In this section, it will be shown how to write the evolution of given fields to disk, e.g. the contact force as function of time. This is done with what is called “result curves”.

These curves are saved for each time step while archiving files (bfac) are usually saved at a lower sampling frequency. This leads to a very good temporal resolution for these curves.

The respective files are saved in the folder of the test case (workspace/test_name by default). The information of each curve is saved twice, once as a binary file used internally (values.v), and once as a text file (valeurs.ascii), easy to load in Matlab, Excel, …

The class “ValuesManager” manages the interfac, allowing :

• the definition of a ValueExtractor (extracting results),
• the retrieval of a vector to view it in real time,
• …

Depending on whether one or several values are extracted, the file on disk will be a vector or a matrix. The number of values saved for each time step depends on the extraction command.

The ValuesManager manages the extraction of data at each time step. It is a container of ValueExtractors defined in the analysis metafor :

valuesmanager = metafor.getValuesManager()
valuesmanager.add(nbr, extractor, name = "")        # manages extraction, result storage... 
valuesmanager.add(nbr, extractor, v2sOp, name = "") # same + transformation from vector to scalar
valuesmanager.getDataVector(nbr)                    # returns a reference of the vector storing values     
                                                    # (for example to create and view curves)
valuesmanager.setOnFile(False)                      # Keep curves in memory instead of writing 
                                                    # .v and .ascii files
                                                    

where

The FacValuesManager manages the extraction of data at each time a “bfac” file is written. It is exactly the same object as the ValuesManager, but called at different times of the time integration.

To access the FacValuesManager, just get it from metafor. The rest of the syntax is the same.

facValuesManager = metafor.getFacValuesManager()

The StageValuesManager manages the extraction of data at the end of each stage. It is exactly the same object as the ValuesManager, but called at different times of the time integration.

To access the StageValuesManager, just get it from metafor. The rest of the syntax is the same.

  stageValuesManager = metafor.getStageValuesManager()

ValueExtractor defines which values are to be archived. It manages:

• selecting an entity on which the value is extracted (node, point, line, interaction, …),
• the field to extract (value in data base, extrapolated internal field, averaged internal field, thermodynamic field, …),
• operations to apply on these fields (average, max, min, … ).

Extract values stored in the data base, so fields which are indeed stored in nodes (positions, displacements, temperature, forces, velocities, …).

valueExtractor = DbNodalValueExtractor(gObject, dbField)
valueExtractor = DbNodalValueExtractor(gObject, dbField, sOp = None, maxV = -1)

where

Example:

valuesmanager.add(8, DbNodalValueExtractor( curveset(1), Field1D(TY,GF2)), 
                  SumOperator(), 'totalForce_X')

Extract a result curve numbered 8 defined by the sum of all internal forces along line 1. This curve is named totalForce_X.

Extract Internal Fields Values at nodes. As these values only exists at integration point level of the elements, the extracted values are the result of the extrapolation of Integration points values to the node (a contribution of each element using the node is taken into account).

valueExtractor = IFNodalValueExtractor(gObject, InternalField, sOp=None, maxV=-1)

where

A set of extractor can be defined on points that do not correspond to node position.

The value is computed from the interpolation of elementary values from the first element that belong the point. An outer tolerance is defined (OutsideTol) to allow detection of point just outside the mesh.

The point can be Lagrangian (fixed to material : default) or Eulerian (geometrically defined fixed or not) where element and reduced coordinate are computed at each extraction)

Extract values stored in the data base, On geometrically defined point (positions, displacements, temperature, forces, velocities, …).

valueExtractor = DbGeoPointValueExtractor (pointList, meshedObject, field)
valueExtractor = DbGeoPointValueExtractor (pointList, meshedObjectList, field)
valueExtractor.setEulerian(True) 
valueExtractor.setOutsideTol(tol)

where

Example:

  pt102 = pointset.define(102,0.15*Lx,0.75*Ly,0)     # geo point of extraction (must be in pointset)
  dyPt102 = DbGeoPointValueExtractor([pt102,], [volset(idx+1), volset(idx+2)], Field1D(TY, RE))
  dyPt102.setEulerian(True)                       # Eulerian point (not moving with elements)
  dyPt102.setOutsideTol(0.5)                      # half an element outside detection tolerance

Extract Internal Fields Values on geometrically defined point(s). Value are interpolated from Integration Points Values.

valueExtractor = IFGeoPointValueExtractor (pointList, meshedObject, InternalField)
valueExtractor = IFGeoPointValueExtractor (pointList, meshedObjectList, InternalField)
valueExtractor.setEulerian(True) 
valueExtractor.setOutsideTol(tol)

where

Example:

  pt102 = pointset.define(102,0.15*Lx,0.75*Ly,0)     # geo point of extraction (must be in pointset)
  eplPt102 = IFGeoPointValueExtractor([pt102,], volset(101), IF_EPL) 
  eplPt102.setEulerian(True)                        # Eulerian point (not moving with elements)
  eplPt102.setOutsideTol(0.5)                       # half an element outside detection tolerance 
  

It is possible to modelize a strainGauge in Metafor using GeoPointValueExtractors. Selecting the 2 geometrical points (anywhere in the mesh) defining the Strain Gauge, the distance between the tho points can be computed during the simulation allowing to define a StrainGaufeValueExtractor. The strain measure define the kind of extractor :

valueExtractor = BiotStrainGaugeValueExtractor(listPt, meshedObject)
valueExtractor = BiotStrainGaugeValueExtractor(listPt, meshedObjectList)
valueExtractor = GLStrainGaugeValueExtractor(listPt, meshedObject)
valueExtractor = GLStrainGaugeValueExtractor(listPt, meshedObjectList)
valueExtractor = NatStrainGaugeValueExtractor(listPt, meshedObject)
valueExtractor = NatStrainGaugeValueExtractor(listPt, meshedObjectList)

where

and if $\lambda = \frac{l}{l_0}$ the ratio of current to initial length of the Strain Gauge

Extract thermodynamic fields :

  valueExtractor = TdFieldValueExtractor(meta, gObject, tdFieldID)
  valueExtractor = TdFieldValueExtractor(meta, nodeSet, tdFieldID)

momentVE = MomentValueExtractor(target, center, momentNature, targetVariant,sOp=None, maxV=-1)

Extract a component of the moment force vector (internal, external, inertial) with respect to a center of an object containing these nodes (meshed object, group, …).

• the center can be a point or a node, fixed or moving
• MomentValueExtractor has all its meaning if used with VectorToScalarOperator

moment2AxeVE = Moment2AxeValueExtractor(target, axis, targetVariant,sOp=None, maxV=-1)

Extract the moment force (internal, external, inertial) with respect to an axis containing these nodes (meshed object, group, …). It computes the torque of forces around the axis.

• the axis can be fixed or moving
• Moment2AxeValueExtractor has all its meaning if used with VectorToScalarOperator

Extract values of internal fields at the integration points.

valueExtractor = IFGaussPointValueExtractor (topoCell, ifield)

where

works, but it is difficult to select the topoCell

Extract values of internal fields at the integration points for all the elements of aninteraction.

valueExtractor = IFGPInteractionValueExtractor(inter, ifield)

where

Extract a value of internal fields averaged over an element.

valueExtractor = IFElementValueExtractor (topoCell, ifield)

where

works, but selection of the topoCell may be difficult

Extract values of internal fields averaged on each element of an interaction (1 mean value by element).

valueExtractor = IFElementsValueExtractor (inter, ifield)

where

Extract values associated to the computation (analysis values)

valueExtractor = MiscValueExtractor(meta, type)

Extractors of virtual memory in Linux and Windows

Example:

valuesmanager.add(1, MiscValueExtractor(metafor, EXT_T),'time')

Extract the time value for each time step, in the vector 1 named time.

Extract a component of a vector computed by the elements of an interaction.

valueExtractor = InteractionValueExtractor (interaction, natureId, vectorId=GEN_EXT_FORC)

where

Extract the time evolution of the position of the center of gravity and mass of an interaction. At each archiving step the extractor fills a four columns text file, where columns 1-3 contain x, y, and z coordinates of the center of gravity respectively, and column 4 contains the value of the mass.

valueExtractor = InteractionGravityCenterAndMassValueExtractor (interaction)

where

interaction –> Reference of an interaction.

Series of extractors associated to contact interaction. They give values for contact elements, which is to say in each slave nodes.

The matricial output can be sorted and reduced using SortingOperators and/or can be made scalar (at the ValuesManager level) using a VectorToScalarOperator.

Extracted values have a filter allowing to archive the extractor name and a subset of slave nodes of the contact interaction.

valueExtractor = ContactStatusValueExtractor(contInt, sOp=None, maxV=-1)
valueExtractor.setGeoFilter(gObject)
gObject = meshed geometric object, included in the object on which the contact interaction is defined. 

By default, all contact elements associated to the interaction are considered (for defo-defo contact in two stages, both master and slave nodes are considered).

Operations are done in the following order:

- Filter operation - Sorting operation - “resize” operation, so reducing the number of stored values after filtering and sorting.

Extract the status of normal contact in each slave node:

valueExtractor = ContactStatusValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Outputs:

The number of nodes in contact is easily deduced:

valuesmanager.add(no, ContactStatusValueExtractor(ci), SumOperator(), 'NodesInContact') 

Extract the status of tangential contact in each slave node:

valueExtractor = SlidingStatusValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Outputs :

Extract the normal gap in each slave node:

valueExtractor = NormalGapValueExtractor(contInt, sOp=None, maxV=-1 , _nonContactGapsSetToZero=True)

Inputs :

Outputs :

The maximal normal gap is easily deduced:

valuesmanager.add(no, NormalGapValueExtractor(ci), AbsMaxOperator(), 'GapMax') 

Extract the norm of tangential gap in each slave node:

valueExtractor = TangentGapValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

The value corresponds to the total gap (sticking gap + sliding gap) with respect to the sticking point of the previous balanced configuration when the slave node is sliding/or sticking. But, when the slave node is sliding, this gap is considered as zero in this extractor and thus only the slave node in sticking contact receives a non-zero value.

It is possible to archive the sliding and the sticking gaps :

valueExtractor.setNonStickingGapsSetToZero(False)

Extract the component 1 of tangential gap in each slave node:

valueExtractor = TangentGap1ValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of tangential gap are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)

The value corresponds to the total gap (sticking gap + sliding gap) with respect to the sticking point of the previous balanced configuration when the slave node is sliding/or sticking. But, when the slave node is sliding, this gap is considered as zero in this extractor and thus only the slave node in sticking contact receives a non-zero value.

It is possible to archive the sliding and the sticking gaps :

valueExtractor.setNonStickingGapsSetToZero(False)

Extract the component 2 of tangential gap in each slave node:

valueExtractor = TangentGap2ValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of tangential gap are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)

The value corresponds to the total gap (sticking gap + sliding gap) with respect to the sticking point of the previous balanced configuration when the slave node is sliding/or sticking. But, when the slave node is sliding, this gap is considered as zero in this extractor and thus only the slave node in sticking contact receives a non-zero value.

It is possible to archive the sliding and the sticking gaps :

valueExtractor.setNonStickingGapsSetToZero(False)

Extract the nodal normal force in each slave node:

valueExtractor = NormalForceValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Extract the contact pressure (negative or positive, if bodies are pushed against each other ???) in each slave node:

valueExtractor = PressureContactValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Extract the normal augmented lagrangian in each slave node:

valueExtractor = NormalAugmentedLagrangianValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Extract the norm of tangential force in each slave node:

valueExtractor = TangentForceValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Extract the component 1 of tangential force in each slave node:

valueExtractor = Tangent1ForceValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of tangential force are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)

Extract the component 2 of tangential force in each slave node:

valueExtractor = Tangent2ForceValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of tangential force are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)

Extract the norm of shear stress in each slave node:

valueExtractor = ShearContactValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Extract the component 1 of shear stress in each slave node:

valueExtractor = Shear1ContactValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of shear stress are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)

Extract the component 2 of shear stress in each slave node:

valueExtractor = Shear2ContactValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of shear stress are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)

Extract the norm of tangential augmented lagrangian in each slave node:

valueExtractor = TangentAugmentedLagrangianValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Extract the component 1 of tangential augmented lagrangien in each slave node:

valueExtractor = TangentAugmentedLagrangian1ValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of tangential augmented lagrangian are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)

Extract the component 2 of tangential augmented lagrangien in each slave node:

valueExtractor = TangentAugmentedLagrangian2ValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

By default, the components of tangential augmented lagrangian are related to the local tangent system defined by the sliding direction (The tangent 1 is aligned with this direction and the tangent 2 is obtained with the right hand rule.). It is possible to use another local tangent system related to the tool tangents (Pay attention when using with a defo-defo contact interaction !) :

valueExtractor.setUseToolLocalSystemAxes(True)
 

Extract the slave node contact area in each slave node:

areaInContactValues=AreaInContactValueExtractor(contInt, sOp=None, maxV=-1)

Inputs:

Then, the area potentially in contact can be deduced:

valuesmanager.add(no, areaInContactValues, SumOperator(), 'AreaInContact')

Nodal contact area of slave nodes in contact (and master nodes in two stages defo-defo):

activeAreaInContactValues=AreaInContactValueExtractor(contInt, sOp=None, maxV=-1)
activeAreaInContactValues.setOnlyInContactStatus()

Then, the active contact area (area which is truly in contact)

valuesmanager.add(no, activeAreaInContactValues, SumOperator(), 'ActiveAreaInContact')

Extract contact resultant forces along TX, TY or TZ of a contact interaction

contactForceValueExtractor=ContactForceValueExtractor(contInt,  natureId, contactForceType=TOTAL_FORCE, sOp=None, maxV=-1)

Inputs:

The contact force on a slave entity of a contact interaction is only taken into consideration in the extractor

Extract values associated to transfert during remeshing of an interaction (ALE or complete remeshing).

Extract the value of the field integral before or after transfer, the value of the difference between both or the value of the transfer error.

valueExtractor = TransferValueExtractor(transferRegion, field, type)

Inputs:

Value of the integral before transfer → type = BEFORE
Value of the integral after transfer → type = AFTER
Value of the difference between the integral before and after transfer → type = DIFF
value of the transfer error → type = TRANSFER_ERROR

The transfer error is defined as:

$$\frac{\int f^{old}-f^{new}}{\int f^{new} }$$

Number of active elements:

valueExtractor = NumberOfActiveElementsExtractor(interaction)

Number of inactive elements:

valueExtractor = NumberOfInactiveElementsExtractor(interaction)

where

Example to generate a file brokenelements.ascii which contains the number of elements broken for interaction 1:

  valuesmanager.add(1, NumberOfInactiveElementsExtractor(interactionset(1)),'brokenelements')

When a curve is defined by the ValuesManager, a ''SortingOperator'' and the number of points to keep after sorting can be added. For example (see also apps/qs/cont2.py):

valuesManager = metafor.getValuesManager()  
valuesManager .add(8, DbNodalValueExtractor(curveset(1), Field1D(TY,GF2), SortByDist0(0.5,0.0,0.0), 2), 'totalForce_X')
valuesManager .add(9, IFNodalValueExtractor(curveset(1), IF_J2, SortByKsi0(curset(3), 8),'j2OnBaseLine')

The first curve displays the force field as a function of time, on the two nodes closest to (0.5, 0). This can be viewed in Matlab using :

  load totalForce_X;
  mesh(totalForce_X);

The second curve displays the equivalent stress field as a function of time, on the 8 first nodes of line 1, sorted by their curvilinear abscissa when projected on curve 3.

Available sorting operators :

In the previous example, note the parameter None in the command defining values to extract. This parameter can be replaced by a mathematical operator which transforms the list of extracted value at a given time into a scalar.

Several operators exist :

• None: no operator (all component,s by default)
• MaxOperator: maximal value
• MinOperator: minimal value
• AbsMaxOperator: compute the value whose absolute value is maximal (but keeps its sign)
• AbsMinOperator: compute the value whose absolute value is minimal (but keeps its sign)
• MaxAbsOperator: compute the maximal value of the vector containing absolute values (always positive)
• MinAbsOperator: compute the minimal value of the vector containing absolute values (always positive)
• MaxOfNonZeroOperator: maximal value excluding zero values
• MinOfNonZeroOperator: minimal value excluding zero values
• AbsMaxNonZeroOperator: compute the value whose absolute value is maximal (but keeps its sign), excluding zero values
• AbsMinNonZeroOperator: compute the value whose absolute value is minimal (but keeps its sign), excluding zero values
• MaxAbsNonZeroOperator: compute the maximal value of the vector containing absolute values (always positive), excluding zero values
• MinAbsNonZeroOperator: compute the minimal value of the vector containing absolute values (always positive), excluding zero values
• MeanOperator: compute the average value
• SumOperator: compute the sum (used toe extract the resultant force exercised on a given geometric entity)

Use:

Extraction of maximal value of plastic deformation on a volume:

curves = metafor.getValuesManager()
ext =  IFNodalValueExtractor(curset(1), IF_EPL)
curves.add(1, ext, MeanOperator(), 'meanEplOnCurve1')