An experimental study of surface waves on a periodic surface

Rayleigh waves have been excited and detected on the edge of a disc with a periodic surface and on the edge of a smooth surfaced disc. The experimental velocity results for the smooth surface show that the measured velocity changes correspond to the earlier vrark performed by Sinclair (17). However, the experimental results for the two periodic surfaces used in this investigation show that above a certain frequency, the cutoff frequency, no waves will propagate. This cutoff frequency was found to vary with the size of the protrusions forming the periodic surface. For the waves propagating in the transmitted band, the periodic surface increased the measured wave velocities by a maximum of 2.9% for the smallest protrusion and 1.7% for the largest protrusion, with the greatest effect at the lower frequencies. This effect is explained by defining an effective density and modulus of rigidity. The experimental results also show a phase shift in the transmitted band. By comparing these experimental results to those of existing mechanical filters, it appears that there is a relationship between the two.Mechanical Engineering, Department o