Modeling of Light-Driven Bending Vibration of a Liquid Crystal Elastomer Beam

Li, Kai; Cai, Shengqiang

doi:10.1115/1.4032073

Cited by 31 publications

(12 citation statements)

References 34 publications

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“…Soft active materials undergo various morphological changes and large deformations under externally applied mechanical [ 1 , 2 ], heat [ 3 ], light [ 4 ], magnetic [ 5 , 6 ], electric [ 7 , 8 , 9 , 10 ], humidity [ 11 ] and/or solvent [ 12 ] fields. Some soft active materials include dielectric elastomers [ 13 , 14 ], hydrogels [ 15 , 16 ], liquid crystal elastomers [ 17 , 18 ], magneto-active elastomers [ 19 , 20 , 21 , 22 , 23 ], etc. In the recent years, these active materials have become greatly attractive due to their possible uses in the fields of soft robotics [ 24 , 25 , 26 ], flexible electronic devices [ 27 ], biomedical devices [ 28 , 29 ], wearable devices [ 30 , 31 ], soft actuators and sensors [ 32 , 33 , 34 ], among many others.…”

Section: Introductionmentioning

confidence: 99%

Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

et al. 2022

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Hard-magnetic soft materials belong to a class of the highly deformable magneto-active elastomer family of smart materials and provide a promising technology for flexible electronics, soft robots, and functional metamaterials. When hard-magnetic soft actuators are driven by a multiple-step input signal (Heaviside magnetic field signal), the residual oscillations exhibited by the actuator about equilibrium positions may limit their performance and accuracy in practical applications. This work aims at developing a command-shaping scheme for alleviating residual vibrations in a magnetically driven planar hard-magnetic soft actuator. The control scheme is based on the balance of magnetic and elastic forces at a critical point in an oscillation cycle. The equation governing the dynamics of the actuator is devised using the Euler–Lagrange equation. The constitutive behaviour of the hard-magnetic soft material is modeled using the Gent model of hyperelasticity, which accounts for the strain-stiffening effects. The dynamic response of the actuator under a step input signal is obtained by numerically solving the devised dynamic governing equation using MATLAB ODE solver. To demonstrate the applicability of the developed command-shaping scheme, a thorough investigation showing the effect of various parameters such as material damping, the sequence of desired equilibrium positions, and polymer chain extensibility on the performance of the proposed scheme is performed. The designed control scheme is found to be effective in controlling the motion of the hard-magnetic soft actuator at any desired equilibrium position. The present study can find its potential application in the design and development of an open-loop controller for hard-magnetic soft actuators.

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Section: Introductionmentioning

confidence: 99%

Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

et al. 2022

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“…The light-powered oscillation is caused by the large deformation of LCE due to the orientation sequence change in liquid crystal molecule [ 53 , 54 , 55 , 56 , 57 ]. For example, ultraviolet light can induce the photoisomerization of azobenzene molecules, which leads to the large deformation of LCE [ 58 , 59 ]. Finkelmann et al synthesized LCE containing azobenzene molecules with a photoinduced contraction strain close to 20% [ 60 ].…”

Section: Introductionmentioning

confidence: 99%

Beating of a Spherical Liquid Crystal Elastomer Balloon under Periodic Illumination

Cheng

et al. 2022

Micromachines

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Periodic excitation is a relatively simple and common active control mode. Owing to the advantages of direct access to environmental energy and controllability under periodic illumination, it enjoys broad prospects for application in soft robotics and opto-mechanical energy conversion systems. More new oscillating systems need to be excavated to meet the various application requirements. A spherical liquid crystal elastomer (LCE) balloon model driven by periodic illumination is proposed and its periodic beating is studied theoretically. Based on the existing dynamic LCE model and the ideal gas model, the governing equation of motion for the LCE balloon is established. The numerical calculations show that periodic illumination can cause periodic beating of the LCE balloon, and the beating period of the LCE balloon depends on the illumination period. For the maximum steady-state amplitude of the beating, there exists an optimum illumination period and illumination time rate. The optimal illumination period is proved to be equivalent to the natural period of balloon oscillation. The effect of system parameters on beating amplitude are also studied. The amplitude is mainly affected by light intensity, contraction coefficient, amount of gaseous substance, volume of LCE balloon, mass density, external pressure, and damping coefficient, but not the initial velocity. It is expected that the beating LCE balloon will be suitable for the design of light-powered machines including engines, prosthetic blood pumps, aircraft, and swimmers.

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“…Obviously, accurate description of the performance of the LCE cantilever is the key point in the accurate prediction of the energy transformation efficiency, as well as the proper design of auxiliary circuit. Li and Cai [28] theoretically modeled the light driven bending vibration of an LCE cantilever. Mahdian Parrany [29] numerically studied the light induced vibration of LCE beam considering the geometrical nonlinearity effect based on finite element formulation.…”

Section: Introductionmentioning

confidence: 99%

Photomechanical vibration energy harvesting based on liquid crystal elastomer cantilever

Zhao

Liu

2019

Smart Mater. Struct.

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Due to the coupling of external light stimuli with mechanical deformation, light induced responses of liquid crystal elastomer (LCE) cantilevers have been widely studied considering the prospective application in light energy harvesting devices. In this paper, a theoretical study about photomechanical vibration of a LCE cantilever is presented for the further application in energy harvester design. The emphasis is placed on the clarification of light induced inhomogeneous strain distribution on the cantilever responses. Through introducing the physical neutral surface deviation, the governing equation is reformed. The equations are solved by using the superposition method and the Duhamel integral. An empire equation for the maximum tip deflection of the cantilever with respect to characteristic parameters is formulated. The results show that the light induced inhomogeneous strain distribution could not be ignored. The predicted critical values to trigger cantilever vibration agree with the experiment result. This work paves a way to the accurate design of light harvester, light-driven actuators and sensors.

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Modeling of Light-Driven Bending Vibration of a Liquid Crystal Elastomer Beam

Cited by 31 publications

References 34 publications

Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

Alleviation of Residual Vibrations in Hard-Magnetic Soft Actuators Using a Command-Shaping Scheme

Beating of a Spherical Liquid Crystal Elastomer Balloon under Periodic Illumination

Photomechanical vibration energy harvesting based on liquid crystal elastomer cantilever

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