The effective electromechanical properties of three-dimensional piezoelectric fiber networks

Cellular piezoelectric fiber networks are highly flexible and ultra-sensitive and are promising for functional devices. However, only a few studies on the correlation between their properties and complex microstructures are available. In this paper, stochastic piezoelectric network models with either uniformly or normally distributed fiber orientations are developed. The interactions between adjacent fibers are modeled by cross-linkers. The effective electromechanical properties of the networks are investigated by a commercially available finite element (FE) software in conjunction with a piezoelectric beam theory based user element. Theoretical analyses are also presented. A linear dependency of the effective elastic constants and piezoelectric stress constants on relative density is obtained, consistent with the stretching dominated deformation mechanism of the networks. The role of fiber orientation in the macroscopic electromechanical properties is elucidated, showing that piezoelectric networks with fiber orientation deviating from uniform distribution can have better elastic and piezoelectric stress coefficients. These findings can provide a design guide for the applications of fiber-based piezoelectric sensors and energy harvesters.