This demo assumes that a modal test will be conducted on two configurations of a general purpose truck-trailer, where the difference is the presence of a loaded container as shown in Figure 17. The GA will select a single set of accelerometer locations that will capture the target modes of both configurations.
The full FEMs for each of the configurations are supplied in Nastran
decks in truck_wload_fem_modes.dat and truck_fem_modes.dat.
These decks also employ the write_modes alter which writes the
full FEM modeshapes to an OP4 file to be used with the Iterative Residual
Kinetic Energy alter, as described below.[6]
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Figure
17. Two configurations of the general truck-trailer
It is assumed that the purpose of the modal test is to determine the mechanical properties of the truck’s suspension system. The first 10 modes of each configuration capture about 90% of the effective mass in the three translational directions, so these modes are the target modes. The modal effective mass of the target modes of each configuration are shown in Table 1.
Table 1. Target mode Modal Effective Mass of two truck configurations
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