Studies in the area of ultrasonics have seen the advancement of many industries today. Applications for the use of ultrasound vary from medical treatment and diagnosis to structural health evaluation, to fluid flow measurements systems. Non-Destructive Evaluation (NDE) is one such area that is seeing dramatic improvement in both knowledge and technology.
This thesis entitles ‘Wave Propagation in Damaged Beams,’ presents an analytical approach using higher order models to determine wave reflections through a defective region of a beam using guided wave techniques. In addition, experiments were conducted in order to verify the analytical methods. In order to achieve this, the theoretical models were studied and summarised. Once an understanding of the theoretical models was gained, experimentation was then conducted in order to verify the studied analytical models.
The resultant theoretical and experimental flexural wave velocities proved to be remarkably close. A 1% difference between values was recorded. Longitudinal wave velocities, on the other hand, were more difficult to determine accurately from a theoretical perspective. This is because the theoretical model studied was not entirely accurate for the experimental excitation frequency. Comparisons between wave reflection amplitudes from the defective region of the beam showed acceptable results. Flexural wave reflections for non-symmetric delamination showed a 15% difference in theoretical and experimental results. Similarly for the longitudinal case, a difference of approximately 8% was recorded.
Future developments of this project could be made more accurate by ensuring the material properties are better know over the region of the delamination. This could be achieved by cutting a section from the beam rather that adding mass to the surface.