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Elastomeric joints are utilized in many automotive applications, and exhibit frequency and excitation amplitude dependent properties. Current methods commonly identify only the cross-point joint property using displacement excitation at stepped single frequencies. This process is often time consuming and is limited to measuring a single dynamic stiffness term of the joint stiffness matrix. This study focuses on developing tractable laboratory inverse experiments to identify frequency dependent stiffness matrices up to 1000 Hz. Direct measurements are performed on a commercial elastomer test system and an inverse experiment consisting of an elastic beam (with a square cross section) attached to a cylindrical elastomeric joint. Sources of error in the inverse methodology are thoroughly examined and explained through simulation which include ill-conditioning of matrices and the sensitivity to modeling error.

Elastomeric joints such as mounts and suspension bushings undergo broadband excitation and are often characterized through a cross-point dynamic stiffness measurement; yet, at frequencies above 100 Hz for many elastomeric components, the cross- and driving-point dynamic stiffness results significantly deviate. An illustrative example is developed where two different sized mounts, constructed of the same material and are shaped to achieve the same static stiffness behavior, exhibit drastically different dynamic behavior. Physical insight is provided through the development of a reduced order single-degree-of-freedom model where an internal resonance is explained. Next, a method to extract the parameters for the reduced order model from a detailed finite element bushing model is provided.