Papers by Keyword: Thermal Field

Abstract: Magnesium along with its alloy has garnered significant attention for potential utilization in biomedical applications, owing to its biodegradable and biocompatible characteristics. This paper aims to present preliminary research on the microwave heating of a concrete crucible designed to ensure the proper temperature for the sintering of magnesium alloy. Due to the reflection coefficient of microwaves by the magnesium alloy, the utilization of a microwave susceptor becomes imperative for effective heating. The research primarily focuses on modeling the temperature distribution within the concrete crucible to ensure a consistent level of heat for the sintering process of the magnesium alloy. As a result of the modeling process, temperatures up to 298°C have been achieved across a broad range of microwave power inputs (600-1200 W).

Abstract: The method to determine thermal fields considering dependence of thermophysical and mechanical properties of coating materials and a base from the temperature, the running of plastic deformations and stresses relaxation at plasma spraying is suggested. The mathematical model of calculation of thermal field with moving boundary considering nonlinear feature of coating growth at layer-by-layer deposition and dependences from thermophysical properties of materials of the system «coating-base» is developed. The model application helps to estimate the effect of the parameters of plasma spraying process on the level of the residual stresses in the increased coatings.

Abstract: The Al-Cu-Mg alloy is a precipitation-strengthening alloy, which is traditionally dissolving lots of secondary phase and precipitating in subsequent aging process, thus having been applied to aerospace and automobile industry due to its low density and high strength. However, the high temperature and long operating time needed for the dissolution of secondary phase consume numerous energy. In this work, rapid dissolution of secondary phase in cold-rolling Al-Cu-Mg alloy was achieved by coupling treatment of thermal field and pulsed electric current. The energy consumption for dissolving secondary phasewas reduced from 495°C operating 1h to 450°C operating several minutes. Therefore, the coupling treatment of thermal field and pulsed electric current significantly improves the dissolving rate and decreases the energy consumption.

Abstract: AlN crystals are one of the representative III-V group semiconductor materials. AlN has good electric field characteristics, thermal conductivity and thermal stability. Owing to its wide direct band gap of 6.2eV [1], it can achieve a luminescent wavelength of 210 nanometers in deep ultraviolet, which is an ideal material for UV and deep UV LED devices. But preparation of AlN crystals with PVT for growing conditions demanding, 0.3-0.5 atm of high purity nitrogen atmosphere of growth and the growth of 2100-2400 K temperature [2, 3]. In this paper, two kinds of growth chamber structures are designed and compared. In order to ensure that the temperature gradient between the source material surface and the seed surface satisfy the crystal growth and keep stability in the larger transverse region, [4, 5] the crystal grown on the seed crystal can get better quality.

Abstract: The paper presents the results of a mathematical model of the material flow during Friction Stir Welding (FSW) of aluminium alloys using a Finite Element Analysis. The authors presented their work on a two-dimensional visco-plastic model, using User Define Functions (UDF) in a commercial CFD code (FLUENT). The model developed was validated by microstructural investigations on experimental FSW joints and by a comparative analysis of temperature distribution field of the experimental FSW joint and numerical simulated model. The results confirmed that the mathematical model describes with a good precision the material flow and temperature field during FSW process.

Abstract: When the space vehicle re-enters the earth’s atmosphere at a tremendous speed the frictional resistance creates enormous heat which may penetrate the vehicle leading to wreckage, if not dissipated to the surrounding. In the present study, CFD analysis of the thermal field generated on the surface of the solid model of the nose cone of the space vehicle is analyzed. Various configurations of the surface contour of the nose cone are considered to mimic the real life situation. The commercial CFD tool SolidWorks Flow Simulation module was used for the analysis. Four different surface contours were considered for the analysis of the temperature generated on its surface. The results indicate that the surface contour and re-entry velocity has a decided effect on the thermal field developed due to frictional resistance. Nose cone with larger half cone angle with small bluntness ratio offers greater resistance and hence lower temperature is generated compared to small half cone angle configuration.

Abstract: One of the key controllable and influential factors to obtain a casting simulation, representative of reality, is the choice of boundary condition. The thermal boundary condition to be specified at the metal-mold interface must account for complex heat transfer phenomena associated with solidifying casting. The present study aims at estimating the heat flux at the interface of the mold and the solidifying metal by Inverse Heat Conduction Problem (IHCP) approach. Solidification studies were conducted on casting of aluminum reinforced with boron carbide composite. Copper, cast iron and stainless steel were used as mold materials. The temperature data of the mold was recorded from the beginning to end of solidification using k-type thermocouples connected to temperature data logger. This time-temperature history was used as input to the IHCP algorithm to simulate the interface heat flux and thermal field of the mold. The results indicate that the interface heat flux is highly transient and varies with the variation in the thermo-physical properties of the mold materials. The study also demonstrates that heat conduction is one dimensional in copper mold and two dimensional in cast iron and stainless steel mold during phase change.

Abstract: Friction Stir Welding (FSW) is an innovative solid state welding process, relatively new in industry, which allow welding of two or more materials which have very different properties, particularly thermal properties as fusion temperature, thermal expansion coefficient, specific heat and thermal conduction and have a predisposition to form intermetallic brittle phases, neither one of the components to be weld reach to the melting point. Being a solid state welding process temperature field is very important for the quality of the welded joint, and a lot of researches focused on this topic. This paper presents some results in modeling and estimation of thermal field developed during FSW of dissimilar joints, using Finite Element Analysis. Numerical modeling of thermal field allows engineers to predict, in advance, the evolution of temperature and to estimate the behavior of the welded materials during the welding process. This will reduce significantly the time and number of experiments that have to be carried out, in the process of establishing a good FSW technology, as well as reducing significantly the cost of the tests.

Abstract: In order to improve the production efficiency, numerical simulation and experiments of continuous casting of a multi-crystalline silicon (mc-silicon) billet were carried out. Modeling works were done firstly to optimize casting recipe and predict billet cooling behaviors, a three-dimensional finite element model for the simulation of thermal field and fluid flow was built. The continuous casting of cylindrical silicon billet was studied considering different casting parameters such as withdrawal speed and heat transfer ability of mold. The simulation results indicate that lower casting speed and lower heat transfer coefficient of mold are beneficial to acquire better morphology. Experimental works were practiced lying on the modeling results, using the self-designed mc-silicon continuous casting apparatus, mc-silicon billet with a diameter of 100 mm was obtained.

Abstract: A thermal mathematical model of the induction traction motor was developed. The thermal model calculates the motor node temperatures with minimum number of input parameters. It can be applied as a thermal control condition system of electric traction motors during the operation. The adequacy testing results of the mathematical model in ELCUT were presented. Also, the comparison of mathematical model information and the results of experimental researches were submitted.