A Comparison of Reduced Order Modeling Techniques Used in Dynamic Substructuring

Abstract

Experimental dynamic substructuring is a means whereby a mathematical model for a substructure can be obtained experimentally and then coupled to a model for the rest of the assembly to predict the response. Recently, various methods have been proposed that use a transmission simulator to overcome sensitivity to measurement errors and to exercise the interface between the substructures; including the Craig-Bampton, Dual Craig-Bampton, and Craig-Mayes methods. This work compares the advantages and disadvantages of these reduced order modeling strategies for two dynamic substructuring problems. The methods are first used on an analytical beam model to validate the methodologies. Then they are used to obtain an experimental model for structure consisting of a cylinder with several components inside connected to the outside case by foam with uncertain properties. This represents an exceedingly difficult structure to model and so experimental substructuring could be an attractive way to obtain a model of the system.

Reduction of Coupling Interface Degrees of Freedom in Mixed-Interface Component Mode Synthesis

“…The process of mode synthesis with reduced coupling interface DOFs is basically as same as mentioned above (i.e., Equations (21)-(34)), except that the coordinates involving in docking are u n and g n instead of u B and g. Assuming that the shape function and the number of IBNs chosen for all the substructures are same, so that A = B. Substituting Equation 42into Equations (21) and (22) leads to…”

“…In any type of the CMS methods, the most important and difficult task is choosing an appropriate reduced component modes involving modal reduction and mode synthesis, and this continues to be an area of research [15][16][17][18][19][20][21][22]. Lots of work have been done to make improvements on modal reduction of internal DOFs [23][24][25][26][27], but no order reduction is performed on the boundary.…”