021 ◽  
Vol 321 ◽  
pp. 02017
Author(s):  
Magda Joachimiak ◽  
Damian Joachimiak
Keyword(s):  
Inverse Problem ◽  
Surface Layer ◽  
High Temperature ◽  
Numerical Analysis ◽  
Chemical Treatment ◽  
Temperature Gradients ◽  
Cooling Process ◽  
Multi Stage ◽  
Fast Cooling ◽  
The Given

Processes of thermo-chemical treatment, such as nitriding, are used to create a surface layer of high mechanical values. When the nitriding process, often consisting of a multi-stage heating and soaking, is ended, elements being under treatment are cooled. The cooling rate depends on the massiveness and geometry of the given element. Too fast cooling can result in the formation of high temperature gradients, which leads to the element damage. This paper presents numerical analysis of a cylinder cooling. The non-linear, unsteady inverse problem for the heat equation was solved. Test examples were chosen based on experimental research conducted in the furnace for thermo-chemical treatment.

Surface modification of die steels with B—Al-layers by thermal-chemical treatment

2021 ◽  
pp. 557-564
Author(s):  
N.S. Ulakhanov ◽  
U.L. Mishigdorzhiyn ◽  
A.G. Tikhonov ◽  
A.I. Shustov ◽  
A.S. Pyatykh
Keyword(s):  
Mechanical Properties ◽  
Wear Resistance ◽  
Surface Layer ◽  
Surface Modification ◽  
High Temperature ◽  
Chemical Treatment ◽  
Quality Parameters ◽  
Processing Temperature ◽  
Die Steels ◽  
Composite Layers

The effect of diffusion high-temperature boroaluminizing (HBA) on the mechanical properties and quality parameters of the surface layer of stamp steels 5KhNM and 3Kh2V8F is shown. An analysis of the microstructure and composition of diffusion composite layers obtained as a result of thermal-chemical treatment (TCT) is presented and the distribution of microhardness in these layers is studied depending on the formed borides and carbides. The influence of processing temperature modes of on the parameters of roughness was experimentally established and the wear resistance characteristics of the processed surfaces of the investigated materials were determined.

scholarly journals Bandwidth Detection of Graph Signals with a Small Sample Size

Sensors ◽  
2020 ◽  
Vol 21 (1) ◽  
pp. 146
Author(s):  
Xuan Xie ◽  
Hui Feng ◽  
Bo Hu
Keyword(s):  
Numerical Analysis ◽  
Sample Size ◽  
Null Hypothesis ◽  
Small Sample Size ◽  
Score Test ◽  
Small Sample ◽  
High Dimensional ◽  
Multi Stage ◽  
Spectral Components ◽  
The Given

Bandwidth is the crucial knowledge to sampling, reconstruction or estimation of the graph signal (GS). However, it is typically unknown in practice. In this paper, we focus on detecting the bandwidth of bandlimited GS with a small sample size, where the number of spectral components of GS to be tested may greatly exceed the sample size. To control the significance of the result, the detection procedure is implemented by multi-stage testing. In each stage, a Bayesian score test, which introduces a prior to the spectral components, is adopted to face the high dimensional challenge. By setting different priors in each stage, we make the test more powerful against alternatives that have similar bandwidth to the null hypothesis. We prove that the Bayesian score test is locally most powerful in expectation against the alternatives following the given prior. Finally, numerical analysis shows that our method has a good performance in bandwidth detection and is robust to the noise.

scholarly journals Numerical Analysis of the Dislocation Density in Multicrystalline Silicon for Solar Cells by the Vertical Bridgman Process

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Makoto Inoue ◽  
Satoshi Nakano ◽  
Hirofumi Harada ◽  
Yoshiji Miyamura ◽  
Bing Gao ◽  
...  
Keyword(s):  
Residual Stress ◽  
Temperature Field ◽  
Numerical Analysis ◽  
Strain Field ◽  
Thermal Strain ◽  
Multicrystalline Silicon ◽  
Cooling Process ◽  
Vertical Bridgman ◽  
Fast Cooling ◽  
Bridgman Process

We studied the effects of cooling process on the generation of dislocations in multicrystalline silicon grown by the vertical Bridgman process. From the temperature field obtained by a global model, the stress relaxation and multiplication of dislocations were calculated using the Haasen-Alexander-Sumino model. It was found that the multiplication of dislocations is higher in fast cooling processes. It was confirmed that residual stress is low at high temperatures because the movement of the dislocations relaxes the thermal strain, while the residual stress increases with decreasing temperature, because of reduced motion of dislocations and formation of a strain field at lower temperatures.

Use of ultrasonic surface hardening in modifi cation of surface layer

2020 ◽  
pp. 200-204
Author(s):  
Yu.S. Semenova ◽  
A.G. Samul’ ◽  
S.V. Mazhuga
Keyword(s):  
Surface Layer ◽  
Chemical Treatment ◽  
Surface Hardening ◽  
Manufacturing Cost ◽  
Ultrasonic Vibrations ◽  
Surface Microrelief ◽  
Scientific Schools ◽  
Structure Changes ◽  
Wide Range ◽  
Finishing Machining

Overview of the research results got by various scientific schools in the field of application of ultrasonic surface hardening is provided. Wide range of opportunities of ultrasonic surface hardening is shown for the application in the preliminary machining of surfaces before thermal and chemical treatment, coating, and also as finishing machining. The effect of the energy of ultrasonic vibrations on structure changes in the material of the surface layer and on surface microrelief on parts performance is considered. The prospects of using of the ultrasonic surface hardening method in combination with other methods of the material modification are presented. In addition the possibilities of reducing the manufacturing cost of product by introducing ultrasonic surface hardening into the technological process are shown.

scholarly journals Numerical Evaluation of Structural Safety of Linear Actuator for Flap Control of Aircraft Based on Airworthiness Standard

Aerospace ◽  
2021 ◽  
Vol 8 (4) ◽  
pp. 104
Author(s):  
Dong-Hyeop Kim ◽  
Young-Cheol Kim ◽  
Sang-Woo Kim
Keyword(s):  
Numerical Analysis ◽  
Analytical Method ◽  
Safety Evaluation ◽  
Experimental Tests ◽  
Structural Safety ◽  
Linear Actuator ◽  
The Finite Element Method ◽  
Margin Of Safety ◽  
Verification Methodology ◽  
The Given

Airworthiness standards of Korea recommend verifying structural safety by experimental tests and analytical methods, owing to the development of analysis technology. In this study, we propose a methodology to verify the structural safety of aircraft components based on airworthiness requirements using an analytical method. The structural safety and fatigue integrity of a linear actuator for flap control of aircraft was evaluated through numerical analysis. The static and fatigue analyses for the given loads obtained from the multibody dynamics analysis were performed using the finite element method. Subsequently, the margin of safety and vulnerable area were acquired and the feasibility of the structural safety evaluation using the analytical method was confirmed. The proposed numerical analysis method in this study can be adopted as an analytical verification methodology for the airworthiness standards of civilian aircraft in Korea.

scholarly journals SCC Behavior at Hardened Surface Layer of 316(LC) in Water on High Temperature

2009 ◽  
Vol 58 (6) ◽  
pp. 228-233 ◽  
Author(s):  
Kiyoko Takeda ◽  
Akira Taniyama ◽  
Takeo Kudo ◽  
Hitoshi Uchida ◽  
Jun-ichiro Mizuki
Keyword(s):  
Surface Layer ◽  
High Temperature ◽  
Hardened Surface

Utilizing Novel Expandable Steel Packers to Overcome Multi-Stage Fracturing Completion Deployment Challenges in Horizontal Gas Wells

2021 ◽  
Author(s):  
Ebikebena M. Ombe ◽  
Ernesto G. Gomez ◽  
Aldia Syamsudhuha ◽  
Abdullah M. AlKwiter
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Cost Effective ◽  
Outer Diameter ◽  
Gas Wells ◽  
Multi Stage ◽  
High Pressure High Temperature ◽  
Zonal Isolation ◽  
Gas Bearing ◽  
Productive Time

Abstract This paper discusses the successful deployment of Multi-stage Fracturing (MSF) completions, composed of novel expandable steel packers, in high pressure, high temperature (HP/HT) horizontal gas wells. The 5-7/8" horizontal sections of these wells were drilled in high pressure, high temperature gas bearing formations. There were also washed-outs & high "dog-legs" along their wellbores, due to constant geo-steering required to keep the laterals within the hydrocarbon bearing zones. These factors introduced challenges to deploying the conventional MSF completion in these laterals. Due to the delicate nature of their packer elastomers and their susceptibility to degradation at high temperature, these conventional MSF completions could not be run in such hostile down-hole conditions without the risk of damage or getting stuck off-bottom. This paper describes the deployment of a novel expandable steel packer MSF completion in these tough down-hole conditions. These expandable steel packers could overcome the challenges mentioned above due to the following unique features: High temperature durability. Enhanced ruggedness which gave them the ability to be rotated & reciprocated during without risk of damage. Reduced packer outer diameter (OD) of 5.500" as compared to the 5.625" OD of conventional elastomer MSF packers. Enhanced flexibility which enabled them to be deployed in wellbores with high dog-leg severity (DLS). With the ability to rotate & reciprocate them while running-in-hole (RIH), coupled with their higher annular clearance & tolerance of high temperature, the expandable steel packers were key to overcoming the risk of damaging or getting stuck with the MSF completion while RIH. Also, due to the higher setting pressure of the expandable steel packers when compared to conventional elastomer packers, there was a reduced risk of prematurely setting the packers if high circulating pressure were encountered during deployment. Another notable advantage of these expandable packers is that they provided an optimization opportunity to reduce the number of packers required in the MSF completion. In a conventional MSF completion, two elastomer packers are usually required to ensure optimum zonal isolation between each MSF stage. However, due to their superior sealing capability, only one expandable steel packer is required to ensure good inter-stage isolation. This greatly reduces the number of packers required in the MSF completion, thereby reducing its stiffness & ultimately reducing the probability of getting stuck while RIH. The results of using these expandable steel packers is the successful deployment of the MSF completions in these harsh down-hole conditions, elimination of non-productive time associated with stuck or damaged MSF completion as well as the safe & cost-effective completion in these critical horizontal gas wells.

Research on high-temperature oxidation resistance, hot forming ability, and microstructure of Al–Si–Cu coating for 22MnB5 steel

2021 ◽  
Vol 40 (1) ◽  
pp. 397-409
Author(s):  
Ziliu Xiong ◽  
Zhangguo Lin ◽  
Jianjun Qi ◽  
Li Sun ◽  
Guangxin Wu ◽  
...  
Keyword(s):  
Surface Layer ◽  
High Temperature ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Hot Stamping ◽  
Optical Microscope ◽  
Hot Forming ◽  
Metal Compound ◽  
Temperature Oxidation ◽  
Substrate Steel

Abstract High-temperature oxidation resistance, hot formability, element distribution, and microstructure of Al-10% Si-(0.5–3.0%)Cu coating were investigated by means of glow discharge spectroscopy, optical microscope, scanning electron microscope, and energy-dispersive spectroscopy. Results show that the addition of Cu can increase high-temperature oxidation resistance above 950°C and improve hot formability so that no crack spreads into substrate steel as hot forming at 33.3% strain. Oxidation film structure is continual and compacting, and Si highly concentrates in the surface layer. The distribution of Cu has skin effect with peaking content 8.2% in the surface layer. After hot stamping, Al and Si diffuse into substrate steel, and Cu diffuses from inner to outer coating. Al–Si–Cu coating has smoother surface, straighter diffusion layer, and finer metal compound than Al–Si coating. Surface and diffusion layers are identified as aluminum oxide, Si-rich, and Cu phase and Al7SiFe2, Al3Fe, and CuAl3, respectively. Al-rich phase and the metal compound are composed of α-Al dissolving Fe, Si, and Cu and Al–Si matrix, Cu3Al, respectively.

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