Finite Element Modeling and Simulation of a Soft Array of Dielectric Elastomer Actuators

Croce, Sipontina; Moretti, Giacomo; Neu, Julian; Hubertus, Jonas; Seelecke, Stefan; Schultes, Günter; Rizzello, Gianluca

doi:10.1115/smasis2021-67752

Cited by 5 publications

(5 citation statements)

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“…The electrical coupling arises when the Maxwell pressure acting on a DE, resulting from the application of an external electric field, induces a stress distribution which affects the mechanical response of the neighboring elements. This effect has already been studied experimentally in [43], and also validated with a model-based approach in [44]. In these works, it was shown that the electrical activation of one DE has generally a small influence on the reaction force of its neighbors.…”

Section: Single Membrane Dea-array Conceptmentioning

confidence: 68%

Distributed Electro-Mechanical Coupling Effects in a Dielectric Elastomer Membrane Array

et al. 2022

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Background Dielectric elastomer (DE) transducers permit to effectively develop large-deformation, energy-efficient, and compliant mechatronic devices. By arranging many DE elements in an array-like configuration, a soft actuator/sensor system capable of cooperative features can be obtained. When many DE elements are densely packed onto a common elastic membrane, spatial coupling effects introduce electro-mechanical interactions among neighbors, which strongly affect the system actuation and sensing performance. To effectively design cooperative DE systems, those coupling effects must be systematically characterized and understood first. Objective As a first step towards the development of complex cooperative DE systems, in this work we present a systematic characterization of the spatial electro-mechanical interactions in a 1-by-3 array of silicone DEs. More specifically, we investigate how the force and capacitance characteristics of each DE in the array change when its neighbors are subject to different types of mechanical or electrical loads. Force and capacitance are chosen for this investigation, since those quantities are directly tied to the DE actuation and sensing behaviors, respectively. Methods An electro-mechanical characterization procedure is implemented through a novel experimental setup, which is specifically developed for testing soft DE arrays. The setup allows to investigate how the force and capacitance characteristics of each DE are affected by static deformations and/or electrical voltages applied to its nearby elements. Different combinations of electro-mechanical loads and DE neighbors are considered in an extensive experimental campaign. ResultsThe conducted investigation shows the existence of strong electro-mechanical coupling effects among the different array elements. The interaction intensity depends on multiple parameters, such as the distance between active DEs or the amount of deformation/voltage applied to the neighbors, and provides essential information for the design of array actuators. In some cases, such coupling effects may lead to changes in force up to 9% compared to the reference configuration. A further coupling is also observed in the DE capacitive response, and opens up the possibility of implementing advanced and/or distributed self-sensing strategies in future applications. Conclusion By means of the conducted experiments, we clearly show that the actuation and sensing characteristics of each DE in the array are strongly influenced by the electro-mechanical loading state of its neighbors. The coupling effects may significantly affect the overall cooperative system performance, if not properly accounted for during the design. In future works, the obtained results will allow developing cooperative DE systems which are robust to, and possibly take advantage of, such spatial coupling effects.

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Section: Single Membrane Dea-array Conceptmentioning

confidence: 68%

Distributed Electro-Mechanical Coupling Effects in a Dielectric Elastomer Membrane Array

et al. 2022

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“…Based on the above COMSOL approach, Croce et al also developed a lumpedparameter version of the model [21,22], which will allow for the computationally efficient implementation of future cooperative control strategies (see Figure 6). Based on the above COMSOL approach, Croce et al also developed a lumped-parameter version of the model [21,22], which will allow for the computationally efficient implementation of future cooperative control strategies (see Figure 6).…”

Section: Modeling and Simulationmentioning

confidence: 99%

“…Operating the DE afterwards in a strain range below the pre-stretch level unfolds the wrinkles, which, coupled with the extremely low electrode thickness of <20 nm, does not impact the stiffness of the DEA negatively (Figure 7a, top right), hence allowing for efficient actuation. Based on the above COMSOL approach, Croce et al also developed a lumped-parameter version of the model [21,22], which will allow for the computationally efficient implementation of future cooperative control strategies (see Figure 6).…”

Section: Electrodesmentioning

confidence: 99%

Dielectric Elastomer Cooperative Microactuator Systems—DECMAS

et al. 2023

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This paper presents results of the first phase of “Dielectric Elastomer Cooperative Microactuator Systems” (DECMAS), a project within the German Research Foundation Priority Program 2206, “Cooperative Multistable Multistage Microactuator Systems” (KOMMMA). The goal is the development of a soft cooperative microactuator system combining high flexibility with large-stroke/high-frequency actuation and self-sensing capabilities. The softness is due to a completely polymer-based approach using dielectric elastomer membrane structures and a specific silicone bias system designed to achieve large strokes. The approach thus avoids fluidic or pneumatic compo-nents, enabling, e.g., future smart textile applications with cooperative sensing, haptics, and even acoustic features. The paper introduces design concepts and a first soft, single-actuator demonstrator along with experimental characterization, before expanding it to a 3 × 1 system. This system is used to experimentally study coupling effects, supported by finite element and lumped parameter simulations, which represent the basis for future cooperative control methods. Finally, the paper also introduces a new methodology to fabricate metal-based electrodes of sub-micrometer thickness with high membrane-straining capability and extremely low resistance. These electrodes will enable further miniaturization towards future microscale applications.

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“…For the sake of this analysis, we consider a single DE membrane with the dimension defined in figure 9(a) (the same numerical values as discussed in section 3.1 are used), subject to a pre-stretch λ p = 1.10. For the simulations, the material parameters are chosen as in our previous work [53], while the boundary conditions are set equivalently to section 4.1.3. The membrane deformation is applied on the central portion of the active area as a prescribed displacement (9), and the reaction-force along the Z-axis is evaluated accordingly.…”

Section: Comparison With a Fully-coupled Three-dimensional Formulationmentioning

confidence: 99%

“…Because of the extremely high surface-tothickness ratio of the considered membrane (on the order of 10 5 m), the formulation presented in section 4.1 treats the DE as a thin membrane element, assuming that the electric field distribution is the same as in a parallel plate capacitor, and neglecting fringe electric fields (the latter assumption is also motivated by our previous studies in [53], in which we showed that fringing fields have a negligible impact on the overall array output). In this section, we validate these assumptions by comparing the predictions of the presented formulation with those of a fully-coupled three-dimensional formulation.…”

Section: Comparison With a Fully-coupled Three-dimensional Formulationmentioning

confidence: 99%

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

Croce

Neu

Moretti

et al. 2022

Smart Mater. Struct.

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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.

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Finite Element Modeling and Simulation of a Soft Array of Dielectric Elastomer Actuators

Cited by 5 publications

References 0 publications

Distributed Electro-Mechanical Coupling Effects in a Dielectric Elastomer Membrane Array

Distributed Electro-Mechanical Coupling Effects in a Dielectric Elastomer Membrane Array

Dielectric Elastomer Cooperative Microactuator Systems—DECMAS

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

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