5 Prediction of Forced Response on Ancillary Subsystem Components Attached to Reduced Linear Systems 71 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 -8 -6 -4 -2 0 2 4 6 x 10-4 Time (sec) Displacement Node 1 and 37 Time Domain Response of System 2 at Connecting DOF SEREP Red. Model Anc SEREP Red. Model Top Reference Model 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 Time (sec) SEREP Red. Model Anc SEREP Red. Model Top Reference Model Fig. 5.23 Comparison of connecting DOF time response for both ancillary subcomponent and top red beamof System2 Guyan and SEREP reduction were used to obtain the reduced order models but mode truncation in the Guyan reduced system resulted in poor correlation of the response of the system. SEREP reduced models and the expanded models were shown to accurately preserve the dynamics of the system as well as the dynamics of the embedded ancillary subcomponent; the reduced model did not contain any DOF associated with the ancillary connection to the subcomponent. No additional gain was found from the addition of the connecting DOF of the subcomponents as long as the modes selected were sufficient in accordance to the U12 contribution matrix. KM_AMI updating of the Guyan reduced mass and stiffness matrices with target frequencies and mode shapes showed to mitigate the inherent errors in Guyan reduction process and ADOF selection. Addition of modes to the SEREP and KM-AMI models was shown to give significant gains in the correlation of the system to the full space reference solution. Acknowledgements Some of the work presented herein was partially funded by Air Force Research Laboratory Award No. FA8651-10-10009 “Development of Dynamic Response Modeling Techniques for Linear Modal Components”. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the particular funding agency. The authors are grateful for the support obtained. References 1. Thibault L (2012) Development of equivalent reduced model technique for linear modal components interconnected with nonlinear connection elements. Master’s Thesis, University of Massachusetts Lowell 2. Marinone T (2012) Efficient computational nonlinear dynamic analysis using modal modification response technique. Master’s Thesis, University of Massachusetts Lowell 3. Marinone T, Thibault L, Avitabile P (2013) Expansion of nonlinear system response using linear transformation matrices from reduced component model representations. Proceedings of the thirty-first international modal analysis conference, Garden Grove, CA, Feb 2013 4. Pingle P, Niezrecki C, Avitabile P (2011) Full field numerical stress-strain from dynamic experimental measured data. EURODYN 2011, Leuven, Belgium, July 2011
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