Structure Design And Mechanical Behavior Of Light Driven Self-excited Oscillation Based On Liquid Crystal Elastomer

Self excited oscillation is a phenomenon that the system changes periodically under constant external stimulation.In recent years,the light driven self-excited oscillation system based on liquid crystal elastomer has attracted extensive attention because of its wide application potential in many fields,such as energy acquisition,soft robots,medical equipment,micro and nano devices and so on.Self excited oscillations with different structures and motion modes have been constructed in many active material systems.In particular,liquid crystal elastomer is a polymer network structure formed by the cross-linking of liquid crystal monomer molecules.When stimulated by external fields such as light,heat,electricity and magnetism,the liquid crystal monomer molecules will rotate or undergo phase transformation to change the configuration,resulting in macroscopic deformation.Liquid crystal elastomer has the advantages of fast response deformation,recoverable deformation and no noise.However,the design and research of various self-excited vibration systems based on liquid crystal elastomer mostly focus on the experimental field,and the theoretical modeling is very scarce.The internal mechanism and details of self-excited motion are not fully revealed.At the same time,the current self-excited vibration systems and motion modes are not rich enough,which limits the application of these self-excited vibration systems in traditional industries and new scientific and technological fields.Therefore,based on liquid crystal elastomer,this paper puts forward many new types of self-excited oscillation systems,such as liquid crystal elastomer self-excited rotor,two self-excited oscillator coupling synchronous structure,liquid crystal elastomer balloon,liquid crystal elastomer inverted pendulum and so on,and expounds their internal self-excited mechanism.This paper mainly carries out the following work:Firstly,a self-excited oscillating rotor system is proposed,which is composed of a liquid crystal elastomer rotor rotating around an axis.Through detailed mechanical analysis and derivation,the motion control equation of the system is obtained.Through numerical calculation,it is found that the system has three motion modes,namely static mode,oscillation mode and rotation mode.According to the motion dynamics,the mechanism of self-excited oscillation and self-excited rotation is expounded in detail.The specific influence of system parameters on the amplitude of self-excited oscillation is discussed,which provides a basis for the specific design of self-excited oscillation.Secondly,on the basis of the previous chapter,two coupled light response liquid crystal elastomer self-excited oscillator structures are proposed,which mainly study the interaction and group behavior between the two self-excited oscillators.Through numerical calculation,it is found that the self-excited oscillation of the system has two synchronization modes: in-phase synchronization mode and anti phase synchronization mode.The time history diagram of each physical quantity is drawn,and the mechanism of self-excited oscillation is clarified.The effects of initial conditions,contraction coefficient,light intensity and damping coefficient on self-excited oscillation and two synchronous modes are also systematically studied.Thirdly,a self oscillating liquid crystal elastomer balloon system is proposed.The theoretical model is established and solved numerically.It is found that the reason why the liquid crystal elastomer balloon can expand and contract continuously is due to the self shading effect of the coating.The free liquid crystal elastomer balloon can oscillate automatically under constant and uniform ambient light.The periodic oscillation can be self-sustaining through the internal self-regulation feedback mechanism,that is,the light driven contraction and relaxation of the liquid crystal elastomer film are coupled with the expansion / contraction process of the balloon.The constant ambient light is transformed into the film tension of liquid crystal elastomer to produce positive net work,so as to compensate the damping dissipation of the system.The system parameters are analyzed in detail,the trigger conditions of various parameters on the self oscillating balloon system are calculated,and how the parameters affect the amplitude and frequency of the system oscillation is discussed.Finally,a new self stable inverted pendulum system is proposed.It consists of a V-shaped liquid crystal elastomer rod,which can oscillate around the central axis under stable light.Numerical calculation shows that the inverted pendulum system always evolves into static state or self stable oscillation state.The mechanism of self stable oscillation is clarified by reversing the weight moment of inverted pendulum.The effects of system parameters on the amplitude and frequency of self-excited oscillation of inverted pendulum are discussed.The above self-excited oscillation structure is proposed and theoretically analyzed,which greatly enriches the structure and mode of self-excited oscillation system,effectively supplements the current scarce self-excited vibration system theory,and provides sufficient theoretical guidance and support for the application of various new self-excited vibration modes in the future.Figure[49]、reference[72]...