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This paper presents a systematic investigation of power and energy transduction in piezoelectric wafer active sensors
(PWAS) for structural health monitoring (SHM). After a literature review of the state of the art, the paper develops a
simplified pitch-catch model of power and energy transduction of PWAS attached to structure. The model assumptions
include: (a) 1-D axial and flexural wave propagation; (b) ideal bonding (pin-force) connection between PWAS and
structure; (c) ideal excitation source at the transmitter PWAS and fully-resistive external load at the receiver PWAS.
Frequency response functions are developed for voltage, current, complex power, active power, etc.
First, we examined PWAS transmitter and determined the active power, reactive power, power rating of electrical
requirement under harmonic voltage excitation. It was found that the reactive power is dominant and defines the power
requirement for power supply / amplifier for PWAS applications. The electrical and mechanical power analysis at the
PWAS structure interface indicates all the active electrical power provides the mechanical power at the interface. This
provides the power and energy for the axial and flexural waves power and energy that propagate into the structure. The
sum of forward and backward wave power equals the mechanical power PWAS applied to the structure. The parametric
study of PWAS transmitter size shows the proper size and excitation frequency selection based on the tuning effects.
Second, we studied the PWAS receiver structural interface acoustic and electrical energy transduction. The parametric
study of receiver size, receiver impedance and external electrical load gives the PWAS design guideline for PWAS
sensing and power harvesting applications.
Finally we considered the power flow for a complete pitch-catch setup. In pitch-catch mode, the power flows from
electrical source into piezoelectric power at the transmitter; the piezoelectric conduction converts the electrical power
into the mechanical interface power at the transmitter PWAS and then into the acoustic wave power travelling in the
structure. The wave power arrives at the receiver PWAS and is captured at the mechanical interface between the
receiver PWAS and the structure; the captured mechanical power is converted back into electrical power at the receiver
PWAS and measured by the receiver electrical instrument. Our numerical simulation and graphical chart show the
trends in the power and energy flow behavior with remarkable peaks and valleys that can be exploited for optimum
design.
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