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首页> 外文学位 >Numerical simulation of heat transfer, fluid flow and mechanical behavior in laser- based material processing technologies.
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Numerical simulation of heat transfer, fluid flow and mechanical behavior in laser- based material processing technologies.

机译：基于激光的材料加工技术中的传热，流体流动和机械性能的数值模拟。

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摘要

The increasing requirement for laser in material processing can be attributed to its distinct advantages over traditional processing, such as reduced processing cost, higher productivity, non-contact processing, improved product quality, higher material utilization, and minimum heat-affected zone. Numerical simulations combined with reasonable experimental design are implemented for understanding the thermal, mechanical, and metallurgical behaviors in laser-based material processing. Three typical topics including laser welding, laser heat treatment and laser cladding are studied in detail.;An experiment-based finite element model is developed to investigate the thermal field of hybrid laser-arc welding, involving the influence of nonlinear material properties and the variable location of the laser head and arc torch. Optical microscopy and thermocouples are used to validate the numerical model. In addition, a thermo-mechanical finite element model is developed to investigate the transient thermal stress and residual stress distributions in the hybrid laser-arc welding process. The effect of arc preheating on the weld geometry and the level of thermally induced stress and its distortion in the welded joint is also studied. The X-ray diffraction technique is used to measure the residual stress of welded coupons.;A transient multiphase unified mathematical model with experimental validation is also developed to investigate the temperature field, and flow velocity field of the liquid phase in the laser-based multilayer cladding of H13 powder onto a substrate of AISI 4140 steel. The effects of the laser power, scanning speed, and powder feed rate on the geometry of the clad are studied. The relevant experiments are also performed to validate the numerical modeling.;From another view, a finite element method (FEM) combined with a Monte Carlo (MC) model is developed to further study the grain growth in the heat-affected zone (HAZ) during laser heat treatment, in which the heat transfer process is analyzed by FEM and the grain growth is simulated by a MC model. The 3D heat transfer model provides the temperature data for the MC simulation.
机译：材料加工中对激光的要求不断提高，可以归因于其相对于传统加工的独特优势，例如降低的加工成本，更高的生产率，非接触式加工，提高的产品质量，更高的材料利用率以及最小的热影响区。进行了数值模拟和合理的实验设计，以了解基于激光的材料加工中的热，机械和冶金行为。详细研究了激光焊接，激光热处理和激光熔覆这三个典型的主题。；建立了基于实验的有限元模型，研究了混合激光电弧焊接的热场，其中涉及非线性材料性能的影响和变量。激光头和电弧炬的位置。光学显微镜和热电偶用于验证数值模型。此外，建立了一个热机械有限元模型，以研究混合激光电弧焊过程中的瞬态热应力和残余应力分布。还研究了电弧预热对焊缝几何形状和热诱导应力水平及其在焊接接头中的变形的影响。 X射线衍射技术用于测量焊接试样的残余应力。；还建立了一个具有实验验证的瞬态多相统一数学模型，以研究激光基多层板中液相的温度场和流速场。将H13粉末熔覆在AISI 4140钢的基底上。研究了激光功率，扫描速度和送粉速度对包层几何形状的影响。还进行了相关实验以验证数值建模。从另一个角度来看，开发了结合蒙特卡洛（MC）模型的有限元方法（FEM）以进一步研究热影响区（HAZ）中的晶粒长大在激光热处理过程中，通过有限元分析传热过程，并通过MC模型模拟晶粒生长。 3D传热模型为MC模拟提供温度数据。

著录项

  • 作者

    Kong, Fanrong.;

  • 作者单位

    Southern Methodist University.;

  • 授予单位 Southern Methodist University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 209 p.
  • 总页数 209
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

  • 入库时间 2022-08-17 11:38:24

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