scholarly journals Temperature Distribution And Mechanical Properties of FSW Medium Thickness 2219 Aluminum Alloy

2021 ◽  
Author(s):  
Xiaohong Lu ◽  
Yihan Luan ◽  
Xiangyue Meng ◽  
Yu Zhou ◽  
Ning Zhao ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Aluminum Alloy ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Thermodynamic Model ◽  
Generation Model ◽  
Medium Thickness ◽  
Welding Temperature ◽  
Friction Heat ◽  
2219 Aluminum Alloy

Abstract Friction stir welding (FSW) is a solid-state jointing technology, which has the advantages of high joint strength, low residual stress aXnd small deformation after welding. During the process of FSW, the welding temperature has an important effect on the quality of the weldment. Therefore, the heat generation model of FSW of medium thickness 2219 aluminum alloy is established based on the friction heat generation at the interface between the tool and the workpiece and the plastic deformation heat generation of the weldment material near the tool. The heat transfer model is set under the premise of considering heat conduction, thermal convection, and thermal radiation. Using JMatPro technology, the temperature-related material parameters of 2219 aluminum alloy are calculated based on the material composition, and the heat generation model is imported into the ABAQUS simulation software based on the DFLUX subroutine, and the establishment of the FSW thermodynamic model is realized. The effectiveness of the model is verified by FSW experiments. The thermodynamic model takes into account both heat generation (friction heat generation and plastic deformation heat generation) and heat transfer (heat conduction, thermal convection and thermal radiation), so it has a high prediction accuracy. Based on the FSW thermodynamic model, the influence of welding parameters on temperature distribution is explored, subsequently the influence of welding temperature on mechanical properties of welded joint are also studied. The research can provide guidance for predicting and characterizing the temperature distribution and the improvement of mechanical performance of FSW.

scholarly journals Welding Parameters Optimization in Plunging and Dwelling Phase of FSW Medium Thickness 2219 Aluminum Alloy

2021 ◽  
Author(s):  
Xiaohong Lu ◽  
Jinhui Qiao ◽  
Junyu Qian ◽  
Shixuan Sun ◽  
Steven Y. Liang
Keyword(s):  
Aluminum Alloy ◽  
Temperature Distribution ◽  
Simulation Model ◽  
Rotational Speed ◽  
Parameters Optimization ◽  
Welding Parameters ◽  
Medium Thickness ◽  
Dwelling Time ◽  
Friction Stir ◽  
2219 Aluminum Alloy

Abstract The influence of welding parameters on temperature distribution in plunging and dwelling phase of friction stir welding (FSW) medium thickness 2219 aluminum alloy is blank. Improper selection of welding parameters will result in uneven temperature distribution along the thickness of the weldment, which will lead to welding defects and ultimately affect the mechanical properties of the weldment. To realize the prediction of temperature distribution and achieve the optimization of welding parameters, a simulation model of FSW 18mm thick 2219 aluminum alloy is built based on DEFORM. The validity of the simulation model is verified by temperature measurement experiments. With the minimum temperature difference in the core area of the weldment as target value, and weldable temperature range of 2219 aluminum alloy as constraint conditions, orthogonal experiments are conducted considering the rotational speed, the press amount, the tool tilt angle, the plunging traverse speed and the dwelling time. The results of variance analysis show that the rotational speed and the dwelling time are significant factors affecting temperature field during plunging and dwelling phase. Through single factor simulation, the welding parameters in plunging and dwelling phase are optimized. This study provides a reference for realizing high-quality welding of a heavy rocket fuel tank.

Simulation of Heat Transfer in Bridge-Based Micro Calorimeters

2009 ◽  
Author(s):  
Jun Yu ◽  
Zhen’an Tang ◽  
Zhengxing Huang ◽  
Chong Feng
Keyword(s):  
Heat Transfer ◽  
Heat Capacity ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Silicon Substrate ◽  
Three Dimensional ◽  
Temperature Response ◽  
Differential Method ◽  
Three Dimensional Finite Element ◽  
Micro Calorimeter

Previous studies of bridge-based micro calorimeters have shown that these devices can measure heat capacity and melting point of ultra thin films with pulse scan calorimetry. The bridge-based micro calorimeters consist of a sample region and several beams that connecting the sample region with silicon substrate. Both the sample region and the beams are suspending on the silicon substrate for thermal isolation. The temperature distribution of the micro calorimeter during a heating pulse depends on the joule-heating of the heating resistor, the heat absorption and heat conduct of the bridge. The heat transfer through the beams during a pulse scan measurement is complex because there is heat generation on some beams and the temperature distribution along the beams is not uniform. Using three dimensional finite element analyses (FEA), the thermal-electrical simulations of the heat transfer in the bridge-based micro calorimeters have been performed. The heat consumption and temperature distribution at steady state analyses, the temperature response of the bridge and the heat generation of the heater at transient analyses have been calculated for the bridge-based micro calorimeter with different sample thermal conductivities and heat capacities. The simulation results indicate that for the bridge-based microcalorimeter using pulse calorimetry, when the heat capacity of the sample film is close to or larger than the heat capacity of an empty calorimeter, the differential method of getting the sample heat capacity from the difference between a micro calorimeter with and without the sample is no longer suitable because the heat transfer and temperature distributions of the two calorimeters are no longer comparable to each other.

scholarly journals Mathematical Model of a Three-Dimensional Non-Isothermal Glacier

1976 ◽  
Vol 16 (74) ◽  
pp. 308-309
Author(s):  
S.S. Grigoryan ◽  
M.S. Krass ◽  
P.A. Shumskiy
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Small Parameter ◽  
Heat Generation ◽  
Curvilinear Coordinates ◽  
Shear Stresses ◽  
System Of Equations ◽  
Equation Of Heat Conduction

Abstract In the case of a non-isothermal glacier it is necessary to integrate the equations of dynamics together with the equation of heat conduction, heat transfer, and heat generation because of the interdependence (1) of strain-rate of ice on its temperature, and (2) of ice temperature on the rate of heat transfer by moving ice and on the intensity of heat generation in its strain. In view of the complexity of the whole system of equations, simplified mathematical models have been constructed for dynamically different glaciers. The present model concerns land glaciers with thicknesses much less than their horizontal dimensions and radii of curvature of large bottom irregularities, so that the method of a thin boundary layer may be used. The principal assumption is the validity of averaging over a distance of the order of magnitude of ice thickness. Two component shear stresses parallel to the bottom in glaciers of this type considerably exceed the normal stresses and the third shear stress, so the dynamics are described by a statically determined system of equations. For the general case, expressions for the stresses have been obtained in dimensionless affine orthogonal curvilinear coordinates, parallel and normal to the glacier bottom, and taking into account the geometry of the lower and upper surfaces. The statically undetermined problem for ice divides is solved using the equations of continuity and rheology, so the result for stresses depends considerably on temperature distribution. In the case of a flat bottom the dynamics of an ice divide is determined by the curvature of the upper surface. The calculation of the interrelating velocity and temperature distributions is made by means of the iteration of solutions (1) for the components of velocity from the stress expressions using the rheological equations (a power law or the more precise hyberbolic one) with the assigned temperature distribution, and (2) for the temperature with the assigned velocity distribution. The temperature distribution in the coordinate system used is determined by a parabolic equation with a small parameter at the principal derivative. Its solution is reduced to the solution of a system of recurrent non-uniform differential equations of the first order by means of a series expansion of the small parameter: the right part for the largest term of the expansion contains a function of the heat sources, and for the other terms it contains the second derivative along the vertical coordinate from the previous expansion term. Thus advection makes the main contribution to the heat transfer, and temperature in a glacier is distributed along the particle paths, changing simultaneously under the influence of heat generation. A relatively thin conducting boundary layer adjoins the upper and lower surfaces of a glacier, playing the role of a temperature damper in the ablation area. The equation of heat conduction (at the free surface) or of heat conduction and heat transfer (at the bottom) with the boundary conditions, and with the condition of the connection with the solution of the problem for the internal temperature distribution, is being solved for the boundary layer because of its small thickness. Beyond the limits of the boundary layer, heat conduction makes a small change in the temperature distribution, which can be calculated with any degree of accuracy.

scholarly journals Mathematical Model of a Three-Dimensional Non-Isothermal Glacier

1976 ◽  
Vol 16 (74) ◽  
pp. 308-309
Author(s):  
S.S. Grigoryan ◽  
M.S. Krass ◽  
P.A. Shumskiy
Keyword(s):  
Heat Transfer ◽  
Boundary Layer ◽  
Heat Conduction ◽  
Temperature Distribution ◽  
Small Parameter ◽  
Heat Generation ◽  
Curvilinear Coordinates ◽  
Shear Stresses ◽  
System Of Equations ◽  
Equation Of Heat Conduction

AbstractIn the case of a non-isothermal glacier it is necessary to integrate the equations of dynamics together with the equation of heat conduction, heat transfer, and heat generation because of the interdependence (1) of strain-rate of ice on its temperature, and (2) of ice temperature on the rate of heat transfer by moving ice and on the intensity of heat generation in its strain. In view of the complexity of the whole system of equations, simplified mathematical models have been constructed for dynamically different glaciers. The present model concerns land glaciers with thicknesses much less than their horizontal dimensions and radii of curvature of large bottom irregularities, so that the method of a thin boundary layer may be used. The principal assumption is the validity of averaging over a distance of the order of magnitude of ice thickness.Two component shear stresses parallel to the bottom in glaciers of this type considerably exceed the normal stresses and the third shear stress, so the dynamics are described by a statically determined system of equations. For the general case, expressions for the stresses have been obtained in dimensionless affine orthogonal curvilinear coordinates, parallel and normal to the glacier bottom, and taking into account the geometry of the lower and upper surfaces. The statically undetermined problem for ice divides is solved using the equations of continuity and rheology, so the result for stresses depends considerably on temperature distribution. In the case of a flat bottom the dynamics of an ice divide is determined by the curvature of the upper surface.The calculation of the interrelating velocity and temperature distributions is made by means of the iteration of solutions (1) for the components of velocity from the stress expressions using the rheological equations (a power law or the more precise hyberbolic one) with the assigned temperature distribution, and (2) for the temperature with the assigned velocity distribution. The temperature distribution in the coordinate system used is determined by a parabolic equation with a small parameter at the principal derivative. Its solution is reduced to the solution of a system of recurrent non-uniform differential equations of the first order by means of a series expansion of the small parameter: the right part for the largest term of the expansion contains a function of the heat sources, and for the other terms it contains the second derivative along the vertical coordinate from the previous expansion term.Thus advection makes the main contribution to the heat transfer, and temperature in a glacier is distributed along the particle paths, changing simultaneously under the influence of heat generation. A relatively thin conducting boundary layer adjoins the upper and lower surfaces of a glacier, playing the role of a temperature damper in the ablation area. The equation of heat conduction (at the free surface) or of heat conduction and heat transfer (at the bottom) with the boundary conditions, and with the condition of the connection with the solution of the problem for the internal temperature distribution, is being solved for the boundary layer because of its small thickness. Beyond the limits of the boundary layer, heat conduction makes a small change in the temperature distribution, which can be calculated with any degree of accuracy.

Heat Transfer of Thin Fins With Temperature-Dependent Thermal Properties and Internal Heat Generation

1967 ◽  
Vol 89 (2) ◽  
pp. 155-162 ◽  
Author(s):  
H. M. Hung ◽  
F. C. Appl
Keyword(s):  
Heat Transfer ◽  
Thermal Properties ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Analytical Study ◽  
Internal Heat ◽  
Internal Heat Generation ◽  
Temperature Dependent ◽  
Numerical Examples

An analytical study of the temperature distribution along thin fins with temperature-dependent thermal properties and internal heat generation is presented. The analysis utilizes a recently published bounding procedure which yields analytical and continuous bounding functions for the temperature distribution. Several numerical examples are considered. Tabular and graphical results are given. The effects of variable thermal properties and internal heat generation are also shown.

Investigation of Conjugate Heat Transfer in Brush Seals Using Porous Media Approach Under Local Thermal Non-Equilibrium Conditions

2015 ◽  
Author(s):  
Bo Qiu ◽  
Jun Li ◽  
Zhenping Feng
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Frictional Force ◽  
Conjugate Heat Transfer ◽  
Frictional Heat ◽  
Equilibrium Conditions ◽  
Frictional Heat Generation ◽  
Brush Seal ◽  
Brush Seals

As a type of contacting seal technology, brush seals provide superior sealing performance and flexible behavior. Brush seals have found increasing application in more challenging high-temperature locations in recent years. Thus, the frictional heat generation between the seal bristles and mating surfaces is becoming another major concern for stable operation of brush seals. This study presents detailed investigations on the conjugate heat transfer behavior of brush seals using Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) approaches. A dual-energy equation was proposed to describe the conjugate heat transfer in the porous bristle pack region under local thermal non-equilibrium conditions. The heat transfer CFD model was established with consideration of anisotropic thermal conductivity and a radius-dependent porosity of the bristle pack. The frictional heat generation was calculated from the product of the bristle-rotor frictional force and sliding velocity. The bristle-rotor frictional force was obtained from the brush seal FEM model with consideration of internal friction and aerodynamic load on the bristles. The temperature distribution of the brush seal was predicted at various operational conditions using the iterative CFD and FEM brush seal model. The effects of pressure ratios and rotational speeds on the temperature distribution and bristle maximum temperature of the brush seal were investigated based on the developed numerical approach. The effect of frictional heat generation on brush seal leakage was also analyzed.

scholarly journals Study on the Thermal Performance and Temperature Distribution of Ball Bearings in the Traction Motor of a High-Speed EMU

2020 ◽  
Vol 10 (12) ◽  
pp. 4373
Author(s):  
Yu Wang ◽  
Junci Cao ◽  
Qingbin Tong ◽  
Guoping An ◽  
Ruifang Liu ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Heat Generation ◽  
Thermal Performance ◽  
High Speed ◽  
Convection Heat Transfer ◽  
Ball Bearings ◽  
Convection Heat ◽  
Rolling Bearings ◽  
Traction Motors

The transient thermal performance of rolling bearings affects the mechanical performance and system safety of traction motors. Most of the traditional empirical formulas used in temperature analysis have been simplified and cannot be completely applied to the calculation of heat generation and convection heat transfer coefficients. Based on the comparative analysis of finite element transient temperature and experimental data, this paper proposes a correction method of mathematical model and derives an accurate calculation formula for the heat generation and lubricant convection heat transfer coefficient of ball bearings applicable for the non-driving end in the traction motor of a high-speed EMU (Electric Multiple Unit). The accuracy of the results has been verified by durability experiment data. In addition, with changes in speed, radial load and other factors taken into account, we have analyzed the influence of these time-varying factors on ball bearing temperature, as well as the temperature distribution law of each component in a grease-lubricated bearing, in a bid to lay a foundation for follow-up research on the heat transfer laws of traction motors and rolling bearings.

Friction-Induced Heating in Axially Loaded Ball Bearings

1970 ◽  
Vol 92 (1) ◽  
pp. 105-111 ◽  
Author(s):  
J. I. Schwartz
Keyword(s):  
Heat Transfer ◽  
Heat Generation ◽  
Accurate Prediction ◽  
Experimental Results ◽  
Constant Speed ◽  
Ball Bearings ◽  
Friction Heat ◽  
Prediction Technique ◽  
Axially Loaded

This paper compares theoretical and experimental results on the friction-induced heating in thrust-loaded ball bearings at constant speed. Heat transfer and friction heat-generation models are developed for the bearings using computer techniques. The comparisons indicate that the models are reasonable since the predictions are within ±10 percent of the measured values. More work is needed, however, before a more accurate prediction technique will be available.

Finite Volume Method for Analysis of Convective Longitudinal Fin with Temperature-Dependent Thermal Conductivity and Internal Heat Generation

2017 ◽  
Vol 374 ◽  
pp. 106-120 ◽  
Author(s):  
Gbeminiyi M. Sobamowo ◽  
Bayo Y. Ogunmola ◽  
Gaius Nzebuka
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Heat Generation ◽  
Internal Heat ◽  
Internal Heat Generation ◽  
Temperature Dependent ◽  
Volume Method

In this study, heat transfer in a longitudinal rectangular fin with temperature-dependent thermal properties and internal heat generation has been analyzed using finite volume method. The numerical solution was validated with the exact solution for the linear problem. The developed heat transfer models were used to investigate the effects of thermo-geometric parameters, coefficient of heat transfer and thermal conductivity (non-linear) parameters on the temperature distribution, heat transfer and thermal performance of the longitudinal rectangular fin. From the results, it shows that the fin temperature distribution, the total heat transfer, and the fin efficiency are significantly affected by the thermo-geometric of the fin. Therefore, the results obtained in this analysis serve as basis for comparison of any other method of analysis of the problem and they also provide platform for improvement in the design of fin in heat transfer equipment.

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