Design of a Dielectric Elastomer Cylindrical Actuator With Quasi-Constant Available Thrust: Modeling Procedure and Experimental Validation

A novel design for a dielectric elastomer (DE) actuator is presented. The actuator is obtained by coupling a cylindrical DE film with a series of slender beams axially loaded beyond their buckling limit. Similar to previous published solutions, where different actuator geometries were coupled with compliant mechanisms of various topologies, the elastic beams are designed so as to provide a suitable compensating force that allows obtaining a quasi-constant available thrust along the entire actuator stroke. Whilst the elastic beam are sized on the basis of an analytical procedure, the overall system performance is evaluated by means of multiphysics finite element (FE) analysis, accounting for the large deflection of the buckled-beam springs (BBSs) and for the DE material hyperelasticity. Numerical and experimental results are finally provided, which demonstrate the prediction capabilities of the proposed modeling method and confirm that well behaved cylindrical actuators can be conceived and produced

DESIGN AND MODELING OF A DIELECTRIC ELASTOMER CYLINDRICAL ACTUATOR WITH QUASI-CONSTANT AVAILABLE THRUST

A novel design for a Dielectric Elastomer (DE) actuator is presented. The actuator is obtained by coupling a cylindrical DE film with a series of slender beams axially loaded beyond their buckling limit. Similarly to previous published solutions, where different actuator geometries were coupled with compliant mechanisms of various topologies, the elastic beams are designed so as to provide a suitable compensating force that allows obtaining a quasi-constant available thrust along the entire actuator stroke. The overall system performance are subsequently evaluated by means finite element analysis, accounting for the large deflection of the buckled-beam springs and for the DE material hyperelasticity. Final results confirm that compact and better behaved constant force cylindrical actuators can be obtained, which potentially outperform similar devices in terms of achievable stroke

Accelerometri MEMS: caratterizzazione dinamica e confronto con i sensoripiezoelettrici

Gli accelerometri di tipo piezoelettrico sono probabilmente i pi\uf9 diffusi sensori diaccelerazione attualmente in commercio per l\u2019ambito industriale. Hanno infatti un\u2019ampiabanda dinamica di linearit\ue0,sono influenzati in modo trascurabile da rumore etemperatura, e possono misurare elevati valori di accelerazione. Negli ultimi anni sonostati proposti sul mercato dei nuovi tipi di accelerometri di tipo MEMS (Micro Electro-Mechanical Systems) che hanno la caratteristica di essere molto meno costosi deipiezoelettrici sia per i materiali impiegati sia per il processo di fabbricazione di massa. Sefino a poco tempo fa la qualit\ue0 degli accelerometri MEMS non era paragonabile a quelladei piezoelettrici, la continua evoluzione tecnologica ha estremamente ridotto le differenzetra le due tipologie di sensori. Lo scopo di questo articolo \ue8 di confrontare le prestazionidinamiche di alcuni accelerometri di tipo piezoelettrico e di tipo MEMS, per valutarne ledifferenze, qualit\ue0 e difetti, e fornire un\u2019introduzione alle problematiche che nascono nelpassaggio da una tecnologia all\u2019altr