Dielectric elastomer actuators have attracted growing interest for soft robot due to their large deformation and fast response.However,continuous high-voltage loading tends to cause the electric breakdown of the actua...Dielectric elastomer actuators have attracted growing interest for soft robot due to their large deformation and fast response.However,continuous high-voltage loading tends to cause the electric breakdown of the actuator due to heat accumulation,and viscoelasticity complicates precise control.The snap-through bistability of the Venus flytrap is one of the essential inspirations for bionic structure,which can be adopted to improve the shortcoming of dielectric elastomer actuators and develop a new actuation structure with low energy consumption,variable configuration,and multi-mode actuation.Hence,in this paper,the structural design principles of electroactive bistable actuators are first presented based on the total potential energy of the structure.Following that,a feasible design parameter region is provided,the influence of crucial parameters on the actuation stroke,trigger voltage,and actuation charge are discussed.Finally,according to the coupling relationship between the bending stiffness and the bistable property of the actuator,the adjusting methods of bistable actuation are explored.A qualitative experiment was performed to verify the feasibility and correctness of the bistable design methodology and the actuation regulation strategy.This study provides significant theoretical guidance and technical support for developing and applying dielectric elastomer actuators with multi-mode,high-performance,and long-life characteristics.展开更多
There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat area.Th...There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat area.The FEM model of the bistable surface is established with hinged constraint,and the bistability condition and structural transition process are investigated in detail.Moreover,the effects of loading method,loading position and structural parameters on critical driving force,input energy and structural strain are studied.Finally,the influences of an elastic boundary condition on the structural bistability are discussed.The results show that the bistability of the adjustable bump surface requires a certain boundary constraint and geometric parameter combination,and that there are local and overall snap-through phenomena during transition which are related to the loading position and structural parameters.Therefore,suitable loading position and structural material could reduce input energy and meet the demand of structural strain.展开更多
The effects in electrostatic models of chevron surface-stabilized ferroelectric liquid crystals are investigated through numerical modeling. To study smectic C＊ director distribution within the cell, we consider two ...The effects in electrostatic models of chevron surface-stabilized ferroelectric liquid crystals are investigated through numerical modeling. To study smectic C＊ director distribution within the cell, we consider two nonlinear approaches： the chevron interface does not interplay with the electric field; the electric field interplays with the chevron interface. The obtained results of the director field distribution are compared with the earlier linearized studies. We find that whether or not the electric field interplays with the chevron interface, the electro-optic response requires a generalized approach for its description. The threshold electric field, which is necessary for switching between two stable director states in the chevron cell is evaluated. This study suggests that, in many cases of practical interest, electro-optic response to the electric field and the threshold electric field can be precisely estimated. We argue that, beside being numerically efficient, our approach provides a convenient and a novel standpoint for looking at the electro-optic response problem.展开更多
In this paper,we focus on the dynamic behaviors of the bistability for a two-species Lotka–Volterra competition model with stage structure.Using the theory of generalized saddle-point behaviors,it is shown that there...In this paper,we focus on the dynamic behaviors of the bistability for a two-species Lotka–Volterra competition model with stage structure.Using the theory of generalized saddle-point behaviors,it is shown that there exists a C1-separatrixΓon its state space such that Species 2 wins the competition whenever the initial distribution is aboveΓ,while Species 1 wins the competition whenever the initial distribution is belowΓ.Combining with the previous conclusions of the system,we give a complete classification for global competitive dynamics.Furthermore,we carefully analyze the changes of the competition outcome after introducing the stage structure.Finally,some numerical simulations are provided to illustrate the effectiveness of the theoretical results.展开更多
基金the National Key Research and Development Program of China(2019YFB1311600)Natural Science Foundation of China(Grant No.11902248 and 52075411)+1 种基金Shaanxi Key Research and Development Program(2020ZDLGY06-11)the State Key Laboratory for Strength and Vibration of Mechanical Structures(SV2018-KF-08).
文摘Dielectric elastomer actuators have attracted growing interest for soft robot due to their large deformation and fast response.However,continuous high-voltage loading tends to cause the electric breakdown of the actuator due to heat accumulation,and viscoelasticity complicates precise control.The snap-through bistability of the Venus flytrap is one of the essential inspirations for bionic structure,which can be adopted to improve the shortcoming of dielectric elastomer actuators and develop a new actuation structure with low energy consumption,variable configuration,and multi-mode actuation.Hence,in this paper,the structural design principles of electroactive bistable actuators are first presented based on the total potential energy of the structure.Following that,a feasible design parameter region is provided,the influence of crucial parameters on the actuation stroke,trigger voltage,and actuation charge are discussed.Finally,according to the coupling relationship between the bending stiffness and the bistable property of the actuator,the adjusting methods of bistable actuation are explored.A qualitative experiment was performed to verify the feasibility and correctness of the bistable design methodology and the actuation regulation strategy.This study provides significant theoretical guidance and technical support for developing and applying dielectric elastomer actuators with multi-mode,high-performance,and long-life characteristics.
基金supported by the National Natural Science Foundation of China(Nos.11172128,51475228)the Specialized Research Fund for the Doctoral Program of Higher Education of China (No.20123218110001)+1 种基金the Research Fund of State Key Laboratory of Mechanics and Control of Mechanics Structures (Nanjing University of Aeronautics and Astronautics)(No.0515G01)the Priority Academic Program Development of Jiangsu Higher Education Institutions and the Funding of Jiangsu Innovation Program for Graduate Education(the Fundamental Research Funds for the Central Universities)(No.CXZZ12_ 0139)
文摘There exists inlet-engine match conflict between high and low speeds for a non-adjustable bump inlet.A scheme of using a bistable bump surface at the throat region of the inlet is proposed to adjust the throat area.The FEM model of the bistable surface is established with hinged constraint,and the bistability condition and structural transition process are investigated in detail.Moreover,the effects of loading method,loading position and structural parameters on critical driving force,input energy and structural strain are studied.Finally,the influences of an elastic boundary condition on the structural bistability are discussed.The results show that the bistability of the adjustable bump surface requires a certain boundary constraint and geometric parameter combination,and that there are local and overall snap-through phenomena during transition which are related to the loading position and structural parameters.Therefore,suitable loading position and structural material could reduce input energy and meet the demand of structural strain.
基金Project supported by the Russian Foundation for Basic Research(RFBR)(Grant Nos.16-32-00043 and 14-02-97026)
文摘The effects in electrostatic models of chevron surface-stabilized ferroelectric liquid crystals are investigated through numerical modeling. To study smectic C＊ director distribution within the cell, we consider two nonlinear approaches： the chevron interface does not interplay with the electric field; the electric field interplays with the chevron interface. The obtained results of the director field distribution are compared with the earlier linearized studies. We find that whether or not the electric field interplays with the chevron interface, the electro-optic response requires a generalized approach for its description. The threshold electric field, which is necessary for switching between two stable director states in the chevron cell is evaluated. This study suggests that, in many cases of practical interest, electro-optic response to the electric field and the threshold electric field can be precisely estimated. We argue that, beside being numerically efficient, our approach provides a convenient and a novel standpoint for looking at the electro-optic response problem.
基金This research was partially supported by tlie National Natural Science Foundation of China(11871231,11,526095).
文摘In this paper,we focus on the dynamic behaviors of the bistability for a two-species Lotka–Volterra competition model with stage structure.Using the theory of generalized saddle-point behaviors,it is shown that there exists a C1-separatrixΓon its state space such that Species 2 wins the competition whenever the initial distribution is aboveΓ,while Species 1 wins the competition whenever the initial distribution is belowΓ.Combining with the previous conclusions of the system,we give a complete classification for global competitive dynamics.Furthermore,we carefully analyze the changes of the competition outcome after introducing the stage structure.Finally,some numerical simulations are provided to illustrate the effectiveness of the theoretical results.
