An accurate modeling of piezoelectric smart beams with first-order shear deformation theory

A finite element model for piezoelectric smart beam in extension mode based on First-order Shear Deformation Theory(FSDT)with an appropriate through-thickness distribution of electric potential is presented.Accuracy of piezoelectric finite element formulations depends on the selection of assumed mechanical and electrical fields.Most of the conventional FSDT-based piezoelectric beam formulations available in the literature use linear through-thickness distribution of electric potential which is actually nonlinear.Here,a novel quadratic profile of the through-thickness electric potential is proposed to include the nonlinear effects.The results obtained show that the accuracy of conventional formulations with linear through-thickness potential approximation is affected by the material configuration,especially when the piezoelectric material dominates the beam cross section.It is shown that the present formulation gives the same level of accuracy for all regimes of material configurations in the beam cross section.Also,a modified form of the FSDT displacements is employed,which utilizes the shear angle as a degree of freedom instead of section rotation.Such a FSDT displacement field shows improved performance compared to the conventional field.The present formulation is validated by comparing the results with ANSYS 2D simulation.The comparison of results proves the improved efficiency and accuracy of the present formulation over the conventional formulations.

Dynamic analysis of a rotating rigid-flexible coupled smart structure with large deformations

Based on Hamilton＇s principle, a new kind of fully coupled nonlinear dynamic model for a rotating rigid-flexible smart structure with a tip mass is proposed. The geometrically nonlinear effects of the axial, transverse displacement and rotation angle are considered by means of the first-order approximation coupling （FOAC） model theory, in which large deformations and the centrifugal stiffening effects are considered. Three kinds of systems are established respectively, which are a structure without piezoelectric layer, with piezoelectric layer in open circuit and closed circuit. Several simulations based on simplified models are presented to show the differences in characteristics between structures with and without the tip mass, between smart beams in closed and open circuit, and between the centrifugal effects in high speed rotating state or not. The last simulation calculates the dynamic response of the structure subjected to external electrical loading.

Smart beam via electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystals

Smart beams play a vital role in modern intelligent vehicles and have recently attracted significant attention.A spatial light modulator with high optical efficiency,low cost,and compact size is crucial for designing smart beams.Here,we mix cholesteric liquid crystals with dichroic black dye and a monomer.After UV polymerization,the sample exhibits a low driving voltage of 26 V,a high transmittance of over 70%,and an On-off ratio over 280,thanks to the joint contribution of both the absorption and the scattering effect.A smart beam device is demonstrated by electrically addressing the dye-doped and polymer-stabilized cholesteric liquid crystal with pixelated electrodes.Light patterns with arbitrary designs are projected dynamically.The switching time reaches several tens of milliseconds.This strategy brings new designs to intelligent vehicles and may also inspire applications in public information displays,advertising,and even AR/VR displays.