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对20号钢进行了超声振动单向拉伸试验,对其内部应力进行了有限元分析,得出了工件在直径最小处两端的应力最大,中间次之,这和断口断裂的位置是一致的。研究了工件中心点处塑性应变及应力随时间变化的曲线,证明了在超声振动单向拉伸下工件内部受到的是一个交变的应力载荷。通过对超声与常态拉伸断口的比较,发现了所有断口都是杯锥型断口,而超声拉伸的断口杯状边缘更明显,断口内部更平整,断口更明亮;还发现了随着频率的降低,断口变得粗糙且不均匀,功率越大,典型疲劳条纹也越明显。
The uniaxial tensile test of 20 # steel was carried out and the internal stress was analyzed by finite element method. The results showed that the stress at the two ends of the workpiece with the smallest diameter was the highest, followed by the middle, which was consistent with the fracture location of the fracture . The curve of plastic strain and stress at the center of the workpiece with time is studied. It is proved that the internal stress of the workpiece under the uniaxial tension of ultrasonic vibration is an alternating stress load. By comparing the ultrasonic and normal tensile fracture, it was found that all the fracture were cup-cone fracture, while the ultrasonic tensile fracture edge of the cup is more obvious, the fracture inside the more smooth, more bright fracture; also found with the frequency Lower, the fracture becomes rough and uneven, the greater the power, the more obvious the typical fatigue stripes.