Design and Optimization of an Aluminum Nitride Sublimation Growth System

2003 ◽  
Author(s):  
Bei Wu ◽  
Ronghui Ma ◽  
Hui Zhang
Keyword(s):  
Thermal Stress ◽  
Temperature Distribution ◽  
Stress Distribution ◽  
Aluminum Nitride ◽  
Elastic Stress ◽  
Transient Temperature ◽  
Design And Optimization ◽  
Transient Temperature Distribution ◽  
Growth System ◽  
Growth Method

In this paper, an integrated model considering induction heating, heat transfer, growth kinetics and thermo-elastic stress has been developed to study temperature distribution in the growth system, crystal shape and stress distribution in the asgrown aluminum nitride (AIN) crystal. The electromagnetic field and induction heat generation are calculated by the Maxwell equations. Transient temperature distribution in the growth chamber is simulated by energy accounting for conduction/radiation within and between various components. To reduce thermal stress and dislocation, a growth method to enlarge the ingot diameter from a smaller seed and maintain low thermal stress in the crystal has been proposed. The thermo-elastic stress fields have been calculated for several designed temperature profiles along the crucible inner wall and stress distribution has been correlated to dislocation density distribution.

Numerical Simulation of Temperature Field and Residual Stress in Multi-Pass Welds in 2.25Cr-1Mo-0.25V Steel Plate and Comparison With Experimental Measurements

2017 ◽  
Author(s):  
Mu Qin ◽  
Guangxu Cheng ◽  
Zaoxiao Zhang ◽  
Qing Li ◽  
Jianxiao Zhang
Keyword(s):  
Residual Stress ◽  
Temperature Distribution ◽  
Stress Distribution ◽  
Residual Stresses ◽  
Pressure Vessels ◽  
Residual Stress Distribution ◽  
Bottom Surface ◽  
Transient Temperature ◽  
Transient Temperature Distribution ◽  
Welding Processes

The 2.25Cr-1Mo-0.25V steels are widely used in the petroleum chemical industry for the manufacturing of pressure vessels. The multi-pass welding is a critical type of fabrication in hydrogenation reactor. However, very complicated residual stresses could be generated during the multi-pass welding process. The presence of residual stresses could have significant influence on the performance of welded product. In the present work, the transient temperature distribution and residual stress distribution in welding of 2.25Cr-1Mo-0.25V steel are analyzed by using numerical method. An uncoupled thermal-mechanical two-dimensional (2-D) FEM is proposed under the ABAQUS environment. The transient temperature distribution and the residual stress distribution during the welding processes are determined through the finite element method. A group of experiments by using the blind-hole method have been conducted to validate the numerical results. The results of 2-D model agree well with the experiment. The result shows that the maximum welding stress generated at heat affected zone (HAZ) both at the top and bottom surface whether to transverse stress or longitudinal stress.

A method of convergence for finite difference thermal stress computation in axially symmetrical bodies

1967 ◽  
Vol 2 (4) ◽  
pp. 332-340
Author(s):  
C L Chow ◽  
R Hoyle
Keyword(s):  
Thermal Stress ◽  
Temperature Distribution ◽  
Finite Difference ◽  
Rate Of Convergence ◽  
Thermal Load ◽  
Turbine Rotor ◽  
Transient Temperature ◽  
Rapid Rate ◽  
Transient Temperature Distribution ◽  
Stress Computation

The most general axially symmetrical thermal load is one in which a transient temperature distribution, varying axially and radially, is applied to an axially symmetrical system with an irregular axial boundary. When the thermal stress equations are applied to such a system, using the conventional Gauss-Siedel or Liebmann method, severe oscillation has been experienced making convergence impossible to achieve. The authors present in this paper a method which not only converts a diverging solution but also yields a rapid rate of convergence. This method has been successfully applied to the problem of a steam turbine rotor.

Finite Element Modeling of Transient Temperature and Residual Stress Distribution Analysis in Multi-Pass Welding Process

2012 ◽  
Author(s):  
Guang-Ming Fu ◽  
Chen An ◽  
Marcelo Igor Lourenço ◽  
Meng-Lan Duan ◽  
Segen F. Estefen
Keyword(s):  
Residual Stress ◽  
Temperature Distribution ◽  
Stress Distribution ◽  
Heat Source ◽  
Welding Process ◽  
Source Model ◽  
Residual Stress Distribution ◽  
Transient Temperature ◽  
Fe Model ◽  
Transient Temperature Distribution

The residual stress and deformation due to the welding process have significant influences on the service performance of the welded deepwater platform hull. An exact prediction of transient temperature distribution is the important prerequisite to ensure the simulation accuracy of the welding residual stress and deformation fields, especially in the multi-pass welding process. Although the transient temperature distribution and residual stress distribution was studied in the past by various authors, the literature on 3D finite element (FE) simulation of multi-pass welding process is limited. In this paper, a FE model is developed to analyze the transient temperature and residual stress distribution of AH36 steel sheets in multi-pass welding process. A moving heat source model based on Goldak’s double-ellipsoidal heat flux distribution is employed for the heated plates. The addition of the volumetric heat source into the FE model and its movement along the welding pass are realized through a dedicated FORTRAN subroutine. The element birth and death technique in Abaqus/Standard is employed to simulate the weld filler variation with time in welded joints. The transient temperature calculated in the first stage is utilized as the input to the residual stress and distortion due to thermal shrinkage during the welding process and subsequent cooling. The results show good agreements between the temperature distribution and the geometry of weld pool obtained in the present work and those previously reported. Finally, a parametric study is performed to investigate the effect of welding variables, such as geometric parameters of Goldak’s heat source model, welding speed, pre-heat temperature and power input in the multi-pass welds, on the residual stress and distortion of the steel sheets.

Direct observation of three-dimensional transient temperature distribution in SiC Schottky barrier diode under operation by optical-interference contactless thermometry (OICT) imaging

2022 ◽  
Author(s):  
Keiya Fujimoto ◽  
Hiroaki Hanafusa ◽  
Takuma Sato ◽  
Seiichiro HIGASHI
Keyword(s):  
Temperature Distribution ◽  
Schottky Barrier ◽  
Hot Spot ◽  
Local Heating ◽  
Three Dimensional ◽  
Schottky Barrier Diode ◽  
Transient Temperature ◽  
Optical Interference ◽  
Transient Temperature Distribution ◽  
Heating And Cooling

Abstract We have developed optical-interference contactless thermometry (OICT) imaging technique to visualize three-dimensional transient temperature distribution in 4H-SiC Schottky barrier diode (SBD) under operation. When a 1 ms forward pulse bias was applied, clear variation of optical interference fringes induced by self-heating and cooling were observed. Thermal diffusion and optical analysis revealed three-dimensional temperature distribution with high spatial (≤ 10 μm) and temporal (≤ 100 μs) resolutions. A hot spot that signals breakdown of the SBD was successfully captured as an anormal interference, which indicated a local heating to a temperature as high as 805 K at the time of failure.

Measurement of Transient Temperature Distribution at Anode Surface After Current Zero in Vacuum Interrupter

2021 ◽  
Vol 141 (11) ◽  
pp. 712-717
Author(s):  
Akira Daibo ◽  
Yoshimitsu Niwa ◽  
Naoki Asari ◽  
Wataru Sakaguchi ◽  
Yo Sasaki ◽  
...  
Keyword(s):  
Temperature Distribution ◽  
Anode Surface ◽  
Transient Temperature ◽  
Vacuum Interrupter ◽  
Transient Temperature Distribution ◽  
Current Zero

scholarly journals Exact Solution of Heat Transport Equation for a Heterogeneous Geothermal Reservoir

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 2935 ◽  
Author(s):  
Sayantan Ganguly
Keyword(s):  
Temperature Distribution ◽  
Transport Equation ◽  
Heat Transport ◽  
Transport Processes ◽  
Geothermal Reservoir ◽  
Transient Temperature ◽  
Thermal Front ◽  
Transient Temperature Distribution ◽  
Heat Transport Equation ◽  
Geothermal Aquifer

An exact integral solution for transient temperature distribution, due to injection-production, in a heterogeneous porous confined geothermal reservoir, is presented in this paper. The heat transport processes taken into account are advection, longitudinal conduction and conduction to the confining rock layers due to the vertical temperature gradient. A quasi 2D heat transport equation in a semi-infinite porous media is solved using the Laplace transform. The internal heterogeneity of the geothermal reservoir is expressed by spatial variation of the flow velocity and the effective thermal conductivity of the medium. The model results predict the transient temperature distribution and thermal-front movement in a geothermal reservoir and the confining rocks. Another transient solution is also derived, assuming that longitudinal conduction in the geothermal aquifer is negligible. Steady-state solutions are presented, which determine the maximum penetration of the cold water thermal front into the geothermal aquifer.

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