Ultrasound acoustic energy transfer systems are receiving growing attention in the area of contactless energy transfer for its advantages over other approaches, such as inductive coupling method. To date, most research on this approach has been on modeling and proof-of-concept experiments in the linear regime where nonlinear effects associated with high excitation levels are not significant. We present an acoustic-electroelastic model of a piezoelectric receiver in water by considering its nonlinear constitutive relations. The theory is based on ideal spherical sound wave propagation in conjunction with the electroelastic distributed-parameter governing equations for the receiver’s vibration and the electrical circuit.
Contactless energy transfer (CET) is a technology that is particularly relevant in applications where wired electrical contact is dangerous or impractical. Furthermore, it would enhance the development, use, and reliability of low-power sensors in applications where changing batteries is not practical or may not be a viable option. One CET method that has recently attracted interest is the ultrasonic acoustic energy transfer, which is based on the reception of acoustic waves at ultrasonic frequencies by a piezoelectric receiver. Patterning and focusing the transmitted acoustic energy in space is one of the challenges for enhancing the power transmission and locally charging sensors or devices. We use a mathematically designed passive metamaterial-based acoustic hologram to selectively power an array of piezoelectric receivers using an unfocused transmitter. The acoustic hologram is employed to create a multifocal pressure pattern in the target plane where the receivers are located inside focal regions. We conduct multiphysics simulations in which a single transmitter is used to power multiple receivers with an arbitrary two-dimensional spatial pattern via wave controlling and manipulation, using the hologram. We show that the multi-focal pressure pattern created by the passive acoustic hologram will enhance the power transmission for most receivers.
Variations in parameters representing natural frequency, damping and effective nonlinearities before and after
damage initiation in a beam carrying a lumped mass are assessed. The identification of these parameters is
performed by exploiting and modeling nonlinear behavior of the beam-mass system and matching an approximate
solution of the representative model with quantities obtained from spectral analysis of measured vibrations. The
representative model and identified coefficients are validated through comparison of measured and predicted
responses. Percentage variations of the identified parameters before and after damage initiation are determined
to establish their sensitivities to the state of damage of the beam. The results show that damping and effective
nonlinearity parameters are more sensitive to damage initiation than the system's natural frequency. Moreover,
the sensitivity of nonlinear parameters to damage is better established using a physically-derived parameter
rather than spectral amplitudes of harmonic components.