Finite element modeling and validation of a soft array of spatially coupled dielectric elastomer transducers

Abstract

Dielectric elastomer (DE) transducers are suitable candidates for the development of compliant mechatronic devices, such as wearable smart skins and soft robots. If many independently-controllable DEs are closely arranged in an array-like configuration, sharing a common elastomer membrane, novel types of cooperative and soft actuator/sensor systems can be obtained. The common elastic substrate, however, introduces strong electro-mechanical coupling effects among neighborg DEs, which highly influence the overall membrane system actuation and sensing characteristics. To effectively design soft cooperative systems based on DEs, these effects need to be systematically understood and modeled first. As a first step towards the development of soft cooperative DE systems, in this paper we present a finite element (FE) simulation approach for a 1-by-3 silicone array of DE units. After defining the system constitutive equations and the numerical assumptions, an externsive experimental campaign is conducted to calibrate and validate the model. The simulations results accurately predict the changes in force (actuation behavior) and capacitance (sensing behavior) of the different elements of the array, when their neighbors are subjected to different electro-mechanical loads. Quantitatively, the model reproduces the force and capacitance responses with an average fit higher than 93% and 92%, respectively. Finally, the validated model is used to perform parameter studies, aimed at highlighting how the array performance depends on a relevant set of design parameters, i.e., DE-DE spacing, DE-outer structure spacing, membrane pre-stretch, array scale, and electrode shape. The obtained results will provide important guidelines for the future design of cooperative actuator/sensor systems based on DE transducers.

Finite element modeling and numerical investigation of the effects of miniaturization on the performance of dielectric elastomer actuators

“…The Neo-Hookean parameter is selected as C 10 = 0.18 MPa according to existing identification procedures based on Wacker Elastosil 2030 material, 23 while its bulk modulus is chosen according to commonly used values for the family of silicone rubbers as K c = 1.5 GPa. 24 By then choosing a sufficiently small value of compressive stretch along the 3rd dimension equal to λ 3 = 0.99, corresponding to a compressive strain ε 3 = λ 3 − 1 = −0.01, the appropriate value voltage value V b is determined with equation (7).…”

Self-sensing investigation of a dielectric elastomer actuator array

“…In our previous research 31 , we observed that single DEA elements, when placed onto the same elastomer membrane, exhibit a strong mechanical interaction with their neighboring actuators. This interaction manifests itself as variations in the mechanical actuation (Figure 3(a)) and sensing curves (Figure 3(b)) of individual DE elements during electrical activation of nearby units.…”

A Review of Cooperative Actuator and Sensor Systems Based on Dielectric Elastomer Transducers

“…This, in turn, results into high electric fields which are close to the breakdown strength of the material [79,80], negatively affecting the lifetime of the device. In addition, the strong nonlinearities of the material, in combination with the large deformations, makes their accurate modeling and control a highly challenging task [81,82].…”

“…By means of model-based optimization, it was possible to optimize the design of the biasing domes and, in turn, achieve a fully polymeric DEA capable of a stroke on the order of 3 mm for an actuator with a radius of 20 mm [109], see Figure 7b. Current research studies focus on the characterization [127] and modeling [82] of the electro-mechanical coupling effects occurring when many of those elements are placed onto a common elastic substrate in an array configuration (cf. Figure 7c), as well as on the development of laser-structuring electrode techniques for enabling local activation of the DEAs [71].…”