You can create filters in ABAQUS/CAE and apply them to history output requests for ABAQUS/Explicit analyses. ABAQUS filters history data while the analysis is running; filtering during the analysis (“real time” filtering) can reduce the size of the output database by excluding high-frequency data before it is saved. Real time filtering also avoids potential aliasing problems in the resulting data. Aliasing is a loss of valid results data; aliasing will occur if the sampling frequency (the frequency at which the data are saved) is less than twice the highest frequency expected in the results. For example, if a sine wave was sampled at only two points, the aliased result would appear to be a straight line, whereas sampling at least four points would reproduce the shape of the curve.
The Filter toolset allows you to create the following filters for use with ABAQUS/Explicit history output requests:
Butterworth
Type I Chebyshev
Type II Chebyshev
In addition to the filters that you can define using the Filter toolset, ABAQUS also includes a default Antialiasing filter. ABAQUS automatically sets the cutoff frequency of the Antialiasing filter based on the time interval at which the history output is saved during the analysis. When you define a filter, you must specify the cutoff frequency based on your knowledge of the frequencies expected in the solution. Whether you set the cutoff or ABAQUS calculates it, no checks are performed to ensure that the cutoff frequency is appropriate. If the cutoff is set too low, valid data will be filtered from the results; if it is set too high (above half the sampling frequency), no filtering will be performed.
Select ToolsFilter
Create from the main menu to create a new filter definition; select Edit from the same menu to make changes to an existing definition. Either command opens the filter editor, which allows you to select the options and provide the data needed to define your filter.
To apply a filter to an analysis, include it in a history output request for an ABAQUS/Explicit analysis procedure (for more information, see Defining output requests, Section 14.12).