scholarly journals Simulating Convective-Radiative Heat Sinks Effect by means of FEA-based Gaussian Heat Sources and Its Approximate Analytical Solutions for Semi-Infinite Body

2021 ◽  
Author(s):  
Ninh The Nguyen ◽  
John H Chujutalli
Keyword(s):  
Temperature Field ◽  
Heat Source ◽  
Analytical Solutions ◽  
Radiative Heat ◽  
Source Model ◽  
Heat Sinks ◽  
Transient Temperature ◽  
Measured Temperature ◽  
Heat Source Model ◽  
Transient Temperature Field

Abstract FEA-based Gaussian density heat source models were developed to study the effect of convective and radiative heat sinks on the transient temperature field predicted by the available approximate analytical solution of the purely conduction-based Goldak’s heat source. A new complex 3D Gaussian heat source model, incorporating all three modes of heat transfer, i.e., conduction, convection and radiation, has been developed as an extension of the Goldak heat source. Its approximate transient analytical solutions for this 3-D moving heat source were derived and numerically benchmarked with the available measured temperature & weld pool geometry data by Matlab programming with ~5 to 6 times faster than FEA-based simulation. The new complex 3D Gaussian heat source model and its approximate solution could significantly reduce the computing time in generating the transient temperature field and become an efficient alternative to extensive FEA-based simulations of heating sequences, where virtual optimisation of a melting heat source (i.e. used in welding, heating, cutting or other advanced manufacturing processes) is desirable for characterisation of material behaviour in microstructure evolution, melted pool, microhardness, residual stress and distortions.

Nonlinear Optimization Methods for the Determination of Heat Source Model Parameters

2016 ◽  
Vol 879 ◽  
pp. 2008-2013
Author(s):  
Udo Hartel ◽  
Alexander Ilin ◽  
Steffen Sonntag ◽  
Vesselin Michailov
Keyword(s):  
Experimental Data ◽  
Heat Source ◽  
Parameter Identification ◽  
Nonlinear Optimization ◽  
Laser Beam Welding ◽  
Source Model ◽  
Transient Temperature ◽  
Surface Model ◽  
Model Parameters ◽  
Heat Source Model

In this paper the technique of parameter identification is investigated to reconstruct the 3D transient temperature field for the simulation of laser beam welding. The reconstruction bases on volume heat source models and makes use of experimental data. The parameter identification leads to an inverse heat conduction problem which cannot be solved exactly but in terms of an optimal alignment of the simulation and experimental data. To solve the inverse problem, methods of nonlinear optimization are applied to minimize a problem dependent objective function.In particular the objective function is generated based on the Response Surface Model (RSM) technique. Sampling points on the RSM are determined by means of Finite-Element-Analysis (FEA). The scope of this research paper is the evaluation and comparison of gradient based and stochastic optimization algorithms. The proposed parameter identification makes it possible to determine the heat source model parameters in an automated way. The methodology is applied on welds of dissimilar material joints.

Modeling of the Temperature Field during Electron Beam Welding of Aluminum Alloy by a Pre-Defined Keyhole

2007 ◽  
Vol 353-358 ◽  
pp. 2011-2014
Author(s):  
Yan Hong Tian ◽  
Chun Qing Wang ◽  
Dan Yang Zhu
Keyword(s):  
Temperature Field ◽  
Electron Beam ◽  
Heat Source ◽  
Electron Beam Welding ◽  
Three Dimensional ◽  
Source Model ◽  
Transient Temperature ◽  
Al Alloy ◽  
Welding Pool ◽  
Welding Line

The transient temperature field of Al alloy during electron beam welding (EBW) process was simulated using a three-dimensional finite element method. Different from the most previous models which were based on the assumption that the welding pool was solid and neglected the existence of keyhole by meshing the solid as a whole, a dynamic three-dimensional keyhole was applied in this model. The profile of the keyhole was ellipse and its size was determined before simulation based on the results of experiments. Following the heat source, the pre-defined keyhole moved along the welding line. A three-dimensional complex heat source model, including a modified Gaussian distribution source and a uniform source, was used in this study. The result shows that the shape of the keyhole had a direct effect on the temperature distribution and contribution to the special shape of the welding pool in EBW.

Numerical Analysis of Transient Temperature Field and Thermal Stress on Coke Drum With 1.25Cr-0.5Mo Steel Based on Iterative Algorithm

2017 ◽  
Author(s):  
Zhibing Lu ◽  
Xuedong Chen ◽  
Zhichao Fan ◽  
Jie Dong ◽  
Jinhua Zhu
Keyword(s):  
Temperature Field ◽  
Thermal Stress ◽  
Iterative Algorithm ◽  
Thermal Structure ◽  
Transient Temperature ◽  
Main Process ◽  
Measured Temperature ◽  
Operating Cycle ◽  
Transient Temperature Field ◽  
Variation Characteristics

Coke drum is typical industrial equipment which experiences complex thermal and mechanical cyclic load during its operation, and the thermal stress which is produced by the drastic change of temperature is the main cause of the cracking failure of coke drum. This paper aims at coke drum with 1.25Cr–0.5Mo steel, and is based on iterative algorithm. Then we simulate the process of liquid medium climbing the inner surface of coke drum in the stages of oil filling and water quenching with dynamic thermal boundary, and carry out the numerical calculation of transient temperature field of coke drum in main process stages for one operating cycle. After the comparison of simulated temperature values with the measured temperature data at several locations on the outer surface of coke drum, the appropriate equivalent coefficients of convective heat transfer will be obtained. The variation rules of transient temperature field for the key parts of coke drum are discussed. Based on the simulation results of temperature field, the thermal-structure coupling analysis of coke drum is carried out, and the variation characteristics of thermal stress on coke drum are studied later.

Numerical and Experimental Study of Temperature Field for Double Electrode Gas Metal Arc Welding

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
Yu Shi ◽  
Rihong Han ◽  
Jiankang Huang ◽  
Shao Yan
Keyword(s):  
Temperature Field ◽  
Heat Source ◽  
Base Metal ◽  
Heat Input ◽  
Gas Metal Arc Welding ◽  
Source Model ◽  
Welding Parameters ◽  
Heat Source Model ◽  
Double Electrode ◽  
Simulation Results

Based on the features of double electrode gas metal arc welding (DE-GMAW), a new hybrid heat-source model for DE-GMAW was proposed. Using this heat-source model, the temperature fields of DE-GMAW with different welding parameters were simulated. According to the simulation results with different welding parameters, the influence of welding parameters to the heat input to base metal in DE-GMAW were analyzed. To verify the rationality of the hybrid heat-source model of DE-GMAW, the simulation results of the temperature field were compared with the experimental results with same welding parameters. The research results indicate that under the same total current, the heat input to base metal decrease gradually with the increase of by-pass current. In addition, the closer to the welding line from the measured point the greater decrease rate of the heat input to base metal. By the study and comparison of the thermal cycle curve of measured points, the simulation results were in good agreement with the experimental results. These results indicate that the calculated temperature field is accurate and the hybrid heat-source model is rational.

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