Quantitative analysis of design influences on the dynamic properties of elastomers

Elastomeric o-rings are widely used as a source of passive damping in structures. Due to their viscoelastic nature, the dynamic response of elastomers depends on the strain rate. Dynamic Mechanical Analysis (DMA) is an inexpensive experimental method to obtain the resulting material properties. However, the dynamic behavior of an elastomeric product also depends on design factors such as its shape and the level of pre-stress applied in-situ, which cannot be measured using DMA. This paper provides a quantitative comparison between ex-situ DMA performed using a rheometer and in-situ tests that replicate the operating environment. The effect of squeeze, temperature, shape, and material on the frequency-dependent stiffness and damping of elastomeric o-rings is presented in order to understand the relationship between properties measured in-situ and ex-situ. The interactions between these design and operational parameters are also discussed. Understanding these interactions helps in designing o-rings that perform optimally under varying conditions and the comparison with ex-situ measurements provides a basis for future low-fidelity modeling efforts.