chrono::ChLoadBodyMesh Class Reference

Description

Loads applied to a triangle mesh associated with a ChBody, as a cluster of forces operating on the rigid body.

This is useful for data exchange during co-simulation in a force-displacement setting. The states (positions and velocities) of the mesh vertices are extracted from the Chrono simulation (consistent with the kinematics of the asociated body). Forces on the mesh vertices, computed externally, are then applied to the associated rigid body using this object. Note that this class is based on a cluster of std::vector<std::shared_ptr<ChLoadBodyForce>>, but the class itself could bypass all methods of ChLoadBodyForce and directly implement a more efficient LoadIntLoadResidual_F.

#include <ChLoadBodyMesh.h>

Inheritance diagram for chrono::ChLoadBodyMesh:
Collaboration diagram for chrono::ChLoadBodyMesh:

Public Member Functions

 ChLoadBodyMesh (std::shared_ptr< ChBody > body, const ChTriangleMeshConnected &mesh)
 
virtual ChLoadBodyMeshClone () const override
 "Virtual" copy constructor (covariant return type).
 
void OutputSimpleMesh (std::vector< ChVector3d > &vert_pos, std::vector< ChVector3d > &vert_vel, std::vector< ChVector3i > &triangles)
 Get the collision mesh where vertex are given in a vector of xyz points, expressed in absolute coordinates, and triangles are given as indexes to the three vertexes in that vector (similar to Wavefront OBJ meshes). More...
 
void InputSimpleForces (const std::vector< ChVector3d > vert_forces, const std::vector< int > vert_indices)
 Set the forces to the body, where forces are given as a vector of xyz vectors (expressed in absolute coordinates) and indexes to the referenced vertex, as obtained by OutputSimpleMesh. More...
 
void SetContactMesh (const ChTriangleMeshConnected &mesh)
 Set the contact mesh (also resets the applied nodes).
 
ChTriangleMeshConnectedGetContactMesh ()
 Get the contact mesh.
 
std::vector< std::shared_ptr< ChLoadBodyForce > > & GetForces ()
 Access the list of applied forces, to allow adding new ones, removing them, counting them, etc. More...
 
virtual int LoadGetNumCoordsPosLevel () override
 Gets the number of DOFs affected by this load (position part).
 
virtual int LoadGetNumCoordsVelLevel () override
 Gets the number of DOFs affected by this load (speed part).
 
virtual void LoadGetStateBlock_x (ChState &mD) override
 Gets all the current DOFs packed in a single vector (position part).
 
virtual void LoadGetStateBlock_w (ChStateDelta &mD) override
 Gets all the current DOFs packed in a single vector (speed part).
 
virtual void LoadStateIncrement (const ChState &x, const ChStateDelta &dw, ChState &x_new) override
 Increment a packed state (e.g., as obtained by LoadGetStateBlock_x()) by a given packed state-delta. More...
 
virtual int LoadGetNumFieldCoords () override
 Number of coordinates in the interpolated field. More...
 
virtual void ComputeQ (ChState *state_x, ChStateDelta *state_w) override
 Compute the generalized load(s). More...
 
virtual void ComputeJacobian (ChState *state_x, ChStateDelta *state_w) override
 Compute the K=-dQ/dx, R=-dQ/dv, M=-dQ/da Jacobians. More...
 
virtual bool IsStiff () override
 Report if this is load is stiff. More...
 
virtual void CreateJacobianMatrices () override
 Create the Jacobian loads if needed and set the ChVariables referenced by the sparse KRM block.
 
virtual void LoadIntLoadResidual_F (ChVectorDynamic<> &R, double c) override
 Add the internal loads Q (pasted at global offsets) into a global vector R, multiplied by a scaling factor c. More...
 
virtual void LoadIntLoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, double c) override
 Increment a vector R with the matrix-vector product M*w, scaled by the factor c. More...
 
virtual void LoadIntLoadLumpedMass_Md (ChVectorDynamic<> &Md, double &err, double c) override
 Add the lumped mass to an Md vector, representing a mass diagonal matrix. More...
 
virtual void InjectKRMMatrices (ChSystemDescriptor &descriptor) override
 Register with the given system descriptor any ChKRMBlock objects associated with this item.
 
virtual void LoadKRMMatrices (double Kfactor, double Rfactor, double Mfactor) override
 Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects. More...
 
- Public Member Functions inherited from chrono::ChLoadBase
ChLoadJacobiansGetJacobians ()
 Access the Jacobians (if any, i.e. if this is a stiff load).
 
virtual void Update (double time)
 Update, called at least at each time step. More...
 
- Public Member Functions inherited from chrono::ChObj
 ChObj (const ChObj &other)
 
int GetIdentifier () const
 Get the unique integer identifier of this object. More...
 
void SetTag (int tag)
 Set an object integer tag (default: -1). More...
 
int GetTag () const
 Get the tag of this object.
 
void SetName (const std::string &myname)
 Set the name of this object.
 
const std::string & GetName () const
 Get the name of this object.
 
double GetChTime () const
 Gets the simulation time of this object.
 
void SetChTime (double m_time)
 Sets the simulation time of this object.
 
virtual void ArchiveOut (ChArchiveOut &archive_out)
 Method to allow serialization of transient data to archives.
 
virtual void ArchiveIn (ChArchiveIn &archive_in)
 Method to allow de-serialization of transient data from archives.
 
virtual std::string & ArchiveContainerName ()
 

Additional Inherited Members

- Protected Member Functions inherited from chrono::ChObj
int GenerateUniqueIdentifier ()
 
- Protected Attributes inherited from chrono::ChLoadBase
ChLoadJacobiansm_jacobians
 
- Protected Attributes inherited from chrono::ChObj
double ChTime
 object simulation time
 
std::string m_name
 object name
 
int m_identifier
 object unique identifier
 
int m_tag
 user-supplied tag
 

Member Function Documentation

◆ ComputeJacobian()

void chrono::ChLoadBodyMesh::ComputeJacobian ( ChState state_x,
ChStateDelta state_w 
)
overridevirtual

Compute the K=-dQ/dx, R=-dQ/dv, M=-dQ/da Jacobians.

Load the Jacobian matrices K, R, M in the structure 'm_jacobians'.

Parameters
state_xstate position to evaluate jacobians
state_wstate speed to evaluate jacobians

Implements chrono::ChLoadBase.

◆ ComputeQ()

void chrono::ChLoadBodyMesh::ComputeQ ( ChState state_x,
ChStateDelta state_w 
)
overridevirtual

Compute the generalized load(s).

Parameters
state_xstate position to evaluate Q
state_wstate speed to evaluate Q

Implements chrono::ChLoadBase.

◆ GetForces()

std::vector<std::shared_ptr<ChLoadBodyForce> >& chrono::ChLoadBodyMesh::GetForces ( )
inline

Access the list of applied forces, to allow adding new ones, removing them, counting them, etc.

Note that only nodes from the reference mesh should be added.

◆ InputSimpleForces()

void chrono::ChLoadBodyMesh::InputSimpleForces ( const std::vector< ChVector3d vert_forces,
const std::vector< int >  vert_indices 
)

Set the forces to the body, where forces are given as a vector of xyz vectors (expressed in absolute coordinates) and indexes to the referenced vertex, as obtained by OutputSimpleMesh.

NOTE: do not insert/remove nodes from the collision mesh between the OutputSimpleMesh-InputSimpleForces pair!

Parameters
vert_forcesarray of forces (in absolute frame)
vert_indicesindices of vertices with applied forces

◆ IsStiff()

virtual bool chrono::ChLoadBodyMesh::IsStiff ( )
inlineoverridevirtual

Report if this is load is stiff.

If so, InjectKRMMatrices will provide the Jacobians of the load.

Implements chrono::ChLoadBase.

◆ LoadGetNumFieldCoords()

virtual int chrono::ChLoadBodyMesh::LoadGetNumFieldCoords ( )
inlineoverridevirtual

Number of coordinates in the interpolated field.

For example, 3 for a tetrahedron finite element or a cable, 1 for a thermal problem, etc.

Implements chrono::ChLoadBase.

◆ LoadIntLoadLumpedMass_Md()

virtual void chrono::ChLoadBodyMesh::LoadIntLoadLumpedMass_Md ( ChVectorDynamic<> &  Md,
double &  err,
double  c 
)
inlineoverridevirtual

Add the lumped mass to an Md vector, representing a mass diagonal matrix.

In other words, perform the operation: Md += c*diag(M). Used by lumped explicit integrators. If mass lumping is impossible or approximate, adds scalar error to "err" parameter. If no mass matrix M is present (i.e., no inertial effects), implement as no-op.

Parameters
Mdresult: Md vector, diagonal of the lumped mass matrix
errresult: not touched if lumping does not introduce errors
ca scaling factor

Implements chrono::ChLoadBase.

◆ LoadIntLoadResidual_F()

void chrono::ChLoadBodyMesh::LoadIntLoadResidual_F ( ChVectorDynamic<> &  R,
double  c 
)
overridevirtual

Add the internal loads Q (pasted at global offsets) into a global vector R, multiplied by a scaling factor c.

In other words, perform the operation: R += forces * c

Implements chrono::ChLoadBase.

◆ LoadIntLoadResidual_Mv()

virtual void chrono::ChLoadBodyMesh::LoadIntLoadResidual_Mv ( ChVectorDynamic<> &  R,
const ChVectorDynamic<> &  w,
double  c 
)
inlineoverridevirtual

Increment a vector R with the matrix-vector product M*w, scaled by the factor c.

In other words, perform the operation: R += c*M*w (i.e., R += c*(-dQ/da)*w). If no mass matrix M is present (i.e., no inertial effects), implement as no-op.

Parameters
Rresult: the R residual, R += c*M*v
wthe w vector
cscaling factor

Implements chrono::ChLoadBase.

◆ LoadKRMMatrices()

void chrono::ChLoadBodyMesh::LoadKRMMatrices ( double  Kfactor,
double  Rfactor,
double  Mfactor 
)
overridevirtual

Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects.

The resulting KRM blocks represent linear combinations of the K, R, and M matrices, with the specified coefficients Kfactor, Rfactor,and Mfactor, respectively.

Reimplemented from chrono::ChLoadBase.

◆ LoadStateIncrement()

void chrono::ChLoadBodyMesh::LoadStateIncrement ( const ChState x,
const ChStateDelta dw,
ChState x_new 
)
overridevirtual

Increment a packed state (e.g., as obtained by LoadGetStateBlock_x()) by a given packed state-delta.

Compute: x_new = x + dw. This method is used in calculating Jacobians with finite difference approximations (default implementations of ComputeJacobian).

Implements chrono::ChLoadBase.

◆ OutputSimpleMesh()

void chrono::ChLoadBodyMesh::OutputSimpleMesh ( std::vector< ChVector3d > &  vert_pos,
std::vector< ChVector3d > &  vert_vel,
std::vector< ChVector3i > &  triangles 
)

Get the collision mesh where vertex are given in a vector of xyz points, expressed in absolute coordinates, and triangles are given as indexes to the three vertexes in that vector (similar to Wavefront OBJ meshes).

Note that indexes are 0-based. These vectors can be later sent to another computing node that computes, say, CFD forces on the mesh.

Parameters
vert_posarray of vertex aabsolute xyz positions
vert_velarray of vertex absolute xyz velocities
trianglesarray of triangles (vertex indices, ccw)

The documentation for this class was generated from the following files:
  • /builds/uwsbel/chrono/src/chrono/physics/ChLoadBodyMesh.h
  • /builds/uwsbel/chrono/src/chrono/physics/ChLoadBodyMesh.cpp