Dynamics of Coupled Structures, Volume 4 by Matthew S. Allen Randall L. Mayes & Daniel Jean Rixen

Author:Matthew S. Allen, Randall L. Mayes & Daniel Jean Rixen
Language: eng
Format: epub
Publisher: Springer International Publishing, Cham

A Craig-Bampton (CB) model was extracted from the FEM program. This model was derived from the model used by Gross, Lacayo, et al. in [15]. The CB model contained 30 fixed interface modes and the three virtual nodes at interface locations with 6 degrees of freedom each. After the CB model was extracted, linear springs were added between the two beams except in the axial direction. At each of the three virtual nodes, the DOFs in the axial direction were instead coupled using a 4-parameter Iwan model. The parameters of these discrete Iwan elements will later be updated to match experimental measurements from the assembled Brake-Reuss Beam. Note that, although one could connect each pair of the nodes at the joint surface with a nonlinear element, this would be contrary to the idea of using an Iwan element, which internally contains a parallel array of slider elements that are tuned to represent the stiffness and damping of an entire joint.

The two beams were assembled as described above with the Iwan elements represented by springs with the low amplitude stiffness, K 0, and the eigen value problem was solved to obtain the natural frequencies and mode shapes, see Table 16.3. Also included in Table 16.3 are the MAC values between the FEM and experimental mode shapes. The model matches very well with frequency errors under 2% and MAC values above .98 for all the modes of interest. Figure 16.6 shows a comparison for the first two elastic modes between the FEM model and the experimentally extracted mode shapes. Table 16.3System C experimental parameters

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.