Pull-in instability often occurs when a film of a dielectric elastomer is subjected to an electric field. In this work, we concoct a set of simple, experimentally implementable, conditions that render the dielectric elastomer film impervious to pull-in instability for all practical loading conditions. We show that a uniaxially pre-stretched film has a significantly large actuation stretch in th...

The natural frequency and pull-in instability of clamped-clamped nano-actuators in the presence of a dielectric layer are analyzed. The influence of the presence of Casimir force, electrostatic force, fringing field effect, axial force, stretching effects and the size effect are taken into account. The governing equation of the dynamic response of the actuator is transformed in a non-dimensiona...

The present research attempts to explain dynamic pull-in instability of functionally graded micro-cantilevers actuated by step DC voltage while the fringing-field effect is taken into account in the vibrational equation of motion. By employing modern asymptotic approach namely Homotopy Perturbation Method with an auxiliary term, high-order frequency-amplitude relation is obtained, then the infl...

background: tibial avulsion fractures of the posterior cruciate ligament are not infrequent. however, controversies exist between the fixation of the fragments and their reconstruction in the cases with small bony fragments. this prospective study was undertaken to study the results after fixation of the fragments by the malleolar screw and the pull through suture techniques.   methods: from ju...

BACKGROUND The Fahn's pull (or retropulsion) test is an item in the motor section of the Unified Parkinson's Disease Rating Scale, which is used almost exclusively to classify postural instability in Parkinson's disease (PD). However, the test is hard to standardize and is often performed incorrectly, making it hard to interpret. Moreover, it may not be safe to administer in patients who experi...

We analyze transient finite electroelastodynamic deformations of a perfect electrically conducting undamped clamped–clamped beam, a clamped–clamped parabolic arch and a clamped–clamped bell-shaped arch suspended over a flat rigid semi-infinite perfect conductor. The pull-in instability in a beam and the pull-in and the snap-through instabilities in the two arches due to time-dependent potential...

This paper examines the pull-in behavior of a bio-mass sensor with a cantilevered CNT actuated electrostatically by considering rippling deformation. Although this phenomenon can remarkably change the behavior of CNT, its effect on the performance of a CNT-based mass sensor has not been investigated thus far. This investigation is based on modified Euler-Bernoulli beam theory and rippling effec...

This study is devoted to providing predictions of the pull-in parameters (pull-in voltage and pull-in displacement) of electro-statically actuated micro-beams based on a continuous model using Genetic Algorithm (GA) technique. A phenomenon in which the actuated electrode comes in direct contact with the fixed electrode due to the electrostatic force is called pull-in instability. Accurate deter...