chrono::ChLoadBodyMesh Class Reference

Description

Class for applying loads to a triangle mesh belonging to a ChBody, as a cluster of forces operating on the underlying rigid body.

It is useful for doing cosimulation: one can pass this object's vertex & faces to an external software (ex. CFD) that in turn will perform collision detection with its entities, compute forces, send forces back to Chrono via this object. Note, this 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 > cbody, geometry::ChTriangleMeshConnected &cmesh)
 
virtual ChLoadBodyMeshClone () const override
 "Virtual" copy constructor (covariant return type).
 
void OutputSimpleMesh (std::vector< ChVector<>> &vert_pos, std::vector< ChVector<>> &vert_vel, std::vector< ChVector< int >> &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< ChVector<>> vert_forces, const std::vector< int > vert_ind)
 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 (geometry::ChTriangleMeshConnected &mmesh)
 Set the contact mesh (also resets the applied nodes).
 
geometry::ChTriangleMeshConnectedGetContactMesh ()
 Get the contact mesh.
 
std::vector< std::shared_ptr< ChLoadBodyForce > > & GetForceList ()
 Access the list of applied forces, to allow adding new ones, removing them, counting them, etc. More...
 
virtual int LoadGet_ndof_x () override
 Gets the number of DOFs affected by this load (position part)
 
virtual int LoadGet_ndof_w () 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 (ex. More...
 
virtual int LoadGet_field_ncoords () override
 Number of coordinates in the interpolated field, ex=3 for a tetrahedron finite element or a cable, = 1 for a thermal problem, etc.
 
virtual void ComputeQ (ChState *state_x, ChStateDelta *state_w) override
 Compute Q, the generalized load. More...
 
virtual void ComputeJacobian (ChState *state_x, ChStateDelta *state_w, ChMatrixRef mK, ChMatrixRef mR, ChMatrixRef mM) override
 Compute 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 also set the ChVariables referenced by the sparse KRM block.
 
virtual void LoadIntLoadResidual_F (ChVectorDynamic<> &R, double c) override
 Adds the internal loads Q (pasted at global nodes offsets) into a global vector R, multiplied by a scaling factor c, as R += forces * c.
 
virtual void LoadIntLoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, double c) override
 Increment a vector R with a term that has M multiplied a given vector w: R += c*M*w also R += c*(-dQ/da)*w Not needed (ex. More...
 
virtual void LoadIntLoadLumpedMass_Md (ChVectorDynamic<> &Md, double &err, double c) override
 Adds the lumped mass to a Md vector, representing a mass diagonal matrix. More...
 
virtual void InjectKRMmatrices (ChSystemDescriptor &mdescriptor) override
 Tell to a system descriptor that there are item(s) of type ChKblock in this object (for further passing it to a solver)
 
virtual void KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor) override
 Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. 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: this is called at least at each time step. More...
 
- Public Member Functions inherited from chrono::ChObj
 ChObj (const ChObj &other)
 
int GetIdentifier () const
 Gets the numerical identifier of the object.
 
void SetIdentifier (int id)
 Sets the numerical identifier of the object.
 
double GetChTime () const
 Gets the simulation time of this object.
 
void SetChTime (double m_time)
 Sets the simulation time of this object.
 
const char * GetName () const
 Gets the name of the object as C Ascii null-terminated string -for reading only!
 
void SetName (const char myname[])
 Sets the name of this object, as ascii string.
 
std::string GetNameString () const
 Gets the name of the object as C Ascii null-terminated string.
 
void SetNameString (const std::string &myname)
 Sets the name of this object, as std::string.
 
void MFlagsSetAllOFF (int &mflag)
 
void MFlagsSetAllON (int &mflag)
 
void MFlagSetON (int &mflag, int mask)
 
void MFlagSetOFF (int &mflag, int mask)
 
int MFlagGet (int &mflag, int mask)
 
virtual void ArchiveOut (ChArchiveOut &marchive)
 Method to allow serialization of transient data to archives.
 
virtual void ArchiveIn (ChArchiveIn &marchive)
 Method to allow de-serialization of transient data from archives.
 
virtual std::string & ArchiveContainerName ()
 

Additional Inherited Members

- Protected Attributes inherited from chrono::ChLoadBase
ChLoadJacobiansjacobians
 
- Protected Attributes inherited from chrono::ChObj
double ChTime
 the time of simulation for the object
 

Member Function Documentation

◆ ComputeJacobian()

void chrono::ChLoadBodyMesh::ComputeJacobian ( ChState state_x,
ChStateDelta state_w,
ChMatrixRef  mK,
ChMatrixRef  mR,
ChMatrixRef  mM 
)
overridevirtual

Compute jacobians.

Not needed when forces are constant, btw.

Parameters
state_xstate position to evaluate jacobians
state_wstate speed to evaluate jacobians
mKresult dQ/dx
mRresult dQ/dv
mMresult dQ/da

Implements chrono::ChLoadBase.

◆ ComputeQ()

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

Compute Q, the generalized load.

Parameters
state_xstate position to evaluate Q
state_wstate speed to evaluate Q

Implements chrono::ChLoadBase.

◆ GetForceList()

std::vector<std::shared_ptr<ChLoadBodyForce> >& chrono::ChLoadBodyMesh::GetForceList ( )
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< ChVector<>>  vert_forces,
const std::vector< int >  vert_ind 
)

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_indindexes 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.

◆ KRMmatricesLoad()

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

Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any.

The K, R, M matrices are added with scaling values Kfactor, Rfactor, Mfactor.

Reimplemented from chrono::ChLoadBase.

◆ LoadIntLoadLumpedMass_Md()

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

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

Used by lumped explicit integrators. If mass lumping is impossible or approximate, adds scalar error to "err" parameter. Md += c*diag(M) Not needed (ex. override to {} ) if no M is involved, ex. no inertial effects.

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_Mv()

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

Increment a vector R with a term that has M multiplied a given vector w: R += c*M*w also R += c*(-dQ/da)*w Not needed (ex.

override to {} ) if no M is involved, ex. no inertial effects.

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

Implements chrono::ChLoadBase.

◆ LoadStateIncrement()

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

Increment a packed state (ex.

as obtained by LoadGetStateBlock_x()) by a given packed state-delta. Compute: x_new = x + dw. Ex. this is called by the BDF numerical differentiation routine that computes jacobian in the default ComputeJacobian() fallback, if not overriding ComputeJacobian() with an analytical form.

Implements chrono::ChLoadBase.

◆ OutputSimpleMesh()

void chrono::ChLoadBodyMesh::OutputSimpleMesh ( std::vector< ChVector<>> &  vert_pos,
std::vector< ChVector<>> &  vert_vel,
std::vector< ChVector< int >> &  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 vertexes (absolute xyz positions)
vert_velarray of vertexes (absolute xyz velocities, might be useful)
trianglesarray of triangles (indexes to vertexes, 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