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The application of hydraulic body mounts between a pickup truck frame and cabin have been shown to reduce freeway hop and smooth road shake; yet, this process is typically performed through iterative prototype evaluations on vehicles. Prior studies developing physics-based reduced-order models have demonstrated the preload and amplitude dependence of these components; however, the nature of the component's geometric nonlinearities has not been examined. Here, physical insight is provided through the development and analysis of three illustrative hydraulic mounts configurations. The chamber compliance and effective pumping areas are shown to be constant, preload dependent, or chamber pressure-differential dependent depending upon the placement and shape of the internal elastomeric springs. This thesis develops methodologies to extract the parameters for the reduced-order model parameters from a detailed dynamic nonlinear finite element hydraulic mount model. The fluid-structure interaction is captured using fluid cavity and exchange definitions within the finite element model. Comparisons are made between the dynamic nonlinear finite element and reduced-order models for purposes of model verification. Finally, the analysis methods are applied to a production hydraulic body mount. It is demonstrated that the middle spring undergoes a snap-through like, geometric nonlinearity that influences the effective pumping area and pressure differential dependence on chamber compliance. |
