Fracture toughness, hysteresis and stretchability of dielectric elastomers under equibiaxial and biaxial loading
TL;DR: In this paper, two potential dielectric elastomers, acrylic-based VHB and silicone-based Ecoflex, are tested and characterized under common loading conditions called equibiaxial and biaxial loading.
About: This article is published in Polymer Testing.The article was published on 2019-10-01. It has received 20 citations till now. The article focuses on the topics: Fracture toughness & Deformation (engineering).
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TL;DR: In this article, the authors carried out an experimental study of the rupture behavior of membranes of an acrylic dielectric elastomer and found that introducing a pre-crack into a membrane drastically reduced the stretch at rupture.
Abstract: Dielectric elastomer transducers are often subject to large tensile stretches and are susceptible to rupture. Here we carry out an experimental study of the rupture behavior of membranes of an acrylic dielectric elastomer. Pure-shear test specimens are used to measure force-displacement curves, using samples with and without pre-cracks. We find that introducing a pre-crack into a membrane drastically reduces the stretch at rupture. Furthermore, we measure the stretch at rupture and fracture energy using samples of different heights at various stretch-rates. The stretch at rupture is found to decrease with sample height, and the fracture energy is found to increase with stretch-rate.
52 citations
01 Sep 2021
TL;DR: In this paper, a bioinspired inchworm and earthworm-like soft structures with intrinsic strain sensing achieved by seamless embedding of a graphite-paste-based sensor material are presented.
Abstract: Stimulus-responsive soft structures, with biological organs like intrinsic sensing, are needed to enable controlled movements and hence bring the transformative advances in soft robotics. Herein, bioinspired inchworm- and earthworm-like soft structures with intrinsic strain sensing achieved by seamless embedding of a graphite-paste-based sensor material are presented. The developed strain sensor exhibits a record stretchability (900%) and sensitivity (of 103 up to ≈200 and of the order of 105 at around 700% linear strain). With tiny permanent magnets incorporated at the ends of these soft structures, the sensory-feedback-based controlled movements of magnetically driven inchworm- and earthworm-like soft robots are also demonstrated. The presented results potentially boost the prospects of self-sensing in soft robots and advance the field toward cognitive soft robotics.
26 citations
20 Apr 2022
8 citations
TL;DR: In this paper , the effect of biaxial strain rates and prestretch ratios on elastomeric morphing skin properties such as stiffness, hysteresis losses (%), and stress relaxations (%) from an experimental perspective was investigated.
6 citations
References
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03 Mar 2017
TL;DR: Fracture Mechanics: Fundamentals and Applications, Fourth Edition as discussed by the authors is the most useful and comprehensive guide to fracture mechanics available It has been adopted by more than 150 universities worldwide and used by thousands of engineers and researchers.
Abstract: Fracture Mechanics: Fundamentals and Applications, Fourth Edition is the most useful and comprehensive guide to fracture mechanics available It has been adopted by more than 150 universities worldwide and used by thousands of engineers and researchers This new edition reflects the latest research, industry practices, applications, and computational analysis and modeling It encompasses theory and applications, linear and nonlinear fracture mechanics, solid mechanics, and materials science with a unified, balanced, and in-depth approach Numerous chapter problems have been added or revised, and additional resources are available for those teaching college courses or training sessions Dr Anderson’s own website can be accessed at wwwFractureMechanicscom
5,035 citations
TL;DR: It is shown that prestraining the film further improves the performance of electrical actuators made from films of dielectric elastomers coated on both sides with compliant electrode material.
Abstract: Electrical actuators were made from films of dielectric elastomers (such as silicones) coated on both sides with compliant electrode material. When voltage was applied, the resulting electrostatic forces compressed the film in thickness and expanded it in area, producing strains up to 30 to 40%. It is now shown that prestraining the film further improves the performance of these devices. Actuated strains up to 117% were demonstrated with silicone elastomers, and up to 215% with acrylic elastomers using biaxially and uniaxially prestrained films. The strain, pressure, and response time of silicone exceeded those of natural muscle; specific energy densities greatly exceeded those of other field-actuated materials. Because the actuation mechanism is faster than in other high-strain electroactive polymers, this technology may be suitable for diverse applications.
2,969 citations
TL;DR: A number of materials have been explored for their use as artificial muscles, but dielectric elastomers appear to provide the best combination of properties for true muscle-like actuation, and widespread adoption of DEs has been hindered by premature breakdown and the requirement for high voltages and bulky support frames.
Abstract: A number of materials have been explored for their use as artificial muscles Among these, dielectric elastomers (DEs) appear to provide the best combination of properties for true muscle-like actuation DEs behave as compliant capacitors, expanding in area and shrinking in thickness when a voltage is applied Materials combining very high energy densities, strains, and efficiencies have been known for some time To date, however, the widespread adoption of DEs has been hindered by premature breakdown and the requirement for high voltages and bulky support frames Recent advances seem poised to remove these restrictions and allow for the production of highly reliable, high-performance transducers for artificial muscle applications
1,299 citations
TL;DR: In this paper, stress-strain data were given for two types of vulcanized rubber: (1) an 8% S rubber and (2) a latex rubber, and the types of deformation studied were simple elongation, 2-dimensional extension, compression, pure shear, and combined elongation and shear.
Abstract: Stress-strain data are given for two types of vulcanized rubber: (1) an 8% S rubber, and (2) a latex rubber. The types of deformation studied were simple elongation, 2-dimensional extension (or compression), pure shear, and combined elongation and shear. Comparison with the theoretical relations based on the molecular-network model shows the agreement to be good for the 2-dimensional extension, but less good for simple elongation and shear. The effect of combined elongation and shear is satisfactorily accounted for. It is concluded that the theory provides a satisfactory explanation of rubberlike elasticity, and forms a useful basis for the description of the mechanical properties of rubber subjected to large deformations of any type.
579 citations
TL;DR: In this article, a soft dielectric membrane is shown to be prone to snap-through instability, and the instability can be harnessed to achieve giant voltage-triggered deformation.
Abstract: A soft dielectric membrane is prone to snap-through instability. We present theory and experiment to show that the instability can be harnessed to achieve giant voltage-triggered deformation. We mount a membrane on a chamber of a suitable volume, pressurize the membrane into a state near the verge of the instability, and apply a voltage to trigger the snap without causing electrical breakdown. For an acrylic membrane we demonstrate voltage-triggered expansion of area by 1692%, far beyond the largest value reported in the literature. The large expansion can even be retained after the voltage is switched off.
374 citations