The interaction of the fundamental symmetric Lamb wave mode with material discontinuity: a finite element analysis

Speaker:
Mustapha, Samir; American University of Beirut Faculty of Engineering and Architecture; Lebanon

Authors:
Fakih, M.A.; American University of Beirut; Lebanon
Hamade, R.; American University of Beirut; Lebanon
Mustapha, S.A.; American University of Beirut; Lebanon
Salman, F.; American University of Beirut; Lebanon

ID: ECNDT-0569-2018

This study investigates the propagation behavior of the fundamental symmetric Lamb wave mode (S0 mode) upon interaction with weld lines of dissimilar materials. The effect of the angle of incidence and propagation direction on the reflection and transmission behavior of the S0 mode was explored. An intact AA6061-T6/AZ31B dissimilar joint was employed for the investigation, and the interaction of the transmitted wave with the weld interface was scrutinized using “COMSOL Multiphysics” finite element software. The study was conducted as the wave propagates from AA6061-T6 to AZ31B and vice versa, to examine the effect of different propagation directions.

Lamb waves were excited, through the welded plate, at different incident angles (0, 15, 30, and 45 degrees). The S0 mode reflection and transmission were assessed through a direct comparison of the wave amplitudes along the incident and reflection directions. The wave attenuation curves of the S0 mode were constructed in order to have a better understanding of the effect of the interface. A method for filtering the reflection caused by the material interface was proposed, based on the frequency-wavenumber filtering technique.

It was observed that the incidence angle has minimal effect on the S0 reflection from the material interface. Further, no mode conversion was detected upon crossing the material discontinuity.