This paper discusses combined transfer matrix method (TMM) with stiffness matrix method (SMM) for obtaining a
stable solution for dispersion curves of Lamb wave propagation in non-isotropic layers. TMM developed by Thomson
and Haskell experiences numerical deficiency at high frequency thickness simulations. SMM was proposed by different
researchers to solve the instability issue of TMM. This study shows that stable SMM is good at high frequencies, and
TMM needs to be combined with SMM to obtain stable and robust behavior over the frequency range. Numerical
simulations of dispersion curves are presented for wave propagation in orthotropic unidirectional fiber composites and
cross ply composites. The paper ends with conclusions and future work.
This paper discusses shear horizontal (SH) guided waves that can be excited with shear type piezoelectric wafer active
sensors (PWAS). The paper starts with a review of the state of the art in SH waves modeling and their importance in
non-destructive evaluation (NDE). This is followed by basic sensing and actuation equations of shear-poled PWAS
transducers with appropriate electro-mechanical coupling coefficients. The electro-mechanical impedance of the SHPWAS
transducer is studied. The equations for shear stress transfer between PWAS and the structure are developed. The
amplitudes of shear horizontal wave modes are normalized with respect to the wave power; normal mode expansion
(NME) method is used to account for superpositioning multimodal SH waves. Modal participation factors are presented
to show the contribution of every mode. Model assumption includes: (a) straight crested guided wave propagation; (b)
evanescent waves are ignored; and (c) ideal bonding between PWAS and structure with shear load transfer concentrated
at PWAS tips. Power and energy transfer between PWAS and the structure is analyzed in order to optimize sensor size
and excitation frequency for maximum wave energy production for a given source. The paper ends with summary,
conclusion and suggestion of future work.
This paper presents a theoretical modeling of power and energy transduction of structurally-bonded piezoelectric wafer
active sensors (PWAS) for structural health monitoring (SHM). After a literature review of the state of the art, we
developed a model of power and energy transduction between the PWAS and a structure containing multimodal
ultrasonic guided waves. The use of exact Lamb waves modes for power modeling is an extension of our previously
presented simplified model that considered axial and flexural waves with low frequency approximation. The model
assumptions include: (a) straight-crested multimodal ultrasonic guided 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. Multimodal ultrasonic guided wave, normal mode expansion, electromechanical energy
transformation of PWAS and structure were considered. The parametric study of PWAS size and impedance match
gives the PWAS design guideline for PWAS sensing and power harvesting applications
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