Papers by Keyword: Temperature Field

Abstract: In the production of layered steel-based composite materials by the liquid-phase method, an importance is attached to preserving the structural and physical-mechanical characteristics of the steel sheet serving as the middle layer. The temperature field in such a steel layer contacting with aluminum melt at a temperature of ~700°C in a roller-crystallizer is analyzed. A formula is obtained that can be used to determine the temperature distribution in the middle layer of steel at the initial stage of the technological process. A comparison of the theoretical results with experimental studies of the thermal modes of obtaining a layered steel–aluminum composite by the liquid-phase method is carried out.

Abstract: We compared the evolution of three different SiC sources during standard PVT growth runs. The evolution of the growing crystal and the morphological changes in the SiC source were visualized using in-situ X-ray visualization. Computer simulation was used to calculate the temperature field distributions. It is found that the densification and shrinkage of the SiC source material during the growth process can affect the growth conditions in such a way that the convexity of the growth interface is increased in an unfavorable manner. While unfavorable growth conditions can be related to thermal properties due to less favorable SiC powder evolution, predicting such behavior is a rather complex task that still relies on the support of experimental methods.

Abstract: A method of thermal structure analysis is developed for supersonic missile rudder. The method calculates the aerodynamic heat based on Eckert reference enthalpy method, and calculates the temperature field by finite element method. The temperature field is taken as the volume load while calculating the thermal stress gradient and time history. Considering the influence of thermal stress, the natural vibration characteristics such as the mode and vibration frequency with time are obtained. The numerical computation results show that the aerodynamic heat is distributed unevenly across the rudder, such as stagnation point, laminar flow, transition and turbulence. The solid blocks of rudder shaft, longitudinal and transverse wall plates cause local low temperature, and large temperature gradient leads to higher thermal stress. Due to the change of material properties and thermal stress, the natural vibration frequency of the rudder has a significant decrease at sometime. The software of ANSYS was used to calculate and output cloud diagrams. The software of Microsoft Office was used to make curve graphics. The developed APDL command flow is very efficient and portable, which is convenient for complex structural model, and can provide technical support for supersonic missile rudder.

Abstract: In order to investigate the temperature distribution and cracking risk of concrete in winter under the combined action of heating zone and air layer, the analytical calculation method of early age concrete temperature field of concrete component under the combined action of self-limiting temperature band, cement hydration and air layer was established by taking concrete prism with self-limiting temperature band as an example. The model is applied to calculate and analyze the temperature distribution of concrete under different boundary conditions and different additional thermal field modes. The results show that: Under the conditions of internal layout, surface layout and thermal insulation layer outside the formwork, all components reach the critical strength after heating and curing for three days, which indicates that the heating band can provide temperature conditions for concrete curing in winter. Comparing the temperature field of different layout positions of heating belt, the uniformity of temperature field of heating belt outside the formwork is better than the other two layout methods.

Abstract: A method for determining temperature stresses in a welded joint of a thin-walled pipe with a base is described. The method is based on experimental data of temperature measurement at reference points of the structure. The features of the elements of the welded joint made of carbon and high-alloy structural steels and the modes of electric arc welding were taken into account. The efficiency of using spline approximation of experimental data to obtain analytical dependences of the distribution of temperature fields and stresses, as well as to obtain a solution of the heat equation by numerical differentiation and integration for this case, is shown. Formulas for calculating temperature stresses for the case of an asymmetric temperature distribution in a cylinder under the action of a moving high-intensity heat source are obtained.

Abstract: The uniformity of temperature field distribution in creep aging process is very important to the forming accuracy of components. In this paper, the temperature field distribution of 2219 aluminum alloy tank cover during aging forming is simulated by using the finite element software FLUENT, and a two-stage heating process is proposed to reduce the temperature field distribution heterogeneity. The results show that the temperature difference of the tank cover is large in the single-stage heating process, and the maximum temperature difference is above 27°C,which seriously affects the forming accuracy of the tank cover. With two-stage heating process, the temperature difference in the first stage has almost no direct impact on the forming accuracy of the top cover. In the second stage, the temperature difference of the tank cover is controlled within 10°C, compared with the single-stage heating, the maximum temperature difference is reduced by more than 17°C. The two-stage heating effectively reduces the heterogeneity of the temperature field of the top cover. The research provides technical support for the precise thermal mechanical coupling of large-scale creep aging forming components.

Abstract: To investigate influences of multi-track overlapping on melting of preset MCrAlY coating during laser cladding plasma spraying, a three-dimensional finite element model of the continuously moving temperature field during multi-track laser cladding was constructed using the ANSYS parametric design language (APDL) based on the existing temperature field model during single-track laser cladding. According to analysis results of temperature field, temperature of samples increases gradually during laser cladding due to heat accumulation effect of laser scanning, and the molten pool expands gradually. There are evident differences among different scanning pathways. Therefore, it is impossible to get high-quality cladding coating with uniform melting and small dilution ratio. Molten pools with basically same sizes in different scanning pathways can be gained by decreasing laser power or increasing scanning speed in different tracks one by one. Similarly, differences of molten pools in different scanning pathways can be relieved effectively through preheating of samples. Through a closed-loop control over the highest cladding temperature, a more even cladding coating can be gained through adaptive control of laser power and / or scanning speed.

Abstract: A finite element model of temperature field for plasma spraying preset MCrAlY coating during laser cladding was constructed using ANSYS parametric design language (APDL) in accordance to characteristics of preset laser cladding. Influencing laws of laser cladding parameters on temperature field were analyzed. Results show that laser power influences temperature field of cladding samples more than laser scanning speed. Experimental results agree well with simulation results, which prove the accuracy and reliability of the constructed calculation model of temperature field. Heating and cooling laws in the laser cladding process could be mastered through this calculation model. Research conclusions provide some references to optimization parameters in preparing high-performance laser cladding coatings.

Abstract: The current paper deals with the application of numerical experiment of joining light alloys. Modelling and numerical simulation and finite element method in the ANSYS program were used to investigate the course of thermal cycles, the joining process of light alloys by welding. Joining process of light alloys by welding is defined as a moving point source of heat, which generates temperature fields of various kinds, depending on the time and thickness of the material being welded. The paper is therefore devoted to: Thermal energy transfer and solution to differential equation of heat conduction, Initial and boundary conditions for temperatures distribution of a moving point source of heat, Generation (definition) of thermal cycle. Another part of the paper deals with the analysis of the heat-affected zone. Of the result of the solution will be expressed as the temperature field generated in the base material during the welding process.

Abstract: The finite-difference model for calculating temperature fields in linear friction welding is described. A feature of the model is the heat transfer across the friction surface accounting, which makes it possible to study the case of welding parts with different physical and mechanical properties. Modelling results, obtained for combination of VT6 and VT8-1 titanium alloys welding, are described. An assessment of the temperature field and heat transfer during the parts from VT6 and VT8-1 welding is given.