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ParallelHexahedronFEMForceField

ParallelHexahedronFEMForceField is the multi-threaded equivalent of HexahedronFEMForceField.

This implementation is the most efficient when:

1) the number of hexahedron is large (> 1000) 2) the global system matrix is not assembled. It is usually the case with a CGLinearSolver templated with GraphScattered types. 3) the method is 'large'. If the method is 'polar' or 'small', addForce is executed sequentially, but addDForce in parallel.

The following methods are executed in parallel:

  • addForce for method 'large'.
  • addDForce

The method addKToMatrix is not executed in parallel. This method is called with an assembled system, usually with a direct solver or a CGLinearSolver templated with types different from GraphScattered. In this case, the most time-consuming step is to invert the matrix. This is where efforts should be put to accelerate the simulation.

Parallel implementation of a linear elastic material using hexahedral finite elements.

Vec3d

Templates:

  • Vec3d

Target: MultiThreading

namespace: multithreading::component::forcefield::solidmechanics::fem::elastic

parents:

  • HexahedronFEMForceField

Data

Name Description Default value
name object name unnamed
printLog if true, emits extra messages at runtime. 0
tags list of the subsets the object 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
poissonRatio FEM Poisson Ratio in Hooke's law [0,0.5[ 0.45
youngModulus FEM Young's Modulus in Hooke's law 5000
method "large" or "polar" or "small" displacements large
updateStiffnessMatrix 0
gatherPt number of dof accumulated per threads during the gather operation (Only use in GPU version)
gatherBsize number of dof accumulated per threads during the gather operation (Only use in GPU version)
stiffnessMatrices Stiffness matrices per element (K_i)
initialPoints Initial Position
nbThreads If not yet initialized, the main task scheduler is initialized with this number of threads. 0 corresponds to the number of available cores on the CPU. -n (minus) corresponds to the number of available cores on the CPU minus the provided number. 0
taskSchedulerType Type of task scheduler to use. _default
Visualization
drawing draw the forcefield if true 1
drawPercentageOffset size of the hexa 0.15
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

ParallelHexahedronFEMForceField.scn

<?xml version="1.0" ?>
<Node name="root" dt="0.02">
    <RequiredPlugin name="MultiThreading"/> <!-- Needed to use components [ParallelHexahedronFEMForceField] -->
    <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 [UniformMass] -->
    <RequiredPlugin name="Sofa.Component.ODESolver.Backward"/> <!-- Needed to use components [EulerImplicitSolver] -->
    <RequiredPlugin name="Sofa.Component.StateContainer"/> <!-- Needed to use components [MechanicalObject] -->
    <RequiredPlugin name="Sofa.Component.Topology.Container.Grid"/> <!-- Needed to use components [RegularGridTopology] -->
    <RequiredPlugin name="Sofa.Component.Visual"/> <!-- Needed to use components [VisualStyle] -->
    <RequiredPlugin name="Sofa.Component.Mapping.Linear"/> <!-- Needed to use components [IdentityMapping] -->
    <RequiredPlugin name="Sofa.Component.Topology.Container.Dynamic"/> <!-- Needed to use components [HexahedronSetTopologyContainer, HexahedronSetTopologyModifier, QuadSetTopologyContainer, QuadSetTopologyModifier] -->
    <RequiredPlugin name="Sofa.Component.Topology.Mapping"/> <!-- Needed to use components [Hexa2QuadTopologicalMapping] -->
    <RequiredPlugin name="Sofa.GL.Component.Rendering3D"/> <!-- Needed to use components [OglModel] -->


    <VisualStyle displayFlags="showBehaviorModels hideForceFields showWireframe" />

    <Node name="M1">
        <EulerImplicitSolver name="cg_odesolver" printLog="false" rayleighStiffness="0.1" rayleighMass="0.1" />
        <CGLinearSolver iterations="25" name="linear solver" tolerance="1.0e-9" threshold="1.0e-9" />
        <MechanicalObject name="Volume" template="Vec3"/>
        <UniformMass vertexMass="1" />
        <RegularGridTopology name="grid" nx="8" ny="8" nz="40" xmin="-1.5" xmax="1.5" ymin="-1.5" ymax="1.5" zmin="0" zmax="19" />

        <HexahedronSetTopologyContainer name="Container" src="@grid"/>
        <HexahedronSetTopologyModifier name="Modifier" />

        <BoxROI box="-1.5 -1.5 0 1.5 1.5 0.0001" name="box"/>
        <FixedProjectiveConstraint indices="@box.indices" />
        <ParallelHexahedronFEMForceField name="FEM" youngModulus="400000" poissonRatio="0.4" method="large" updateStiffnessMatrix="false"/>

        <Node name="surface">
            <QuadSetTopologyContainer name="Container" />
            <QuadSetTopologyModifier name="Modifier" />

            <Hexa2QuadTopologicalMapping input="@../Container" output="@Container" />
            <Node name="Visu">
                <OglModel name="Visual" color="red" />
                <IdentityMapping input="@../../Volume" output="@Visual" />
            </Node>
        </Node>
    </Node>
</Node>

def createScene(root_node):

   root = root_node.addChild('root', dt="0.02")

   root.addObject('RequiredPlugin', name="MultiThreading")
   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.StateContainer")
   root.addObject('RequiredPlugin', name="Sofa.Component.Topology.Container.Grid")
   root.addObject('RequiredPlugin', name="Sofa.Component.Visual")
   root.addObject('RequiredPlugin', name="Sofa.Component.Mapping.Linear")
   root.addObject('RequiredPlugin', name="Sofa.Component.Topology.Container.Dynamic")
   root.addObject('RequiredPlugin', name="Sofa.Component.Topology.Mapping")
   root.addObject('RequiredPlugin', name="Sofa.GL.Component.Rendering3D")
   root.addObject('VisualStyle', displayFlags="showBehaviorModels hideForceFields showWireframe")

   m1 = root.addChild('M1')

   m1.addObject('EulerImplicitSolver', name="cg_odesolver", printLog="false", rayleighStiffness="0.1", rayleighMass="0.1")
   m1.addObject('CGLinearSolver', iterations="25", name="linear solver", tolerance="1.0e-9", threshold="1.0e-9")
   m1.addObject('MechanicalObject', name="Volume", template="Vec3")
   m1.addObject('UniformMass', vertexMass="1")
   m1.addObject('RegularGridTopology', name="grid", nx="8", ny="8", nz="40", xmin="-1.5", xmax="1.5", ymin="-1.5", ymax="1.5", zmin="0", zmax="19")
   m1.addObject('HexahedronSetTopologyContainer', name="Container", src="@grid")
   m1.addObject('HexahedronSetTopologyModifier', name="Modifier")
   m1.addObject('BoxROI', box="-1.5 -1.5 0 1.5 1.5 0.0001", name="box")
   m1.addObject('FixedProjectiveConstraint', indices="@box.indices")
   m1.addObject('ParallelHexahedronFEMForceField', name="FEM", youngModulus="400000", poissonRatio="0.4", method="large", updateStiffnessMatrix="false")

   surface = M1.addChild('surface')

   surface.addObject('QuadSetTopologyContainer', name="Container")
   surface.addObject('QuadSetTopologyModifier', name="Modifier")
   surface.addObject('Hexa2QuadTopologicalMapping', input="@../Container", output="@Container")

   visu = surface.addChild('Visu')

   visu.addObject('OglModel', name="Visual", color="red")
   visu.addObject('IdentityMapping', input="@../../Volume", output="@Visual")