Mechanical design of uniform strain-gradient schemes for transverse and longitudinal flexoelectricity

Abstract

Flexoelectricity is an electro-mechanical coupling effect in which dielectric materials polarize in response to deformation gradients. Typical models—including bending beams, trapezoidal terraces, and torquing bars—are adopted to generate strain gradients for studying flexoelectricity. Also, non-uniformities are introduced, which can induce possible problems related to electric polarization induced by higher-order components of the non-uniform strain gradient. Mechanical design is proposed to solve the problem of higher order components. Specifically, we propose mechanical design of two uniform strain-gradient schemes for transverse and longitudinal flexoelectricity—a special-designed beam and a circular terrace. Theoretical and numerical analysis support the uniformity of strain gradients of these designs. Experiments were conducted to obtain the two types of flexoelectric response of uniform strain-gradient schemes. By proposing a way to achieve uniform strain gradient through mechanical design, this work promotes research on flexoelectricity by eliminating possible impacts of non-uniform strain gradients. A uniform strain-gradient beam is an ideal tool for studying uniform strain gradient, and is applicable to various avenues of research besides flexoelectricity.