Development of egg-configuration heat source model in numerical simulation of autogenous fusion welding process
Development of egg-configuration heat source model in numerical simulation of autogenous fusion welding process
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DOI：
10.1016/j.ijthermalsci.2014.06.032
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发表时间：
2014-12
影响因子：
4.5
通讯作者：
N. Yadaiah;S. Bag
中科院分区：
文献类型：
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作者：
N. Yadaiah;S. Bag
热源模型的数学结构至少应该近似地表示真实的热源现象。在熔焊过程中，由于熔池内材料动量输运的主导作用，只有表面热流不能实现强化换热。熔池内的对流可以用表观体积热源来代替，而表观体积热源在熔池体积之外的定义是不现实的。确定合适的体积热源的关键问题是几何形状和大小，以及由于弧光或激光的运动而引起的非对称热密度分布。在本工作中，提出了蛋形体积热源模型来解决这些问题。该热源模型从椭球体出发，以较少的模型参数提供了非对称的热能分布，并在移动热源问题中保持了轮廓的连续性。卵形热源的一般方程为高斯分布的圆盘、半球和半椭球的体积热源模型提供了基础，这些热源模型可以看作是所提出的热源模型的特例。利用所提出的热源模型，对钨极气体保护焊(GTAW)和半导体激光焊接过程进行了三维有限元分析。与实验结果相比，熔池尺寸估算的最大偏差为10%。时间-温度历史证实了GTAW和激光焊接工艺的峰值温度分别为940℃和1060℃。预测的GTAW最大冷却速度为603K/S，明显低于激光焊接的11.1K/103K/S。总体而言，所提出的热源模型推广了对各种材料和自熔焊工艺的适用性。
The mathematical structure of the heat source models should at least approximately represent the phenomena of real heat source. In fusion welding process, only the surface heat flux fails to realize enhanced heat transfer due to predominant effect of momentum transport of the material within molten pool. The convection in the weld pool can be substituted by apparent volumetric heat source which is unrealistic to define outside the molten pool volume. The key issues to define a decent volumetric heat source are the geometric shape and size, non-symmetric heat density distribution due to moving arc or laser beam. In present work, the egg-configuration volumetric heat source model is proposed to address these issues. The proposed heat source model which is derived from ellipsoid shape provides the non-symmetry heat energy distribution with less number of model parameters and conserves the continuity in profile during moving heat source problem. The general equation of egg-configuration heat source provides the basis of Gaussian distributed disc, hemispherical, and semi-ellipsoidal volumetric heat source models which can be considered as the special cases of proposed heat source model. A 3D finite element based transient heat transfer analyses is conducted using the proposed heat source model for gas tungsten arc welding (GTAW) and diode laser welding processes. The maximum deviation of 10% in weld pool size estimation is observed as compared to experimental results. The time-temperature history confirms the peak temperatures of 940 K and 1060 K, respectively for GTAW and laser welding processes. The amount of the maximum cooling rate predicted for GTAW is 603 K/s which is significantly lower than 11.1 × 103K/s for laser welding. Overall, the proposed heat source model generalized the applicability over a wide variety of materials and autogenous fusion welding processes.