When a dielectric elastomer (DE) balloon is subjected to electromechanical loading, instability may happen. In recent experiments, it has been shown that the instability configuration of a DE balloon under electromechanical loading can be very different from that only subjected to mechanical load. It has also been observed in the experiments that the electromechanical instability phenomena of a DE balloon can be highly time-dependent. In this article, we adopt a nonlinear viscoelastic model for the DE membrane to investigate the time-dependent electromechanical instability of a DE balloon. Using the model, we show that under a constant electromechanical loading, a DE balloon may gradually evolve from a convex shape to a non-convex shape with bulging out in the centre, and compressive hoop stress can also gradually develop the balloon, resulting in wrinkles as observed in the experiments. We have further shown that the snap-through instability phenomenon of the DE balloon also greatly depends on the ramping rate of the applied voltage.
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http://dx.doi.org/10.1098/rspa.2019.0316 | DOI Listing |
Polymers (Basel)
December 2024
School of Science, Harbin Institute of Technology, Shenzhen 518055, China.
As a category of polymeric materials, soft dielectrics, such as most elastomers and rubber-like materials, have shown great potential for extensive applications in various fields. Owing to their intriguing electromechanical coupling behaviors, the morphological instabilities in soft dielectrics have been an active research field in recent years. In this work, the recent progress in experimental and theoretical research on their electromechanical morphological instabilities is reviewed, especially regarding the theoretical aspect.
View Article and Find Full Text PDFSci Rep
December 2024
Guangzhou Institute of Technology, Xidian University, Guangzhou, 510555, China.
Reflector antenna has been widely used in deep space exploration, radar warning, and other fields, all of which requires high pointing accuracy. The antenna elevation bearings are the key component that guarantees its pointing accuracy, while any degradation or fault can seriously affect the antenna's performance, leading to deviations in antenna pointing and instability during operation. However, the relationship between the antenna elevation bearing fault and its pointing accuracy remains unclear because there is insufficient experimental faulty transmission data and pointing error collected from the test-rig simultaneously.
View Article and Find Full Text PDFAdv Sci (Weinh)
December 2024
Key Laboratory of Urban Rail Transit Intelligent Operation and Maintenance Technology & Equipment of Zhejiang Province, College of Engineering, Zhejiang Normal University, Jinhua, 321004, P. R. China.
Small
December 2024
Institute for Composites Science Innovation (InCSI), School of Materials Science and Engineering, Zhejiang University, 866 Yuhangtang Road, Hangzhou, 310058, P. R. China.
Capacitive flexible sensors often encounter instability caused by temperature fluctuations, electromagnetic interference, stray capacitance effects, and signal noise induced by ubiquitous vibrations. The challenge lies in achieving comprehensive anti-jamming abilities while preserving a simplistic structure and manufacturing process. To tackle this dilemma, a straightforward and effective design is utilized to achieve comprehensive and robust anti-jamming properties in capacitive sensors.
View Article and Find Full Text PDFEur Heart J Case Rep
November 2024
Department of Cardiology, CHU Clermont-Ferrand, CNRS, Université Clermont Auvergne, 58 rue Montalembert, 63000 Clermont-Ferrand, France.
Background: Spontaneous coronary artery dissection (SCAD) remains a rare form of acute coronary syndrome (ACS) in young women. It is not always easy to diagnose and its management can be complex, particularly in the case of severe forms.
Case Summary: A 29-year-old Mahorese woman presented with non-ST-elevation acute coronary syndrome 72 h after vaginal delivery of an uncomplicated twin pregnancy.
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