Use the saeFilter function to apply an SAE filtering operation to a previously saved X–Y data object (a collection of ordered pairs) to produce a new X–Y data object. This filtering operation can be used, for example, to remove high frequency noise.
The SAE filtering operation performs two-pass, zero phase shift, second-order Butterworth filtering. The SAE filtering classes that are allowed in ABAQUS/CAE are 60, 100, 180, and 600, as defined in SAE Standard J211 (OCT88). The Visualization module uses the Crashworthiness Signal Analysis Software obtained from the National Highway Traffic Safety Administration (NHTSA).
The parameters required for the saeFilter function are the data object name and the SAE class. Possible SAE class values are 60, 100, 180, and 600. ABAQUS/CAE computes the cut-off frequency from the SAE class as follows:
Your X–Y data object must have a constant time step for it to be filtered. If the time step is not constant, ABAQUS/CAE computes additional points at constant intervals by interpolation. The constant time step for SAE filtering is defined by the smallest time step in the X–Y data object to be filtered.
Figure 30–20 illustrates the type of X–Y plot that can be produced using the saeFilter operation.
To apply SAE filtering to an X–Y data object:
Locate the Operate on XY Data dialog box.
From the main menu bar, select Tools
XY DataCreate. Click Operate on XY data in the dialog box that appears; then click Continue. The Operate on XY Data dialog box appears.
From the Operators listed, click saeFilter(X,I).
The saeFilter function appears in the expression window.
From the XY Data choices, click the name of the X–Y data object on which to operate and click Add to Expression. You can choose from all X–Y data objects previously saved within this session (listed alphabetically in the XY Data field).
The X–Y data object name appears within the saeFilter function parentheses in the expression window.
Enter the SAE class.
Position your cursor after the data object name in the expression window. Enter a comma, then enter either 60, 100, 180, or 600, depending on the filtering class you want to apply.
To continue to build your expression, position the cursor in the expression window and type in or select the functions, operators, and X–Y data you want to include.
To evaluate and display your expression, click Plot Expression.
To save your new X–Y data object, click Save As and then provide a name in the dialog box that appears.
Saving your data object makes it available for future operations within this session and for inclusion in X–Y plots containing multiple data objects.
When you are finished, click Cancel to close the dialog box.
