Experimental and constitutive modeling of a filled rubber with emphasis on the dynamical properties
Abstract
This study relates to a project that aims to develop a specific numerical tool to simulate the behavior of elastomeric bearings or laminated devices used in helicopter rotors. In these applications, the elastomeric material can be filler-reinforced synthetic rubber or natural rubber. In normal flight conditions, such structures are submitted to multi-axial, multi-frequencies and multi-amplitudes loadings. Furthermore, the design of these parts has to take into account of a large range of temperatures (−40o C to 70o C). Here, characterization tests carried out on a carbon-black filled butadiene rubber are presented. The expremental campaign comprises static and dynamic tests at various controlled temperatures on uniaxial (tension, compression, simple shear and torsion) or multiaxial specimens (tension-torsion). The aim of this characterization is to determine the dynamical stabilized behavior (de-Mullinsized). As expected, the material exhibits a non-linear viscoelastic behavior. The Payne effect and the frequency dependency are observed in a range of amplitudes and frequencies corresponding to flight conditions. Multi-step relaxation tests show that the dissipation is not fully viscoelastic and that other dissipative phenomena take place in the material. To model the material behavior, we investigate the reliability of three material models to predict uni- and multi-axial stabilized dynamic behavior. These models are all based on the thermodynamics of irreversible processes at finite strain. The first one is based on a statistical rheological approach and is mainly an extension of the model developed by Martinez et al. (Martinez, Boukamel, Meo, & Lejeunes 2011). The second one is purely phenomenological: scalar internal variables associated with time-dependent effects are introduced and combined with a Zener model. The last one is the Linder et al. model (Linder, Tkachuk, & Miehe 2011).
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