2 Prediction of Forced Response Using Expansion of Perturbed Reduced Order Models with Inexact Representation of System Modes 31 Nodes 4, 9, 12, 16 and 20 DOF 7,17, 23, 31, 39 F 0 2 4 6 8 10121416182022242628303234363840 -60 -40 -20 0 20 40 60 Length along Beam (in) Amplitude of Response 0 5 10 15 20 25 30 35 40 45 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 TRAC NDOF Average TRAC: 1.0 Average MAC : 1.0 N U a X Tˆ *X ~ Fig. 2.15 Selection of ADOF for reduced model (Left). TRAC correlation of expanded QXN reduced order model response and unmodified reference model (Right) 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 Time (sec) Displacement Time Domain Response Near Base Reference Mod. Ref New Expanded Reference Mod. Ref New Expanded Nodes 4, 9, 12, 16 and 20 DOF 7,17, 23, 31, 39 F Fig. 2.16 Time response comparison for expanded QXN reduced order model response (ingreen) and reference unmodified model (inred) using new ADOF set. Also shown in blue, modified reference model forced response
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