Second order looks like a big contributor to the overall noise level (Figure 1). Is there a way to see how much the overall level would improve if second order was removed from the data?
Figure 1: Overall level versus rpm (red) versus 2nd order versus rpm (green).
Guess that second order would have to be filtered out while leaving everything else behind (Figure 2).
Figure 2: Overall level versus rpm (red) versus 2nd order versus rpm (green).
Can this be done in Simcenter Testlab? If so, how?
Yes, in Simcenter Testlab it is possible to recalculate the overall level with an order removed. In fact, multiple orders can be removed.
Using the original time history, the Time Signal Calculator can be used to filter out any orders desired. The original data and filtered data can be processed and compared.
Here are the steps:
1. Activate Time Signal Calculator and Signature Throughput Processing 2. Select Time Data for Filtering 3. Define Order Based Filters in TIme Signal Calculator 4. Create Filtered Time Histories 5. Process Original and Filtered Data for Comparison
Steps in detail
1. Activate Time Signal Calculator and Signature Throughput Processing
After starting Simcenter Testlab and opening the project of interest, select “Tools -> Add-ins” from the main menu. In the add-in menu, turn on “Time Signal Calculator” and “Signature Throughput Processing” as shown in Figure 3.
Figure 3: Turn on “Time Signal Calculator” and “Signature Throughput Processing” under “Tools -> Add-ins”.
Then select the data for processing. If using Simcenter Testlab token licensing, the Time Signal Calculator used 26 tokens while Signature Throughput Processing uses 36 tokens.
2. Select Time Data for Filtering
In the Simcenter Testlab project, right click on the time history to be processed and select “Add to Input Basket” as shown in Figure 4.
Figure 4: Right click on the time history to be processed and select “Add to Input Basket”.
At the bottom of the Simcenter Testlab screen, choose the “Time Data Selection” worksheet.
After entering the worksheet, select "Input Basket" at the top right (under the "..." button) and press the "Replace" button..
Then in the lower left corner, highlight the first formula cell and then select the “f(x)” button as shown in Figure 5.
Figure 5: In the Time Signal Calculator, highlight the first formula cell and choose the “f(x)” button.
In the “Select Function” menu, define the order filters as explained in the next section..
3. Define Order Based Filters in Time Signal Calculator
Choose the “Conditioning” group from the left side of the menu, and the select FILTER_ORDER on the right side as shown in Figure 6.
Figure 6: Select the Conditioning group on the left, and FILTER_ORDER on the right.
Press OK when finished. The formula argument menu for the FILTER_ORDER function will appear.
In the FILTER_ORDER menu (Figure 7), set the following: • Function1: Enter the channel number (CH1, CH2, or what is appropriate) of the data to be filtered. • Tracking Signal: Enter the channel number of tracking rpm • Order_Value: Enter the order number to be removed. • Order_Width: Enter the width for the filter. The filter should be set to only remove the order of interest. Best to view the colormap of the data to see how much is removed. • Attenuation: The amount of reduction (in db) to reduce the targeted order.
Figure 7: Select the rpm tachometer channel (blue line) and data channel (red line) in the FILTER_ORDER menu.
Press the OK button after entering all of the filter parameters.
In the formula field area, enter a name in the "Point Id" field to denote the filtered data from the original data.
Press the “Calculate” button to apply the order filters to the data as shown in Figure 8.
Figure 8: Press “Calculate” to create new time histories with the filter applied.
The new time histories will have an orange color next to them. This indicates that the data is not stored yet. Use the Save button on the middle right to permanently save the data.
Even without saving, the data can be processed. Click on the “Time Data Processing” worksheet to recalculate the levels as explained in the next section..
5. Process Original and Filtered Data for Comparison
In the Time Data Processing worksheet, enter processing parameters with the “Change Settings” buttons. See the Knowledge article “Throughput Processing Tips” for more information on setting parameters.
Both the original and filtered time histories should be selected in the upper left. After entering the settings, press the “Calculate” button to process the data (Figure 9).
Figure 9: After selecting both the filtered and original data from the upper left, press “Calculate” to create new time histories with the filter applied.
In the “Results Preview” area, the colormap of the processed data can be viewed to see how the filtered performed.
Any calculated results, like overall levels with the filtered order and without the filter order can be compared and overlaid (Figure 10).
Figure 10: Original overall level versus rpm (red curve) overlaid with overall level with second order removed (green curve).
In this way, the potential improvement of addressing an order can be quantified. See the knowledge article “Intrepreting colormaps” for more information on addressing orders.