Analysis Of Mechanical Behaviors Of Piezoelectric Structures Considering Flexoelectric Effect

Flexoelectricity is a kind of electromechanical coupling effect of electric polarization induced by a strain gradient or an inhomogeneous deformation. It can not only enhance the apparent electromechanical effect of piezoelectric structures, but also make centrosymmetric materials exhibit piezoelectricity. At the nanoscale, flexoelectric effect presents a very significant effect on the macroscopic mechanical behavior of materials and structures. Firstly, the governing equations of piezoelectric nano-beams with considering flexoelectric effect are developed by using the Hamilton principle. Based on Euler-Bernoulli beam and Timoshenko-beam models, the influence of flexoelectric effect on static bending and polarization of simply supported piezoelectric beam with open circuit condition is investigated. Secondly, the influence of flexoelectric effect on piezoelectric circular nano-plates with open circuit and short circuit conditions are studied. Finally, taking flexoelectricity into consideration, the basic equations of multiferroic composite nano-bilayers with coupled extensional and flexural deformations are derived. The static magnetoelectric (ME) effect in a multiferroic composite bilayer under a constant magnetic field is analyzed. Numerical results show that flexoelectrictiy has a remarkable influence on the macroscopic mechanical properties of piezoelectric and multiferroic composite structures at the nanoscale. The research results of the thesis provide a helpful theoretical guidance for devices’design.