Mechanical characterization of an electrostrictive polymer for actuation and energy harvesting

Abstract

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.

Enhanced electrostriction based on plasticized relaxor ferroelectric P(VDF-TrFE-CFE/CTFE) blends

“…During the mechanical characterization, the applied mechanical strain was fixed at a value that is lower than strain at yield point of the terpolymer (above 3%). 17 Thus, a Young's modulus value can be calculated from the slope of the dynamic stress versus strain measurements.…”

“…A Newport table microcontroller and a force sensor were used to measure the displacement and the force, respectively, and convert in strain and stress of the sample. During the mechanical characterization, the applied mechanical strain was fixed at a value that is lower than strain at yield point of the terpolymer (above 3%) . Thus, a Young's modulus value can be calculated from the slope of the dynamic stress versus strain measurements.…”

Multimodal vibration damping using energy transfer

“…Compared with the active control, SSD control system is very simple to implement and can easily be self-powered from the vibration itself. In these techniques, the switch in the circuit is intermittently switched leading to a non-linear voltage processing (Richard et al 1999;Ji et al 2014;Lefeuvre et al 2006;Badel et al 2006;Eddiai et al 2012). The piezo-force induced by such voltage always shows an opposite sign with the structure velocity which leading the vibration suppression on the structure.…”

Damage induced dissipation in electroactive polymer harvesters

“…18,23 These are the result of a continuous process of damage and healing at the microstructure level, leading to stiffening/softening effects, which can be appreciated at the macroscopic level by hysteretic behavior.…”

“…II leads to an efficiency g % 60% for j ¼ 0.67, meaning that for this material almost the 40% of the mechanical work done during the harvesting cycle is dissipated to create damage at the level of the microstructure of the polymeric material. We remark that this analysis is focussed on the Mullins effect and that all other sources of dissipation were neglected, although it is well known that these play an important role [18][19][20][21][22][23]25,31 in harvesting devices.…”