Thermal Engineering Study on Friction Stir Welding(FSW)

2003学年，自行设计制作了搅拌摩擦焊实验用试件夹持系统，并利用该系统收集了基础数据。利用安装在夹持系统中的红外测温仪和反射镜测量了试件背面的瞬时温度行为。通过压力传感器和数据采集系统采集搅拌棒施加在试件上的摩擦压力和扭矩数据。在不同叶尖形状、搅拌棒旋转次数和轴向载荷的条件下，对铝试件进行了一系列的试验。在此基础上，应用Excel电子表格，提出了一种与上述实验系统相对应的搅拌棒、试件和衬板内的温度场模拟计算方法，并在实际计算中取得了较好的效果。从比较测量的温度变化…的对准过程随着时间的推移和相应的数值结果，搅拌棒与试件之间的动摩擦系数在实际应用中得到了成功的估算。在下一学年的2002学年，在上一学年的基础上，进行了以下的实验和理论研究。在试验研究方面，收集了铝等试件动摩擦系数计算所需的大量基础数据，并对其进行了分析。还测量了平移运动试件的瞬时温度行为。此外，通过对施加于试件的测量扭矩的分析，估算了搅拌棒与试件之间的动摩擦系数。在理论研究方面，进一步利用Excel电子表格进行了非稳态数值分析，并进行了一系列的计算和实验。此外，通过对纯铝、铝合金、铜和镍等试件的数值计算，建立了试件上下表面温度的无因次关联式，通过实验和理论研究，得到了许多有价值的结果。也就是说，例如，本研究明确了搅拌棒与试件之间的动摩擦系数的特定值(例如，A7075铝合金的动摩擦系数约为0.25~0.76)；利用所提出的试件底表面温度的无量纲关联式，可以估算各种焊接材料的动摩擦系数。较少

In the academic year 2003,the holding system of specimens for FSW experiment was designed and fabricated, and by using it, fundamental data were collected. Transient temperature behaviors of the back side surface of specimen were measured by using an infrared thermometer and a mirror which were incorporated in the holding system. Data on the friction pressure and the torque applied to the specimen by the stir rod were collected by pressure sensors and dada acquisition system. A series of experiments were performed on aluminum specimens under the conditions of various tip configurations, numbers of rotations of stir rod and axial loads. Further, a new calculation method for simulating the temperature fields in the stir rod, specimens and the backing plate corresponding to the above experimental system, which applies the spread sheet of Excel was proposed and was shown effective for practical calculation purposes. From the alignment process which compares the measured temperature change … More with time and the corresponding numerical results, the coefficient of dynamic friction between the stir rod and the specimen was successfully evaluated within practical purposes.In the next academic year 2002,based on the results obtained in the previous year, the following experimental and theoretical studies were conducted. Concerning experimental study, lots of basic data, which are required for evaluation of the coefficient of dynamic friction, were collected on aluminum and other specimens, and were analyzed. The transient temperature behaviors of the specimens with translational motion were also measured. Further, the coefficient of dynamic friction between the stir rod and the specimen was evaluated by analyzing measured torques applied to the specimen. Regarding theoretical study, the unsteady-state numerical analysis which applies the spreadsheet of Excel was further developed, and a series of calculations corresponding experiments were performed. In addition, by conducting numerical calculations on such specimens as pure aluminum, aluminum alloy, copper and nickel, non-dimensional correlation equations on top and bottom surface temperatures of specimens were proposed.From the experimental and theoretical studies, a lot of valuable results have been obtained. Namely, for example, the specific values of coefficient of dynamic friction between the stir rod and the specimen which have not shown so far were made clear in this study (for instance, about 0.25 to 0.76 for aluminum alloy A7075) ; evaluation of coefficient of dynamic friction for various weld materials were shown possible by using the proposed non-dimensional correlation equation for bottom surface temperature of specimen. Less