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LMS Test.Lab: Calculating Statistics from Time Histories

Siemens Experimenter Siemens Experimenter
Siemens Experimenter

 

(view in My Videos)

LMS Test.Lab: Calculating Statistics from Time Histories

 

Collected some time data and want to calculate statistics like maximums, minimums, and means? It is easy to calculate many different statistics and export them to Excel in LMS Test.Lab.

 

Getting Started

 

First, right click on the time file that statistics should be calculated upon and choose “Replace in Input Basket” as shown in Figure 1.

 

Figure 1: Right click on throughput time file and select “Replace in Input Basket”Figure 1: Right click on throughput time file and select “Replace in Input Basket”

Using “Replace in Input Basket” clears out the current contents of the input basket.  To add additional time files for analysis, right click on them and select “Add to Input Basket”.

 

Make sure that the ‘Time Data Selection’ worksheet is ON under ‘Tools -> Add-ins” from the main LMS Test.Lab menu.

 

Time Data Selection

 

In the ‘Time Data Selection’ worksheet, click on the button with a “…” in the upper left of the screen as shown in Figure 2.

 

Figure 2: Make sure data source selection is set to ‘Input Basket’ and press the ‘Add’ buttonFigure 2: Make sure data source selection is set to ‘Input Basket’ and press the ‘Add’ button

Once the ‘Data Source Selection’ menu is open, make sure it is on ‘Input Basket’ and press the ‘Replace’ button. The time data channels will appear on the left side.

 

Optionally, before calculating the statistics, the time history channels can be viewed as shown in Figure 3.

Figure 3: Click on the view checkbox (left) to display time history data (right)Figure 3: Click on the view checkbox (left) to display time history data (right)

Viewing the time histories has no bearing on the statistic calculations, it is just a convenience.

 

To calculate the statistics, click in the upper corner and toggle to ‘Single Value Statistics’ as shown in Figure 4.

 

Figure 4: Toggle to ‘Single Value Statistics’ in upper right to get open statistical calculation area in lower rightFigure 4: Toggle to ‘Single Value Statistics’ in upper right to get open statistical calculation area in lower right

An area for statistical calculations appears in the lower right of the ‘Time Data Selection’ worksheet.

 

Next, click on the words ‘Select Function…’ in the lower right as shown in Figure 5.

 

Figure 5: Choose ‘Select Functions….’ in the lower right to select functions to be calculatedFigure 5: Choose ‘Select Functions….’ in the lower right to select functions to be calculated

In the ‘Function Selection’ menu, highlight the desired statistical functions to be calculated on the left side of the dialog.

 

Functions include:

  • MIN – The minimum value of the time history
  • MIN_X – The time value where the minimum occurs in the time history
  • MAX – The maximum value of the time history
  • MAX_X – The time value where the maximum occurs in the time history
  • RANGE – Difference between maximum and minimum
  • MEAN – Sum of data values in time history divided by number of values, mean is important in fatigue life, see SN-Curve knowledge base article
  • KURTOSIS_EXCESS – Indicates the “peakiness” of the data, see Kurtosis knowledge base article
  • AND MORE…

Use the arrow key in the center to move the functions from the left to the right side to make the statistics active as shown in Figure 6.

Figure 6: Move highlighted functions from left to right to make them activeFigure 6: Move highlighted functions from left to right to make them active

Press ‘OK’ when finished.  Press the word ‘Calculate’ in the lower right to compute the statistics as shown in Figure 7.

 

Figure 7: Press ‘Calculate’ to compute the selected statisticsFigure 7: Press ‘Calculate’ to compute the selected statistics

After the calculations are done and the statistics are available, it is possible to copy them to Excel. First click in the upper left corner of the statistics area to highlight all the cells (Figure 8). 

 

Figure 8: Highlight all cells by clicking once in upper left corner of statistics area, then copy and paste to ExcelFigure 8: Highlight all cells by clicking once in upper left corner of statistics area, then copy and paste to Excel

After highlighting the cells, right click and choose ‘Copy’.  Then open Excel, right click, and choose ‘Paste’.

 

All the values will be in Excel.  Each row represents one channel, with all the selected statistics shown.

 

Hope this helps with calculating statistics from time files! Questions?  Call us!

 

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