Hong-Hao Yue

Wireless Active Vibration Control of Thin Cylindrical Shells Laminated with Photostrictive Actuators

In this study, a thin cylindrical shell is actively controlled by photostrictive patches which can produce photodeformation strains under the illumination of ultraviolet lights. Governing equations of the cylindrical shell laminated with the photostrictive actuators oriented in the circumferential direction are established. With the uniform illumination and the alternate illumination schemes, the bending control effect and the membrane control effect of the new actuator configuration are analyzed and evaluated with respect to the curvature angles of the cylindrical shell. Considering the multi-field coupling behavior of the photostrictive actuators, two types of control algorithms with constant light intensity and variable light intensity are adopted. Using the two control algorithms, time histories of the transverse displacement, control light intensity, photo-induced electric field, temperature, and control force are presented. The results of time history analysis show that the constant light intensity control provides better control performance as compared with the variable light intensity control. Based on the configuration of two paired actuators, both the uniform illumination and the alternate illumination schemes are analyzed and compared. The alternate illumination scheme improves the modal control effects to some modes which are decided by the actuator configuration and the mode shapes of the cylindrical shell.

Finite difference based vibration simulation analysis of a segmented distributed piezoelectric structronic plate system

Electrical modeling of piezoelectric structronic systems by analog circuits has the disadvantages of huge circuit structure and low precision. However, studies of electrical simulation of segmented distributed piezoelectric structronic plate systems (PSPSs) by using output voltage signals of high-speed digital circuits to evaluate the real-time dynamic displacements are scarce in the literature. Therefore, an equivalent dynamic model based on the finite difference method (FDM) is presented to simulate the actual physical model of the segmented distributed PSPS with simply supported boundary conditions. By means of the FDM, the four-ordered dynamic partial differential equations (PDEs) of the main structure/segmented distributed sensor signals/control moments of the segmented distributed actuator of the PSPS are transformed to finite difference equations. A dynamics matrix model based on the Newmark-β integration method is established. The output voltage signal characteristics of the lower modes (m ≤ 3, n ≤ 3) with different finite difference mesh dimensions and different integration time steps are analyzed by digital signal processing (DSP) circuit simulation software. The control effects of segmented distributed actuators with different effective areas are consistent with the results of the analytical model in relevant references. Therefore, the method of digital simulation for vibration analysis of segmented distributed PSPSs presented in this paper can provide a reference for further research into the electrical simulation of PSPSs.

Vibration control of cylindrical shells with a hybrid photovoltaic/piezoelectric actuation mechanism

Photovoltaic materials, which can directly turn light energy into electric energy, can offer the advantage of generating large voltages without external power supplies. When a near ultraviolet light illuminates on polarized PbLaZrTi (PLZT) mate- rials, an electrical field can be generated along the spontaneous polarization direction due to the phovoltaic effect. This voltage generation mechanism exhibits many advantages, such as (1) high electrical output voltage, (2) wireless energy generation, (3) immune from electric/magnetic disturbances, (4) remote or non-contact control. In this study, Distributed vibration control of cylindrical shells using a hybrid photovoltaic/piezoelectric actuation mechanism is investigated. The light-driven photovoltaic generator induced voltage is used to drive a skew-quad piezoelectric actuator which can induce non-uniform control froces and control moments. Based on theoretical analysis and experimental validation, the constitutive equations defining the piezo- electric actuator induced actuation strain under the actuation mechanism are presented. Each region of the actuator system can induce both positive and negative control forces and moments using logical switches to shift the sign of control voltage of actuator system. Control effectiveness with constant light intensity control algorithm is evaluated and the time history analysis is presented.

Modelling and experiments of PLZT/PVDF hybrid drive method for non-contact shape adjustment

In order to improve the technical specifications of space reflectors, antennas and other payloads on Earth observation, space communication, deep space exploration and other fields of space applications, people urgently need to enhance the surface shape control accuracy of these large complex curvature flexible structures. Based on the photovoltaic effect and converse piezoelectric effect, this paper presents a non-contact shape-adjusting method which adopts a new space energy conversion: using the PLZT photovoltage, which is controlled by the ultraviolet, to activate the PVDF attached on the flexible structure surface, and adjust and control the structures shape. This paper firstly built up the electric model of the PLZT/PVDF hybrid drive, derived the constitutive relation of light-electric-mechanical energy field conversion, and determined the key parameters inmathematical model by principle experiments. Then, taking aflexiblecantilever beam as thecontrol object, actuation equation of the PVDF bonded structure was built, and actuation properties and influence factors of the cantilever beam actuated by the PLZT/PVDF hybrid drive were simulated and analyzed. After that, the hybrid drive experiment system was built up, and deflecting effect of using ultraviolet illuminated PLZT to actuate PVDF bonded cantilever beam was tested, whose result verified the validity of theoretical modeling and simulation analysis. Lastly, characteristics of the hybrid drive method and conventional PVDF driving were compared, and space application direction of this method was pointed out.

Finite Difference Based Electrical Modeling and Vibration Control Simulation of Piezoelectric Structronic Plate System

Electrical modeling and vibration control analysis of piezoelectric structronic systems are of great significance in design of new smart structures. However, studies of electrical modeling of piezoelectric structronic plate systems by using voltage signals to evaluate real-time dynamic displacements are scarce in open literatures. An equivalent circuit model is presented to simulate the piezoelectric structronic plate/sensor/actuator system with simply supported boundary conditions, so that the actual physical model could be replaced by a single circuit chip in the future. By means of the finite difference (FD) discretization method, the higher order dynamic partial differential equations (PDE) of plate’s structure/sensor signal/control system are transformed to finite difference equations and further represented by electronic components. Electrical simulation model of the piezoelectric structronic plate systems based on finite difference discretization is established. Meanwhile, an equivalent circuit design program is proposed. Control characteristics of the structronic plate model are analyzed and the control effects are compatible with the results of the numerical model in relevant references. Thus, numerical simulation result presented in this paper can provide a reference for the further research of electrical modeling of more complex piezoelectric structronic plate systems.© 2009 ASME

Research on Active Control for Thermal Deformation of Precise Membrane Reflector With Boundary SMA Actuators

Along with the rapid development of space exploration, communication and earth observation technology, the large space membrane structure gains its widely application. With poor stiffness and large flexibility, the surface accuracy of membrane structures can be easily interfered by the space environment variety, so precise shape control of in-orbit space membrane reflector becomes the focus in space technology area. As an object for this paper, the active control of the membrane reflector deformation under typical thermal disturbance in space is investigated. Considering of Von-Karman geometrical nonlinearity, the equilibrium equations of a circular membrane are firstly presented based on Hamilton’s Principle and Love’s thin shell theory. As a simplification for equilibrium equations, the nonlinear mathematical model for the circular membrane in a symmetrical temperature field is obtained. In the next place, an FE model for a circular membrane under thermal load is developed in Abaqus as an example. By contrasting the FEM deformation analysis with mathematical modeling solutions of circular membrane reflectors under typical thermal load, it is demonstrated that the theoretical model is capable of predicting the amplitude of membrane surface deformation. At last, a boundary actuation strategy for membrane shape control is proposed, which could effectively decrease the membrane wrinkle induced by thermal disturbance via precisely control to the tension of the SMA wire actuators. The simulation result indicates the effectiveness of boundary active control strategy on improving membrane surface accuracy with different temperature distributions. The conclusions of modeling and analysis in this paper will be an essential theoretical foundation for future research on active flatness control for in-orbit large space membrane structure.Copyright

Analysis and Design of Active Morphing Units Based on SMA Actuators

Morphing wings can change their shapes in flight to optimize aircraft’s aerodynamics, which increases aircraft’s performance for a given flight stage. This paper introduces an active morphing unit (AMU) which can deform by the two-way actuator comprising two one-way shape memory alloy (SMA) elements. The mathematical model and the forward kinematics of AMU are established. The structure of AMU is design. Then, the paper demonstrates that the combination of AMUs can function as the main spar of distributed multi-freedom active morphing wing. Three different combination strategies of AMUs are analyzed by forward kinematics and realizable variable geometries of wing. A configuration sample of one-dimension morphing wing is presented to demonstrate a combination strategy. The rotation function and stiffness of AMU prototype are tested. Experimental results illustrate that AMU can realize desired deformation and has high stiffness. This research will lay the foundations of next generation morphing aircrafts.© 2013 ASME

Cylindrical Shell Control With Center- and Corner-Placed Photostrictive Skew-Quad Actuators

Light-driven photostrictive actuators can induce control actions capable of wireless non-contact actuation and control of precision structures and systems. Conventional distributed actuators laminated on shells and plates usually introduce only uniform control forces and moments. Structural actuation and control based on uniform control forces and moments have been investigated for over two decades. This paper is to exploit a new photostrictive actuator design, i.e., a skew-quad (SQ) actuator system and this new distributed SQ system laminated on shells and plates can introduce non-uniform control forces and moments. The new SQ actuator system is composed of four pieces of photostrictive materials and inner two edges of each piece are bonded to a cross fixture. Under the irradiation of high-energy lights, each piece generates non-uniform control forces and moments, due to its uneven nonsymmetrical boundary conditions. Modal actuation characteristics of a cylindrical shell coupled with a center-placed and corner-placed skew-quad actuator system are evaluated respectively. A paired-design regulating positive/negative control forces of each actuator region is proposed to improve the control effectiveness of the center-located skew-quad actuator system. Parametric analysis proves improved control effectiveness of unsymmetrical shell modes.Copyright

Non-Uniform Control Moments Induced by a Skew-Quad Actuator Design Applied to Plate Controls

Distributed vibration control of flexible structures using piezoelectric materials has been extensively studied for decades. A number of design configurations of distributed actuators with uniform control forces and moments have been investigated to improve modal control effectiveness of distributed structures, e.g., shells and plates. In this study, a new skew-quad actuator design which consists of four pieces of mono-axial piezoelectric actuator is proposed and evaluated. Due to the uneven boundary conditions of each region, this new actuator can induce non-uniform control forces and moments. Based on the variation method, the non-uniform distribution of the actuator induced forces and moments are defined. The coupling equation of a simply supported plate laminated with this new design is derived; distributed control action resulting from the non-uniform control moments is also defined in the modal domain. The actuator induced control actions are calculated respectively on a square plate and a rectangle plate, and the effects of varying actuator size are also evaluated. These control effects of the skew-quad actuator are compared with those of a multi-DOF actuator. Parametric analyses suggest that due to the non-uniform control moments, the new skew-quad actuator induces better modal control actions in certain plate modes as compared with the multi-DOF actuator. This new skew-quad actuator has great potential to improve control effects to other shell structures.Copyright

A New Multi-DOF Photostrictive Actuator for Dynamic Control of Shells: Modeling and Analysis

Based on the photovoltaic effect and the converse piezoelectric effect, the lanthanum-modified lead zirconate titanate (PLZT) actuator can transform the photonic energy to mechanical strain/stress — the photodeformation effect. This photodeformation process can be further used for non-contact precision actuation and control in various structural, biomedical and electromechanical systems. Although there are a number of design configurations of distributed actuators, e.g., segmentation and shaping, been investigated over the years, this study is to explore a new actuator configuration spatially bonded on the surface of shell structures to broaden the spatial modal controllability. A mathematical model of a new multi-degree-of-freedom (DOF) photostrictive actuator configuration is presented first, followed by the photostrictive/shell coupling equations of a cylindrical shell structure laminated with the newly proposed multi-DOF distributed actuator. Distributed microscopic photostrictive actuation and its contributing components are analyzed in the modal domain. Effects of shell’s curvature and actuator’s size are evaluated. Parametric analyses suggest that the new multi-DOF distributed actuator, indeed, provides better performance and control effect to shell actuation and control. This multi-DOF configuration can be further applied to actuation and control of various shell and non-shell structures.Copyright