The effect of particle aspect ratio on the electroelastic properties of piezoelectric nanocomposites

Abstract

Piezoelectric materials offer exceptional sensing and actuation properties; however, they are prone to breakage and difficult to apply on curved surfaces in their monolithic form. One method of alleviating these issues is through the use of 0-3 nanocomposites, which are formed by embedding piezoelectric particles into a polymer matrix. Material of this class offers certain advantages over monolithic materials; however, it has seen little use due to its low coupling.Here we develop micromechanics and finite element models to study the electroelastic properties of an active nanocomposite, as a function of the aspect ratio and alignment of the piezoelectric filler. Our results show that the aspect ratio is critical for achieving high electromechanical coupling, and with an increase from 1 to 10 at 30% volume fraction of piezoelectric filler the coupling can increase to 60 times its initial value and achieve a bulk composite coupling as high as 90% for a pure PZT-7A piezoelectric constituent.

Dielectrophoretically structured piezoelectric composites with high aspect ratio piezoelectric particles inclusions

“…30 The R eff values for all composite samples were calculated using Eq. (22). The distributions of orientation angles of short fibers within the DEP aligned composites were found to closely resemble a folded half normal distribution centered around h ¼ 90 and folded at h ¼ 0 .…”

“…These models are based on the calculation of effective electroeleastic moduli, by substituting equivalent electroelastic Eshelby tensors in a model for finite concentrations of these inclusions, such as Mori-Tanaka approaches. [19][20][21][22] Finite element method (FEM) approaches have also been explored. 20,22 However, these studies have all considered equidistant spacing of the piezoelectric particles in the matrix as a function of volume fraction, a condition that is not satisfied by the DEP processed composites, as the dielectric particles tend to align end-to-end during the processing.…”

“…[19][20][21][22] Finite element method (FEM) approaches have also been explored. 20,22 However, these studies have all considered equidistant spacing of the piezoelectric particles in the matrix as a function of volume fraction, a condition that is not satisfied by the DEP processed composites, as the dielectric particles tend to align end-to-end during the processing. Thus, even at low concentrations, aligned particles are still in close proximity of each other.…”

“…Using Eq. (22), samples with similar R eff were selected. For the mean R eff , the corresponding fitted value C ef f for these samples was calculated using Eq.…”

“…The normalized e 33 Other models for oriented high aspect ratio particles 21,22 assume uniform dispersion and orientation of the particles. The effective composite properties are calculated using piezoelectric equivalents of Eshelby's tensors in combination with the Mori-Tanaka method.…”