User's Manual

Table Of Contents
6. Press Enter to collect the data.
One or more plots display the data.
7.
Press F2 Next Response Input to display data for the next response, if you set up more
than two inputs.
8. Press F9 Store Data to save the data to a route or a job, or press F8 Start to redo the
measurement.
6.9.12 Impact test
Impact testing lets you identify resonant frequencies, measure stiffness, and determine
system response. Impact tests are also used in modal analysis. An impact test can find
structural cracks and measure the dynamic stiffness of a structure.
To measure the resonant frequency, hit the equipment with an impact hammer. A
frequency near the resonance takes longer to decay than other frequencies, and the
equipment “rings” at the resonant frequency. Use the analyzer to analyze the ringing
frequency that corresponds to the resonant frequency.
Bump tests and Impact tests
The analyzer has two bump test Analysis Experts and an Impact mode in Manual Analyze. Both
the bump tests and impact tests help confirm resonance and remove background
vibration. The Impact test is different from a bump test in the following ways:
Requires a two or four channel measurement
Allows a Force/Exponential window
Requires an impact hammer while bump tests use a normal hammer
Displays additional plots
Lets you export data to ME'scope VES
for animation
Hammers
Most impact tests require an impact hammer that provides from 500 to 1,000 pounds of
force into the structure. By default, the impact hammer is not automatically set up in
Analyze. You must go to the Input Setup screen and configure the hammer before collecting
data.
The hammer tip affects the amount of force input into the test structure. The hammer tip
can control the frequency range. A very soft tip has most of the force, at a higher
amplitude, concentrated in the lower frequency range. Use a soft tip when you suspect
lower frequency resonance. A very hard hammer tip causes a lower amplitude input force
into the structure, but over a greater frequency range. Use the harder tips when you
suspect higher frequency resonances.
Single channel vs multi-channel
A single-channel measurement can only record the impact and identify the resonant
frequency (or frequencies) of a structure. Use a multi-channel measurement to measure
the amplification of a resonant frequency, determine stiffness and damping, and confirm
Analyze and Advanced Analyze
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