FILTER

Bulk Data Entry Defines filtering rules for time history output request for an explicit analysis.

Format

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FILTER FID TYPE Filter_type PARAM1 VALUE PARAM2 VALUE
PARAM3 VALUE

Example

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FILTER 2 TYPE BUT2 FDIV 10.0 FCUT 100.0
ALPH 0.85

Definitions

Field Contents SI Unit Example
FID Identification number for a unique FILTER entry.

No default (Integer > 0)

TYPE Flag indicating the type of filter applied is to follow.

No default (String)

Filter_type Defines the type of filter applied.
EXPO
Exponential filter is applied.
BUT2
Butterworth 2nd order is applied.
BUT4
Butterworth 4th order is applied.
BUT6
Butterworth 6th order is applied.

Default = BUT4 <String>

List of PARAMs
PARAMi VALUE
FDIV Factor by which the sampling/output frequency (computed from DTTH in THIST card) is divided to find the cutoff frequency.

Default = 20.0 (Real > 0.0)

FCUT Cut-off frequency for Butterworth filters.

No default (Real > 0.0)

ALPH Weightage factor for exponential filter.

Default = 0.95 (0.0 < Real < 1.0)

Comments

  1. Time history filtering can be applied to an explicit analysis output to remove any high frequency noise and even possibly reduce the size of output files by only saving data below a specified cut-off frequency. Exponential filter and 3 types of Butterworth filters are currently available.
  2. If no filter options are specified in a model with a FORCE output request, a FILTER card with default options is applied (only for the force output).