Using SEMM to Identify the Joint Dynamics in Multiple Degrees of Freedom Without Measuring Interfaces

As the number of models created in a modular fashion increase, the need for accurate identification of real joint dynamics rises. Since joint dynamics are a consequence of component-to-component interaction, they are only present in the assembled state. Yet, it is in the assembled state that measuring the interface degrees of freedom is practically infeasible. Nevertheless, the effects of the joint are present in measurements throughout the component, i.e. the joint dynamics are observable. In this work, system equivalent model mixing is used to expand an experimental measurement with interface degrees of freedom—either rotational or translational—extracted from a numerical model. Subsequently, joint dynamics can be obtained by applying classic frequency based decoupling methods. The strength of this method lies in the ability to test different interface configurations from a single measurement campaign, limited only by the actual number of sensor or impact locations. The paper shows that an updating scheme can be used to identify joint dynamics without directly measuring interfaces.