TetrahedronHyperelasticityFEMForceField

This component belongs to the category of ForceField. The TetrahedronHyperelasticityFEMForceField implements - for tetrahedral topology only - several non-linear mechanical constitutive laws, also named as hyperelastic constitutive laws. The available models are:

• Arruda-Boyce model
• Costa model
• Mooney-Rivlin model
• Neo-Hookean model
• Ogden model (order 1)
• St Venant-Kirchhoff model
• Veronda-Westmann model

Note that the ParameterSet data changes depending on the chosen material. It corresponds to: - for "ArrudaBoyce", two parameters are required: \(\left[ \mu ,k_0\right]\) - for "Costa", eight parameters are required: \(\left[ a,k_{0},b_{ff},b_{fs},b_{ss},b_{fn},b_{sn},b_{nn}\right]\) - for "MooneyRivlin", three parameters are required: \(\left[ C_{01},C_{10},k_{0}\right]\) - for "NeoHookean", two parameters are required: \(\left[ \mu,k\right]\) - for "Ogden", three parameters are required: \(\left[ k,\mu_1,\alpha_1\right]\) - for "StVenantKirchhoff", two parameters are required: \(\left[ \mu,\lambda \right]\) - for "VerondaWestman", parameters are required: \(\left[ C_{1},C_{2},k_0\right]\)

Usage

As a Forcefield, the TetrahedronHyperelasticityFEMForceField requires a MechanicalObject and the associated solvers (integration scheme and linear solver), as well as a TetrahedronSetTopologyContainer.

Generic Hyperelastic Tetrahedral finite elements.

Vec3d

Templates:

• Vec3d

Target: Sofa.Component.SolidMechanics.FEM.HyperElastic

namespace: sofa::component::solidmechanics::fem::hyperelastic

parents:

• ForceField

Data

Name	Description	Default value
name	object name	unnamed
printLog	if true, emits extra messages at runtime.	0
tags	list of the subsets the objet belongs to
bbox	this object bounding box
componentState	The state of the component among (Dirty, Valid, Undefined, Loading, Invalid).	Undefined
listening	if true, handle the events, otherwise ignore the events	0
rayleighStiffness	Rayleigh damping - stiffness matrix coefficient	0
matrixRegularization	Regularization of the Stiffness Matrix (between true or false)	0
materialName	the name of the material to be used. Possible options are: 'ArrudaBoyce', 'Costa', 'MooneyRivlin', 'NeoHookean', 'Ogden', 'StVenantKirchhoff', 'VerondaWestman', 'StableNeoHookean'	ArrudaBoyce
ParameterSet	The global parameters specifying the material
AnisotropyDirections	The global directions of anisotropy of the material: vector containing anisotropic directions. The vector size is 0 if the material is isotropic, 1 if it is transversely isotropic and 2 for orthotropic materials
tetrahedronInfo	Internal tetrahedron data
edgeInfo	Internal edge data

Links

Name	Description	Destination type name
context	Graph Node containing this object (or BaseContext::getDefault() if no graph is used)	BaseContext
slaves	Sub-objects used internally by this object	BaseObject
master	nullptr for regular objects, or master object for which this object is one sub-objects	BaseObject
mechanicalStates	List of mechanical states to which this component is associated	BaseMechanicalState
mstate	MechanicalState used by this component	MechanicalState<Vec3d>
topology	link to the topology container	BaseMeshTopology

Examples

TetrahedronHyperelasticityFEMForceField.scn

XMLPython

<?xml version="1.0" ?>
<Node name="root" dt="0.005" showBoundingTree="0" gravity="0 -9 0">
        <RequiredPlugin name="Sofa.Component.Collision.Detection.Algorithm"/> <!-- Needed to use components [BVHNarrowPhase BruteForceBroadPhase CollisionPipeline] -->
        <RequiredPlugin name="Sofa.Component.Collision.Detection.Intersection"/> <!-- Needed to use components [MinProximityIntersection] -->
        <RequiredPlugin name="Sofa.Component.Collision.Response.Contact"/> <!-- Needed to use components [CollisionResponse] -->
        <RequiredPlugin name="Sofa.Component.Constraint.Projective"/> <!-- Needed to use components [FixedProjectiveConstraint] -->
        <RequiredPlugin name="Sofa.Component.Engine.Select"/> <!-- Needed to use components [BoxROI] -->
        <RequiredPlugin name="Sofa.Component.LinearSolver.Iterative"/> <!-- Needed to use components [CGLinearSolver] -->
        <RequiredPlugin name="Sofa.Component.Mass"/> <!-- Needed to use components [MeshMatrixMass] -->
        <RequiredPlugin name="Sofa.Component.ODESolver.Backward"/> <!-- Needed to use components [EulerImplicitSolver] -->
        <RequiredPlugin name="Sofa.Component.SolidMechanics.FEM.Elastic"/> <!-- Needed to use components [TetrahedronFEMForceField] -->
        <RequiredPlugin name="Sofa.Component.SolidMechanics.FEM.HyperElastic"/> <!-- Needed to use components [TetrahedronHyperelasticityFEMForceField] -->
        <RequiredPlugin name="Sofa.Component.StateContainer"/> <!-- Needed to use components [MechanicalObject] -->
        <RequiredPlugin name="Sofa.Component.Topology.Container.Dynamic"/> <!-- Needed to use components [TetrahedronSetGeometryAlgorithms TetrahedronSetTopologyContainer TetrahedronSetTopologyModifier] -->
        <RequiredPlugin name="Sofa.Component.Topology.Container.Grid"/> <!-- Needed to use components [RegularGridTopology] -->
        <RequiredPlugin name="Sofa.Component.Topology.Mapping"/> <!-- Needed to use components [Hexa2TetraTopologicalMapping] -->
        <RequiredPlugin name="Sofa.Component.Visual"/> <!-- Needed to use components [Visual3DText VisualStyle] -->

        <VisualStyle displayFlags="showForceFields showBehaviorModels" />
        <CollisionPipeline verbose="0" />
        <BruteForceBroadPhase/>
    <BVHNarrowPhase/>
        <CollisionResponse response="PenalityContactForceField" />
        <MinProximityIntersection name="Proximity" alarmDistance="0.8" contactDistance="0.5" />
        <DefaultAnimationLoop/>

        <Node name="Corrotational">
                <EulerImplicitSolver name="cg_odesolver" printLog="false" />
                <CGLinearSolver iterations="25" name="linear solver" tolerance="1.0e-9" threshold="1.0e-9" />

                <RegularGridTopology name="hexaGrid" min="0 0 0" max="1 1 2.7" n="3 3 8" p0="0 0 0"/>

                <MechanicalObject name="mechObj"/>

                <MeshMatrixMass totalMass="1.0"/>
                <TetrahedronFEMForceField name="FEM" youngModulus="10000" poissonRatio="0.45" method="large" />

                <BoxROI drawBoxes="0" box="0 0 0 1 1 0.05" name="box"/>
                <FixedProjectiveConstraint indices="@box.indices"/>
                <Visual3DText text="Corrotational" position="1 0 -0.5" scale="0.2" />
        </Node>

        <Node name="ArrudaBoyce">
                <EulerImplicitSolver name="cg_odesolver" printLog="false" />
                <CGLinearSolver iterations="25" name="linear solver" tolerance="1.0e-9" threshold="1.0e-9" />

                <RegularGridTopology name="hexaGrid" min="0 0 0" max="1 1 2.7" n="3 3 8" p0="2 0 0"/>

                <MechanicalObject name="mechObj"/>

                <MeshMatrixMass totalMass="1.0"/>

                <Node name="tetras">
                        <TetrahedronSetTopologyContainer name="Container"/>
                        <TetrahedronSetTopologyModifier name="Modifier" />
                        <TetrahedronSetGeometryAlgorithms template="Vec3" name="GeomAlgo" />
                        <Hexa2TetraTopologicalMapping name="default28" input="@../" output="@Container" printLog="0" />

                        <TetrahedronHyperelasticityFEMForceField name="FEM" ParameterSet="3448.2759 31034.483"/>
                </Node>

                <BoxROI drawBoxes="1" box="2 0 0 3 1 0.05" name="box"/>
                <FixedProjectiveConstraint indices="@box.indices"/>
                <Visual3DText text="ArrudaBoyce" position="3 0 -0.5" scale="0.2" />
        </Node>

        <Node name="StVenantKirchhoff">
                <EulerImplicitSolver name="cg_odesolver" printLog="false" />
                <CGLinearSolver iterations="25" name="linear solver" tolerance="1.0e-9" threshold="1.0e-9" />

                <RegularGridTopology name="hexaGrid" min="0 0 0" max="1 1 2.7" n="3 3 8" p0="4 0 0"/>

                <MechanicalObject name="mechObj"/>

                <MeshMatrixMass totalMass="1.0"/>

                <Node name="tetras">
                        <TetrahedronSetTopologyContainer name="Container"/>
                        <TetrahedronSetTopologyModifier name="Modifier" />
                        <TetrahedronSetGeometryAlgorithms template="Vec3" name="GeomAlgo" />
                        <Hexa2TetraTopologicalMapping name="default28" input="@../" output="@Container" printLog="0" />

                        <TetrahedronHyperelasticityFEMForceField name="FEM" ParameterSet="3448.2759 31034.483" materialName="StVenantKirchhoff"/>
                </Node>

                <BoxROI drawBoxes="1" box="4 0 0 5 1 0.05" name="box"/>
                <FixedProjectiveConstraint indices="@box.indices"/>
                <Visual3DText text="StVenantKirchhoff" position="5 0 -0.5" scale="0.2" />
        </Node>


        <Node name="NeoHookean">
                <EulerImplicitSolver name="cg_odesolver" printLog="false" />
                <CGLinearSolver iterations="25" name="linear solver" tolerance="1.0e-9" threshold="1.0e-9" />

                <RegularGridTopology name="hexaGrid" min="0 0 0" max="1 1 2.7" n="3 3 8" p0="6 0 0"/>

                <MechanicalObject name="mechObj"/>

                <MeshMatrixMass totalMass="1.0"/>

                <Node name="tetras">
                        <TetrahedronSetTopologyContainer name="Container"/>
                        <TetrahedronSetTopologyModifier name="Modifier" />
                        <TetrahedronSetGeometryAlgorithms template="Vec3" name="GeomAlgo" />
                        <Hexa2TetraTopologicalMapping name="default28" input="@../" output="@Container" printLog="0" />

                        <TetrahedronHyperelasticityFEMForceField name="FEM" ParameterSet="3448.2759 31034.483" materialName="NeoHookean"/>
                </Node>

                <BoxROI drawBoxes="1" box="6 0 0 7 1 0.05" name="box"/>
                <FixedProjectiveConstraint indices="@box.indices"/>
                <Visual3DText text="NeoHookean" position="7 0 -0.5" scale="0.2" />
        </Node>


        <Node name="MooneyRivlin">
                <EulerImplicitSolver name="cg_odesolver" printLog="false" />
                <CGLinearSolver iterations="25" name="linear solver" tolerance="1.0e-9" threshold="1.0e-9" />

                <RegularGridTopology name="hexaGrid" min="0 0 0" max="1 1 2.7" n="3 3 8" p0="8 0 0"/>

                <MechanicalObject name="mechObj"/>

                <MeshMatrixMass totalMass="1.0"/>

                <Node name="tetras">
                        <TetrahedronSetTopologyContainer name="Container"/>
                        <TetrahedronSetTopologyModifier name="Modifier" />
                        <TetrahedronSetGeometryAlgorithms template="Vec3" name="GeomAlgo" />
                        <Hexa2TetraTopologicalMapping name="default28" input="@../" output="@Container" printLog="0" />

                        <TetrahedronHyperelasticityFEMForceField name="FEM" ParameterSet="5000 7000 10" materialName="MooneyRivlin"/>
                </Node>

                <BoxROI drawBoxes="1" box="8 0 0 9 1 0.05" name="box"/>
                <FixedProjectiveConstraint indices="@box.indices"/>
                <Visual3DText text="MooneyRivlin" position="9 0 -0.5" scale="0.2" />
        </Node>
</Node>

def createScene(root_node):

   root = root_node.addChild('root', dt="0.005", showBoundingTree="0", gravity="0 -9 0")

   root.addObject('RequiredPlugin', name="Sofa.Component.Collision.Detection.Algorithm")
   root.addObject('RequiredPlugin', name="Sofa.Component.Collision.Detection.Intersection")
   root.addObject('RequiredPlugin', name="Sofa.Component.Collision.Response.Contact")
   root.addObject('RequiredPlugin', name="Sofa.Component.Constraint.Projective")
   root.addObject('RequiredPlugin', name="Sofa.Component.Engine.Select")
   root.addObject('RequiredPlugin', name="Sofa.Component.LinearSolver.Iterative")
   root.addObject('RequiredPlugin', name="Sofa.Component.Mass")
   root.addObject('RequiredPlugin', name="Sofa.Component.ODESolver.Backward")
   root.addObject('RequiredPlugin', name="Sofa.Component.SolidMechanics.FEM.Elastic")
   root.addObject('RequiredPlugin', name="Sofa.Component.SolidMechanics.FEM.HyperElastic")
   root.addObject('RequiredPlugin', name="Sofa.Component.StateContainer")
   root.addObject('RequiredPlugin', name="Sofa.Component.Topology.Container.Dynamic")
   root.addObject('RequiredPlugin', name="Sofa.Component.Topology.Container.Grid")
   root.addObject('RequiredPlugin', name="Sofa.Component.Topology.Mapping")
   root.addObject('RequiredPlugin', name="Sofa.Component.Visual")
   root.addObject('VisualStyle', displayFlags="showForceFields showBehaviorModels")
   root.addObject('CollisionPipeline', verbose="0")
   root.addObject('BruteForceBroadPhase', )
   root.addObject('BVHNarrowPhase', )
   root.addObject('CollisionResponse', response="PenalityContactForceField")
   root.addObject('MinProximityIntersection', name="Proximity", alarmDistance="0.8", contactDistance="0.5")
   root.addObject('DefaultAnimationLoop', )

   corrotational = root.addChild('Corrotational')

   corrotational.addObject('EulerImplicitSolver', name="cg_odesolver", printLog="false")
   corrotational.addObject('CGLinearSolver', iterations="25", name="linear solver", tolerance="1.0e-9", threshold="1.0e-9")
   corrotational.addObject('RegularGridTopology', name="hexaGrid", min="0 0 0", max="1 1 2.7", n="3 3 8", p0="0 0 0")
   corrotational.addObject('MechanicalObject', name="mechObj")
   corrotational.addObject('MeshMatrixMass', totalMass="1.0")
   corrotational.addObject('TetrahedronFEMForceField', name="FEM", youngModulus="10000", poissonRatio="0.45", method="large")
   corrotational.addObject('BoxROI', drawBoxes="0", box="0 0 0 1 1 0.05", name="box")
   corrotational.addObject('FixedProjectiveConstraint', indices="@box.indices")
   corrotational.addObject('Visual3DText', text="Corrotational", position="1 0 -0.5", scale="0.2")

   arruda_boyce = root.addChild('ArrudaBoyce')

   arruda_boyce.addObject('EulerImplicitSolver', name="cg_odesolver", printLog="false")
   arruda_boyce.addObject('CGLinearSolver', iterations="25", name="linear solver", tolerance="1.0e-9", threshold="1.0e-9")
   arruda_boyce.addObject('RegularGridTopology', name="hexaGrid", min="0 0 0", max="1 1 2.7", n="3 3 8", p0="2 0 0")
   arruda_boyce.addObject('MechanicalObject', name="mechObj")
   arruda_boyce.addObject('MeshMatrixMass', totalMass="1.0")

   tetras = ArrudaBoyce.addChild('tetras')

   tetras.addObject('TetrahedronSetTopologyContainer', name="Container")
   tetras.addObject('TetrahedronSetTopologyModifier', name="Modifier")
   tetras.addObject('TetrahedronSetGeometryAlgorithms', template="Vec3", name="GeomAlgo")
   tetras.addObject('Hexa2TetraTopologicalMapping', name="default28", input="@../", output="@Container", printLog="0")
   tetras.addObject('TetrahedronHyperelasticityFEMForceField', name="FEM", ParameterSet="3448.2759 31034.483")

   arruda_boyce.addObject('BoxROI', drawBoxes="1", box="2 0 0 3 1 0.05", name="box")
   arruda_boyce.addObject('FixedProjectiveConstraint', indices="@box.indices")
   arruda_boyce.addObject('Visual3DText', text="ArrudaBoyce", position="3 0 -0.5", scale="0.2")

   st_venant_kirchhoff = root.addChild('StVenantKirchhoff')

   st_venant_kirchhoff.addObject('EulerImplicitSolver', name="cg_odesolver", printLog="false")
   st_venant_kirchhoff.addObject('CGLinearSolver', iterations="25", name="linear solver", tolerance="1.0e-9", threshold="1.0e-9")
   st_venant_kirchhoff.addObject('RegularGridTopology', name="hexaGrid", min="0 0 0", max="1 1 2.7", n="3 3 8", p0="4 0 0")
   st_venant_kirchhoff.addObject('MechanicalObject', name="mechObj")
   st_venant_kirchhoff.addObject('MeshMatrixMass', totalMass="1.0")

   tetras = StVenantKirchhoff.addChild('tetras')

   tetras.addObject('TetrahedronSetTopologyContainer', name="Container")
   tetras.addObject('TetrahedronSetTopologyModifier', name="Modifier")
   tetras.addObject('TetrahedronSetGeometryAlgorithms', template="Vec3", name="GeomAlgo")
   tetras.addObject('Hexa2TetraTopologicalMapping', name="default28", input="@../", output="@Container", printLog="0")
   tetras.addObject('TetrahedronHyperelasticityFEMForceField', name="FEM", ParameterSet="3448.2759 31034.483", materialName="StVenantKirchhoff")

   st_venant_kirchhoff.addObject('BoxROI', drawBoxes="1", box="4 0 0 5 1 0.05", name="box")
   st_venant_kirchhoff.addObject('FixedProjectiveConstraint', indices="@box.indices")
   st_venant_kirchhoff.addObject('Visual3DText', text="StVenantKirchhoff", position="5 0 -0.5", scale="0.2")

   neo_hookean = root.addChild('NeoHookean')

   neo_hookean.addObject('EulerImplicitSolver', name="cg_odesolver", printLog="false")
   neo_hookean.addObject('CGLinearSolver', iterations="25", name="linear solver", tolerance="1.0e-9", threshold="1.0e-9")
   neo_hookean.addObject('RegularGridTopology', name="hexaGrid", min="0 0 0", max="1 1 2.7", n="3 3 8", p0="6 0 0")
   neo_hookean.addObject('MechanicalObject', name="mechObj")
   neo_hookean.addObject('MeshMatrixMass', totalMass="1.0")

   tetras = NeoHookean.addChild('tetras')

   tetras.addObject('TetrahedronSetTopologyContainer', name="Container")
   tetras.addObject('TetrahedronSetTopologyModifier', name="Modifier")
   tetras.addObject('TetrahedronSetGeometryAlgorithms', template="Vec3", name="GeomAlgo")
   tetras.addObject('Hexa2TetraTopologicalMapping', name="default28", input="@../", output="@Container", printLog="0")
   tetras.addObject('TetrahedronHyperelasticityFEMForceField', name="FEM", ParameterSet="3448.2759 31034.483", materialName="NeoHookean")

   neo_hookean.addObject('BoxROI', drawBoxes="1", box="6 0 0 7 1 0.05", name="box")
   neo_hookean.addObject('FixedProjectiveConstraint', indices="@box.indices")
   neo_hookean.addObject('Visual3DText', text="NeoHookean", position="7 0 -0.5", scale="0.2")

   mooney_rivlin = root.addChild('MooneyRivlin')

   mooney_rivlin.addObject('EulerImplicitSolver', name="cg_odesolver", printLog="false")
   mooney_rivlin.addObject('CGLinearSolver', iterations="25", name="linear solver", tolerance="1.0e-9", threshold="1.0e-9")
   mooney_rivlin.addObject('RegularGridTopology', name="hexaGrid", min="0 0 0", max="1 1 2.7", n="3 3 8", p0="8 0 0")
   mooney_rivlin.addObject('MechanicalObject', name="mechObj")
   mooney_rivlin.addObject('MeshMatrixMass', totalMass="1.0")

   tetras = MooneyRivlin.addChild('tetras')

   tetras.addObject('TetrahedronSetTopologyContainer', name="Container")
   tetras.addObject('TetrahedronSetTopologyModifier', name="Modifier")
   tetras.addObject('TetrahedronSetGeometryAlgorithms', template="Vec3", name="GeomAlgo")
   tetras.addObject('Hexa2TetraTopologicalMapping', name="default28", input="@../", output="@Container", printLog="0")
   tetras.addObject('TetrahedronHyperelasticityFEMForceField', name="FEM", ParameterSet="5000 7000 10", materialName="MooneyRivlin")

   mooney_rivlin.addObject('BoxROI', drawBoxes="1", box="8 0 0 9 1 0.05", name="box")
   mooney_rivlin.addObject('FixedProjectiveConstraint', indices="@box.indices")
   mooney_rivlin.addObject('Visual3DText', text="MooneyRivlin", position="9 0 -0.5", scale="0.2")

TetrahedronHyperelasticityFEMForceField_invertedTets.scn

XMLPython

<?xml version="1.0" ?>
<Node name="root" dt="0.00005" showBoundingTree="0" gravity="0 0 0">
    <Node name="plugins">
        <RequiredPlugin name="Sofa.Component.Constraint.Projective"/> <!-- Needed to use components [FixedProjectiveConstraint] -->
        <RequiredPlugin name="Sofa.Component.Engine.Select"/> <!-- Needed to use components [BoxROI] -->
        <RequiredPlugin name="Sofa.Component.LinearSolver.Direct"/> <!-- Needed to use components [SparseLDLSolver] -->
        <RequiredPlugin name="Sofa.Component.LinearSystem"/> <!-- Needed to use components [ConstantSparsityPatternSystem] -->
        <RequiredPlugin name="Sofa.Component.Mass"/> <!-- Needed to use components [MeshMatrixMass] -->
        <RequiredPlugin name="Sofa.Component.ODESolver.Backward"/> <!-- Needed to use components [EulerImplicitSolver] -->
        <RequiredPlugin name="Sofa.Component.SolidMechanics.FEM.HyperElastic"/> <!-- Needed to use components [TetrahedronHyperelasticityFEMForceField] -->
        <RequiredPlugin name="Sofa.Component.StateContainer"/> <!-- Needed to use components [MechanicalObject] -->
        <RequiredPlugin name="Sofa.Component.Topology.Container.Dynamic"/> <!-- Needed to use components [TetrahedronSetGeometryAlgorithms TetrahedronSetTopologyContainer TetrahedronSetTopologyModifier] -->
        <RequiredPlugin name="Sofa.Component.Topology.Container.Grid"/> <!-- Needed to use components [RegularGridTopology] -->
        <RequiredPlugin name="Sofa.Component.Topology.Mapping"/> <!-- Needed to use components [Hexa2TetraTopologicalMapping] -->
        <RequiredPlugin name="Sofa.Component.Visual"/> <!-- Needed to use components [VisualStyle] -->
    </Node>

    <VisualStyle displayFlags="showForceFields showBehaviorModels" />

    <DefaultAnimationLoop/>

    <Node name="StableNeoHookean">
        <EulerImplicitSolver name="odesolver"/>
        <ConstantSparsityPatternSystem template="CompressedRowSparseMatrixd" name="A"/>
        <SparseLDLSolver template="CompressedRowSparseMatrixd"/>

        <RegularGridTopology name="hexaGrid"     min="0 0 0" max="1 1 2.7" n="6 6 16" p0="0 0 0"/>
        <RegularGridTopology name="hexaGridRest" min="0 0 0" max="1 1 -2.7"   n="6 6 16" p0="0 0 0"/>

        <MechanicalObject name="mechObj" rest_position="@hexaGrid.position" position="@hexaGridRest.position"/>
        <MeshMatrixMass totalMass="1.0"/>

        <Node name="tetras">
            <TetrahedronSetTopologyContainer name="Container"/>
            <TetrahedronSetTopologyModifier name="Modifier" />
            <TetrahedronSetGeometryAlgorithms template="Vec3" name="GeomAlgo" />
            <Hexa2TetraTopologicalMapping name="default28" input="@../hexaGrid" output="@Container" printLog="0" />

            <TetrahedronHyperelasticityFEMForceField name="FEM" ParameterSet="1644295.30201342 33557.0469798658" materialName="StableNeoHookean"/>
        </Node>

        <BoxROI drawBoxes="1" box="0 0 0 1 1 0.05" name="box"/>
        <FixedProjectiveConstraint indices="@box.indices"/>
    </Node>

</Node>

def createScene(root_node):

   root = root_node.addChild('root', dt="0.00005", showBoundingTree="0", gravity="0 0 0")

   plugins = root.addChild('plugins')

   plugins.addObject('RequiredPlugin', name="Sofa.Component.Constraint.Projective")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.Engine.Select")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.LinearSolver.Direct")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.LinearSystem")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.Mass")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.ODESolver.Backward")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.SolidMechanics.FEM.HyperElastic")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.StateContainer")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.Topology.Container.Dynamic")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.Topology.Container.Grid")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.Topology.Mapping")
   plugins.addObject('RequiredPlugin', name="Sofa.Component.Visual")

   root.addObject('VisualStyle', displayFlags="showForceFields showBehaviorModels")
   root.addObject('DefaultAnimationLoop', )

   stable_neo_hookean = root.addChild('StableNeoHookean')

   stable_neo_hookean.addObject('EulerImplicitSolver', name="odesolver")
   stable_neo_hookean.addObject('ConstantSparsityPatternSystem', template="CompressedRowSparseMatrixd", name="A")
   stable_neo_hookean.addObject('SparseLDLSolver', template="CompressedRowSparseMatrixd")
   stable_neo_hookean.addObject('RegularGridTopology', name="hexaGrid", min="0 0 0", max="1 1 2.7", n="6 6 16", p0="0 0 0")
   stable_neo_hookean.addObject('RegularGridTopology', name="hexaGridRest", min="0 0 0", max="1 1 -2.7", n="6 6 16", p0="0 0 0")
   stable_neo_hookean.addObject('MechanicalObject', name="mechObj", rest_position="@hexaGrid.position", position="@hexaGridRest.position")
   stable_neo_hookean.addObject('MeshMatrixMass', totalMass="1.0")

   tetras = StableNeoHookean.addChild('tetras')

   tetras.addObject('TetrahedronSetTopologyContainer', name="Container")
   tetras.addObject('TetrahedronSetTopologyModifier', name="Modifier")
   tetras.addObject('TetrahedronSetGeometryAlgorithms', template="Vec3", name="GeomAlgo")
   tetras.addObject('Hexa2TetraTopologicalMapping', name="default28", input="@../hexaGrid", output="@Container", printLog="0")
   tetras.addObject('TetrahedronHyperelasticityFEMForceField', name="FEM", ParameterSet="1644295.30201342 33557.0469798658", materialName="StableNeoHookean")

   stable_neo_hookean.addObject('BoxROI', drawBoxes="1", box="0 0 0 1 1 0.05", name="box")
   stable_neo_hookean.addObject('FixedProjectiveConstraint', indices="@box.indices")