Multiphysics modeling of ultrasonic elastic wave attenuation for wireless power transfer including viscoelasticity and acoustic emission

A COMSOL Multiphysics model is developed to computationally predict power attenuation in an ultrasonic elastic wave wireless power transfer application. This model invokes the complete equations of elastodynamics, coupled electric field and piezoelectric elastic response, and coupled transmitter and receiver circuits. Structural damping is captured in the adhesive layers by treating them as isotropic viscoelastic media with complex valued elastic moduli. Structural damping is captured in the parent structure by modeling the acoustic emission from the exposed surfaces which couples the displacement field of the parent structure with the surrounding fluid medium. This model quantitatively predicts the electrical power transduction efficiency to within 5% over a range of excitation frequencies. This model is also able to predict the voltage gain to between 10 and 25% over the same range of excitation frequencies.