The stacks of carbon fiber-reinforced polymer (CFRP) and aluminum are widely used in aviation industry due to its excellent mechanical and physical properties. Recently, rotary ultrasonic drilling technology which is recognized as a useful machining method has been introduced to machining these stacks. Thrust force influences the machinability directly such as tool wear, cutting temperature, and hole qualities. In this study, a theoretical model of thrust force for rotary ultrasonic drilling of CFRP/aluminum stacks is proposed. Based on the analysis of kinematic characteristics, the axial uncut chip thickness of rotary ultrasonic drilling is presented. Then the whole machining process of stacks is divided into five different states. Forces on cutting edge and chisel edge in different materials are modeled, respectively. After that, the thrust forces of five-state rotary ultrasonic drilling process are achieved by integrating with integral limits analysis in each state. Finally, verification experiments are conducted, and experimental results show that the trends of thrust forces agree well with the thrust force model. Therefore, this theoretical model can be used to evaluate the thrust force in rotary ultrasonic drilling of CFRP/aluminum stacks.

中文翻译：

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碳纤维复合材料/铝叠层旋转超声钻孔推力研究

碳纤维增强聚合物（CFRP）和铝的堆叠由于其优异的机械和物理性能而被广泛应用于航空工业。近来，被认为是一种有用的加工方法的旋转超声钻孔技术已被引入到加工这些叠层​​中。推力直接影响可加工性，例如刀具磨损、切削温度和孔质量。在这项研究中，提出了一种用于 CFRP/铝堆旋转超声钻孔的推力理论模型。在分析运动学特性的基础上，提出了旋转超声钻孔轴向未切屑厚度。然后将堆栈的整个加工过程分为五种不同的状态。分别模拟了不同材料中切削刃和凿刃上的力。之后，五状态旋转超声钻孔过程的推力是通过结合各状态的积分极限分析来实现的。最后进行了验证实验，实验结果表明推力趋势与推力模型吻合较好。因此，该理论模型可用于评估 CFRP/铝堆旋转超声钻孔中的推力。