【作者】 熊智军；

【导师】 赵熹华；

【作者基本信息】 吉林大学 ， 材料加工工程， 2006， 硕士

【摘要】 对激光深熔焊接数值模拟中的解析解和数值解热源模型进行了总结,分析了它们各自的优点与局限性。通过对激光深熔焊接机理的分析,建立了一个新的面体组合热源模型来模拟激光深熔焊接的传热过程。基于有限元法和ANSYS软件,建立了铝合金激光焊搭接接头数值模拟的三维有限元模型。讨论了焊接热过程数值模拟中几何模型、控制方程、热源模型、材料属性、单元类型、网格划分、边界条件等相关技术与参数设置。通过APDL语言的循环加载技术,并设定合适的载荷步和载荷子步,模拟了激光焊接过程中,激光热源不断沿焊缝向前移动的热载荷问题。通过数值分析,定量揭示了预热温度条件下铝合金激光深熔焊接热过程的温度场分布规律。对铝合金LF3Y2搭接板进行了带预热温度的激光深熔焊接。将计算结果与实测结果进行了比较,验证了使用面体组合热源模型进行激光深熔焊温度场分析研究的可靠性。将室温和预热条件下的激光深熔焊接进行对比,分析了预热温度对焊缝成形、气孔缺陷的影响。更多还原

【Abstract】 Aluminum alloy is regarded as one of environmental protection materials and preferred in the fields of automobile manufacture and aviation with its advantages. The technology of laser deep penetration welding (LDPW) for aluminum alloy has become a main reason which impedes the application of aluminum alloy in these fields. The high reflectivity and thermal conductivity of aluminum alloy and compact oxide film (Al2O3) on its surface make its weldability of LDPW poor. The existence of these problem in LDPW for aluminum alloy greatly restrictes the scope of the application of welding technology. Therefore,it is of great significance to understand the welding heat process, improve laser energy efficiency, reduce welding defects and control weld shape. The scientific numerical simulation with technical experimental verification is implemented to investigate the heat process of LDPW for aluminum alloy in this thesis. the law of temperature field and the influence of welding parameters during the process of LDPW for aluminum alloy under preheating condition are analyzed, which provides the theoretical basis for the basal research on hybrid welding method of laser welding and resistance seam welding.In numerical simulation of LDPW, the selection of heat source model is directly related to the simulation accuracy. This paper summarizes the analytical and numerical solutions of the heat source model of LDPW and analyses its advantage and limitation. Based on the analysis of LDPW theory, a new surface-body combination heat source model is established to simulate the heat transfer process. The combination heat source model uses Gaussian surface heat source model to simulate the heating effect of plasma and surface melting pool and uses rotation Gaussian body heat source model to simulate the heating effect of keyholes. Experimental verification shows that the use of this surface-body combination to simulate the temperature field of LDPW is reasonable.According to describe the heat transfer equation of welding process, based on the finite element method and ANSYS software, three-dimensional finite element model of numerical simulation of LDPW for aluminum alloy lap joints is established. By analyzing the performance change of metal materials at high temperature phase, combined with the middle and low temperature performance parameters, the curve of materials hot physical parameters in the welding temperature range is acquired. The transitional mesh can reduce the model freedom degree and amount effectively. The mesh size of laser beam process region is更多还原