An Experimental Exercise as Part of the Substructuring Benchmark Structure Challenge

Some years ago, the Society for Experimental Mechanics’ (SEM) Dynamic Substructuring Technical Division (TD) recognized a need for a simpler, yet challenging benchmark structure for experimental–numerical substructuring exercises. That structure should replace the modified version of an Ampair 600 wind turbine as the common test object within the TD. Representatives from several research institutes formed a group that defined several desirable properties for the new benchmark structure. The outcome is a frame structure together with different plates. Together, they can represent various structures such as automotive frames, wing-fuselage structures, and building floors. The frame is made as a one-piece structure with many 10/32 tapped holes that can be used to attach other components, sensors, or excitation devices. Sandia National Labs has manufactured the benchmark structure’s components, an aluminum frame together with two aluminum rectangular wings. An exercise/challenge has been formulated. The components have been shipped to the ones that have shown interest in participating in the exercise. The idea of the exercise is to compare different strategies to tackle an experimental substructuring task, containing both decoupling and coupling, thereby learning from each other. In the exercise, the participants start with an assembly built up by the frame and the thinner of the rectangular wings. That wing should then be numerically decoupled from the fuselage. To that numerical representation of the fuselage, the thicker wing should be coupled numerically. These decoupling and coupling operations render a numerical representation of the thicker wing attached to the fuselage; a representation whose output is compared with test data stemming from the real structure counterpart. Here, virtual points are used in the decoupling and coupling operations. Four attachment points, for example, four screws, are used. In addition, washers between the fuselage and the wings are used in the connections. The purpose is to avoid too challenging nonlinearities to start with. The component mode synthesis (CMS) technique is used.