Analogy Between Cavitation Development and Solid Fracture Process Evaluated by AE Method

为了研究空化发展与固体断裂过程之间的相似性，用声发射方法测量了过栅栏空化流动和低碳钢拉伸变形过程中的声发射脉冲数和脉冲高度分布，研究了空化方面和应力应变关系。研究结果表明：(1)从亚空化状态到超空化状态的空化过程与固体破裂过程非常相似，因为声发射脉冲数-空化数曲线和数-应力曲线在空化过程的临界状态和破裂过程中都有两个峰，(2)在空化数高和应力区的第一个峰值处的声发射信号是连续爆发型的，而孤立的爆破型信号出现在空化数和应力区较低的第二个峰上。由脉冲高度分布计算出的指数在屈服点的起始点和终点附近呈正态分布。这一事实可以用来评估这两个过程的类比。

In order to study the analogy between cavitation development and solid fracture processes, the number of AE pulses and the pulse-height distributions were measured by means of acoustic emission AE method, both in the cavitating flow past a fence and in tensile deformation of mild steel, with respect to cavitation aspects and stress-strain relation. The results are summarized as follows ;(1) Cavitation process from the subcavitation state to the super-cavitation state is very similar to the solid fracture process, since both the number of AE pulses - cavitation number curve and the number - stress curve have two peaks in the critical state of the cavitation process and the fracture process.(2) The AE signal at the 1st peaks in the highly cavitation number and the stress regions, is the successive burst-type, while the isolated burst-type signal takes place at the 2nd peaks in the lower cavitation number and stress regions. This fact suggests the similarity between them.(3) The exponents calculated from the pulse-height distributions show the normal distribution near the inception and the end of the yield point. This fact is available to evaluate the analogy both processes.