Mechanical characterization and identification of a dielectric elastomer

International audience; Mechanical structures are subjected to ambient vibrations or acoustic pressures which can be used to produce energy using adequate transducers that convert mechanical loadings into electrical polarization. The use of smart materials such as EAP (electro-active polymer) to harvest energy from the mechanical vibrations of the surrounding environment is a recent and promising concept. This study focuses on the characterization and identification of mechanical properties for an elastomer material (3M R VHB 4910) which can be functionalized such as an EAP material for acoustic energy control. Mechanical tests have been carried out using tensile testing machine equipped with a thermo-conditioning device to control the environmental conditions (temperature and humidity). Tensile test have been performed with an imposed loading–unloading strain rate for various temperatures. The measured force–displacement data have been filtered by moving mean.The force–displacement response exhibits an energy storage within the material and a dependence on temperature. Assuming incompressibility, three hyperelastic models have been considered : the Neo-Hookean model with one parameter, the Mooney-Rivlin model with two parameters and the Ogden model with two parameters. Each set of material parameters has been identified by using a non-linear inverse method based on non-linear least squares. It has been observed that, not only the Neo-Hookean model does not fit well with experimental data, , but also the Mooney-Rivlin model is more precise than the Ogden model. Thus, it has been found that the Mooney-Rivlin model is the best compromise between complexity and suitability. The relationship between initial shear modulus and temperature has been approximated by a linear relationship with a sufficiently small residual error.