Module 2.1 – Simple Random Test

March 29, 2018

Use the Hardware, Inputs, and System Limits configuration from Module 1.1.

1. Create a Simple Random Test

a. Click New Test > Random
b. Create a breakpoint table as displayed in the image below:

Simple random test settings

c. Set the duration to 7m30s (7 minutes and 30 seconds)
d. Click OK, accept the changes, and save the test as Name_SimpleRandom

2. Create the Graphs

a. Click New Graph
b. Graph 1 configuration

  • Graph Type: Acceleration vs. Frequency (Acceleration Spectral Density)
  • Control Loop Traces: blank
  • Input Channels: Ch 1 and Ch 2
  • Select Show only active lines

c. Graph 2 configuration

  • Graph Type: Acceleration vs. Time (Acceleration Waveform)
  • Input Channels: Ch 1

d. Graph 3 configuration

  • Graph Type: Transmissibility vs. Frequency
  • Reference: Ch 1
  • Input Channels: Ch 2
  • Select Show only active lines

e. Graph 4 configuration

  • Graph Type: Probability Density
  • Point to Axis Limits and change the y-axis to Log
  • Input Channels: Ch 1

f. Click OK

3. Run the Test

a. While the test is running, watch and listen for the differences between a sine and random test. Do you still observe a resonance?
b. Save the data

4. Create a Report

a. Click Report
b. In the report, include the following information:

  • VibrationVIEW Screen
  • Acceleration Waveform
  • Breakpoint Table
  • Accelerometer calibration details
  • Channel Measurements

Your report should look like the following:

Simple random test acceleration waveform

Breakpoint Table

Frequency 10Hz 40Hz 500Hz 2,000Hz
G²/Hz 0.015 0.015 0.00015 0.0002607
dB/Octave 0 -5.489 1.2


Channel Measurements

Overall InBand
Ch 1 1.191 G RMS 1.19 G RMS
Ch 2 1.19 G RMS 1.189 G RMS
Ch 3 1.826 G RMS 1.826 G RMS
Ch 4 1.6 G RMS 1.599 G RMS


c. Copy the Probability Density Graph onto your report. The Probability Density graph shows the distribution of the accelerations of the shaker. In this case, much of the acceleration is in the +/- 1G range. This corresponds with the acceleration waveform graph.
Simple random test PDF

d. What do you hear while the test is running? The sound is a molded “white noise.” There is no particular frequency or pitch, just a static sound.