Testing and Characterization of Elastomeric Bushings for Large Deflection Behavior

Elastomeric components are used extensively in the construction of the modern automobile to accommodate relative movement between metal parts, absorb shocks and to provide isolation from undesirable vibrations. Their small-amplitude dynamic stiffness and damping characteristics are the key mechanical properties most influencing vehicle NVH performance. Their large-amplitude static force-deflection characteristics are crucial for vehicle ride and handling performance. On the other hand, when a vehicle is driven on a rough road durability course at a proving ground, all elastomeric components experience large-amplitude dynamic loads. The durability loads transferred through each elastomeric component highly depend on the stiffness and damping characteristics of these components. Although a large amount of small-amplitude dynamic stiffness and damping data and large-amplitude static force deflection data are available for various vehicle elastomeric components in the industry, relatively limited information is available for large-amplitude dynamic stiffness and damping values.

In the current paper, large-deflection static and dynamic tests are conducted on five different types of elastomeric components from a production vehicle. The tests include static, force-relaxation, harmonic and transient impact loads. Most importantly, the amplitudes used in the tests reflect the ones that these elastomeric components actually experience in a vehicle durability test. The purpose of the study is to develop a good understanding of the mechanical behavior of typical vehicle elastomeric components in the operating range of a durability test. The generic stiffness and damping characteristics are presented which can be used as a guideline in elastomeric component modeling and in vehicle durability design.