Verify Input Sensitivities & Displacement

March 29, 2018

VibrationVIEW’s System Check can be used to verify sensor input sensitivities and shaker displacement prior to running a test.

Determine Unknown Sensitivity of a Sensor

With a Reference Accelerometer

The goal is to enter a known sensitivity and guess an unknown sensitivity. If a sine wave produces the same response on both channels, the guess is correct.*

  1. Mount both accelerometers on shaker head
  2. Click Configuration > System Limits
  • Ensure the system limits are configured correctly
  1. Click the Inputs tab
  • Enter known sensitivities of reference accelerometer on Channel 1 (any accelerometer with a known sensitivity)
  • Enter a sensitivity value of accelerometer with unknown sensitivity on Channel 2

If in doubt about the sensitivity, always start low! If the accelerometer has low sensitivity and you enter a high sensitivity, you will receive much higher acceleration values on this channel. For example, if the accelerometer is 10 mV/g and your first guess is 100mV/g, then the channel will read 10 times the true acceleration. Your guess is 10 times higher than the actual value. By starting low and working up, you can avoid any potentially dangerous situations.

  1. Point to Test > Test Type and click System Check
  2. Set a frequency value; the default is 30Hz (works well for ED shakers)
  3. Set a displacement value; the default is 0.1″ (works well for ED shakers)
  4. Run the test
  • If the sine wave response matches on both channels, the guessed sensitivity on Channel 2 is fairly accurate
  • If the sine wave response does not match on both channels, gradually increase the sensitivity guess on Channel 2 until both channels produce the same result

*Results are not precise measurements

Without Any Reference Accelerometer

The goal is to enter an unknown sensitivity and use displacement to determine the accuracy of the guess. A sensitivity value close to the actual sensitivity of the shaker should result in the shaker’s visual displacement matching the software’s required displacement.*

  1. Mount the accelerometer with unknown sensitivity on shaker head
  2. Place a displacement wedge sticker on the shaker
  3. Point to Configuration and click System Limits
  • Ensure the system limits are configured correctly
  1. Click Inputs
  • Enter the sensitivity value for the accelerometer with unknown sensitivity on Channel 1.

If in doubt about the sensitivity, always start low! If the accelerometer has low sensitivity and you enter a high sensitivity, you will receive much higher acceleration values on this channel. For example, if the accelerometer is 10 mV/g and your first guess is 100mV/g, then the channel will read 10 times the true acceleration. Your guess is 10 times higher than the actual value. By starting low and working up, you can avoid any potentially dangerous situations.

  1. Point to Test > Test Type and click System Check
  2. Set a frequency value; the default is 30Hz (works well for ED shakers)
  3. Set a displacement value; the default is 0.1″ (works well for ED shakers)
  4. Walk to the shaker and visually verify the displacement
  • If the displacement wedge shows the same displacement value in the software, the sensitivity guess was fairly accurate
  • If the displacement wedge shows a lower displacement value than what is shown in the software, gradually increase the guess until the displacement values match

*Results are not precise measurements

Compare Two or More Sensors

Ensure all sensors are functioning properly.

  1. Mount sensors on shaker head
  2. Point to Configuration and click System Limits
  • Ensure the system limits are configured correctly
  1. Click Inputs
  • Enter the sensitivity values for all sensors
  1. Point to Test > Test Type and click System Check
  • Set a frequency value; the default is 30Hz (works well for ED shakers)
  • Set a displacement value; the default is 0.1″ (works well for ED shakers)
  1. Run the test
  • If the sine wave matches on all channels, all sensors are functioning properly
  • If the sine wave doesn’t match on one or more channels, re-verify the input sensitivities or repair the malfunctioning sensor

Visually Verify Displacement

Verify that the shaker is operating as expected.

  1. Mount the control sensor on the shaker head
  2. Place the displacement wedge sticker on the shaker
  3. Point to Configuration and click System Limits
  • Ensure system limits are configured correctly
  1. Click Inputs
  • Enter the sensitivity value of the sensor
  1. Point to Test > Test Type and click System Check
  • Set a frequency value; the default is 30Hz (works well for ED shakers)
  • Set a displacement value; the default is 0.1″ (works well for ED shakers)
  1. Run the test
  2. Walk to the shaker and visually verify the displacement to determine that it is operating as expected