The residual stresses in the machined workpiece are of great importance due to their influence on the workpiece fatigue life, as well as its dimensional and geometric accuracy. The metal cutting process has always been accompanied by heat generation and severe plastic deformation. This thermo mechanical loading along with the resulted metallurgical changes are the main sources of residual stresses generation at the surface of machined workpiece. The Ultrasonic Assisted Turning (UAT) reduces the temperature in the cutting region and reduces the average machining forces due to the discontinuous contact of the tool and the workpiece. Reducing the intensity of thermo mechanical loading in the UAT process will affect the residual stresses caused by machining. In this paper, the results of thermo mechanical finite element simulation and experimental studies of residual stresses during UAT of AISI 4140 has been studied. The results of this simulation make it possible to determine the effect of vibration and machining parameters (cutting speed and feed rate) on the magnitude and type of surface residual stresses in the workpiece machined by UAT. Finally, the simulation results are compared with experimental measurements of residual stresses using X-ray diffraction technique. Based on the obtained results, the hoop component of the residual stresses in case of UAT became more compressive averagely by about 73.34% compared to the traditional turning; for instance at constant feed of 0.11 mm/rev and cutting speed of 0.261 m/s, for three different vibration amplitudes of 4, 8 and 12 µm, the machining induced residual stresses became more compressive respectively by 53.34%, 73.00% and 100%.

中文翻译：

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超声辅助车削残余应力有限元模拟与试验研究

加工工件中的残余应力非常重要，因为它们会影响工件疲劳寿命以及尺寸和几何精度。金属切削过程一直伴随着发热和剧烈的塑性变形。这种热机械载荷以及由此产生的冶金变化是在加工工件表面产生残余应力的主要来源。超声波辅助车削 (UAT) 降低了切削区域的温度，并降低了由于刀具和工件的不连续接触而导致的平均加工力。降低 UAT 过程中热机械载荷的强度会影响加工产生的残余应力。在本文中，已经研究了 AISI 4140 的 UAT 过程中的热机械有限元模拟和残余应力的实验研究结果。该模拟的结果可以确定振动和加工参数（切削速度和进给率）对 UAT 加工的工件中表面残余应力的大小和类型的影响。最后，将模拟结果与使用 X 射线衍射技术对残余应力的实验测量进行比较。根据所得结果，与传统车削相比，UAT 情况下残余应力的环向分量平均增加了约 73.34%；例如，在 0.11 mm/rev 的恒定进给和 0.261 m/s 的切削速度下，对于 4、8 和 12 µm 三种不同的振动幅度，