Definition and experimental validation of a new model for the fatigue of elastomers incorporating deviations from Miner's linear law of cumulative damage

摘要

Deviations from Miner's linear law of cumulative damage have been observed and modeled many times for the fatigue of metals, but almost no analogous studies have been performed for elastomers. The first aim of this paper is to present a simple phenomenological model, applicable to any type of material and able to quantitatively reproduce such deviations. This model is based on continuum damage mechanics and relates the fatigue damage of the material to the number of cycles through some suitable evolution law, in which the derivative of damage is expressed as a non-factorizable function of the instantaneous cyclic load and the damage itself. The second aim is to report fatigue experiments performed on "diabolo" specimens made of two different elastomeric materials, and subjected to two different successive cyclic loadings. These experiments clearly evidence deviations from Miner's rule: Miner's "total cumulated damage" may be lower or larger than unity by a small or large amount, depending on the sequence of loadings and the type of material. As a rule, the deviation from Miner's rule systematically changes sign upon reversal of the sequence of loadings. The model allows for an acceptable reproduction of the experimental results, and especially of this systematic change of sign.