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doc:user:elements:boundaries:pressure_shear

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Pressure and shear

Materials

Since pressure/shear interactions are boundary conditions interactions (LoadingInteraction), no materials must be associated to the element.

Element

Therefore, the first step consist in defining an ElementProperties, as

prp = ElementProperties(typeEl)
prp.put(param1, value1)
prp.depend(param1, fct1, Lock1)) #optional
...

where

typeEl desired element (for example Traction[2|3]DElement)
param1 name of the property associated to the element (for example PRESSURE
value1 value of the corresponding property
fct1 function which characterizes the dependency of the property (optional: no fct if no dependency)
Lock1 Lock which defines the dependency variable of the property (compulsory if there is a dependency)

Traction[2|3]DElement

Traction/shear element for a mesh made of quadrangles in 2D or hexaedra in 3D.

Parameters

Name Description Dependency
STIFFMETHOD Method used to calculate the stiffness matrix\\= STIFF_ANALYTIC : analytic matrix (default)
= STIFF_NUMERIC : numerical matrix
Not applicable, only the numerical one exists !
-
PRESSURE Pressure on the entity on which the propriety is applied time
SHEAR_KSI / SHEAR_ETA Shear along $\xi$ or $\eta$ on the entity on which the propriety is applied time
NPG Number of integration points (default : 2) -

TriangleTraction3DElement

Traction/shear element for a mesh made of tetrahedra

Parameters

Name Description Dependency
STIFFMETHOD Method used to calculate the stiffness matrix\\= STIFF_ANALYTIC : analytic matrix (default)
= STIFF_NUMERIC : numerical matrix
Not applicable, only the numerical one exists !
-
PRESSURE Pressure on the entity on which the propriety is applied time
SHEAR_KSI / SHEAR_ETA Shear along $\xi$ or $\eta$ on the entity on which the propriety is applied time
NPG Number of integration points (default : 1) -

Interaction

The interaction is defined as:

load = LoadingInteraction(no)
load.push(gObject1)
load.push(gObject2)
...
load.addProperty(prp)
interactionset.add(load)

where

no number of the Interaction
gObject1, gObject2 mesh geometric entity where the boundary conditions are applied
prp Properties of [#Elementboundary condition elements]] to generate

Remark

Traction, pressure and shear is generated by “traction elements”. Their definition requires a specific Interaction called LoadingInteraction, to which is associated an ElementProperties. These should not be mixed with dead loads. In most cases, traction elements should be chosen over dead loads:

  • traction (or pressure/shear) is always defined in local axes, so the direction of the force depends on the orientation of the edge/face on which it is applied.
  • traction is divided properly over all edges/faces on which the Interaction is applied. Consequently, the resultant force does not depend on the mesh.

Elements de pression

:!: Traction element is used backwards in 3D, so a positive value must be applied to generate a pressure. !!

doc/user/elements/boundaries/pressure_shear.1412611042.txt.gz · Last modified: 2016/03/30 15:22 (external edit)