Ultrasonic plate wave properties in thin steel plates

Inspection of structure and evaluation of materials can be conducted with various modes of ultrasonic wave. Recently, guided wave was focused on in nondestructive field since it has an advantage such as long range inspection in thin plates, tubes and pipe lines. An ultrasonic plate wave is guided wave of plane strain that occur in a thin plate with free boundaries. The other hand, this advanced technique required knowledge for characteristics of plate wave such as various wave velocities and modes according to frequency and boundary conditions. Detectability at using the plate wave was evaluated with artificial defect in the steel sheet. Actual internal defects in the steel plate were inspected with the plate wave and verified with the magnetic particle testing.