Wave Propagation in a Multi-Layered Composite

Elastic wave scattering simulation for a layered composite [acrylic/tungsten/acrylic/tungsten/acrylic] between two Al-6063 incident and transmission bars. In the first animation, a plane wave is generated by prescribing an initial displacement on the leftmost edge of the incident wave guide. Although a large portion of the incident wave field is scattered by the layered composite situated between the incident and transmission bars, a portion of the incident wave energy is still permitted to propagate through the layered media.

phononic crys4
If  the incident wave is monochromatic with a frequency of 27.5Ghz, a band gap can be demonstrated. This is because the layered media between the incident and transmission bars has periodic layers with thicknesses close to the value of the wavelength (d = 0.2mm). The incident wave undergoes constructive wave interference at the boundary of the layered composite where the reflected waves have the same phase as the incident wave and the propagating wave is effectively converted to a standing wave. Looking at the transmission bar it is easy to see that very little of the initial wave energy is permitted to propagate through the layered media in the center.

275Ghz_Phononic7777 275Ghz_Phononic3dHeight_cropped.21

COMSOL Multiphysics application file