Papers by Keyword: Temperature Distribution

Abstract: The Selective Laser Melting (SLM) is one of the most demanding additive manufacturing(AM) processes, although it assures some superior advantages in producing complex structural componentsand applies to a wide range of materials. The control of SLM parameters is crucial to guaranteethe quality of manufactured component. The steep thermal variation in part during the SLM processinduces some undesired effects, such as warping, residual thermal stresses and microcracks,as wellas geometrical instability. Effectively predicting the influence of process parameters upon the productquality of part made by SLM is extremely useful in the earliest steps of design, especially whena higher productivity is required. Particularly, thermal simulation is used to suitably calibrate someprocess parameters, to improve efficiency and reduce defects. Besides, such simulation is exploited toimprove the heat transfer between the bed and the first product layer, to reduce thermal stress and theoverall product deformation. This study exemplifies how numerical modeling of temperature distributionin a wind turbine blade made by SLM allows predicting the dimensional stability. The Design ofExperiments (DoE) and ANOVA analysis helped in studying effects on the product geometric stabilityand deformation, of some process parameters, as powder layer thickness, hatch space and laser scanspeed.

Abstract: One major feature of a granary is the uneven distribution of temperature and airflow. Due to the large variability in the parameters to be considered in characterizing the feature, a pilot test serves as the better way to performing the experiment, which subsequently affects the airflow velocity distribution, and is very difficult to determine by natural experiment. This paper develops a model for uneven airflow and temperature distribution through the layers of stored grains, relative to the indicated parameters. The study aims at predicting the various thermo-physical properties of maize grains using the developed model with the incorporated several expressions obtained, and compare with the measured values through the deployed pilot mini silo. To validate the model, the bin was aerated with forced air at constant humidity and temperature. A mini cylindrical silo was also developed and deployed with bulk grains for a pilot test. The predicted results were compared with the measured values of the temperatures obtained in the various locations of the pilot silo. The two results were closely related, thereby establishing the validity of our model. The model provides information on the direction of flow and velocity in each location within the stored volume of grains, and data for grain cooling, airing and drying in the bin. The developed model is useful for predicting the temperature distribution, airflow and the cooling time for bulk grains under varying aeration conditions, and suitable for optimizing the design and operation of granary systems.

Abstract: The problem of heat transfer in solid materials can be described by the well known transient heat transfer equation. However, as the problem is strongly non-linear, the solution to this equation generally cannot be determined directly. Various numerical approaches have been proposed and employed by various authors for solving the problem.However, most of the available numerical solvers are limitedly available as they are often not free to use, they have to be installed, and they are too complex.This paper presents a new web-based solver for the problem of heat transfer over the thickness of a concrete slab during fire developed by the authors.The computational algorithm is based on the finite difference method and implemented using JavaScript.A graphical user interface for the input of user-defined parameters and for the interpretation of results is created using HTML.The paper also briefly presents the theory behind the computational algorithm.Moreover, examples of various problems solved by the web-based solver are presented in the paper.A brief parametric study of the effect of initial density of the material on the temperature distribution in the slab during fire is also presented. From the presented figures and examples, it can be readily seen that the newly developed web-based solver for the assessment of temperature distribution over a slab thickness during fire is user-friendly, easy to use, highly accessible, fast, and intuitive.

Abstract: The SEED (Swirled Enthalpy Equilibrium Device) process was used to produce semi-solid slurries. One of the factors that controls whether or not a slug can be used to produce high quality castings is the solid fraction distribution within the slug, and the solid fraction distribution is strongly dependent upon the temperature distribution. In this study, a model has been developed using ProCAST to investigate the relationship between process parameters and the temperature distribution within slugs. The parameters examined included the heat transfer coefficient between the crucible and slug, the heat transfer coefficient between the crucible and air, the slug diameter, and the initial melt temperature (pouring temperature). It was found that the most important parameters controlling the temperature distribution within slugs were the crucible size and the heat transfer coefficient between crucible and air. Adjustment of other parameters had little influence on the temperature distribution. Processing parameters will be discussed in order to allow the SEED process to be used for the production of large diameter slugs (>100 mm), and for narrow freezing range (0.3<fs<0.5, fs is fraction solid) alloys such as 6063.

Abstract: The paper is devoted to mathematical modeling pyroelectric current of ferroelectric single crystal under the conditions of intensive light heating in view of fractal behavior of these materials. The proposed approach is based on numerical simulation of thermal distribution in a ferroelectric sample using time fractional operator as well as computation of pyroelectric response. The simulation results for typical TGS ferroelectric crystal were described in one-dimensional case of the model in comparison with experimental data. Pyroelectric signals depending on temperature pyroelectric coefficient and thermal physical characteristics were also analyzed.

Abstract: This study focuses on the thermo-elastic rolling contact problem of a graded coating/substrate system. The problem is formulated under the plane thermoelasticity framework. Assuming an exponential variation of the shear modulus within the coating, the governing singular integral equations are extracted by means of the Fourier transform. The solution to problem is provided via the Gauss-Chebyshev integration method. The sensitivity of the contact stresses as well as the surface temperature rise to the stiffness ratio, the coating thickness and the non-dimensional speed is investigated. The results indicate that the thermal expansion ratio substantially affects the contact stresses. Also, the softening coatings will result in maximum surface temperature rise. The coating thickness can alter the surface temperature rise such that an increase of the coating by a factor of 1.6 may result in 50% reduction of the maximum surface temperature.

Abstract: Gas-assisted mold temperature control (GMTC) is a new technique in the field of mold temperature control. It enables rapid heating and cooling of the cavity surface during the injection molding process. In general, the goals of mold temperature control are to increase the mold surface to the target temperature before filling of the melt and to cool the melt to the ejection temperature. In this paper, dynamic mold temperature control is used for a thin-walled molding part as the temperature distribution and the heating rate are observed. The heating step of DMTC is achieved via hot-air flow directly to the thin-walled area. The results show that the heating rate reached 7.0 °C/s and that the temperature of the mold surface increased from 25 °C to greater than 165 °C within 20 s. A comparison showed that the difference between the simulation and experiment temperatures was less than 5.0 °C. Thus, this method can be used to accurately predict the outcome of a heating step before the actual process is carried out.

Abstract: In this study, the temperature distribution equation for a spiral porous fin is presented. Based on Darcy’s model, a mathematical equation of the energy is derived and a suitable dimensionless form is outlined to highlight some characteristic parameters, namely, the spiral fin pitch, the porosity, and the modified Rayleigh number. The behavior of the solution is analyzed for two cases of interest, taking into account the temperature-dependent thermal conductivity of the fin encountered in a hostile environment. A Numerical method is applied to solve this non-linear problem. It is found that the thermal transfer is not affected by the change of the spiral fin pitch, whereas increasing the porosity or the parameter β* makes higher fin temperature and improve the fin efficiency.

Abstract: The application of distributed temperature sensors(DTS) to monitor producing zones ofhorizontal well through a real-time measurement of a temperature profile is becoming increasinglypopular. The information from DTS can potentially be transformed to obtain the permeability alongto the wellbore and well completion method and so on. The relationship between these parametersand the real-time temperature distribution along the wellbore is very important. Based onmass-,momentum-,and energy-balance equations, this paper established a model to predict thetemperature along the horizontal wellbore. The models presented in this paper account for heatconvective, fluid expansion, heat conduction, and viscous dissipative heating. Wellbore temperaturecurves are plotted by computer iterative calculation. In addition, this paper revealed the relationshipbetween wellbore temperature distribution and different characteristics, such as permeability alongto the wellbore and well completion method. The analysis results show that permeability differenceand different well completion methods may lead to different downhole temperature distribution atthe same time step, different production rate, different wellbore temperature as well as the change offriction factor in the wellbore. From the temperature distribution and temperature derivative curvesin different cases, we could easily derive the permeability distribution along wellbore and thelocation of the perforated intervals and the fractures.

Abstract: Resistance spot welding (RSW), generally which is one of the most often used to joint metal plate in the automotive and aviation industries. RSW welding process involves electrical, thermal mechanical, metallurgy, and complex surface phenomenon. Unlike the other welding processes, weld joint formation in RSW process occurs very quick (in milli-seconds) and took place between the workpieces overlap each other. Welding simulation allows visual examination of the weld joint without having to perform an expensive experiment. Weld nugget size is the most important parameter in determining the mechanical behavior of welded joints in RSW process. The quality and strength of the weld joint in RSW process is predominantly determined by the shape and size of the weld nugget. Simulation modeling of RSW process performed using ANSYS Parametric Design Language (APDL) module based on the finite element method (FEM), embedded in ANSYS Workbench. Electrical and transient-thermal interaction was developed to study the weld nugget growth on resistance spot welding of aluminum A1100 metal plate with a thickness of 0.4 mm respectively. Weld nugget diameter can be well predicted by using this simulation model from the temperature distribution during the welding process. Welding is performed by varying the weld current (1 kA and 2 kA) and the welding time for each electric current, which are start from 0.5, 1.0, and 1.5 cycle time. Nugget diameter for each of the welding parameters from the simulation modelling were 4,276 mm, 4,372 mm, 4,668 mm, 5,616 mm and 5,896 mm. Weld expulsion occurred for the specimen with welding current 2 kA and welding time 1.5 cycle time, characterized by the decreasing of the tensile-shear strength of the specimen.