A thermo-viscoelastic-damage constitutive model for cyclically loaded rubbers. Part II: Experimental studies and parameter identification

摘要

AbstractCyclically loaded styrene-butadiene rubber containing different amounts of carbon-black is experimentally examined under different pre-stretch levels at room temperature. The experimental observations, especially related to both the multi-step cyclic response interrupted by relaxation periods and the dissipative heating, provide valuable insights into the pre-stretch and filler effects on the underlying physical mechanisms of this rubber-filler material system. According to the active role of carbon-black fillers dispersed in the rubber matrix on the inelastic phenomena via the local microscopic interactions, the constitutive theory formulated in the Part I of this work is modified in order to incorporate explicitly the filler effects. A deterministic identification procedure is proposed to extract the physically interpretable model parameters of the rubber matrix. The properties of the perfect network and the superimposed (entangled and non-entangled) free chains are identified via an amplification-inspired procedure using, respectively, the relaxed-stress data as a function of the filler content and the history-dependent mechanical cyclic response at the highest filler content. The identified rubber matrix properties are introduced into the finite element simulations as input constants and the same thermo-mechanical boundary conditions regarding the experimental tests are simulated. The capabilities of the proposed constitutive model to predict the thermo-mechanical response under two cyclic loading blocks with different pre-stretch levels are verified by comparisons with experiments. The constitutive model is found able to successfully capture the pr