Often we are tasked with analyzing systems where one or more components are difficult to model analytically. Unknown material properties, Complicated geometry, Difficult to model, Produced and designed by an outside vendor. The dynamics of these parts can have profound impact on the system level performance, Experimental models are often the optimal choice for characterizing the impact of non-modeled hardware it’s the system level response Experimental-analytical substructuring is a tool that can be used to combine the dynamics of an understood analytical system with the dynamics of a difficult to model experimental component