Propagation Of SH Waves Along A Periodic Grating Surface With Grooves Or Mental Strips In A Magneto-electro-elastic Substrate

A periodic grating surface with grooves or strips on a magneto-electro-elastic(MEE)substrate is the basic configuration of surface acoustic wave(SAW)devices.By theoretical analysis and finite element calculation,this paper investigates the propagation behavior of SH surface waves in a MEE substrate with periodic grooves or strips.The main contents are as follows:Dispersion equations of SH surface wave propagating on a MEE substrate with periodic grooves(the substrate and grooves are the same MEE materials)and strips(metal electrodes are covered on the MEE substrate)are deduced theoretically.Dispersion curves and mode shapes are calculated numerically with considering the effects of the height and width of the gratings,as well as the location of the bulge/electrode in a cell.Simultaneously,the finite element calculations are performed to model the above-mentioned by the COMSOL Multiphysics software.The two kinds of results are the same nearly.Here are the main conclusions:Whatever grooves or strips,the first band-gap appears at the resonance condition0?(28)?(43),where both frequencies and wave velocities remain the lowest.The higher are the bulges/electrodes and the wider are the gaps.The gap attains the biggest when the grating width to the grating period is 0.5.For the cells with the same sizes,the gap of the grooves is much wider than that of the strips.SH surface waves are trapped almost in the bulges/electrodes of the cells.With the height and width of the bulges/electrodes increasing,the more SH surface waves are trapped.The maximum stress occurs at the bonding of the bulges and the excavated parts,as well as the edge of electrodes and substrate of the cells.Displacement,electric and magnetic fields of SH surface waves decrease with the depth deepening into the substrate.These conclusions will be helpful to the design and applications for the MEE SAW devices.