| A surface acoustic wave is an acoustic wave which travels along the surface of a material exhibiting elasticity, with an amplitude that typically decays exponentially with depth into the substrate. With this feature, surface acoustic waves are used in structural health monitoring to detect the presence of a crack, the crack depth, size, etc. on the surface of a structure. The project starts with the design, fabrication and construction of a surface acoustic wave generator, with the help of some simulation software. During the simulation, the wave propagation pattern, the frequency, the substrate thickness and many other parameters are analyzed. Finally, an experimental model will be built to verify the simulation results. Meanwhile, a portable structural health monitoring impedance analyzer has been building. It is mainly consisted with the microchips AD5933 and Atmega128, with basic functions of frequency generation, feedback signal collection and structural healthy diagnosis. The functions of the impedance analyzer are being expanded and improved, with the goal it can be used in a real field in the near future. |
