关键词: 非局部模量；裂纹扩展；超声振动；纳米复相陶瓷

Abstract:

This paper presented a research of the attenuation of cyclic stress amplitude and the variation of microstructure under the action of ultrasonic vibration in crack propagation for Al₂O₃-ZrO₂ composite nano-ceramics. To interpret this phenomenon, the nonlocal theory was introduced to establish the constitutive model under the ultrasonic condition based on the specified 2D attenuating function. The mechanics behavior of the ceramics under the action of ultrasonic vibration was analyzed according to the relationship between the internal characteristic length and the external characteristic length i.e. ultrasonic wave length. In addition, the variation law of the cyclic stress amplitude and microstructure with different ultrasonic frequencies was also studied. It is shown that the cyclic stress amplitude is attenuated under the action of ultrasonic vibration, and this attenuation phenomenon becomes more and more evident by increasing the ultrasonic frequency. The results of experiments are in accordance with the theoretical conclusions drawn from the nonlocal theory,which verifies that the action of ultrasonic vibration can actually accelerate the ceramic crack propagation. 

Key words: nonlocal moduli, crack propagation, ultrasonic vibration, composite nano-ceramics