3D Transient Temperature Field Research Articles

Research on the optimization of welding parameters in high-frequency induction welding pipeline

In this paper, numerical simulation and finite element analysis were applied to optimize the important parameters including V-type joint and current frequency for high-frequency induction welding. The coupling of the 3D harmonic electromagnetic field and 3D transient temperature field was analyzed by establishing the physical file of the electromagnetic field and temperature field in high-frequency induction welding. The influence of important welding parameters on the temperature field distribution in the welding area was obtained by using a single control variable method. In the temperature field, the size of the V-type joint determines the heating efficiency, and the current frequency affects the heat produced by the eddy current. The numerical simulation results were verified by the analysis of the actual production experimental results and a good process parameter group was summarized. The shape of the slit between the different V-type joint parameters and the centerline of the squeeze roll showed that the relationship of the welding image and the welding quality and provided a solution for real-time online monitoring of welding quality.

Nonlinear Optimization Methods for the Determination of Heat Source Model Parameters

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.

Reconstruction of 3D transient temperature field for fusion welding processes on basis of discrete experimental data

This paper presents an approach to reconstruct the three-dimensional transient temperature field for fusion welding processes as input data for computational weld mechanics. The methodology to solve this inverse heat conduction problem fast and automatically focuses on analytical temperature field models for volumetric heat sources and application of global optimisation. The important issue addressed here is the question which experimental data is needed to guarantee a unique reconstruction of the experimental temperature field. Different computational-experimental test cases are executed to determine the influence of various sets of discrete experimental data on the solvability of the optimisation problem. The application of energy distributions utilised for laser beam welding allows reconstructing the temperature field efficiently. Furthermore, the heat input into the workpiece determined by the simulation contributes to the evaluation of the thermal efficiency of the welding process.

Numerical Simulation of Three-Dimensional Molten Pool Temperature Field and Flow Field for Laser Melt Injection Based on Fluent

According to the characteristics of laser melt injection, a numerical model for a simplified 3D transient temperature field in molten pool was established using FLUENT software in this paper. In the model, many factors were considered such as liquid metal turbulence, latent heat of phase transformation and material thermo physical properties depending on temperature. The results show that the model can be developed well by FLUENT software. And the results also show that the driving force of the liquid metal flow mechanism.

3D modeling and testing of transient temperature in selective laser sintering (SLS) process

In the process of rapid prototyping by the method of selective laser sintering (SLS), transient temperature has direct effect upon the sintering performance. In the present work, a model is developed in order to generate 3D transient temperature field. It uses Al2O3 coated ceramic powder and involves the finite element method (FEM) variation of thermal properties and solid–liquid two-phase interface. A high-speed charge coupled device (CCD) image temperature measurement system is used to generate for testing. The obtained test results validates the simulation data and implies that the proposed modeling method is useful in simulating the transient sintering temperature specially when the correct thermal properties and key factors of two-phase interface are main concerns. The performance characteristics of the reasonable sintering parameters are predicted by the proposed modeling method.

3D transient temperature field analysis of the stator of a hydro-generator under the sudden short-circuit condition

In this study, Finite Element Method (FEM) is applied to calculate the 3D transient temperature field of the stator of a hydro-generator, SF125-96/15600, under the sudden short-circuit condition. 3D transient equation of the heat conduction and its equivalent functional equations are firstly presented. Then the sudden short current and transient heat generation of the stator are analysed and calculated. Moreover, all the parameters for the simulation such as the heat conductivity coefficients of the iron core and stator coils, heat convection coefficients of each surface as well as iron and copper losses are deduced. These parameters are verified to be reasonable by comparing the simulated temperature results with the measured in the stable state. Finally, the 3D transient stator temperature field of the hydro-generator under the sudden short-circuit condition is simulated. The variation of the temperature field and temperature rise of the key components is also predicted, on which online thermal monitoring of the stator and optimum design can be carried out.

Analysis of predicted residual stress in a weld and comparison with experimental data using regression model

Residual stress in a welded plate is computed in the first part of the paper using a weld analysis software program VrWeld (www.goldaktec.com) that computes the 3D transient temperature field, the evolution of micro-structure and the evolution of stress-strain fields. The computed residual stress is compared to the residual stress distribution measured by Paradowska (J Mater Process 164–165:1099–1105, 2005) with a neutron diffraction method to show that the computational model captures the physics well. Two uncertainty analyses are conducted in the second part to investigate the question of how variations in parameters contribute to the result from part one provided that computational model can predict residual stress well resulted in part one. The difference between the two is the number of parameters. The former has only one parameter and we employed the computational model for perturbation analysis in order to find the uncertainty due to perturbation in the parameter. For such a test, the number of test required in sample space to approximate normality by central limit theorem, is feasible considering computational resources although it is not true when we have higher number of interrelated parameters. The latter therefore has 4 highly interrelated parameters to show that an alternative way can be employed instead of using directly computational model for such a case. Uncertainty analyses are based on Monte Carlo method in this paper and the idea is that if numerical modeling is valid and also there is a need for a great number of tests for Monte Carlo analysis that make it unfeasible to run such an analysis directly by computational model then extracting a regression model from the computational model and working with it, is an effective alternative.

Pilot Calculation Of The Temperature Field Of The Ceramic Material EUCOR

Pilot Calculation Of The Temperature Field Of The Ceramic Material EUCOR