圆柱空腔上裂纹的爬波检测方法

通过牛顿迭代法求解了固体内部圆柱空腔上爬波的频散方程,分析了爬波的频散和衰减特性。利用动态光弹法显示了爬波的直观图像和圆柱空腔附近各散射波的空间关系。根据爬波具有的频散、衰减以及辐射横波特征,设计了斜入射脉冲回波实验装置,测量了特定位置处裂纹反射爬波辐射出的横波信号,其与柱面反射波的时差和理论预测一致。进一步实验研究发现,爬波回波幅度与特定位置的裂纹长度具有近似单调的对应关系,在裂纹长度较大时,回波幅度趋于稳定。以上工作为圆柱空腔上裂纹的爬波定量检测提供了物理基础和实现方法。 

Testing of cracks on a cylindrical cavity by creeping waves

The dispersion equation of the creeping waves around a cylindrical cavity is solved by Newton iteration method,the dispersion and attenuation behaviors of creeping waves are analyzed accordingly.Dynamic photo-elastic technique is employed to show the intuitional image of creeping waves and based on which different types of scattering waves around a cylindrical cavity are analyzed.According to the characteristics of dispersive,attenuation and radiation of shear wave,a wedge-shaped pulse-echo experiment setup is designed to measure the shear waves radiated by creeping waves which are reflected by cracks in a certain position.The measured time difference between creeping wave signal and the reflection from the front surface of the cylinder agrees well with theoretical prediction.Further experiments show that the echo amplitude grows monotonously as the crack size increases and trends to be stable when the crack size is large enough.The above results provide a theoretical foundation as well as an implement method for quantitative testing of cracks on a cylindrical cavity by creeping waves.