Interface Reduction in the Dual Craig-Bampton method based on dual interface modes Daniel J. Rixen Abstract In this paper we propose an interface reduction technique in order to obtain a system of low order for structural problems on which the Dual Craig-Bampton substructuring technique has been applied. In order to develop this strategy we first rewrite the Dual Craig-Bampton method in a new form, where attachment modes are used instead of residual attachment modes. Then it is shown that the interface problem obtained with only static attachment modes can provide essential information on the interface behavior. Those interface modes can be used to efficiently reduce the interface problem in a way dual to the interface reduction technique commonly used for the standard Craig-Bampton approach. The method is applied to two problems: a space frame and a two-dimensional academic solid problem. It is shown that good accuracy can be obtained with the method even for low order reduced systems. We also discuss the physical meaning of the interface modes which can be associated to negative eigenvalues. 1 Introduction The Craig-Bampton substructuring method [3] is one of the most common methods used in structural dynamics to reduce the order of a large model. In [12] a version of the Craig-Bampton method using dually assembled substructures and free interface modes was proposed. It was shown that such method can present some advantages although its application requires non-classical assembly and solution techniques. structure increases, the number of interface degrees of freedom grows unnecessarily. In the standard Craig-Bampton method the interface can be reduced by considering Daniel J. Rixen Delft University of Technology, faculty 3mE, Engineering Dynamics, mekelweg 2, 2628CD Delft, The Netherlands e-mail: d.j.rixen@tudelft.nl T. Proulx (ed.), Linking Models and Experiments, Volume 2, Conference Proceedings of the Society for Experimental Mechanics Series 5, 311 The major bottleneck of substructuring techniques is that, as the number of subDOI 10.1007/978-1-4419-9305-2_22, © The Society for Experimental Mechanics, Inc. 2011
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