Papers by Keyword: Temperature Field

Abstract: Taking a vertical machining center as an example, thermal characteristics of the spindle system were researched by finite element simulation and experimental test. Firstly, temperature field and thermal deformation of the spindle system were simulated considering boundary conditions of the finite element model, such as heat sources, convective heat transfer coefficients and thermal contact resistances between joints. Accuracy of the simulation was verified compared with test. The results shows that key areas of temperature rise locate at spindle bearing; thermal deformation of Y and Z directions are large; thermal characteristics of the spindle system has little influence on other parts. Thermal characteristics of the spindle system were optimized by changing structures and sizes of the cooling passage located at the headstock, and effectiveness of the optimization was verified by finite element simulation. The research results provide guidance for thermal characteristic simulation and optimization of a machining center.

Abstract: In the cryogenic treatments process, the temperature distribution in a work-piece of high speed steel (HSS) is crucial to the effectiveness of the treatment. However, determination of temperature field during the cryogenic process is difficult. In this study, the temperature distribution in W9Mo3Cr4V HSS bars with a diameter of 24mm during cryogenic treatment was investigated using thermocouples so that obtained the optimization of process parameters and improve the high speed steel tool life. Temperatures at different nodes and their variations with time were measured and numerically studied using Pro/E, Workbench and Fluent software. Results from both the simulation study and experimental measurement are in good agreement, indicating that the temperature distribution inside a work-piece during cryogenic treatment can be determined using a combination of simple tests and numerical simulation, and finally provided a theoretical guidance for making the reasonable cryogenic treatment procedure.

Abstract: The purpose of this paper is to investigate the variation of temperature field of ultrasonic vibration assisted milling compared with that of conventional milling by FEM method. An equivalent two-dimensional finite element model was built to simplify the complexity of calculation. As results, the temperature field distribution, the variation of tool tip temperature and the change of heat generation rate in ultrasonic vibration assisted milling were analyzed compared with that in conventional milling process. According to analytical results, the application of ultrasonic vibration in milling process can significantly improve the distribution of cutting temperature, and reduce the impacts of thermal deformation and various thermal effects to cutting process.

Abstract: In this paper, the TIG welding process of 7022 aluminum alloy was analyzed by the ANSYS software. The temperature field and stress field contours were obtained. The temperature and stress variation in the welding process were analyzed by the obtained stress and temperature fields. In this paper, the actual welding process of 7022 aluminum alloy can be predicted by the finite element analysis. It can be avoided unnecessary occurred during the pre-research experiments, and reducing testing costs, further reducing the actual cost of the project. Therefore, the research has practical engineering value.

Abstract: Friction stir welding (FSW) joint is characterized with asymmetric gradient in three dimensions. The purpose of this thesis is trying to find the effective methods to improve the microstructure and strength of AZ31 magnesium alloy joint of FSW. In order to achieve this aim, one heat pipes was designed and applied to the FSW process. Using different cooling methods, FSW experiments were carried out in air and under the conditions of heat pipes controlling. The welding temperature fields, macrostructure, microstructure and mechanical property of the joint were investigated. The result shows that with the heat pipes controlling, the maximum peak temperature decreased by 100 °C. The average duration of high temperature was 36s which shortens 11s compared to that in air. After applying the heat pipes the microstructure in the weld nugget zone were slightly finer than that in air. The average tensile strength of the welding joints was higher than that in air. The highest tensile strength reached 220.4 MPa, more than 90% of the base material strength; The fracture position located between thermal mechanical affected zone and heat affected zone. Under the condition of applying heat pipes, the number of dimple gradually increased and the tensile rupture pattern was ductile-brittle fracture.

Abstract: In-service welding of the pipeline steel is performed under the environment where the delivery of the high pressure pipeline doesn’t stop. When welding under the water, there are high-pressure gas flowing in the pipeline and water flowing outside, causing a difficult and possibly risky of the welding operation. The process of in-service welding with SYSWELD was adopted to establish a geometric model of pipeline repair that the pipeline steel using finite element numerical modeling of the underwater in-service welding was carried out. Furthermore, this study focused on the effect of water velocity on the temperature field and stress field when repairing the in-service pipeline by welding. The results indicated that the water velocity of the pipe has a great influence on the temperature field and the residual stress field.

Abstract: The paper deals with the design and testing of laser power for laser beam welding of titanium Grade 2 and EN AW 5754 aluminium alloy plates. Transient temperature fields during formation of dissimilar butt joints of Ti-Al alloy plates were investigated by FEM simulation using the program code ANSYS. Moving Gaussian volumetric heat source was applied to model the heat input to the weld. The influence of laser power on the temperature distribution in welded materials and parameters of the weld pool were evaluated. Based on the results of numerical simulation, the suitable laser power was suggested for the real experiments of Ti–Al dissimilar laser welding using the TruDisk 4002 disk laser.

Abstract: An investigation of solidification process of as-cast ADC12 aluminum alloy in sand molds with different pouring conditions by temperature field was discussed in the present study. The ADC12 aluminum alloy was investigated in quarzt sand mold and chromite mold using sodium silicate binder with hardening by CO₂ gas under atmospheric and low vacuum conditions. Mechanical properties results indicated that a chromites mold under low vacuum condition has the optimal value. Thermal diffusivity was determined by finite difference method. The maximum thermal diffusivity was obtained in a chromite mold under low vacuum condition and correspondence to the minimum solidification time field.

Abstract: Building construction drying using high-frequency electromagnetic radiation (EMW), or microwave technology (MW), is gaining more usage in practise. It is the quickest way of eliminating water content in construction (wall, ceiling, etc.). Microwave is a term for a part of the electromagnetic radiation of 300 MHz to 300 GHz frequency with a wavelength from 1 mm to 1 m. The frequency of 2,45 GHz and 122 mm wavelength is used for technical practice. Due to the effect of MW radiation a different homogeneity of temperature field can be observed.This article discusses the spreading of the temperature field depending on the water volume and thereby the amount of mass moisture of the material (silica fume). Temperature fields will be shown by the thermo camera at certain time cycles of heating.

Abstract: The cutting heat, during the process of drilling fiber reinforced resin matrix composites, has a significant effect on the quality and the tool wear. In this paper, based on the homogenization hypothesis of the material and the finite difference method, a temperature field model for drilling unidirectional Kevlar composites was developed. During the drilling process, the heat source formed by cutting edge and chisel edge can be seen as a conical heat source. The results show that the temperature field distribution is ellipse away from the drilling zone with the longer axis paralleling to the fiber direction and changes close to the drilling zone.