【作者】 马立；

【导师】 胡绳荪；

【作者基本信息】 天津大学 ， 材料加工工程， 2006， 硕士

【摘要】 等离子弧焊(PAW)是主要的高能密度焊接方法之一,能量高度集中、电弧力强,能直接穿透被焊工件,实现单面焊双面成形;焊缝深宽比大,焊接质量好,在造船、航空、航天以及军事工业等领域有着广泛的应用和广阔的发展前景。近年来,随着电子计算机技术的飞速发展,等离子弧焊接过程的数值模拟成为焊接过程计算机模拟的一个重要方向。本文根据流体力学、流体动力学及传热学理论,建立了运动等离子弧作用下焊接熔池流场、温度场的三维瞬态数值分析模型。该模型综合考虑了熔池内部液态金属的对流传热和熔池外部的固体导热、材料热物理性能参数随温度的变化、焊件表面通过对流和辐射向周围环境的散热以及熔化/凝固相变潜热等对熔池流场与温度场的影响。采用三维锥体热源对等离子弧焊接过程进行了流体动力学分析,利用ANSYS有限元软件及其二次开发对所建立的模型进行了求解。分别计算了三维静态热源及三维移动热源作用下PAW焊接熔池温度场及其动态变化过程;研究了三维锥体热源作用下焊接熔池流体流场、熔池内金属的流动方式以及熔池流体运动速度的变化;分析了焊接工艺参数对等离子弧焊接温度场的影响。通过PAW焊接实验,对数值模拟结果进行了验证和对比分析。研究结果表明,本文建立的等离子弧焊接熔池温度场及流场的数值分析模型是正确的,所采用的数值求解方法是可靠的;在数值模拟研究中,采用三维锥体热源计算的结果比高斯表面热源更接近于等离子弧焊接熔池实际。更多还原

【Abstract】 Plasma arc welding(PAW), a high power density welding method, can fulfill one-side welding of thick plates without grooving for the high temperature, concentrated energy and complete penetration of plasma arc. Meanwhile, high depth-width ratio and better quality is gained. Therefore, PAW has a significant application in the field of aviation, space flight, and shipbuilding etc., and the simulation of plasma arc welding process is a significant research subject in welding research field.Based on theories of hydromechanics, hydrokinetics and heat transfer, a three dimensional transient numerical model of flow and temperature field of the plasma arc welding molten pool with a moving arc is established. In the model, both convection heat transfer of the melted metal inside the pool and heat conduction of solid metal outside the pool, the variation of thermophysical parameters of material with temperature, the effect of the loss of heat, including convection and radiation, and latent heat of phase transformation on the temperature field are considered. Welding heat source is presumed to be 3-D conical heat source. In use of ANSYS, calculating software of finite element technology, the welding pool’s three dimensional flow and temperature fields and their transient variation processes are calculated, the flow style and velocity of molten metal are researched, and the welding variables’infection of temperature field is also analyzed.Corresponding welding experiments are done subsequently. By comparison, it’s found that the calculated results approximately agree with the experimental results, which proves that the model is basically correct and the numerical method is reliable.更多还原