Partial discharge analysis of prestretched and unstretched acrylic elastomers for Dielectric Elastomer Actuators (DEA)

Muffoletto, Daniel P.; Burke, K.; Zirnheld, J.

doi:10.1117/12.915272

Cited by 13 publications

(8 citation statements)

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“…Both water vapor diffusion and charge migration would result in enhanced space charge accumulation within the silicone elastomer and a higher concentration of ionic and conductive species within the silicone elastomer as the voltage increases, thereby leading to higher local electric fields. This could locally initiate partial discharges in air-filled microcavities, triggering a dielectric breakdown event [50,57,58]. As shown in figure 5, higher elastomer prestretch yields higher dielectric breakdown strengths in dry conditions (10%RH) for Elastosil 2030/20, Sylgard 186 and Sylgard 184.…”

Section: Effect Of Temperaturementioning

confidence: 98%

Influence of humidity, temperature and prestretch on the dielectric breakdown strength of silicone elastomer membranes for DEAs

Albuquerque

Shea

2020

Smart Mater. Struct.

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Humidity, temperature and membrane prestretch influence the dielectric breakdown strength of elastomer membranes. These three factors thus also influence the maximum force and strain that dielectric elastomer actuators (DEAs) can generate, as the Maxwell pressure is proportional to the applied voltage squared, and limited by the breakdown field. We compared several commercial silicones, 10 to 25 µm thick under different equibiaxial prestretch conditions, for temperatures between 20 °C and 80 °C and relative humidity from 10% to 90%, measuring both breakdown fields and mechanical properties in order to compute two figures of merit for DEAs. The silicone films all have breakdown strengths of order 100 V µm−1. Higher humidity (90% RH) leads to decreased dielectric breakdown strengths compared to lower humidity (10% RH): up to 43% reduction for prestretches of 1.3 and 1.5, but only 2% to 10% reduction for prestretch of 1.1. Higher prestretch leads to up to 50% higher breakdown field, but also leads to higher effective Young’s modulus due to strain stiffening. Higher temperatures (80 °C) lead to up to 30% lower breakdown voltages compared to lower temperatures (20 °C). Higher prestretch generally enhances the maximum Maxwell stress because of higher dielectric breakdown strength, but reduces the strain figure of merit owing to increased Young’s moduli at high prestretch. For silicone elastomers, Sylgard 184 shows the highest stress figures of merit and LSR 4305 the highest strain figures of merit. Data for VHB is also presented for comparison. This work allows identifying elastomers better suited to harsh environments, and to selecting operating voltages that enable safe operation for a wide range of environmental conditions.

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Section: Effect Of Temperaturementioning

confidence: 98%

Influence of humidity, temperature and prestretch on the dielectric breakdown strength of silicone elastomer membranes for DEAs

Albuquerque

Shea

2020

Smart Mater. Struct.

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“…3 Reasons for enhanced dielectric strength by pre-stretch are explained by: i) suppression of air void in the polymer film, 10 ii) stiffening of the dielectric film. 11 However, DEA even with pre-stretch is still liable to breakdown by electromechanical or pull-in instability.…”

Section: Introductionmentioning

confidence: 99%

Very high breakdown field strength for dielectric elastomer actuators quenched in dielectric liquid bath

Lau

2013

SPIE Proceedings

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Dielectric elastomer actuators (DEAs) are prone to failure by pull-in instability. However, this work showed that DEAs, which were immersed in a silicone oil bath (Dow Corning Fluid 200 50cSt), can survive the pull-instability and operates beyond the pull-in voltage. Membrane DEAs (VHB 4905), which were pre-stretched bi-axially at 200% strain and immersed in the oil bath, survived a very high field strength (>800 MV/m) and demonstrated areal strains up to 140%. The dielectric strength, achieved in the immersion, is approximately two times larger than that in the air (450 MV/m). This is achieved because the dielectric liquid bath helps to quench the localized electrical breakdown, which would have discharged sparks and burnt the dielectric film in the air.

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“…The favourable effect of pre-stretching on breakdown strength has been discussed by severable research groups. Muffoletto et al [10], for instance, argued that improved breakdown strength following pre-stretching was caused by the favourable realignment of material imperfections, such as voids and micro-cracks. Huang et al [11], in the meantime, showed that breakdown strength depends on the thickness of the samples tested.…”

Section: Introductionmentioning

confidence: 99%

The electrical breakdown strength of pre-stretched elastomers, with and without sample volume conservation

Zakaria

Morshuis

Benslimane

et al. 2015

Smart Mater. Struct.

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In practice, the electrical breakdown strength of dielectric electroactive polymers (DEAPs) determines the upper limit for transduction. During DEAP actuation, the thickness of the elastomer decreases, and thus the electrical field increases and the breakdown process is determined by a coupled electro-mechanical failure mechanism. A thorough understanding of the mechanisms behind the electro-mechanical breakdown process is required for developing reliable transducers. In this study, two experimental configurations were used to determine the stretch dependence of the electrical breakdown strength of polydimethylsiloxane (PDMS) elastomers. Breakdown strength was determined for samples with and without volume conservation and was found to depend strongly on the stretch ratio and the thickness of the samples. PDMS elastomers are shown to increase breakdown strength by a factor of ∼3 when sample thickness decreases from 120 to 30 μm, while the biaxial pre-stretching (λ = 2) of samples leads similarly to an increase in breakdown strength by a factor of ∼2.5.

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Partial discharge analysis of prestretched and unstretched acrylic elastomers for Dielectric Elastomer Actuators (DEA)

Cited by 13 publications

References 0 publications

Influence of humidity, temperature and prestretch on the dielectric breakdown strength of silicone elastomer membranes for DEAs

Influence of humidity, temperature and prestretch on the dielectric breakdown strength of silicone elastomer membranes for DEAs

Very high breakdown field strength for dielectric elastomer actuators quenched in dielectric liquid bath

The electrical breakdown strength of pre-stretched elastomers, with and without sample volume conservation

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