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Crack detection with piezoelectric wafer active sensors (PWAS) is emerging as an effective and powerful
technique in structural health monitoring (SHM). Modeling and simulation of PWAS and host structure play an
important role in the SHM applications with PWAS. For decades finite element method has been extensively applied
in the analysis of piezoelectric materials and structures. The advantage of finite element analysis over analytical
solutions is that stress and electrical field measurements of complex geometries, and their variations throughout the
device, are more readily calculated. FEM allows calculation of the stress and electric field distributions under static
loads and under any applied electrical frequency, and so the effect of device geometry can be assessed and optimized
without the need to manufacture and test numerous devices. Coupled field analysis taking both mechanical motions
and electrical characteristics into account should all be employed to provide a systemic overview of the piezoelectric
sensors/actuators (even arrays of them) and the host structures.
This use of PWAS for SHM has followed two main paths: (a). Wave propagation (b). Electromechanical
impedance; Previous research has shown that PWAS can detect damage using wave reflections, changes in wave
signature, or changes in the electromechanical (E/M) impedance spectrum. The primary goal of this paper is to
investigate the use of finite element method (FEM) to simulate various SHM methods with PWAS. For the
simulation of Electro-mechanical (E/M) impedance technique, simple models, like free PWAS of different shapes
and 1-dimmension beam with PWAS are investigated and the simulated structural E/M impedance was presented.
For the wave propagation SHM technique, a long beam with several PWAS installed was studied. One PWAS is
excited by tone burst signals and elastic wave will propagate along the beam. The existence of a crack will affect the
structure integrity and the echo reflected by crack can be observed through the simulations. By using the coupled
field elements, direct simulation of electro-mechanical interaction of the PWAS and the host structure was made
possible. The electrical potential generated on the PWAS surface by the stimulation of elastic wave can be examined
in our FEM analysis. The simulation results are then compared to analytical calculation and experimental data.
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