Calculation Of Temperature Field Research Articles

Исследование напряженно-деформированного и температурного состояния режущей части инструмента с использованием лазерной интерферометрии

Introduction. The efficiency of the metalworking processes highly depends on the performance of the implemented cutting tools that can be increased by studying its stress-strain state and temperature fields. Existing stress analysis methods either have a low accuracy or are inapplicable for research during the operation of the tools made of materials with high mechanical properties. In addition, the study of temperature fields using known methods is difficult due to the small size of the cutting zone, high temperatures, and a heavy temperature gradient appearing during metal cutting. The purpose of this study is to develop new experimental methods for measuring the stress-strain and temperature fields in the cutting tool during its operation using laser interferometry. The methods include: obtaining interference fringe patterns using an interferometer with the original design, obtaining the tool deformation field during the cutting process by recording the changes in interference fringe patterns using a high-speed camera, processing fringe patterns with the separation of deformations caused by heating and cutting forces, and calculating temperature fields and stress distributions using mechanical properties and the coefficient of thermal expansion of the tool material. The advantages of the developed methods include: applicability under real operating conditions of the cutting tool, ability to study the non-stationary stress-strain state and temperatures during an operation, and achievement of a high spatial resolution and a small field of view for the investigated surface. Results and Discussion. The experimental study confirmed the efficiency of the methods. The results of the study included the fields of stresses and temperatures obtained during the orthogonal cutting of heat-resistant steel with a tool made of cemented tungsten carbide WC-8Co. The developed methods can be used to study the cutting tool efficiency at close to real conditions and in obtaining boundary conditions for the study stress-strain state of a workpiece material near the cutting zone.

Mathematical modeling of a new method of transportation of viscous petroleum products at low air temperatures

High viscosity petroleum products such as fuel oils and cracking residues are widely used as marine and boiler fuels both in Russia and in its exports. Conveying viscous petroleum products at low air temperatures has a high cost due to the unloading and cleaning processes of the transport tanks. Refined petroleum product cools and solidifies during transportation, becoming highly viscous, making it impossible to drain it without preheating to restore fluidity. Emerging difficulties are common to all countries with long winters and geographically wide areas. To justify a new method of rail transport of viscous petroleum products while maintaining their high temperature and fluidity by suppressing the natural convection of the petroleum product at the stage of filling the tanker. Temperature field calculations using the finite element method and the ANSYS R18.2 package are presented. The business process of the proposed transport method is universal for all modes of transportation. Using Petri nets and simulation modelling, it is investigated using the example of cleaning a tank car boiler from highly viscous residual oil products. You must perform these operations periodically during the operation of the tank wagon, and they are mandatory before every scheduled inspection and repair. Viscous oil products can be transported in a new way, the duration of the cleaning process of the tank wagon boiler is reduced by three times and the amount of water consumed is reduced by one and a half times.

INFLUENCE OF CONTOUR RADIUS AND FIBER ORIENTATION ON HEAT ACCUMULATION DURING MACHINING OF UNIDIRECTIONAL CFRP

The production of carbon fiber reinforced plastic (CFRP) parts requires edge trimming after primary shaping. Heat accumulates in convex workpiece sections, leading to increased temperatures compared to straight edges, possibly compromising the material. Existing analytical models assume constant thermal conditions and are therefore unable to calculate temperature fields of curved workpiece contours. Accordingly, a numerical simulation for straight contours was extended to convex geometry sections with different radii. The paper outlines this temperature simulation and presents results for various radii and fiber orientations when machining unidirectional CFRP. Temperature measurements during milling of unidirectional CFRP are used to calibrate the simulation.

Method for Determining the Boundary Condition of Heat Transfer in Mold for Slab Casting

The calculation of temperature field in the mold is important for the study of solidification process of liquid steel. In order to calculate the accurate temperature field of slab in the mod, the boundary condition of heat transfer in the mold should be determined before the calculation of slab temperature. In this paper, the relationship among the average heat transfer coefficient in the mold, the physical properties of steel, the cast condition and the cooling condition is derived according to the energy conservation equation and the Fourier law of heat conduction. Furthermore, the method for determining the parameters related to the formula of boundary heat flux is introduced. Results indicate that the average heat transfer coefficient in the mold ranges from 450 to 2000 W·(m2oC)−1 for conventional caster with a casting speed ranging from 0.8 and 1.8 m·min-1. The average heat transfer coefficient increases with the increase of casting speed. Besides, the casting speed has an effect on the parameters in the formula of calculating boundary heat flux, which indicates that the casting speed and the cooling condition should be taken into consideration for determining parameters related to the formula of calculating surface heat flux in the mold.

Simulation calculation and comparative analysis of three-dimensional temperature field of ultra high voltage through wall bushing under different current carrying capacity

As the key equipment of UHV transmission and transformation line, UHV bushing needs to carry the ultra-high voltage and large current of UHV power system at the same time. When the operating temperature of UHV bushing is too high, the operation failure rate will increase significantly, which will affect the stability and safety of UHV transmission line. Therefore, it is particularly important to analyze the temperature field characteristics of UHV bushing. This paper takes UHV bushing as the research object. The finite element software is used to calculate the electro thermal coupling. The three-dimensional thermal field distribution characteristics of UHV bushing are simulated and analyzed. This paper analyzes the influence of eddy current on the temperature distribution of UHV bushing under operation condition, and discusses the influence degree of eddy current on the temperature distribution of bushing, which provides an important basis for the temperature distribution, structure improvement and operation maintenance of bushing.

Semiempirical heat flux model of hard-brittle bone material in ductile microgrinding

Biological compact bone tissue is a typical hard-brittle material, which is extremely sensitive to high temperature. For the calculation of bone microgrinding temperature field, most of the known methods are based on the constant heat flux of the average tangential force without considering the ductile grinding characteristics of bone, leading to large calculation error. A semiempirical heat flux theoretical model based on the dynamic grinding force of hard-brittle bone ductile microgrinding is proposed to solve this bottleneck problem. The mechanism of heat generation and consumption in microgrinding zone under ductile removal mode of bone material is studied first, and the probability statistics of effective cutting abrasive number is analyzed. The heat distribution coefficient in grinding zone is calculated, and the semiempirical heat flux model of the ductile removal of hard-brittle biobone material is developed. Microgrinding experiments are conducted to verify the effectiveness of ductile removal grinding heat flux model. The temperatures of different measuring points on the surface of bone samples and micro grinding force are measured. Results show that the theoretical calculation is consistent with the experimental results, with an average error of <7.7%. Mechanical processing theory is applied to medical rehabilitation for realizing the precise control of temperature field in hard-brittle bone microgrinding process.

Calculation of temperature fields in the zone of the transverse edge of the drill

The wear of the transverse edge of the drill, the features of the drill web and the calculation determination of the temperature fields in the zone of its operation are investigated. Dependences are obtained for determining the total contact temperatures on the front and rear surfaces of the half-web. The results were used to create CAD for blade hole machining modes with application to the processing of heat-resistant materials of gas turbine engines. Keywords: hole, blade processing, drilling, transverse edge, temperature fields. alexbar57@mail.ru

Non-Fourier Heat Conduction and Thermal-Stress Analysis of a Spherical Ice Particle Subjected to Thermal Shock in PEM Fuel Cell at Quick Cold Start-Up

Quick start at low temperature is one of the key bottleneck technologies that restrict the large-scale commercialization of proton exchange membrane (PEM) fuel cell vehicles. Ice and devices in battery systems based on thermal deicing are inevitably subjected to thermal shock. In order to study this problem, a non-Fourier heat conduction model is established to study the temperature response of a spherical ice particle subjected to thermal shock with different boundary conditions on the surface. Furthermore, distribution of thermal stress in the particle is obtained using the calculated temperature field, and the effect of thermal relaxation time and boundary conditions on the temperature response as well as the thermal stress field are also analyzed. The results, which are significantly different from that obtained using Fourier law of heat conduction, show that the mechanical stresses and the serious expansion of the ice particle may lead to the severe deformation of the devices connected to the ice during the cold start-up, imposing a great challenge in controlling structural reliability of PEM fuel cells. The numerical results are expected to provide a scientific theoretical basis for PEM fuel cell design and low-temperature start-up control.

Thermophysical analysis of heat-insulated glued laminated profiled timber for wooden houses

The paper presents the thermophysical analysis of two types of the wall system made of heat-insulated glued laminated timbers with connectors comprised of water-resisting multilayer plywood. The paper describes a novel timber configuration, which reduces the weight of one square meter area by 55% compared with an ordinary timber having a cross-section of 0.21 m × 0.21 m and saves not less than 60% of wood. The latter is highly relevant because forests remove carbon dioxide emissions from the atmosphere; reducing the use of wood in construction is of great importance for ecology. The ANSYS finite element program is used for calculating temperature fields and heat fluxes. It is found that one connector affects not more than 0.2 m of the exterior wall length in relation to the temperature and heat flux fields, whereas the heat loss increase is not over 0.44%.

Semi-analytical thermo-mechanical model for the shield tunnel segmental joint subjected to elevated temperatures

The segmental joint is the most critical component for determining the mechanical response of concrete segmental linings in a shield-tunnel structure. Existing segmental joint models have been developed mainly for the analysis of segmental lining design, but in the event of a fire, the conditions that a tunnel joint may experience could well exceed the normal design range. Consequently, the validity of the existing segmental joint models becomes questionable. In this paper, an improved semi-analytical thermo-mechanical model is derived based on the general plane joint model to consider the thermal effect induced by elevated temperatures. As a benchmark for the development of the model, a laboratory experiment was conducted on concrete lining segmental joints under elevated temperatures. The general heat transfer and special heat flow invading through the joint were deduced by theorical and numerical methods. A finite element (FE) model is developed and calibrated against experimental model tests, whilst the FE model is employed to generate the required parametric data, from which a fitting function is created. A temperature adjustment coefficient is introduced to improve the calculation of the joint section temperature field. The influence of elevated temperature and axial force on the bending moment of a segmental joint is also incorporated according to the stress state of the joint section. The validation of the proposed semi-analytical thermo-mechanical model is demonstrated through comparisons with the results of fire tests. Finally, the influences of the heating curves, bolt location, and axial load on the rotation stiffness of the joint are investigated using the proposed model.

Transient Thermal Stress Calculation of a Shell and Tube Condenser with Fixed Tubesheet

AbstractThe present article deals with transient thermal stress calculation on a safety horizontal shell and tube condenser. This condenser is used in a power plant for cooling of hot steam diverted from the turbine in the case of its emergency shutdown. The standard stress calculation was provided according to the EN 13445 standard in steady regime. As consistent with this calculation, an expansion joint must be used on the shell. The main aim of this article is to describe a detailed calculation of the transient temperature field on the shell and tubes, using finite element method analysis, and longitudinal thermal stresses on the shell and tubes during the start‐up process. Transient analyses are useable for more accurate EN 13445 calculation and, furthermore, for fatigue calculation.

Review of Computer Modeling and Simulation of Spinal Thermal Ablation

Thermal ablation surgery can effectively eliminate bone tumors in the spine and meanwhile reduce damage to the human body. To realize the computer modeling and simulation of spine thermal ablation surgery, it is necessary to ensure the accuracy of both spine modeling and simulation temperature. This review summarizes the research progress of this field and analyzes the prospects from two aspects: computer modeling based on spine segmentation from medical images and simulation calculation of temperature field in ablation surgery. The research on spine segmentation has made great progress, but there are still some problems that prevent it from being applied in clinical simulation. Related research has been trying to solve the problems. For the ablation surgery of the spine, some researchers have tried ablation simulation and obtained simulation results that are relatively consistent with the actual temperature value.

Analytical Solution of the Non-Stationary Heat Conduction Problem in Thin-Walled Products during the Additive Manufacturing Process.

The work is devoted to the development of a model for calculating transient quasiperiodic temperature fields arising in the direct deposition process of thin walls with various configurations. The model allows calculating the temperature field, thermal cycles, temperature gradients, and the cooling rate in the wall during the direct deposition process at any time. The temperature field in the deposited wall is determined based on the analytical solution of the non-stationary heat conduction equation for a moving heat source, taking into account heat transfer to the environment. Heat accumulation and temperature change are calculated based on the superposition principle of transient temperature fields resulting from the heat source action at each pass. The proposed method for calculating temperature fields describes the heat-transfer process and heat accumulation in the wall with satisfactory accuracy. This was confirmed by comparisons with experimental thermocouple data. It takes into account the size of the wall and the substrate, the change in power from layer to layer, the pause time between passes, and the heat-source trajectory. In addition, this calculation method is easy to adapt to various additive manufacturing processes that use both laser and arc heat sources.

Study of Temperature Field Inhomogeneities in Parallel Wire Strand Sections under ISO834 Fire

An accurate prediction of temperatures of parallel wire strands is essential to determine the fire-induced mechanical responses of cable-supported bridges. In this paper, the theoretical formula applicable to the temperature field calculation of parallel wire strand sections is established based on the basic theory of heat transfer, and its accuracy is verified. An equivalent steel round bar numerical model of the parallel wire strand is established, and the temperature history of the parallel wire strand section under ISO834 fire is analyzed using the theoretical formula and the equivalent steel round bar numerical model. The results show that the heating law of each layer steel wires of the parallel wire strand section is basically the same and all have a tendency to approach the fire source temperature with the increase of fire time. Due to the existence of thermal resistance, large temperature gradients occur in the parallel wire strand sections. The temperature field of the parallel wire strand section shows more significant inhomogeneous distribution than that of its equivalent steel round bar section due to the influence of the cavities. It indicates that the traditional equivalent steel round bar model does not genuinely reflect the inhomogeneous temperature rising characteristics of the parallel wire strand section. The temperature of the surface layer steel wires of the parallel wire strand section and its equivalent steel round bar section is very close. In contrast, the temperature difference of the inner steel wires is significant, i.e., the parallel wire strand section has a larger temperature gradient than its equivalent steel round bar section.

Refined Calculation of Temperature Field in Cross-passage by Artificial Ground Freezing

In China, the artificial ground freezing (AGF) method is widely used in the construction of cross-passages, however, it is difficult to accurately calculate the numerical solution of the freezing temperature field. In this paper, the boundary conditions in the numerical calculation are refined through in-suit measurements, and finally the freezing process of the connecting channel is effectively simulated. The calculation results show that the thickness and temperature of the frozen wall at 1.0 m near the main tunnel segment are significantly weakened. The frozen wall at the top of the cross-passage is affected by densely arranged holes, which is prone to excessive freezing. And based on the calculation results, an optimization plan for the highest cooling efficiency in the initial stage of active freezing and speeding up freezing is proposed.

Advanced Calculation Model of V-Belt Temperature Field

In the process of continuous high-strength operation of the harvester, structure aging, surface hardening, brittle fracture, and other features appear on V-belt due to temperature rise, which seriously affects the service life of the belt and stability of the whole machine. To predict the temperature distribution of V-belt and improve its service life, an advanced calculation method of temperature field suitable for multiwheel is proposed. First, on the basis of analysing the heat source of the transmission belt, the values of internal friction and external friction are calculated based on AVL Excite Timing Drive (AVL Excite TD). Secondly, two-dimensional temperature field finite element calculation model is established by analysing the heat balance equation, determining the heat flow distribution coefficient and heat convection conditions. Then, to verify the calculation model of the temperature field, the experimental setup and instrumentation are built based on Controller Area Network-bus (CAN-bus) technology. At last, multi-condition tests are designed in this paper. The experiment results show that the maximum difference between the model calculated value and experiment is 4.77 ℃ in unsteady state, and 0.15 ℃ in steady state. Therefore, the multiwheel V-belt temperature field calculation model developed in this paper can realize the accurate calculation of the temperature field under steady state conditions. It has a very important guiding significance for reasonable selection of operating parameters and improvement of service lifetime of belt.

Assessment of Thermally Stressed State of Concrete Massif

The paper describes a technique for assessing the thermally stressed state of a concrete massif of a foundation slab made of a self-compacting concrete mixture. The proposed method consists in a preliminary calculation of temperature fields in hardening concrete. The objects of research have been self-compacting concrete mix and structural concrete in the structure mass. The choice of materials for the preparation of a concrete mixture is given and substantiated. The composition of self-compacting concrete has been used to assess the thermally stressed state. A binder with a reduced exotherm has been used in order to reduce the self-heating of concrete. Studies have been carried out to assess the specific heat release of the recommended cement depending on the initial water-cement ratio. The effect of a chemical additive on the rate and magnitude of the specific heat release of cement has been studied. The paper presents the main theoretical provisions and an algorithm for calculating the thermal stress state of a concrete massif. The finite difference method has been used to calculate the expected temperatures and their distribution in the structure mass, and the temperature stresses in the sections of the concrete mass have been calculated to assess the thermally stressed state. The performed calculations of the temperature fields have made it possible to estimate the maximum possible temperatures and temperature differences over the sections of the concrete massif depending on the initial temperature of the concrete mixture and the average daily temperature of the outside air. Analysis of the temperature distribution has revealed the most dangerous sections of the concrete mass. An assessment of the thermal stress state of the concrete mass has been made on the basis of the results pertaining to calculation of temperature fields. The calculation of temperature stresses in the most dangerous sections of the concrete massif has been performed. It is shown that the calculated value of the temperature stress can serve as a characteristic of the thermally stressed state of the concrete mass. The formation of temperature cracks in a concrete mass is possible when the calculated value of the temperature stress exceeds the actual tensile strength of concrete. Comparison of the calculated and actual values of temperatures in the sections of the foundation slab has made it possible to conclude that the calculations of the temperature fields and, as a consequence, possible temperature deformations are correct.

Refined Calculation and Demonstration for Sunshine Temperature Difference Effect of Long Span Continuous Beam

The continuous rigid frame bridge of Jiagai River Bridge is (100 + 192 + 100) m, with a main span of 192m, which will break the historical record of 176m of Chaoyang Jialing River Bridge and become the largest continuous rigid frame bridge of single track railway in China. The single track railway continuous rigid frame bridge has the characteristics of large load, poor stability and high prestress requirements. The temperature difference in sunlight will produce temperature deformation and emperature stress in the concrete box girder bridge, which will affect the linear monitoring measurement results. In particular, the sunshine temperature difference will produce nonlinear temperature gradient in the vertical and transverse direction of the cross section of the statically indeterminate box girder bridge, resulting in the generation of temperature self stress and temperature secondary stress. This kind of temperature stress is often large, which leads to the cracking of concrete and even endangers the normal operation in the future. This paper studies the calculation of temperature field, temperature stress and temperature deformation of concrete box girder caused by solar radiation, and compiles a program to realize the visual calculation of sunshine temperature effect.

Heat Transfer and Hydrodynamics in Stirred Tanks with Liquid-Solid Flow Studied by CFD–DEM Method

The heat transfer and hydrodynamics of particle flows in stirred tanks are investigated numerically in this paper by using a coupled CFD–DEM method combined with a standard k-e turbulence model. Particle–fluid and particle–particle interactions, and heat transfer processes are considered in this model. The numerical method is validated by comparing the calculated results of our model to experimental results of the thermal convection of gas-particle flows in a fluidized bed published in the literature. This coupling model of computational fluid dynamics and discrete element (CFD–DEM) method, which could calculate the particle behaviors and individual particle temperature clearly, has been applied for the first time to the study of liquid-solid flows in stirred tanks with convective heat transfers. This paper reports the effect of particles on the temperature field in stirred tanks. The effects on the multiphase flow convective heat transfer of stirred tanks without and with baffles as well as various heights from the bottom are investigated. Temperature range of the multiphase flow is from 340 K to 350 K. The height of the blade is varied from about one-sixth to one-third of the overall height of the stirred tank. The numerical results show that decreasing the blade height and equipping baffles could enhance the heat transfer of the stirred tank. The calculated temperature field that takes into account the effects of particles are more instructive for the actual processes involving solid phases. This paper provides an effective method and is helpful for readers who have interests in the multiphase flows involving heat transfers in complex systems.

Thermal Stress Analysis and Spatial Data Matching of Urban Underground Pipelines

The mining of thermal data of underground pipelines is very important for the construction of urban underground pipeline network data matching model and the proposal of large-scale pipeline spatial data matching mechanism. The existing temperature field calculation and stress field simulation methods for thermal pipelines are quite mature already, but they generally pay less attention to the overall connection features of the underground pipeline network and the local details of network nodes, and the deep-level sharing and utilization of the thermal stress data of pipelines is insufficient during the process of spatial data matching of the pipeline network. To this end, this paper conducted a research on thermal stress analysis and spatial data matching of urban underground pipelines. First, the paper gave a theoretical analysis on the temperature field and stress field of underground pipelines and obtained the simulation calculation results; then it elaborated on the calculation of the similarity of underground pipeline network information, proposed a method for spatial data matching, and gave the corresponding algorithm flow; at last, experimental results verified the reliability of the simulation calculation results of the thermal stress of underground pipelines and the effectiveness of the proposed spatial data matching method.