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, however this is left in this way for didactic reasons.

#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 > cbody, geometry::ChTriangleMeshConnected &cmesh)

virtual ChLoadBodyMesh *	Clone () 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)
	A --> B 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. More...

void	InputSimpleForces (const std::vector< ChVector<>> vert_forces, const std::vector< int > vert_ind)
	A <– B 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::ChTriangleMeshConnected &	GetContactMesh ()
	Get the contact mesh.

std::vector< std::shared_ptr< ChLoadBodyForce > > &	GetForceList ()
	Access the list of applied forces, so you can add new ones by using push_back(), remove them, count 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, const 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	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) Basically does nothing, but inherited classes must specialize this.

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
ChLoadJacobians *	GetJacobians ()
	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
ChLoadJacobians *	jacobians

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_x	state position to evaluate jacobians
state_w	state speed to evaluate jacobians
mK	result dQ/dx
mR	result dQ/dv
mM	result dQ/da

Implements chrono::ChLoadBase.

◆ ComputeQ()

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

overridevirtual

Compute Q, the generalized load.

Parameters

state_x	state position to evaluate Q
state_w	state speed to evaluate Q

Implements chrono::ChLoadBase.

◆ GetForceList()

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

inline

Access the list of applied forces, so you can add new ones by using push_back(), remove them, count them, etc.

Note that if you add nodes, these should belong to the referenced mesh.

◆ InputSimpleForces()

void chrono::ChLoadBodyMesh::InputSimpleForces	(	const std::vector< ChVector<>>	vert_forces,
		const std::vector< int >	vert_ind
	)

A <– B 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 (absolute xyz forces in [N])
vert_ind	array of indexes to vertexes to whom you apply 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.

◆ 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
	)

A --> B 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.

Similarly to Wavefront .OBJ meshes. Note, 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 vertexes (absolute xyz positions)
vert_vel	array of vertexes (absolute xyz velocities, might be useful)
triangles	array 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

Description

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ ComputeJacobian()

◆ ComputeQ()

◆ GetForceList()

◆ InputSimpleForces()

◆ IsStiff()

◆ KRMmatricesLoad()

◆ LoadStateIncrement()

◆ OutputSimpleMesh()