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Piezoelastic response of smart functionally graded structure with integrated piezoelectric layers using discrete double directors shell element
摘要： The purpose of the paper is to predict the electromechanical behavior of composite shell structures with embedded piezoelectric layers using 3D-shell model based on a discrete double directors shell element. The implementation is applicable to the analysis of isotropic and functionally graded shells with integrated piezoelectric layers. The third-order shear deformation theory is introduced in the present method to remove the shear correction factor and improve the accuracy of transverse shear stresses. The present results were compared with reference solutions from literature in order to verify the accuracy of the present formulation and excellent agreement was found. A parametric study is carried out to highlight the in?uence of material composition and curvature radius on the de?ection and axial stress along the thickness.
关键词： Active functionally graded shells,Finite element analysis,Double director shell,Piezoelectric sensors/actuators,Smart structures
更新于2025-09-10 09:29:36
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Smart Materials and Structures: State of the Art and Applications
摘要： The world of materials is an exciting and challenging field of research since it has always played a dominant role in the evolution of human civilization. The demands from aerospace, defence, automotive and industrial branches on more advanced and innovative materials has led to the development of a new generation of materials with much better performance and capabilities than the existing conventional structural and functional materials. As a result, the era of smart materials has started. Smart materials can change their physical properties in response to a specific stimulus input. However, there is still a blurry image over the types and potential applications of smart materials. The objective of this paper is to define the field of smart materials and structures, together with its current status and potential benefits. However, more focus will be devoted to piezoelectric materials and results are presented and discussed. Finally, and in order to demonstrate the characteristics of one class of smart materials, two numerical examples are proposed and results are presented.
关键词： Piezoelectric materials,Actuators and sensors,Smart materials,Shape memory alloys
更新于2025-09-10 09:29:36
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Superfast, Porous and Organic Solvent Sensitive Actuator Based on EVOH Nanofibrous Membrane and PS Microspheres
摘要： Despite much progress in solvent-sensitive actuators, most of the actuators are sensitive to water, ethanol or acetone with low responsive speed and small curvature. Herein, a simple approach was introduced to fabricate a new solvent-sensitive bilayer actuator consisting of poly(vinyl alcohol-co-ethylene) (EVOH) nanofibrous membrane and polystyrene (PS) microspheres. The actuator showed superfast and multi-stimulus responsive ability to organic vapors of toluene, chloroform, THF and acetone. With solvents stimulation, the difference in swelling degree between the EVOH layer and PS microspheres layer contributed to the asymmetric expansions or contractions of two layers, therefore resulting in the mechanical deformation of the actuator. The flexible and porous EVOH nanofibrous membrane, as well as the spherical PS could improve the response rate and deformation scale. This bilayer actuator could bend quickly into a multi-coil with the curvature of 21.02 cm-1 within 0.15 s in response to toluene vapor, and the bending-unbending process could repeat more than 150 times when the deformation degree was controlled by cross-linking PS microspheres with divinylbenzene (DVB). This study will provide an important insight for the development of new solvent-sensitive devices and applications in volatile organic compounds detecting.
关键词： PS microspheres,EVOH nanofibrous membrane,multi-stimulus responsive,organic vapors,solvent-sensitive actuators
更新于2025-09-09 09:28:46
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An enhanced Bouc-Wen model for characterizing rate-dependent hysteresis of piezoelectric actuators
摘要： A classical Bouc-Wen model is widely applied in hysteresis modeling and compensation for piezoelectric ceramic actuators. However, the classical Bouc-Wen model cannot characterize rate-dependent hysteresis under excitations at high frequencies precisely. In this paper, an enhanced Bouc-Wen model is developed by introducing the frequency of input voltage based on the classical Bouc-Wen model. A number of experiments were conducted to characterize the rate-dependent hysteresis of piezoelectric ceramic actuators under sinusoidal excitations at a range of 1–150 Hz. The measured data were used to demonstrate the validity of the developed model. A method of parameter estimation based on the Matlab/Simulink parameter estimation tool is adopted to identify the parameters of models. The comparisons of experiments and simulations show that the developed model can describe rate-dependent hysteresis more accurately than the classical Bouc-Wen model. The modeling errors of the developed model were decreased by nearly 75% compared with that of the classical Bouc-Wen model. The root-mean-square error of the developed model is controlled in 0.1719 μm.
关键词： parameter estimation,Bouc-Wen model,rate-dependent hysteresis,piezoelectric actuators
更新于2025-09-04 15:30:14
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Humidity-Driven Mechanical and Electrical Response of Graphene/Cloisite Hybrid Films
摘要： Humidity-driven and electrically responsive graphene/cloisite hybrid films are obtained by casting water dispersions of graphene oxide and cloisite Na+. Coupling hydrophilicity and a high water vapor barrier in a homogenous film enables to realize humidity-driven actuators which exploit the water gradient generated across the film section under asymmetric exposure to humidity. The hybrid films are self-standing, flexible, and exhibit fast humidity-triggered bidirectional bending up to 75°, which is tuned by varying the relative amount of the two components. Up to 60% of the bending angle can be preserved at the steady state, providing a large and reliable response to humidity. Moreover, thermal treatment results in the reduction of graphene oxide, endowing the films with humidity-dependent electrical conductivity, which increases from 1.5 × 10?6 S at 20% relative humidity (RH) up to 2.7 × 10?5 S at 90% RH. The films are used to realize a humidity-sensitive electrical switching system in which the reversible actuation is due to water desorption induced by the Joule effect. Due to their ease of preparation and tunable properties, this new class of graphene-based materials is suitable for the realization of humidity-driven and electrically responsive actuators and sensors.
关键词： graphene/cloisite hybrids,humidity sensing,humidity-triggered actuators,reversible bending
更新于2025-09-04 15:30:14
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[ASME ASME 2015 International Mechanical Engineering Congress and Exposition - Houston, Texas, USA (Friday 13 November 2015)] Volume 4B: Dynamics, Vibration, and Control - Research on the Driving Mechanism With PLZT Multi-Patches Combination for Optical Actuation Response Improvement
摘要： PLZT actuators taken as one type of photo-deformable actuators have been widely applied for micro-driven systems and active vibration control of photostrictive laminated flexible structures. However, the slow response of photodeformation of single patch PLZT actuator greatly affects its application. In this paper, the main factors for the slow response of the PLZT actuator are investigated using experimental method. The increasing temperature during light on state and the residual photovoltage and photodeformation during light off state are considered to be the main factors for the slow response of the PLZT actuator. To improve the driving performance of PLZT ceramic, some effective measures through reducing the effect of increasing temperature and eliminating residual photovoltage and photodeformation are proposed and experimentally validated in this paper. Considering the effective measures proposed in this paper, two novel optical driving mechanisms based on PLZT bimorph and multi-patches combination for driving source are proposed.
关键词： photovoltage,optical driving mechanisms,temperature,photodeformation,PLZT actuators
更新于2025-09-04 15:30:14