Kind Of Piezoelectric Actuator Research Articles

Nonlinear dynamics and active control of smart beams using shear/extensional mode piezoelectric actuators

In this work, the nonlinear dynamics and active control of smart beams are investigated using the shear mode and extensional mode piezoelectric actuators. The numerical analysis is performed considering two smart beams for separate use of the two kinds of piezoelectric actuators. These smart beams are considered to operate under the transverse or axial compressive harmonic load while the actuators are activated by supplying the external electric field according to the velocity feedback control law. The dynamics of the smart beams is analysed numerically by deriving the geometrically nonlinear electro-elastic incremental equations of motion in the finite element (FE) framework. The FE equations of motion are solved using Bathe time integration method for evaluation of the transient responses while the frequency responses are evaluated by implementing the harmonic balance method in conjunction with a numerical continuation technique. The results for the transverse harmonic load reveal that both the actuators are capable of attenuating the large amplitude vibration of the smart beams; however, the application of the shear/extensional mode actuator is mainly limited to a certain extent of the load-amplitude. Under the axial compressive harmonic load, the dynamics of the smart beams in the pre-buckled state appears through the parametric instabilities. However, once the buckling occurs, the smart beams undergo complex nonlinear dynamics due to the appearance of the snap-through periodic motion and the chaotic motion through the symmetry breaking, period-doubling/demultiplying and saddle-node bifurcations. The presented results mainly reveal the suitability of the shear mode and extensional mode piezoelectric actuators in active control of such dynamic instabilities and the associated complex nonlinear dynamics of the smart beams.

Large deformation mechanical modeling with bilinear stiffness for Macro-Fiber Composite bimorph based on extending mixing rules

Macro-Fiber Composite bimorph is a kind of piezoelectric actuator that allow large bending deformation. However, macro-fiber composites exhibit strong stiffness nonlinearity in their operation range, so it is difficult to accurately estimate their large deformation behavior based on a linear constitutive model. In addition, the macro-fiber composites have active and inactive parts, that significantly differ in their material sizes and properties, so it is not reasonable to consider them as uniform material. Thus, it is necessary develop an accurate modeling and analysis method for the large deformation macro-fiber composite structures. First, the mixing rules are extended to derive the three-dimensional homogenized mechanical and electrical parameters of the macro-fiber composite active part; based on these parameters, the actuation results of linear finite element model is in good agreement with the official data. Then a finite element model of the axially compressed macro-fiber composite bimorph is established, the bilinear tensile stiffness of macro-fiber composite is realized by secondary development in ANSYS. Comparison with the experimental results reveals high accuracy of the established finite element model. Thus, the developed method can be effectively used for the performance evaluation and design of the macro-fiber composite devices with large deformation.

Analytical solutions of two kinds of piezoelectric actuators under shearing load

Under an external shearing load and an electric potential acting simultaneously, twopiezoelectric hollow cylinder actuators, of the expansion and contraction types, are studied.With the Airy stress function method, the analytical solutions of these two kindsof actuators are obtained based on the theory of piezo-elasticity. The solutionsare compared with the finite element results of Ansys and a good agreement isfound. Inherent properties of these two kinds of piezoelectric cylinder actuators arepresented and discussed. This is very helpful for the design of bearing controllers.

Design of a precision compliant parallel positioner driven by dual piezoelectric actuators

This paper presents a precision compliant parallel-structure positioner, which is dually driven by six piezoelectric motors and six piezoelectric ceramics. This compliant system has a high load capacity of more than 2 kg because the parallel mechanism with high load capacity is the main architecture. This system can also provide relatively large workspace and high accuracy simultaneously compared with conventional compliant positioner systems because it perfectly integrates two kinds of piezoelectric actuators in one system. The end platform has the stroke of 10 mm in three linear motion directions and of 6-arc-degrees in three angle motion directions, respectively, for the adoption of large motion range actuator piezoelectric motors. The positioning resolution and repeatability of the end platform is nanometer scale for the adoption of high precision actuator piezoelectric ceramics.