The classical piezoelectric theory fails to capture the size-dependent electromechanical coupling behaviors of piezoelectric microstructures due to the lack of material length-scale parameters.This study presents the ...The classical piezoelectric theory fails to capture the size-dependent electromechanical coupling behaviors of piezoelectric microstructures due to the lack of material length-scale parameters.This study presents the constitutive relations of a piezoelectric material in terms of irreducible transversely isotropic tensors that include material length-scale parameters.Using these relations and the general strain gradient theory,a size-dependent bending model is proposed for a bilayer cantilever microbeam consisting of a transversely isotropic piezoelectric layer and an isotropic elastic layer.Analytical solutions are provided for bilayer cantilever microbeams subjected to force load and voltage load.The proposed model can be simplified to the model incorporating only partial strain gradient effects.This study examines the effect of strain gradient by comparing the normalized electric potentials and deflections of different models.Numerical results show that the proposed model effectively captures size effects in piezoelectric microbeams,whereas simplified models underestimate size effects due to ignoring partial strain gradient effects.展开更多
Flexoelectricity in dielectrics suggests promising smart structures for sensors,actuators and transducers.In this review,dielectric materials,structures and the associated flexoelectric characterization methods are pr...Flexoelectricity in dielectrics suggests promising smart structures for sensors,actuators and transducers.In this review,dielectric materials,structures and the associated flexoelectric characterization methods are presented.First of all,we review structures and methods to measure different flexoelectric coefficients,includingμ1122;μ1111;μ1211;μ3121;μ2312;μ1123,etc.,via direct or converse flexoelectric effect.The flexoelectric materials in the form of bulk,thin films and 2D materials and the reported flexoelectric properties of these dielectrics will then be discussed.Semiconductor materials and the associated flexoelectric studies will also be reviewed.The progress of flexoelectric device study will next be presented,followed by the flexoelectricity research challenges and future trend.展开更多
基金supported by the National Key Research and Development Program of China(2018YFB0703500).
文摘The classical piezoelectric theory fails to capture the size-dependent electromechanical coupling behaviors of piezoelectric microstructures due to the lack of material length-scale parameters.This study presents the constitutive relations of a piezoelectric material in terms of irreducible transversely isotropic tensors that include material length-scale parameters.Using these relations and the general strain gradient theory,a size-dependent bending model is proposed for a bilayer cantilever microbeam consisting of a transversely isotropic piezoelectric layer and an isotropic elastic layer.Analytical solutions are provided for bilayer cantilever microbeams subjected to force load and voltage load.The proposed model can be simplified to the model incorporating only partial strain gradient effects.This study examines the effect of strain gradient by comparing the normalized electric potentials and deflections of different models.Numerical results show that the proposed model effectively captures size effects in piezoelectric microbeams,whereas simplified models underestimate size effects due to ignoring partial strain gradient effects.
文摘Flexoelectricity in dielectrics suggests promising smart structures for sensors,actuators and transducers.In this review,dielectric materials,structures and the associated flexoelectric characterization methods are presented.First of all,we review structures and methods to measure different flexoelectric coefficients,includingμ1122;μ1111;μ1211;μ3121;μ2312;μ1123,etc.,via direct or converse flexoelectric effect.The flexoelectric materials in the form of bulk,thin films and 2D materials and the reported flexoelectric properties of these dielectrics will then be discussed.Semiconductor materials and the associated flexoelectric studies will also be reviewed.The progress of flexoelectric device study will next be presented,followed by the flexoelectricity research challenges and future trend.
