Testing Mechanical Features of Rubber Composites under Biaxial Loading

Abstract

The main object of studies were composites on the base of synthetic rubber filled with various nano- and micro particles, which are already used or intended to be used in the tire industry. Mechanical behavior of such materials under biaxial cyclic loading was studied experimentally. The tests were carried out using the four-vector test rig Zwick/Roell. It allows to define complex deformation trajectories in two mutually perpendicular directions independently. The test program consisted of two or three cycles of load-unload (with stops for relaxation) in one direction and then two or three more such cycles in the perpendicular one. Experiments made it possible to study viscous-elastic properties as well as the effects of softening and the occurrence of induced anisotropy in filled elastomers under the action of a biaxial load. In the case of pure rubber, they are practically absent, so unfilled system can be considered as elastic and isotropic. A different picture is observed for filled systems. All the tested composites become viscoelastic after filler input: a hysteresis loop appeared and its area (dissipative losses) enlarged with increasing amplitude of cyclic deform. Also the dependences of induced anisotropy of mechanical properties and softening on the type of filler in the composite were investigated.