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:

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Collaboration diagram for chrono::ChLoadBodyMesh:

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Public Member Functions
	ChLoadBodyMesh (std::shared_ptr< ChBody > body, const ChTriangleMeshConnected &mesh)

virtual ChLoadBodyMesh *	Clone () 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).

ChTriangleMeshConnected &	GetContactMesh ()
	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
ChLoadJacobians *	GetJacobians ()
	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
ChLoadJacobians *	m_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_x	state position to evaluate jacobians
state_w	state 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_x	state position to evaluate Q
state_w	state 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_forces	array of forces (in absolute frame)
vert_indices	indices 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

Md	result: Md vector, diagonal of the lumped mass matrix
err	result: not touched if lumping does not introduce errors
c	a 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

R	result: the R residual, R += cMv
w	the w vector
c	scaling 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_pos	array of vertex aabsolute xyz positions
vert_vel	array of vertex absolute xyz velocities
triangles	array 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

Description

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ ComputeJacobian()

◆ ComputeQ()

◆ GetForces()

◆ InputSimpleForces()

◆ IsStiff()

◆ LoadGetNumFieldCoords()

◆ LoadIntLoadLumpedMass_Md()

◆ LoadIntLoadResidual_F()

◆ LoadIntLoadResidual_Mv()

◆ LoadKRMMatrices()

◆ LoadStateIncrement()

◆ OutputSimpleMesh()