Description
The PSTRAIN entry defines values for initial stress in a part of the model.
This option sets the strain values in a part to the specified values. An amplitude function may be provided on the optional second line. This amplitude is typically used to ramp-up the strains from zero to the desired values over some time to mitigate dynamic effects that would occur if the strains were to be applied instantaneously at the beginning of time. If no amplitude function TID is provided, the initial strains are applied instantaneously. Note that in this case no stress will be computed and the effect of this option will not have any impact on the analysis results except to set the total strain value to an initial value that does not correspond to any stress.
A release time is typically specified on the optional second line when an amplitude is applied. The release time defines the time at which the amplitude is no longer applied to set the strains in the material. The default value of release time is zero which implies the amplitude function is used throughout the duration of the analysis.
Format
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| PSTRAIN | SID | PID | EPSX | EPSY | EPSZ | GAMXY | GAMYZ | GAMZX | |
| TID | RT |
Example: Initial stress in a 3D solid part
| PSTRAIN | 10 | 99 | -0.004 | -0.0005 | 0.0005 | 0. | 0. | 0. | |
| 19 | 1.E-4 |
Example: Initial stress in a beam part
| PSTRAIN | 10 | 18 | -0.003 |
Example: Initial stress in a shell part
| PSTRAIN | 10 | 33 | -0.003 | -0.002 | -0.0012 |
| Field | Definition | Type | Default |
|---|---|---|---|
| SID | Identification number. | Integer > 0 | Required
See Remark 1 |
| PID | Part identification number. | Integer > 0 | Required
See Remark 2 |
| EPSX | XX component of strain. | Real | 0.0
See Remark 3 |
| EPSY | YY component of strain. | Real | 0.0
See Remark 3 |
| EPSZ | ZZ component of strain. | Real | 0.0
See Remark 3 |
| GAMXY | XY component of strain. | Real | 0.0
See Remark 3 |
| GAMYZ | YZ component of strain. | Real | 0.0
See Remark 3 |
| TAUZX | ZX component of strain. | Real | 0.0
See Remark 3 |
| TID | Identification number. | Integer ≥ 0 | 0
See Remark 4 |
| RT | Release time. | Real ≥ 0.0 | 0.0
See Remark 5 |
Remarks
- The SID must reference a DLOAD ID in the Case control.
- The PID must reference a valid PSOLID, PSHELL, PBEAM, or PROD property ID. All elements connected to the PID specified will have the initial strain applied to them.
- The number of strain components specified in this option depends upon the property type of the referenced property ID.
- The amplitude function is applied to the strain values defined upon the first line as:
ε(t) = A(t)ε0
If no amplitude TID is supplied, the specified initial strains are applied instantaneously at the beginning of time.
- If no release time is supplied, the strains are applied according to the amplitude specification and not released.