Visualization of Zero-group Velocity Lamb Waves and Evaluation of Bonding Quality by a Pulse Photoelasticity Technique

Abstract

  Visualization of zero-group-velocity (ZGV) Lamb waves was done by a photoelasticity technique for understating its vibration behavior associated with bond quality of a polymer adhesive joint. ZGV Lamb wave which cannot propagate but their phase velocity show finite possesses a large potential for assessing bonding quality in an adhesive joint. However, an effect of the bond quality on vibration behavior of the ZGV Lamb wave is still unclear. Photoelasticity technique enable us to understand vibration behavior in Lamb waves intuitively without any boundary conditions in advance. Photoelastic images of ZGV Lamb waves for the glass plates in a lap-joint with well and weak quality were obtained. In the well bonded sample, the identical vibration mode was observed in both glass plates as adherents. On the other hand, in the weak-bonded sample, different vibration modes in the two adherents appeared.