Difference between revisions of "Pressure Traction Law"
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This [[Traction Laws|traction law]] applies a constant stress that is normal to the crack surface. It can be used to model a pressure-loaded crack. The stress can be entered in one of two ways: | This [[Traction Laws|traction law]] applies a constant stress that is normal to the crack surface. It can be used to model a pressure-loaded crack. The stress can be entered in one of two ways: | ||
You can either apply a constant stress or provide a [[User Defined Functions|user-defined function]] to let the stress vary in time. Even if you want a constant stress, experience shows that applying that full stress from the start of calculation | You can either apply a constant stress or provide a [[User Defined Functions|user-defined function]] to let the stress vary in time. Even if you want a constant stress, experience shows that applying that full stress from the start of calculation may cause local vibrations and less stable results. If it often better to ramp the stress up to the constant stress by applying an appropriate ramping [[User Defined Functions|function]]. | ||
== Failure == | == Failure == | ||
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| function || Alternatively, the stress can be entered as a [[User Defined Functions|user-defined function]] of time. || [[ConsistentUnits Command#Legacy and Consistent Units|pressure units]] || none | | function || Alternatively, the stress can be entered as a [[User Defined Functions|user-defined function]] of time. || [[ConsistentUnits Command#Legacy and Consistent Units|pressure units]] || none | ||
|- | |- | ||
| minCOD || Specify a minimum, normal, crack opening displacement below which no pressure is applied. This parameter can model pressure induced by a substance that needs room to enter the crack | | minCOD || Specify a minimum, normal, crack opening displacement (COD) below which no pressure is applied. This parameter can model pressure induced by a substance that needs room to enter the crack. If negative (or omitted), the pressure is applied for all CODs. || [[ConsistentUnits Command#Legacy and Consistent Units|length units]] || -1 | ||
|} | |} | ||
If a function is used, any entered stress property is ignored. | If a function is used, any entered stress property is ignored. If <tt>minCOD</tt> is used and no other boundary conditions cause the crack to open, the crack will never see any pressure. | ||
== Traction History Variables == | |||
This material tracks no history variables. | |||
Latest revision as of 14:55, 14 November 2023
The Traction Law
This traction law applies a constant stress that is normal to the crack surface. It can be used to model a pressure-loaded crack. The stress can be entered in one of two ways:
You can either apply a constant stress or provide a user-defined function to let the stress vary in time. Even if you want a constant stress, experience shows that applying that full stress from the start of calculation may cause local vibrations and less stable results. If it often better to ramp the stress up to the constant stress by applying an appropriate ramping function.
Failure
This traction does not fail; it just continues to apply normal stress. By using a function, the stress can be time dependent.
Traction Law Properties
The following properties are used to create a pressure traction law:
| Property | Description | Units | Default |
|---|---|---|---|
| stress | Enter constant normal stress. Use negative stress for a pressure loaded crack. | pressure units | none |
| function | Alternatively, the stress can be entered as a user-defined function of time. | pressure units | none |
| minCOD | Specify a minimum, normal, crack opening displacement (COD) below which no pressure is applied. This parameter can model pressure induced by a substance that needs room to enter the crack. If negative (or omitted), the pressure is applied for all CODs. | length units | -1 |
If a function is used, any entered stress property is ignored. If minCOD is used and no other boundary conditions cause the crack to open, the crack will never see any pressure.
Traction History Variables
This material tracks no history variables.