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dataPAC User’s Guide
Chapter 6 - Frequency Response Function (FRF)
Select the hammer based on the relative damping of the structure under test. You can use
any force hammer whose output does not exceed 5 volts. Large, heavy structures normally
have a much higher damping rate than smaller, lightweight ones. Refer to the table above for
the force, frequency, and sensitivity ranges of commonly used hammers.
For examples of different tips, see the following plots. The following diagram shows an
impact from the steel hammer tip. This waveform of the force channel shows an impact that
is very sharp and short in duration.
The steel tip is very hard, so when you strike a structure with it there is virtually no “give”
and the hammer bounces back very quickly. On structures that are not firmly anchored or
are lightly damped, this type of tip can cause frequent double hit errors. Pressing <F1>
(Spectrum) switches to the spectrum display of the force channel. The Force Spectrum for a
steel strike is shown below.
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Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com