A system setup for modal testing includes several measurement and test components around the structure under test itself.
Typically one or more electrodynamic shakers (also called modal
exciters) are employed to provide a known excitation input force to
the structure. Dynamic transducers are used to measure the input
excitation force and the resulting vibration responses. Once data
are acquired, the resulting frequency response functions (FRFs)
obtained by the data acquisition system are stored for post processing
calculations, data reduction, curve fitting, and mode extraction.
Figure 1 offers a simple representation of the main instrumentation
components found in a modal test setup.