Research focus on experimental dynamic substructuring has grown in recent years in bothacademic and industrial interests. Methods to couple and decouple in the modal domain, i.e., usingComponent Mode Synthesis (CMS), the frequency domain, i.e., Frequency Based Substructuring(FBS), and the state-space domain have been developed to high pedigree. In addition, the use ofvirtual point transformations in substructuring exercises has opened new opportunities for thedefinition of substructuring constraints. The Society of Experimental Mechanics’ (SEM’s)Technical Division on Dynamic Substructuring recognized a need for a simple, yet challengingbenchmark structure for experimental-analytical substructuring collaborations as compared toprevious benchmark structures [1] [2] [3]. A team with members from many research institutes setout from several desirable properties and a unit-frame structure was designed as a benchmark forcurrent collaborative efforts detailed in [4]. The benchmark structure is built up by a frame withthreaded inserts that is bolted to plates of varying thickness and materials. When assembled thisstructure can span a diverse application space of substructuring techniques including automotiveframes, wing-fuselage structures, and structural frames and floors. The frame is made as a onepiecestructure; it consists of four units cells and includes 10/32 tapped holes that can be used toattach other components. In addition, 10/32 tapped holes are made on the side of the frame toattach impedance heads or force transducers.Substructuring is often used to connect test and finite element (FE) based subassembly models.Each model can play to its strengths with FE models containing high fidelity spatial density andexperimental models capturing difficult to model pieces of an assembly, i.e., joint mechanics. Inthis work the benchmark structure’s components, an aluminum frame together with a rectangularwing manufactured by Sandia National Labs, are combined with swept steel wings manufacturedby Linnaeus University. The study combines a test-based model of the assembled frame andrectangular wing with FE models representing wing subcomponents. The rectangular wing isnumerically decoupled from the fuselage by the use of an FE model representing the wing and theswept wing is then numerically coupled to the frame using an FE model. The modal substructuringpredictions are then compared with results from measurements on the assembly.