| Interaction of ultrasound and rough solid interface is important for ultrasonic nondestructive testing on cracks, defects, injuries in the material or at the material bonding interface. This thesis aims to find the stress-strain relations between the rough contacted-interfaces in the mesoscopic structure and to seek for the interrelation between macroscopic acoustic phenomena and the nonlinear interaction between interfaces, in order to explain nonlinear interaction phenomena observed in macroscopic level with interfaces within the mesoscopic structure, thus provides a theoretical basis for the practical applications. We begin with the introduction of the concept of ultrasonic nondestructive testing technology and its important position at non-destructive testing. Ultrasonic nondestructive testing equipment development process and several commonly used ultrasonic nondestructive testing methods are also described. The second part of the paper focus on the characteristics of acoustic wave propagation in solids, then discovered and analyzed the energy storage phenomenon between solid interfaces. Based on this, we established a model to describe the random elastic contact interface. Then the nonlinear ultrasonic interaction of interfaces with stress-strain relationship is studied by using different models including linear simplified model, exponential model, and gaussian model. At the third part of the thesis, results from numerical simulations and experiments demonstrate that the linear model is a simplification and cannot reflect the exact relationship between mesoscopic parameters and the interfaces’macroscopic states (completely closed, partially closed, fully open). The exponential and gaussian models are based on highly distributed mesoscopic scale interface roughness peaks that is closer to the real situation, they can link mesoscopic phenomena with macroscopic phenomena and explain three different states of macroscopic phenomena with mesoscopic structures. |
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