Thermal Engineering Study on Friction Stir Welding(FSW)

在2003学年，设计并制作了搅拌摩擦焊试验用试样夹持系统，并利用该夹持系统进行了基础数据的采集。利用红外测温仪和反射镜测量了试样背面的瞬态温度行为。通过压力传感器和数据采集系统采集搅拌棒对试样施加的摩擦压力和扭矩数据。在不同的搅拌头结构、搅拌棒转速和轴向载荷条件下，对铝合金试样进行了一系列实验。在此基础上，提出了一种利用Excel电子表格对上述实验系统的搅拌棒、试件和垫板温度场进行模拟计算的新方法，该方法可用于实际计算。从校准过程中比较测得的温度变化 ...更多信息 随着时间的推移和相应的数值结果，搅拌棒和试样之间的动摩擦系数成功地评估在实用目的。在下一个学年2002年，在上一年的结果的基础上，进行了以下实验和理论研究。在实验研究方面，收集了大量的铝合金及其它材料的动摩擦系数的基础数据，并进行了分析。并测量了平动试样的瞬态温度行为。此外，通过分析施加到试样上的测量扭矩来评估搅拌棒和试样之间的动摩擦系数。在理论研究方面，进一步开发了非稳态数值分析软件，并进行了一系列的计算和实验。另外，通过对纯铝、铝合金、铜和镍等试样的数值计算，提出了试样上下表面温度的无量纲关联方程，从实验和理论研究中得到了许多有价值的结果。即，例如，本研究明确了迄今为止尚未显示的搅拌棒与试样之间的动摩擦系数的具体值（例如，对于铝合金A7075，约为0.25至0.76）;各种焊接材料的动摩擦系数的评估是可能的，通过使用所提出的非试件底面温度的量纲关联式。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