Modeling the response of polymer–ionic liquid electromechanical actuators

Drozdov, Aleksey D.

doi:10.1007/s00707-015-1471-7

Cited by 9 publications

(14 citation statements)

References 72 publications

(114 reference statements)

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“…Unsurprisingly, several studies on TPU focused on the correlation between their composition and mechanical properties at small and large strain 1,3–5 with the target to further explore the field of applications of this class of materials. In particular, the presence of a mechanical behavior with the same characteristics as those of the Mullins effect classically observed in filled rubbers 6 (higher energy losses and stress softening during the first loading‐unloading cycle), was reported in several TPU with different composition of HS and SS 3,7,8 …”

Section: Introductionmentioning

confidence: 56%

Strain induced strengthening of soft thermoplastic polyurethanes under cyclic deformation

Scetta

Selles³

et al. 2021

Journal of Polymer Science

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We investigate the cyclic mechanical behavior in uniaxial tension of three different commercial thermoplastic polyurethane elastomers (TPU) often considered as a sustainable replacement for common filled elastomers. All TPU have similar hard segment contents and linear moduli but sensibly different large strain properties as shown by X‐ray analysis. Despite these differences, we found a stiffening effect after conditioning in step cyclic loading which greatly differs from the common softening (also referred as Mullins effect) observed in chemically crosslinked filled rubbers. We propose that this self‐reinforcement is related to the fragmentation of hard domains, naturally present in TPU, in smaller but more numerous sub‐units that may act as new physical crosslinking points. The proposed stiffening mechanism is not dissimilar to the strain‐induced crystallization observed in stretched natural rubber, but it presents a persistent nature. In particular, it may cause a local reinforcement where an inhomogeneous strain field is present, as is the case of a crack propagating in cyclic fatigue, providing a potential explanation for the well‐known toughness and wear resistance of TPU.

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Section: Introductionmentioning

confidence: 56%

Strain induced strengthening of soft thermoplastic polyurethanes under cyclic deformation

Scetta

Selles³

et al. 2021

Journal of Polymer Science

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“…Cha and Porfiri [35] specialise their model to static bending deformations, whereby they investigate the IPMC steady state electrochemical response as a function of an imposed small curvature. A similar investigation has been more recently carried out in [47], also focussing on the porosity evolution in the IPMC membrane.…”

Section: Introductionmentioning

confidence: 89%

Modelling compression sensing in ionic polymer metal composites

Volpini

Bardella

Rodella

et al. 2017

Smart Mater. Struct.

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Ionic polymer metal composites (IPMCs) consist of an ionomeric membrane, including mobile counterions, sandwiched between two thin noble metal electrodes. IPMCs find application as sensors and actuators, where an imposed mechanical loading generates a voltage across the electrodes, and, vice versa, an imposed electric field causes deformation. Here, we present a predictive modelling approach to elucidate the dynamic sensing response of IPMCs subject to a time-varying through-the-thickness compression (‘compression sensing’). The model relies on the continuum theory recently developed by Porfiri and co-workers, which couples finite deformations to the modified Poisson–Nernst–Planck (PNP) system governing the IPMC electrochemistry. For the ‘compression sensing’ problem we establish a perturbative closed-form solution along with a finite element (FE) solution. The systematic comparison between these two solutions is a central contribution of this study, offering insight on accuracy and mathematical complexity. The method of matched asymptotic expansions is employed to find the analytical solution. To this end, we uncouple the force balance from the modified PNP system and separately linearise the PNP equations in the ionomer bulk and in the boundary layers at the ionomer–electrode interfaces. Comparison with FE results for the fully coupled nonlinear system demonstrates the accuracy of the analytical solution to describe IPMC sensing for moderate deformation levels. We finally demonstrate the potential of the modelling scheme to accurately reproduce experimental results from the literature. The proposed model is expected to aid in the design of IPMC sensors, contribute to an improved understanding of IPMC electrochemomechanical response, and offer insight into the role of nonlinear phenomena across mechanics and electrochemistry.

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“…These devices' operating mechanism consists of hydrated ions migration inside the ionomeric channels in response to an electric field generated after a bias application in the metal electrodes 17 . This ionic movement causes an internal pressure gradient, leading to a spatially nonuniform mass accumulation, which causes the device to bend 18 (Figure 1b). Therefore, several factors influence mechanical performance, such as the dependence on the operating environment (temperature and humidity) [19][20][21][22] , counterion type 23 , polymeric membrane dimensions (especially the thickness), and electrode physical properties 24 .…”

Section: Introductionmentioning

confidence: 99%

PI Controller for IPMC Actuators Based on Nafion®/PT Using Machine Vision for Feedback Response at Different Relative Humidities

et al. 2022

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Ionomeric Polymer-Metal Composites (IPMCs) are sandwich-like materials based in a polymeric membrane covered on both sides by metallic electrodes. Its operation mechanism consists of hydrated ions migration in response to an external electrical field generated between the electrodes, leading to a spatially nonuniform mass accumulation which causes the device to bend. Its performance as an actuator depends mainly on the environment's relative humidity and electrical stimuli. Consequently, IPMCs present variations in the electromechanical properties exhibiting nonlinearities and time-varying behaviors, limiting the major applications. For this reason, this paper investigated a PI controller performance to overcome these drawbacks and effectively control a Nafion-based IPMC-Li + exposed to different relative humidities and electrical stimulis. The PI control system uses a camera with a machine vision application as a feedback sensor. Support instrumentation was developed to control the relative humidity, apply an electrical stimulus, and measure the electromechanical response. The pattern recognition algorithm implemented in the controller is efficient, with accuracy above 95%, making the feedback sensor reliable. Therefore, the PI controller was effective, stable, and capable of controlling and characterizing IPMC devices when relative humidity was above 60% at a low-frequency displacement and avoided the undesired back-relaxation phenomenon.

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Modeling the response of polymer–ionic liquid electromechanical actuators

Cited by 9 publications

References 72 publications

Strain induced strengthening of soft thermoplastic polyurethanes under cyclic deformation

Strain induced strengthening of soft thermoplastic polyurethanes under cyclic deformation

Modelling compression sensing in ionic polymer metal composites

PI Controller for IPMC Actuators Based on Nafion®/PT Using Machine Vision for Feedback Response at Different Relative Humidities

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