1 Verification of Experimental Component Mode Synthesis in the Sierra Analysis Framework 3 Fig. 1.1 Workflow for interfacing an experimentally derived CMS model in Sierra analysis 1.4 Demonstration This section presents a demonstration of the aforementioned process for interfacing an experimentally derived Craig-Mayes substructure to a discrete finite element modal for Sierra-SD analysis. First the model/test configuration is described followed by results of the exercise. 1.4.1 Configuration A 2-D simple beam configuration documented in reference [4] was considered for a proof of concept analysis for interfacing an experimentally derived CMS substructure model with Sierra-SD analysis. The configuration is shown in Fig. 1.2. Two beams are connected together over a specified region of overlap. The left beam is to be modeled by finite elements, whereas the dynamics of the right beam are measured experimentally and an experimental CMS model is derived. This is done using a “transmission simulator” shown as “TS Beam” in Fig. 1.2. Details of the transmission simulator are elaborated on in references [4, 5]. The transmission simulator essentially allows one to generate interface degree of freedom responses at discrete locations from those measured from a modal test. This is a very convenient means for interfacing an experimentally derived CMS model to discrete points of a finite element model. Note that there are five nodes in the overlap between the left finite element beam and the right experimental CMS beam. Thus, the transmission simulator approach was used to derive an experimental CMS model with five interface points (coincident with the finite element nodes). Each interface point had 3 degrees of freedom (axial translation, bending translation, and rotation). Therefore, a total of 15 interface degrees of freedom exist in the model. Three modes were retained in the CMS reduction. This resulted in CMS mass, stiffness, and damping matrices that had dimension of 18 18. 1.4.2 Results The Craig-Mayes substructure model of the beam was interfaced to the discrete “FE Beam” model in Sierra-SD described in Sect. 1.2. Results show good agreement between the “truth model” described in reference [4] and the Sierra-SD implementation. Table 1.1 presents a comparison of modal frequencies. The first five modes have 1 % error or less and
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