Transient Temperature Field Analysis Research Articles

The effects of laser line energy on welding strength of PASF/PC using magnesium zinc alloy powders as absorbents in laser transmission welding

The metal powder absorbents have the advantage of fabricating clean and high-strength joints in the process of laser transmission welding dissimilar transparent thermoplastics. However, the joining behavior between metal powders and thermoplastics is vague. Herein, polyarylsulfone (PASF) and polycarbonate (PC) are selected as model materials to investigate the joining behavior using magnesium zinc alloy (MZA) powders at different laser line energies. The shear force test was performed to reveal the effect of laser line energy on the welding. The µ-CT images reveal the evaluation of welding strength is attributed to the specific joint morphology. The multi-scale morphology characterization shows that the fractured surface height increases with increasing the laser line energy. The voids between MZA powders and resins increase the risks of interface failure, and the bubbles in the resins increase the risks of cohesion failure. The effects of laser line energy on the joint characteristics are elaborated based on the thermo-physical property test and transient temperature field analysis. The above results indicate the optimized welding temperature locates the melting temperature of PASF, because of the good fusion of PASF and less decomposition of PC. The study can provide a guideline for choosing proper process parameters when choosing metal powders as laser absorbents in welding dissimilar transparent thermoplastics.

Heat flux distribution model and transient temperature field analysis in grinding of helical raceway

To solve the problem of low processing efficiency of screw helical raceway by using high-efficiency grinding technology, this paper carried out theoretical, simulation, and experimental analyses on the grinding temperature which mainly affects the selection of high-efficiency grinding process parameters. First, based on the distribution characteristics of the grinding allowance of the screw helical raceway, the analysis shows that the geometry of the grinding contact area is trapezoidal. Then, based on the existing triangular heat flux distribution model of the rectangular contact area, two heat flux distribution models of the triangle and the concave triangle are proposed according to the characteristics of the trapezoidal contact area. Finally, the plane grinding experiment was carried out to correct the simulation parameters, and the modified simulation parameters were used to predict the grinding temperature of the screw raceway, so as to achieve the maximum removal efficiency and avoid burns. The analysis results show that the highest temperature in the grinding area is on the lowest point of the helical raceway, and the temperature and temperature gradient in the grinding area obtained by using the concave triangular heat flux distribution model are the highest. By comparing the process parameters for the onset of grinding burns predicted by simulation and experimentally, the temperature predicted by the concave triangle heat flux distribution model in the trapezoidal contact area is higher than the actual temperature, while the temperature predicted by the triangle heat flux distribution model in the trapezoidal contact area is lower than the actual temperature.

Analysis of Sealing Performance of Metal B-ring Self-Tightening Structure

Process industries often use B-ring self-tightening sealing structures and rely on interference assembly to meet the initial sealing requirements. Therefore, determining reasonable B-ring material, size and interference is crucial to ensure the sealing performance of the structure. In this paper, based on elastic deformation analysis, the deformation co-ordination equation of a B-ring sealing structure was established, and a sealing contact pressure calculation formula was obtained, with discussion of the main factors affecting sealing performance. With the finite element method, transient temperature field analysis was carried out for startup and shutdown load cases, and contact analysis was carried out for interference assembly, startup and shutdown. Based on the evaluation criteria of sealing performance with proposed sealing rate and leakage parameters, the effects of material properties, interference, B-ring size, etc., on sealing performance were investigated, revealing that although a B-ring with high material yield stress can meet the sealing requirements, both the B-ring and the sealing surface of a reactor body will yield plastic deformation. B-rings with a low material yield stress exhibit obvious plastic deformation during startup and leak during shutdown. However, leakage parameters can be minimized by smaller interference and moderate wave radius.

Electromagnetic‐Thermal Bi‐directional Coupling Analysis of IEF‐DDPMM Under Different Operation Conditions and Cooling System Optimization Design

Compared with the traditional single stator permanent magnet (PM) direct‐drive motor, the direct‐drive PM motor with inner enhance force (IEF‐DDPMM) has the advantages of high‐torque density, strong heavy‐load starting ability and flexible operation mode, so it is especially suitable for the occasions such as mine winches with a wide load range, frequent heavy‐load starting, light‐load operation, and limited use environment space. It is very important to check the temperature rise of IEF‐DDPMM according to its different operating conditions, including transient temperature rise during heavy‐load starting and steady‐state temperature rise during rated operation, so as to optimize the electromagnetic and thermal performance at the same time. Based on the bi‐directional coupling method (BDCM) of the electromagnetic field and temperature field, the thermal analysis of IEF‐DDPMM and the transient temperature field analysis of the inner motor as a torque motor for short‐term operation are carried out, and then the rated power of inner motor in S1 working system and the maximum operation time of output peak power are determined. The fluid–solid coupling analysis method is used to optimize the design of the cooling system, and the influence of the number of water channels and inlet water velocity on the heat dissipation effect of the motor is analyzed. A cooling system with strong heat dissipation ability is obtained, which can achieve higher power or torque output within the temperature range of winding insulation or demagnetization limitation of PM. Finally, a prototype is developed and equipped with a temperature rise experimental platform, and the experimental results provided a good verification of the simulation results. © 2021 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Study of dynamic vibration characteristics and suppression of CNC machine tool during operation

The rapid development of aerospace, automobile, national defense and other manufacturing industries has continuously improved the performance requirements of high speed and high positioning accuracy of the CNC machine tool feed system. As the thermal deformation error increases, the system structural rigidity decreases, the vibration increases, and accuracy of machine tool reduces. Existing research mainly focuses on the properties of mechanical and single thermal feed system, and less considers the dynamic performance under the action of thermal-mechanical coupling. For the improvement of feed system performance, it is very beneficiary. This paper takes the high-speed tool of CNC feed system as objective, combined with the actual working conditions to analyze the thermal characteristics, dynamic characteristics and vibration characteristics of the system under the effect of thermal-mechanical coupling. The thermal resistance and convective heat transfer of the key joint surface, the application of moving thermal loads, and the establishment of a simulation model to complete the steady-state temperature field, transient temperature field and thermal-structure coupling analysis. The results show that the maximum temperature rise of the feed system is 21.08 °C, The maximum thermal deformation is 17.264 um. The study found that the parameters such as flow rate and airflow temperature have a significant impact on the cooling effect, so the cooling device was further optimized. This paper proposes a control method for cutting chatter of CNC machine tools based on coupling of characteristics of thermal and mechanical. The thermal characteristic of the feed system and the thermal-mechanical coupling vibration characteristic test provides the maximum temperature error of 3.2 %, verifying the correctness of the theoretical method and analysis model. The highest temperature obtained by the test is 39.7 °C, indicating that the high-speed feed system has a large thermal effect. The relative error of the vibration amplitude of the test and simulation is 12.5 %, which verifies coupling in terms of thermal-mechanical. The accuracy of the vibration analysis method; the experiment depicts that the vibration amplitude increases by 19.7 % under the coupling effect of thermal and mechanical, indicating the effectiveness of dynamic characteristics of the high-speed feed system considering the thermal-mechanical coupling effect.

Transient temperature field analysis of steel-plate composite (SC) floor under standard fire

To evaluate the fire resistance of a structural member, the temperature profile in the cross section of the member needs to be obtained first. Full-scale fire tests have not been conducted on floor systems with steel-plate composite structures, termed SC floors. The traditional finite element analysis does not yield reliable temperature predictions in the steel and concrete of the SC floor under a standard fire. In this paper, the effective thermal properties of concrete in an SC floor are proposed for evaluating the transient temperature field according to the special heat transfer mechanism found by test data. The validity of these effective thermal properties is established by incorporating them into a finite element model and comparing the temperature predictions with data from fire tests. It is shown that the proposed effective thermal properties of concrete provide a good prediction of the temperature field in an SC floor under fire. The derivation process of the effective thermal properties based on the heat transfer analysis makes it possible to expand the scope of its application when the situation is similar to an SC floor.

Transient temperature field analysis of variable viscosity RTHSB with a special structural cavity

A radial thrust hydrodynamic sliding bearing (RTHSB) with special shaped cavity had been designed. Taking the instantaneous temperature rise characteristics of RTHSB as an analysis object, considering the influence of inlet lubricating oil velocity and transmission shaft speed, a dynamic simulation method of variable viscosity temperature field is proposed, and the mathematical model of instantaneous temperature rise of time-varying oil film is constructed. The correlation equation between instantaneous temperature rise and oil film variable viscosity is analyzed, the lubricating performance of a special-shaped cavity with variable thickness of the oil film considering real-time full operating conditions is revealed, and the alternating transient laws of oil film thickness with variable viscosity and its instantaneous temperature rise for no-load, heavy-load, and different rotating speeds are studied. It is obtained that the higher temperature area of profiled shaped cavity on reverse flow side extends to oil seal side with increase of rotating speed. The dynamic simulation of variable viscosity of RTHSB with different film thickness is simulated by using FLUENT software and the trend of transient film temperature field distribution of in special-shaped cavity is evaluated. The rationality of the mechanism analysis and numerical simulation results in this paper has been verified.

Transient Temperature Distribution and Thermo-Mechanical Coupling Response of Paper in the Fusing Process of Laser Printers

AbstractThe hot-press fusing process of a laser printer is one of the principal causes for paper folding and bending deformation. In order to predict and control the deformation of paper, first, the following analysis method is proposed for the transient temperature field analysis of the continuous moving paper: discretizing the thermal analysis process, replacing the moving paper model with the moving heat source, and simulating the movement speed of paper by setting the flow boundary conditions. Second, taking the steady-state thermal calculation results of the printer in the standby mode as initial conditions, the temperature distribution characteristics of paper during the movement are obtained with the paper model placed in a whole-machine environment to analyze the transient temperature field. Third, using the method of multi-field coupling, the transient temperature field results of paper are taken as the external load of its static analysis to analyze the deformation of paper during the fusing process; therefore, the quantitative deformation results and deformation characteristics of paper after fusing are obtained. According to the results, more precise boundary conditions can be achieved by calculating the temperature field of paper in a whole-machine environment. The method of transient temperature field analysis for continuous moving objects proposed in this study can effectively simulate the movement process of paper. The results reveal the mechanism of paper wrinkle and bending deformation in the fusing process, which can be used to predict the conveying performance of paper and guide the design work of the printer.

Transient Temperature Field Analysis of Thyristor Turn-on Process under Narrow Pulse Width and Large Current

Thyristor will damage because of local overheating under narrow pulse width and large inrush current, if the selection is unreasonable. In this paper, the thermal field model of thyristor opening process is established and the transient temperature field distribution of thyristor is obtained by simulation. Simulation results show that under the narrow pulse width and large current, the temperature distribution on the silicon chip is not uniform, the temperature at the center gate is the highest, and the temperature is gradually decreased from the center point along the radius. The effect of current rise rate and chip radius on thyristor temperature distribution are simulated. Simulation results show that the higher the current rise rate, the higher the temperature of the thyristor center gate. The effect of chip radius on thyristor temperature is related to the pulse width of large inrush current. When the chip radius is smaller than the extended radius corresponding to the current pulse width, the smaller the radius, the higher the maximum temperature rise. When the radius of the chip is equal to or greater than the extended radius corresponding to the current pulse width, increasing the radius of the chip has no effect on the highest temperature rise.

Dimensionless analysis of transient temperature field of surrounding rock in roadway based on Finite Volume Method

Dimensionless analysis of transient temperature field of surrounding rock in roadway based on Finite Volume Method

Analysis of transient heat source and coupling temperature field during cold strip rolling

In the process of cold thin strip rolling, the effect of the roll gap heat source on the transient temperature of cold rolled strip is very significant, and especially for the lateral temperature difference fluctuation which easily leads to the additional shape deviation of the rolled strip. In this study, according to the new heat resource model, the coupled temperature field model with high precision can be established, and the influence of the heat resource on the transient temperature of the cold rolled strip can be obtained by comprehensively considering the emulsion heat transfer coefficient, the air cooling, and the heat conduction boundary conditions. Based on the above models and the actual working parameters, several cases were performed to show the detailed analyses of the transient temperature distributions under various rolling conditions. The results at different strip positions show that the lateral distributions of the roll gap heat source and the strip transient temperature at every stand or pass can be simulated well. This study can improve the calculation precision of the transient lateral temperature difference for the complex online shape deviations during cold thin strip rolling.

Numerical and experimental analysis of transient temperature field of ventilated disc brake under the condition of hard braking

The ventilated disc brake of vehicles was selected as the objective of this study, which was built on 3D modeling technology. Through establishing thermo-structural coupling model, this study analyzed the transient temperature field of automobile brake under the condition of hard braking. Meanwhile, the test of hard braking was carried out on professional platform of vehicle test bench in this paper, and temperature curves of brake disc in radial and circumferential directions were obtained. By comparison, the experimental values and simulation values were basically equal. The rationality of the selected finite element analysis (FEA) was attributed, which provided a better theoretical basis for further experimental analysis.

Modeling and analysis of transient temperature field in finite thickness plate under symmetrically located moving heat sources

The thermal problem of plate slides against symmetrically located contacting pads is investigated. The aim is to find out the influences of plate thickness, moving speed, and convection on the temperature field of the plate. Proper models and computing methods for specific situations can be determined based on these analyses. Finite element method of moving heat input is used to calculate the temperature field which is validated by comparing with some existing analytical solutions. The results show that the characteristic time for the steady state of temperature can be approximated exponentially as a function of moving speed. If the plate is thinner than the critical thickness, the surface temperature is increased significantly, which means that the temperature field is very sensitive to the plate thickness in this situation. The increasing moving speed increases the peak surface temperature almost linearly, and the convection outside of the contact area can decrease the peak surface temperature significantly if the heat sources move slowly, while it hardly affects the peak surface temperature if the heat sources move fast. Based on these results, the criterion of choosing a model and computing methods for studying the temperature fields in the similar structures is established.

ANSYS Analysis on Thermal Structure of Bionic Brake Discs

The failure of brake performance, which is caused by thermal recession under the emergency brake, results in traffic accident frequently. Based on excellent wear-resisting properties of locust’s non-smooth surface structure, bionic brake disc with special surface micro-structure was designed. According to the thermal analysis theory, transient temperature field analysis of the bionic brake disc during the braking process under different initial velocity was analyzed. The results showed that bionic brake disc has excellent heat dissipation ability, which is beneficial to improve the brake performance. The non-smooth surface can store air and dissipate heat, thus reducing the thermal fatigue and thermal wear caused by temperature rise. This research provides a theoretical basis for designing bionic brake discs with excellent heat dissipation performance.

Analysis of surface transient temperature on large current carrying high-speed sliding electrical contact

The transient temperature of electrical contact surface during high-speed sliding can result in the ablation of the contact surface and the aggravation of its friction and wear through changing the contact surfaces environment. Based on correlation measurement and the academic analysis of the transient temperature field of high-speed sliding electrical contact surface under high current, a model for the calculation of transient temperature field is established, by the thermal analysis of transient temperature field of contact surface with the heat transfer and finite element analysis software ANSYS as theoretical foundation. The influence on the transient temperature field of contact surface under different heat sources is studied. The experimental data on the transient temperature of high speed sliding electrical contact surface under high current were obtained with non-contact radiation temperature measurement. The transient temperature field distributing state was simulated by the finite element methods software ANSYS, comparisons between experimental data and simulation results were made to verify correctness of the simulation model of transient temperature field. The further analysis of simulation results shows that the speed and the changes of electric current have impact on the transient temperature field of the contact surface．In this paper, the study on the transient temperature of high speed sliding electrical contact surface under high current is expected to provide the theoretical and technique foundation for reducing the temperature of contact surface, and selecting the appropriate material as contact surface to decrease the material wear and tear.

The Transient Temperature Field Simulation and Analysis of Machinery’s Components by ABAQUS

By using the Abaqus software, FEM calculation of the quenching process of non-standard component which has complex contour has been operated, the temperature field distribution which accompanies the quenching time has been obtained. The simulation process’s precision and efficiency is excellent, this method is applicable to the quenching technics’s improvement, and can offer the calculation basis to the analysis of the thermal stress field and residual stress. It can also provide the improving scheme for the intensity design of the coal winning machinery.

Numerical Analysis of Transient Temperature Field and Keyhole Geometry in Controlled Pulse Key-Holing Plasma Arc Welding

A three-dimensional transient model is developed for numerical analysis of the temperature field, the weld pool, and keyhole shape during the controlled pulse key-holing plasma arc welding process. With considering the coupled thermal-mechanical actions exerted on the keyhole wall from the arc plasma, the periodic variation of the keyhole undergoing “establishing – expanding – contracting – closing” is numerically simulated in a pulse cycle. The computed accuracy is improved by accounting for the thermal-balance condition on the keyhole wall. The predicted keyhole sustaining period and fusion zones are in agreement with the experimentally measured ones.

Dynamic finite element simulation and transient temperature field analysis in thermoplastic composite tape lay-up process

In the lay-up process of thermoplastic composite tape, the thermal conditions have great influence on the end quality and performance of composites. In the lay-up process of thermoplastic matrix composites, a semi-infinite solid model is used to analyse the heat transfer by simulating the heating of hot gas torch. Temperature of the control volume is calculated based on the model. A dynamic finite element model is developed to obtain the transient temperature field. The birth–death element strategy in ANSYS was used to simulate the movement of lay-up head during dynamic loading and laying-up prepreg onto the composite substrate. The simulation results of using the transient heat transfer model and the finite element model were compared well. The bonding temperature increases linearly with the heater temperature and is closely related to the moving speed of the roller. The bonding temperature changed slowly when the roller moved faster.

An Application for Analysis of Temperature during Cold Rolling

The problem of software creation for the analysis of transient temperature field in cold rolling of metals is under consideration. Firstly, the mathematical model of the process of heating the strip and rolls at cold rolling it is proposed. This model assumes that the generation of heat during the rolling takes place due to friction on the contact surface of the rolls and the strip as well as plastic deformation of the strip material. Next, some fragments of created application for the purpose of an overall numerical analysis of heat partition ratio between the rolls and a strip as well as the temperature in any point of these elements are presented.

Transient Temperature Field Analysis in Laser Cladding Processing

A 3-dimensional (3D) thermal distribution computational methodology for laser cladding is presented. Based on the developed model, which considers the latent heat and change of conductivity in different phase, the transient temperature fields for the preplaced laser cladding processing are performed. The effect of processing parameters including laser power, scanning speed and laser spot diameter on melt pool temperature filed was extensively discussed and some conclusions were drawn.