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MODESELECT |
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MODESELECT |
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MODESELECT |
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MODESELECT |
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MODESELECT – Mode Selection
The MODESELECT command can be used in the I/O Options or the Subcase Information section to select a subset of computed modes in modal dynamic analysis subcases.
Format
MODESELECT (type) = n
Mode selection based on arbitrary mode numbers.
MODESELECT (type, LMODES = lm)
Mode selection based on lowest modes.
MODESELECT (type, LMODENM = lom, HMODENM = him)
Mode selection based on a range of mode numbers.
MODESELECT (type, LFREQ = lof, HFREQ = hif, UNCONSET = m)
Mode selection based on a range of frequencies.
Argument |
Options |
Description |
type |
STRUCTURE (default) |
If STRUCTURE is specified, the MODESELECT command references modes associated with structural analysis only. |
FLUID |
If FLUID is specified, the MODESELECT command references modes associated with fluid analysis only. |
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n |
n > 0 (Integer) |
Set identification number n of a set of mode numbers. The modes corresponding to the mode numbers specified in set n will be included in the analysis. If no such set exists, then mode n will be included in the analysis. |
n < 0 (Integer) |
Set identification number |n| of a set of mode numbers. The modes corresponding to the mode numbers specified in set |n| will be excluded from the analysis. If no such set exists, then mode |n| will be excluded from the analysis. |
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LMODES |
lm (Integer > 0) |
Specifies the number of lowest modes to be selected. |
LMODENM |
lom (Integer > 0) |
Specifies the lower bound of the mode number range for selecting modes (Comment 3). |
HMODENM |
him (Integer > lom > 0) |
Specifies the upper bound of the mode number range for selecting modes (Comment 3). |
LFREQ |
lof (Real > 0.0) |
Specifies the lower bound of the frequency range for selecting modes (Comment 4). |
HFREQ |
hif (Real > lof > 0.0) |
Specifies the upper bound of the frequency range for selecting modes (Comment 4). |
UNCONSET |
UNCONSET |
This flag indicates that the following fields specify a single mode or a set of modes for unconditional inclusion or exclusion. |
m |
m > 0 (Integer) |
Set identification number m of a set of mode numbers. The modes corresponding to the mode numbers specified in set m will be unconditionally included in the analysis. If no such set exists, then mode m will be unconditionally included in the analysis. |
m < 0 (Integer) |
Set identification number |m| of a set of mode numbers. The modes corresponding to the mode numbers specified in set |m| will be unconditionally excluded from the analysis. If no such set exists, then mode |m| will be unconditionally excluded from the analysis. |
| 1. | The MODESELECT I/O Options entry is only supported in modal frequency response, modal transient and complex eignenvalue analyses. It is not supported in Response Spectrum Analysis. |
| 2. | Multiple MODESELECT entries are allowed in a model. MODESELECT entries can be specified above the first subcase or within each subcase. |
| 3. | If LMODENM is specified without HMODENM, a default value of 10000000 (ten million) is assumed for HMODENM. If HMODENM is specified without LMODENM, a default value of 1 is assumed for LMODENM. |
Defaults |
LMODENM |
HMODENM |
specified |
1.0E+7 |
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1 |
specified |
| 4. | If LFREQ is specified without HFREQ, a default value of 1.0E+30 is assumed for HFREQ. If HFREQ is specified without LFREQ, a default value of 0.0 is assumed for LFREQ. |
Defaults |
LFREQ |
HFREQ |
specified |
1.0E+30 |
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0.0 |
specified |
| 5. | When the MODESELECT Case Control command is used in conjunction with the parameter LFREQ, the MODESELECT Case Control takes precedence. |
| 6. | If the use of MODESELECT results in all or none of the computed modes for use, you are informed with a message. |
| 7. | The faster method for modal frequency response analysis (activated by PARAM,FASTFR,YES) cannot be used in conjunction with MODESELECT. |
| 8. | Modes that are eliminated by MODESELECT will display: |
| a) | an “S” next to the mode number, if the mode is eliminated by MODESELECT in one subcase and PARAM, LFREQ or PARAM, HFREQ in another subcase, or |
| b) | an “M” next to the mode number, if eliminated by MODESELECT in at least one subcase. |
See Also: