BASELIN
Bulk Data Entry Corrects the acceleration record to avoid displacement shift.
Format
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
|---|---|---|---|---|---|---|---|---|---|
| BASELIN | ID | PARAM1 | VALUE1 | PARAM2 | VALUE2 | PARAM2 | VALUE2 |
Example
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
|---|---|---|---|---|---|---|---|---|---|
| BASELIN | 99 |
| (1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
|---|---|---|---|---|---|---|---|---|---|
| BASELIN | 99 | ACCELOAD | 20 | METHOD | VELO | TIMESET | 11 |
Definitions
| Field | Contents | SI Unit Example |
|---|---|---|
| ID | Each BASELIN Bulk Data Entry must have a
unique ID. (Integer > 0) |
|
| PARAMi | Name of parameter. (Character) |
|
| VALUEi | Value of parameter. |
| PARAMi | VALUEi (with i=1,2,3) | SI Unit Example |
|---|---|---|
| ACCELOAD | DLOAD or TLOAD1 ID that
contains at least one acceleration record Default: the SID of DLOAD in subcase section (Integer > 0) |
|
| METHOD | Baseline correction method.
(Character) |
|
| TIMESET | This field points to a SET of
TYPE=TIME, which
contains the time points to separate the total time period (not
local subcase time period) into intervals. Set of time points which divides the total time into intervals. Baseline correction calculation is conducted on each separate time interval to independently calculate corresponding coefficients of the polynomial used in the fitting and correction. No default (Integer > 0) |
Comments
- The BASELIN Bulk Data Entry is selected in the Subcase Information section.
- This entry is currently only supported for nonlinear transient analysis.
- Baseline correction is not required for acceleration loads via TLOAD2 as such enforced acceleration are harmonic. Therefore, baseline correction is only applicable to acceleration loads defined via TLOAD1. For baseline correction, if ACCELOAD points to a DLOAD Subcase Entry, then it may either point to a DLOAD Bulk Data Entry containing multiple loads, with at least one of them being a TLOAD1 entry, or point to a TLOAD1 entry directly. If ACCELOAD is not specified on the BASELIN entry, then the SID of DLOAD Subcase Information Entry of a subcase will be taken as the default value.
- For Baseline correction, if the DLOAD Subcase Information Entry, identified by ACCELOAD, references a DLOAD Bulk Data Entry containing multiple loads, then at least one of them should contain acceleration loading specified by TLOAD1 (TYPE=ACCE). The other loads like TLOAD2 will not be corrected. If the referenced DLOAD contains multiple TLOAD1 cards, all of them will be corrected. If the referenced DLOAD contains multiple TLOAD1 cards, but only one of them requires correction, then ACCELOAD should point to that TLOAD1 entry directly.
- ACCE method is based on the second order polynomial curve fitting; thus, it is independent of the initial condition. VELO method is based on the minimization of the velocity, which depends on the initial velocity.
- TIMESET points to a SET with TYPE=TIME, which contains time points to separate the whole time period into several intervals. The time period should be the total time, and not the local subcase time. Baseline correction is performed on each interval separated by TIMESET. For ACCE method, the corrections of intervals are independent of each other. For VELO method, the next interval depends on the velocity of the previous interval.
- BASELIN is supported in subcase continuation. For VELO method, it is recommended to use subcase continuation, instead of intervals.
- If initial velocity is specified on some or all of the same degrees of freedom where acceleration load is also applied (via SPCD and TLOAD1), the initial velocities on such degrees of freedom should match, for baseline correction using VELO method. If such initial velocities are different, then multiple TLOAD1 Bulk Data Entries are to be used.
- Refer to Baseline Correction in Nonlinear Transient Analysis for more information.