Description
This option sets the stress 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 stresses from zero to the desired values over some time to mitigate dynamic effects that would occur if the stresses were to be applied instantaneously at the beginning of time. If no amplitude function TID is provided, the initial stresses are applied instantaneously. If an amplitude function is provided, the elements to which this pre-stress is applied will not compute stress increments from the strain increments using the material model while the amplitude is active.
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 and the material model is released to begin computing stress increments from the strain increments using the material model. The default value of release time is zero which implies the amplitude function is used throughout the analysis.
Format
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |
| PSTRESS | SID | PID | SIGX | SIGY | SIGZ | TAUXY | TAUYZ | TAUZX | |
| TID | RT |
Example: Initial stress in a 3D solid part
| PSTRESS | 10 | 99 | 1882 | -662 | 512 | 118.5 | 331 | -18 | |
| 19 | 0.001 |
Example: Initial stress in a beam part
| PSTRESS | 10 | 18 | 562 |
Example: Initial stress in a shell part
| PSTRESS | 10 | 33 | 118 | 77.5 | -27.6 |
| Field | Definition | Type | Default |
|---|---|---|---|
| SID | Identification number. | Integer > 0 | Required
See Remark 1 |
| PID | Part identification number. | Integer > 0 | Required
See Remark 2 |
| SIGX | XX component of stress. | Real | 0.0
See Remark 3 |
| SIGY | YY component of stress. | Real | 0.0
See Remark 3 |
| SIGZ | ZZ component of stress. | Real | 0.0
See Remark 3 |
| TAUXY | XY component of stress. | Real | 0.0
See Remark 3 |
| TAUYZ | YZ component of stress. | Real | 0.0
See Remark 3 |
| TAUZX | ZX component of stress. | 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 stress components specified in this option depends upon the property type of the referenced property ID.
- The amplitude function is applied to the stress values defined upon the first line as:
σ(t) = A(t)σ0
If no amplitude TID is supplied, the specified initial stresses are applied instantaneously at the beginning of time.
- If no release time is supplied, the stresses are applied according to the amplitude specification and not released.