STRAIN
I/O Options and Subcase Information Entry Used to request strain output for all subcases or individual subcases, respectively.
It can also be used to request electric field output for Structural Analysis with piezoelectric materials. For more information, refer to Piezoelectric Analysis in the User Guide.
Format
STRAIN (sorting,format_list,form,type,location,extras_list,random,peakoutput,modal,Neuber, kpi, creep, rate, statistics, RTHRESH=rthresh, THRESH=thresh, TOP=topn, RTOP=rtop, SUBSYS, TOTAL=total, PLASTIC=plastic, NLOUT, NDIV=nlayer) = option
Definitions
Argument | Options | Descriptions |
---|---|---|
sorting | <SORT1, SORT2> | This argument only applies to the PUNCH format (.pch file) or the OUTPUT2
format (.op2 file) output for normal modes,
frequency response, and transient subcases. It will be ignored
without warning if used elsewhere.
|
format | <HM, H3D, OPTI, PUNCH, OP2, PLOT, HDF5, blank> |
|
form | <COMPLEX, REAL,
IMAG, PHASE,
BOTH> Default (HM only) = COMPLEX Default (all other formats) = REAL |
|
type | <VON, PRINC, MAXS, SHEAR, ALL, TENSOR, DIRECT> |
|
location | <CENTER, CUBIC, SGAGE, CORNER, BILIN, GAUSS> |
|
extras | <MECH,
THER, PLASTIC> No default |
|
random | <PSDF,
RMS, PSDFC> No default |
|
peakoutput | <PEAKOUT> Default = blank |
If PEAKOUT is present, only the filtered frequencies from the PEAKOUT card will be considered for this output. |
modal | <MODAL> Default = blank |
If MODAL is present, strain results of the structural modes and residual vectors are output to the PUNCH, OUTPUT2 and H3D files for Modal Frequency Response and Transient Analyses. |
Neuber | <NEUBER> Default = blank |
If NEUBER is present, the von Mises strain corrected using the Neuber rule are output to the H3D file. 16 |
kpi | <KPI>
Default = blank |
Key Performance Indicators for Strain results are output in the *.kpi ASCII file. 20 |
creep | <CREEP> Default = blank |
Creep strains are output to the H3D file. 23 |
rate | <RATE> Default = blank |
Strain rate it output to the H3D file. 24 |
statistics | <STATIS,
OSTATIS> Default = blank |
Strain statistics over time in linear transient analysis are
controlled by this option. 27
|
THRESH | <thresh> Real Default = blank |
Specifies an absolute threshold under which strain results should
not be output. 28 The threshold to exclude elements from strain output is based on von Mises strain for 2D and 3D elements and on axial strain for 1D elements. |
RTHRESH | <rthresh> 0.0 < Real < 1.0 Default = blank |
Specifies a relative threshold as a fraction of the maximum von Mises strain under (2D and 3D elements) or maximum axial strain (1D elements) which results should not be output. For example, if VMS is the maximum von Mises strain in the model, the 2D and 3D element strain results below VMS*rthresh are excluded from the output. |
TOP | <topn> Integer > 0 Default = blank |
Only the top topn strain values should be
output. The strain values to exclude elements from strain output is based on von Mises strains for 2D and 3D elements and on axial strains for 1D elements. |
RTOP | <rtop> 0.0 < Real < 1.0 Default = blank |
Only the top fraction ("rtop") of the total number
of strains values should be output. For example, if STOT is the
total number of strains values in the model, then only the top
STOT*rtop values are output. The strains values to exclude elements from strains output is based on von Mises strains for 2D and 3D elements and on axial strains for 1D elements. |
NLOUT | <NLOUT_ID> No default |
ID of an NLOUT Bulk Data Entry. If present, the incremental output control parameters are taken from the referenced NLOUT Bulk Data Entry, instead of the one selected by Subcase Entry NLOUT, when results are written into the *_impl.h3d file. 21 For more information, refer to Comment 3 in the NLOUT Bulk Data Entry. |
total | <YES, NO> | |
plastic | <YES, NO, EQPS> | |
SUBSYS | <SUBSYS_ID> No default |
ID of the subsystem. When used along a subsystem definition, this option generates an individual result file for each subsystem with results for that subsystem only. For more information, refer to the SET Bulk Data Entry. |
NDIV | <nlayer> No default |
nlayer is the number of layers for shell element results output. A maximum of 50 layers can be defined. The layers are equally distributed over shell thickness direction from bottom to top. The layer results are available in nonlinear implicit analysis only. 29 |
option | <YES, ALL, NO,
NONE, SID,
PSID> Default = ALL |
|
Comments
- When the STRAIN command is not present, no strain data is output.
- HyperView can internally derive strain results from the strain tensor when the options TENSOR or ALL are used. If the option DIRECT is used, it will display the strain results that were directly computed.
- The von Mises and Principal stress are not available for Frequency Response Analysis.
- For elements that reference PCOMP and PCOMPG properties, the STRAIN I/O Option controls only strain results for the homogenized composite. The CSTRAIN I/O Option must be used to obtain ply strain results.
- The form argument is only applicable for Frequency Response Analysis. It is ignored in other instances.
- The forms BOTH and COMPLEX do not apply to the .frf output files.
- Multiple formats are allowed on the same entry; these should be comma separated. If a format is not specified, this output control applies to all formats defined by the OUTPUT command, for which the result is available.
- Multiple instances of this card are allowed. If instances are
conflicting, the last instance dominates.
However, the SYSSETTING I/O Option Entry (MULTIPLEOUTPUT=YES) can be used in the input file or the Configuration File to request multiple formats of the same output request. For more information, refer to MULTIPLEOUTPUT in the SYSSETTING I/O Option Entry.
- For optimization, the frequency of output to a given format is controlled by the I/O option OUTPUT.
- The mechanical and thermal contributions to strain may be requested in addition to the total strain.
- In general, HyperView does not recognize the SORT2 format for results from the .op2 file. When results are output only in SORT2 format (<Result Keyword> (SORT2, OUTPUT2, ...)), the results are written by OptiStruct into the .op2 file in SORT2 format, but when the .op2 file is imported into HyperView, the results in SORT2 format are not recognized. Therefore, the SORT1 option is recommended for results output in OUTPUT2 format and SORT2 option is recommended for results output in PUNCH format.
- PSDF and RMS von Mises strain results based on the Segalman Method are also written to the .h3d file for Random Response Analysis (only available in the H3D format).
- The four-letter abbreviation STRA is interchangeable with STRAIN.
- format=OUTPUT2 can also be used to request results to be output in the Nastran output2 format (.op2 file).
- The GAUSS results are currently
only supported for H3D and OP2 files. CORNER results are not
supported in OPTI format. To display
CORNER/GAUSS strain results in HyperView, activate the Use Corner Results check box in
the Contour panel. CORNER and GAUSS results (Stress, Total Strain, and Plastic Strain) are supported for both Shell (including composite shells) and Solid elements.
Static Eigenvalue Direct Frequency Response Modal Transient/ Frequency Response Direct Transient Nonlinear Static Nonlinear Transient Response Spectrum Random Corner Stress H3D, OP2, PCH H3D, OP2, PCH H3D, OP2, PCH H3D, OP2, PCH H3D, OP2, PCH H3D, OP2** PCH** H3D, OP2**, PCH** H3D, OP2*, PCH* H3D, OP2, PCH Corner Strain H3D, OP2, PCH H3D, OP2, PCH H3D H3D, OP2** PCH** H3D, OP2**, PCH** OP2* Gauss Stress H3D, OP2 H3D, OP2** H3D, OP2** Gauss Strain H3D, OP2 H3D, OP2** H3D, OP2** * Only for shell elements.
** OP2 and PCH files for NLSTAT and Nonlinear Transient Analysis analysis only include the results at the final timestep.
- Neuber corrected strains are calculated based on the von Mises stresses from elastic analysis, the Young's modulus, and the nonlinear material properties defined on the MATS1 Bulk Data Entry. Neuber Strain results are available as elemental results, grid point strains, Gauss point strains, and Corner Neuber strains. Both plastic strain and total strain output are available. Neuber Stress/Strain is supported for Static, Frequency Response, and Transient Analysis for H3D output.
- Equivalent plastic strain takes into account the z-component of strain tensor for shells. On the other hand, strain tensor output (even with plastic strain tensor) does not output z-component of strain tensor, which would cause the difference in equivalent plastic strain and von Mises based on plastic strain tensor.
- The HDF5 output is printed to a .h5 binary results file. For details of the supported analysis types and elements when the .h5 output format is requested, refer to the .h5 file.
- PSDF and RMS stress results are output in the element coordinate system in H3D file.
- KPI output includes maximum value for Strain with respect to the corresponding property. It is supported for linear and nonlinear static analysis only. Stresses and Strains are supported only for shells and solids. KPI output can also be output for a particular SET using the SID option.
- nlout=<nloutid> applies only to implicit nonlinear subcases.
- If an initial temperature (predefined outside of the subcases) is different from the temperature at the very beginning of a subcase and the resulting thermal expansion is nonzero, the thermal strain due to this temperature difference is counted.
- Element based creep strains are output when STRAIN(CREEP,H3D) is specified. If creep strain energy output is required, then ESE(CREEP,H3D) can be used.
- Support for strain rate output:
- Nonlinear Static and Nonlinear Transient Analysis
- Either equivalent total strain rate and equivalent plastic strain rate is output depending on TYPSTRT=0 or 1 in MATS1, respectively.
- Explicit Dynamic Analysis
- Both equivalent total strain rate and equivalent plastic strain rate are output.
- Only mechanical strain is available for "CBAR/CBEAM Strains". The MECH/THER options are available for "Element Strains (1D)".
- Transverse strain is considered in von Mises strain calculation for beam elements.
- Strain Statistics are only supported
for Direct and Modal Linear Transient Analysis. Only 2D and 3D elements are
currently supported.
Only H3D output is supported for Strain Statistics.
The following statistics over time are output for Linear Transient Analysis when STATIS or OSTATIS is specified:- Statistics
- Supported Strain Result Types
- Minimum
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Time of Minimum
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Maximum
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Time of Maximum
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Abs-Max
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Time of Abs-Max
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Arithmetic Mean
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Root Mean Square (RMS)
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Variance
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
- Standard Deviation
- von Mises, P1 (Major), P2 (Mid), P3 (Minor)
After loading the H3D file, the strain statistics in HyperView can be viewed.
Various statistics can be chosen from the sub-menu under Strain Statistics(s).
Strain Statistics output is also supported for Neuber Strains. For Neuber Strains, the supported components for statistics output are Maximum, Time of Maximum, Arithmetic Mean, RMS, Variance, and Standard Deviation for both Total and Plastic strains.
- The threshold options (THRESH, RTHRESH, TOP, and RTOP) are available in H3D, OP2, and PUNCH format for static, normal mode, frequency response, transient, and random response analyses only. For H3D, the filter is applied to each dimension of elements (shells, solids, beams, welds, etc.), while for OP2 and PUNCH, it is applied to each element type (quad4, tria3, quad8, and so on). Threshold options are also now supported for Neuber Strain. Threshold on Neuber is currently supported only for H3D for static, frequency response, and transient analysis only.
- NDIV can be used to output layer results in shell elements. It can control the output of total strain, plastic strain, thermal strain, mechanical strain and equivalent plastic strain in shell elements. When the nlayer is different from the value defined in STRESS or OLOAD, the maximum value of NDIV across the different output requests is taken for output. NDIV is supported for Small and Large Displacement, Implicit Nonlinear Static, and Implicit Transient Analysis.
- The TOTAL and PLASTIC options are supported for Implicit Nonlinear Static and Implicit Nonlinear Transient analysis. They are supported for both on-the-fly and regular H3D output files.