<?xml version="1.0" ?>
<!--Test case 1: Upper border is fixed and only heavy gravity is applied -->
<Node name="root" dt="0.01" showBoundingTree="0" gravity="0 -10 -3">
<Node name="RequiredPlugins">
<RequiredPlugin name="Sofa.Component.Collision.Detection.Algorithm"/> <!-- Needed to use components [BVHNarrowPhase, BruteForceBroadPhase, DefaultPipeline] -->
<RequiredPlugin name="Sofa.Component.Collision.Detection.Intersection"/> <!-- Needed to use components [MinProximityIntersection] -->
<RequiredPlugin name="Sofa.Component.Collision.Geometry"/> <!-- Needed to use components [TriangleCollisionModel] -->
<RequiredPlugin name="Sofa.Component.Collision.Response.Contact"/> <!-- Needed to use components [DefaultContactManager] -->
<RequiredPlugin name="Sofa.Component.Constraint.Projective"/> <!-- Needed to use components [FixedConstraint] -->
<RequiredPlugin name="Sofa.Component.Engine.Select"/> <!-- Needed to use components [BoxROI] -->
<RequiredPlugin name="Sofa.Component.IO.Mesh"/> <!-- Needed to use components [MeshGmshLoader] -->
<RequiredPlugin name="Sofa.Component.LinearSolver.Iterative"/> <!-- Needed to use components [CGLinearSolver] -->
<RequiredPlugin name="Sofa.Component.Mapping.Linear"/> <!-- Needed to use components [IdentityMapping] -->
<RequiredPlugin name="Sofa.Component.Mass"/> <!-- Needed to use components [DiagonalMass] -->
<RequiredPlugin name="Sofa.Component.ODESolver.Backward"/> <!-- Needed to use components [EulerImplicitSolver] -->
<RequiredPlugin name="Sofa.Component.SceneUtility"/> <!-- Needed to use components [InfoComponent] -->
<RequiredPlugin name="Sofa.Component.SolidMechanics.FEM.Elastic"/> <!-- Needed to use components [TriangularFEMForceField] -->
<RequiredPlugin name="Sofa.Component.SolidMechanics.Spring"/> <!-- Needed to use components [TriangularBendingSprings] -->
<RequiredPlugin name="Sofa.Component.StateContainer"/> <!-- Needed to use components [MechanicalObject] -->
<RequiredPlugin name="Sofa.Component.Topology.Container.Dynamic"/> <!-- Needed to use components [TriangleSetGeometryAlgorithms, TriangleSetTopologyContainer, TriangleSetTopologyModifier] -->
<RequiredPlugin name="Sofa.Component.Visual"/> <!-- Needed to use components [VisualStyle] -->
<RequiredPlugin name="Sofa.GL.Component.Rendering3D"/> <!-- Needed to use components [OglModel] -->
<RequiredPlugin name="tearing"/>
</Node>
<VisualStyle displayFlags="showVisual showBehaviorModels" />
<DefaultAnimationLoop />
<DefaultPipeline verbose="0" />
<BruteForceBroadPhase/>
<BVHNarrowPhase/>
<DefaultContactManager response="PenalityContactForceField" />
<MinProximityIntersection name="Proximity" alarmDistance="0.8" contactDistance="0.5" />
<Node name="SquareGravity_FEM">
<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" />
<MeshGmshLoader name="meshLoader" filename="mesh/square3.msh" scale="10" createSubelements="true" />
<TriangleSetTopologyContainer name="Container" src="@meshLoader" fileTopology="" tags=" " />
<TriangleSetTopologyModifier name="Modifier" />
<TriangleSetGeometryAlgorithms name="GeomAlgo" template="Vec3d" />
<MechanicalObject name="Mo"/>
<DiagonalMass massDensity="10.0" />
<BoxROI name="FixedSide" box="-0.1 9.9 0.1 10.1 10.1 -0.1" drawBoxes="1" />
<FixedConstraint name="FixedConstraint" indices="@FixedSide.indices" />
<TriangularFEMForceField name="FEM" youngModulus="300" poissonRatio="0.3" method="large" computePrincipalStress="1"/>
<TriangularBendingSprings name="FEM-Bend" stiffness="400" />
<PlaneForceField normal="0 1 0" d="-20" stiffness="100000" showPlane="1" showPlaneSize="20"/>
<TriangleCollisionModel />
<TearingEngine name="TearingEngine" input_position="@Mo.position" stressThreshold="10.0"
step="30" nbFractureMax="40" showFracturePath="1"/>
<Node >
<OglModel name="Visual" color="red" />
<IdentityMapping input="@.." output="@Visual" />
</Node>
</Node>
</Node>
Simply change the gravity as gravity="0 -10 -3" and the scene is really unstable