The SAARecorder software interface for vibration presents acceleration data for selected segments as a function of time or frequency. Vibration mode data is sampled at a collection rate of approximately 200 Hz per segment. For example, if vibration data were being collected from 4 ShapeArray (SAA) segments at the same time, the sampling rate would be approximately 200 / 4 = 50 Hz.
The 3 dB bandwidth of the accelerometers used in ShapeArray is set to 50 Hz, so ShapeArray measurements of vibration frequencies above 50 Hz will be attenuated.
The static shape of a ShapeArray cannot be measured at the same time that vibration is being measured on one or more ShapeArray segments. In order to return to measuring the static shape of the ShapeArray, it is necessary to close all of the vibration graphs that are opened.
Step 1 - Disable AIA and Select Vibration Data
In SAARecorder, click the SAA Setup menu and select the View Basic Settings option. Ensure that the Use Averaging-in-Array(AIA) mode checkbox is deselected. Click the OK button to close the Basic Settings dialog and click the OK button again to close the warning dialog.
Figure 1: Disabling AIA mode
From the Data and Graphs menu, select the Get vibration data menu item. If a warning dialog appears, click the OK button to close it.
Figure 2: The Data and Graphs menu in SAARecorder
Select the type of vibration data graph desired and the parts of the ShapeArray the vibration data is for. Click the OK button to continue.
- Acceleration vs. Time vibration data graph
- Acceleration vs. Frequency vibration data graph
Note: For Model 3 or higher ShapeArrays, there are no subarrays; each segment has its own serial number and can be individually selected for viewing vibration data. Model 1 or Model 2 ShapeArrays are in 8 segment sections called an Octet Subarray.
Figure 3: Selecting Acceleration vs. Time graph and the portion of the ShapeArray from which to collect vibration data
There are a variety of things to note when you are collecting vibration data.
- Only every eighth joint of a Model 1 or Model 2 ShapeArray is available for vibration monitoring.
- Every segment of a Model 3 or higher ShapeArray is available for vibration monitoring
- The more segments you select, the slower the data rate
- The vibration sampling rate is inversely proportional to the number of ShapeArray joints viewed
- A sample size for the Fast Fourier Transform (FFT) (when viewing "Acceleration vs. Frequency") is also chosen in this window; the optimal value for this will depend upon the nature of the vibration, time available, and the noise requirements for the test
- Any sample size between 256 and 100,000 can be chosen for the FFT
Step 2 - Review the Acceleration vs. Time Graph
If you choose the View Acceleration vs. Time option, you will be presented with the the Choose Accelerometer View Options window. Here you need to select an appropriate output option and click the OK button.
- Display Total Vibration - View total vibration for ShapeArray segments. Total vibration is the square root of the sum of the squares of the individual x, y and z vibrations.
- Display Individual Vibrations - View individual X, Y, and / or Z–axis accelerations for ShapeArray segments
Figure 4: Selecting output options
A Vibration vs. Time graph will appear. For more information on the Graph Options and Alarm Setup window features, see the Data and Graphs | Graph Data section of the SAARecorder manual.
Figure 5: The Vibration vs. Time graph that appears when you select the Acceleration vs. Time option
Step 3 - Alternatively, Review the Acceleration vs. Frequency Graph
If you select the View Acceleration vs. Frequency option, you must also select the sample size for FFTs in the Choose Vibration Data dialog and then click the OK button.
Figure 6: Selecting Acceleration vs. Frequency graph and the portion of the ShapeArray from which to collect vibration data
After the FFT buffer has filled up, an FFT vibration plot of acceleration (m/s2) vs. frequency graph will appear. For more information on the Graph Options and Alarm Setup window features, see the Data and Graphs | Graph Data section of the SAARecorder manual.
Figure 7: The FFT vibration plot of acceleration (m/s2) vs. frequency graph that appears when you select the Acceleration vs. Frequency option
Step 4 - Save Vibration Data
Save the vibration data by clicking the Save to File button. There are various ways to save vibration data to file. Select the appropriate option and click the OK button.
- Save to raw data (*.rsa) file - Allows the data file to be played back later
- Save to text data (*.txt) file - Saves vibration data as a function of time in text format
- Save snapshot image of vibration graph - Saves an exact replica of the ‘Vibration Graph’ window. The output image file is saved using the Windows Bitmap (BMP) format.
Figure 8: Saving vibration data