FLLWER
Bulk Data Entry Defines parameters for the calculation follower loads in large displacement nonlinear analysis.
- Pressure load
- PLOAD, PLOAD2, PLOAD4, PLOADSF, PLOADE1, PLOADX1 and PRSPENE
- Concentrated load
- FORCE1, FORCE2, MOMENT, MOMENT1, and MOMENT2
Format
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
FLLWER | ID | OPT |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
+ | LOADSET | OPT | LSID1 | LSID2 | LSID3 | LSID4 | |||
+ | DLOADSET | OPT | LSID5 | LSID6 | LSID7 | LSID8 |
Example
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
FLLWER | 99 | 2 |
(1) | (2) | (3) | (4) | (5) | (6) | (7) | (8) | (9) | (10) |
---|---|---|---|---|---|---|---|---|---|
FLLWER | 99 | ||||||||
+ | LOADSET | -1 | 8 | 12 | 13 | ||||
+ | DLOADSET | 1 | 9 | 14 | 15 | 16 | |||
+ | LOADSET | 2 | 10 | 17 | 19 | 20 | 21 | ||
+ | 22 | 23 | 24 |
Definitions
Field | Contents | SI Unit Example |
---|---|---|
ID | Each
FLLWER Bulk Data card must have
a unique ID. No default (Integer > 0) |
|
OPT | Options for the calculation for Follower
Loads.
|
|
LSIDi |
No default (Integer > 0) |
Comments
- The FLLWER Bulk Data Entry is selected by the Subcase Information command FLLWER = option.
- Follower options for concentrated loads (static and dynamic) and the hydrostatic pressure are currently only supported for large-displacement nonlinear static and large displacement nonlinear transient analysis subcases.
- Continuation (by use of entry CNTNLSUB) of a nonlinear solution from a preceding nonlinear subcase is supported. However, if a load set is applied in both subcases, the FLLWER option of the load set must be exactly the same in the two subcases.
- If for a subcase a load set is referenced by a LOAD and by a dynamic LOAD simultaneously, the follower option of this load set should be unique.
- Hash assembly is used for follower effect calculation by default.
- Follower load stiffness is generally un-symmetric. OptiStruct supports both symmetric solvers and un-symmetric solvers for the follower load case. The un-symmetric solver is activated using PARAM,UNSYMSLV,YES.
- Unsymmetric equation solver (PARAM,UNSYMSLV,YES) is recommended for better convergence in large displacement implicit nonlinear analysis with follower loads.
- The available follower
options are listed below with the precedence being from low
to high:
- PARAM,FLLWER entry
- OPT on the first line of FLLWER Bulk Data Entry
- OPT assigned to an LSIDi, which is a top-level LOAD(ADD) or DLOAD entry (as in, the one directly referenced by the LOAD or DLOAD entry in the Subcase Information Entry section).
- OPT assigned to an LSIDi, which is a loadset ID with label LOADSET or, a TLOAD1/TLOAD2 ID with label DLOADSET.
An option with a high precedence would overwrite a lower one. Also, an LOAD(ADD) entry can reference another LOAD(ADD) entry, but the LSIDi of intermediate LOAD(ADD) entries are not supported.
- Follower effect is calculated by default for pressure loading even if PARAM,FLLWER, FLLWER Subcase Information Entry, or the FLLWER Bulk Data Entry are not specified for a large displacement (LGDISP) subcase.
- The follower effects of FORCE1, FORCE2, MOMENT1, and MOMENT2 are based on the vectors formed by the user-specified nodes, while that of FORCE/MOMENT is based on the rotation of the nodes.
- To activate the follower effect for FORCE/MOMENT, an additional flag, ROT is required. For more details, refer to the FORCE/MOMENT Bulk Data Entries.
- In case of Nonlinear Explicit Analysis (NLEXPL), follower loads are supported with DLOAD/TLOAD#, for all supported pressure loads, FORCE1, FORCE2, MOMENT1 and MOMENT2.
- This card is represented as a load collector in HyperMesh.