Phenomena of nonlinear oscillation and special resonance of a dielectric elastomer minimum energy structure rotary joint

Abstract

The dielectric elastomer minimum energy structure can realize large angular deformations by a small voltage-induced strain of the dielectric elastomer, so it is a suitable candidate to make a rotary joint for a soft robot. Driven with an alternating electric field, the joint deformation vibrational frequency follows the input voltage frequency. However, the authors find that if the rotational inertia increases such that the inertial torque makes the frame deform over a negative angle, then the joint motion will become complicated and the vibrational mode will alter with the change of voltage frequency. The vibration with the largest amplitude does not occur while the voltage frequency is equal to natural response frequency of the joint. Rather, the vibrational amplitude will be quite large over a range of other frequencies at which the vibrational frequency is half of the voltage frequency. This phenomenon was analyzed by a comparison of the timing sequences between voltage and joint vibration. This vibrational mode with the largest amplitude can be applied to the generation lift in a flapping wing actuated by dielectric elastomers.

A rotary joint for a flapping wing actuated by dielectric elastomers: design and experiment

“…[20]. The fastest response is restricted by natural frequency, so it is very important to increase the joint natural frequency.…”

“…The relationship between joint torque and dimension b Meccanica angular displacement by method of Ref [20]. as shown inFig.…”

Analysis, experiment, and correlation of a petal-shaped actuator based on dielectric elastomer minimum-energy structures

“…DEMES have attracted intensive attention due to its ease of fabrication, intrinsic combination of soft and hard materials, and diversity of configurations that can be realized by exploring mechanical buckling. Typical DEMES devices include gripper [22], oscillator [23], compliant and bistable mechanisms [24,25], and soft robot [26].…”

Coupled nonlinear oscillation and stability evolution of viscoelastic dielectric elastomers

“…However, a DE membrane exhibits snap-through instability easily without prestretch. Recently, extensive studies have been developed concerning the dynamic performance of DE actuators 8,11,12,[24][25][26][27][28][29][30][31][32] being applied as frequency tuning devices, 25 pumps, 26 acoustic actuators, 12 loudspeakers, 11 vibrotactile displays for mobile application, 2 and so on. 22,23 Under the same area pre-expansion, the equibiaxially prestretched DE exhibits a dominant performance in stability over the non-equibiaxially prestretched one, 21 which reveals the inferior function of non-equibiaxial tensile forces in DE statics.…”