Electroactive polymers have been widely used as smart material for actuators in recent years. Electromechanical applications are currently focused on energy harvesting and actuation, including the development of wireless portable electronic equipment autonomous and specific actuators such as artificial muscles. The problem to be solved is to make its devices the most efficient, as possible in terms of harvested energy and action. These two criteria are controlled by the permittivity of the electrostrictive polymer used, the Young’s modulus, and their dependence on frequency and level of stress. In the present paper, we presented a model describing the mechanical behaviour of electrostrictive polymers with taking into account the mechanical losses. Young’s modulus follows a linear function of strain and stress. However, when the elongation becomes higher, the data obtained from this strain linear trend and significant hysteresis loops appear the reflections on the existence of mechanical losses. In this work, to provide the analysis of the experimental observations, we utilized a theoretical model in order to define a constitutive law implying a representative relationship between stress and strain. After detailing this theoretical model, the simulation results are compared with experimental ones. The results show that hysteresis loss increases with the increase of frequency and strain amplitude. The model used here is in good agreement with the experimental results.
Modal synchronized switch damping on inductor control is a vibration damping technique that combines the advantages of both semiactive and active control techniques based on a modal strategy. This method allows targeting any unwanted vibration mode of a structure while using a semiactive autonomous synchronized switch damping on inductor damping technique. This article presents a performance analysis of an improved modal synchronized switch damping on inductor approach called ''SSDI-Max.'' The particularity of this new approach is to maximize the self-generated voltage amplitude by a proper definition of the switch instants (voltage inversion) according to the chosen targeted mode. Following the basic modal synchronized switch damping on inductor technique, the switch is synchronized with the chosen modal coordinate extremum. In the investigated approach, the voltage is increased by waiting for the next voltage extremum following immediately any targeted modal coordinate extremum in a given time window. This article presents simulations performed on a model representative of a clamped plate. The damping results are given in the case of multimodal, pulse, or noise excitations. This article analyzes the performance of the observer used to focus on a given mode and the influence of the control time window on the damping performance of the system. The results show that substantial damping increase can be obtained with a very slight modification of the control architecture and the same control energy.
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