本文旨在觀察超音波振動輔助拉伸試驗之材料行為，探討超音波軟化效應的機制。本文首先建立超音波振動輔助材料軸向加載試驗系統，並探討不同拉伸速率、不同超音波加載時機以及不同超音波振幅對拉伸試驗之影響。研究結果顯示，本文之超音波系統具有材料軟化之效果，超音波加載於試片時，試片的塑流應力會隨之下降，其下降幅度與加載之超音波振幅成正比例關係；此外，透過實驗可以觀察出明顯的應力疊加現象，故其為超音波主要作用機制之一。;The objective of this paper is to observe the material behavior of specimens under ultrasonic vibration assisted tensile test and to explore the mechanism of acoustic softening effect. In this paper, an experimental tensile test system was designed and made, and the influence of different stroke speed, different ultra-sonic vibration applied timing and different ultrasonic vibration amplitude on tensile test was discussed. The results show that the ultrasonic vibration assisted tensile test system of this paper has effect on material softening. Flow stress of the specimens reduced when the ultrasonic vibrations were applied, and the amounts of flow stress reduction is proportional to the amplitude of the ultrasonic vibrations. Moreover, the obvious phenomenon of stress superposition was observed in this paper, so stress superposition is considered to be one of the main mechanism of stress reduction.
