Description

Base class for loads.

This class can be inherited to implement applied loads to bodies, finite elements, etc. A load is an object that might wrap one or more ChLoader objects, whose value is dependent. It implements functionalities to perform automatic differentiation of the load so it optionally can compute the jacobian (the tangent stiffness matrix of the load) that can be used in implicit integrators, statics, etc.

#include <ChLoad.h>

Inheritance diagram for chrono::ChLoadBase:

[legend]

Collaboration diagram for chrono::ChLoadBase:

[legend]

Public Member Functions
virtual int	LoadGet_ndof_x ()=0
	Gets the number of DOFs affected by this load (position part)

virtual int	LoadGet_ndof_w ()=0
	Gets the number of DOFs affected by this load (speed part)

virtual void	LoadGetStateBlock_x (ChState &mD)=0
	Gets all the current DOFs packed in a single vector (position part)

virtual void	LoadGetStateBlock_w (ChStateDelta &mD)=0
	Gets all the current DOFs packed in a single vector (speed part)

virtual void	LoadStateIncrement (const ChState &x, const ChStateDelta &dw, ChState &x_new)=0
	Increment a packed state (ex. More...

virtual int	LoadGet_field_ncoords ()=0
	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)=0
	Compute Q, the generalized load(s). More...

virtual void	ComputeJacobian (ChState state_x, ChStateDelta state_w, ChMatrixRef mK, ChMatrixRef mR, ChMatrixRef mM)=0
	Compute the K=-dQ/dx, R=-dQ/dv , M=-dQ/da jacobians. More...

ChLoadJacobians *	GetJacobians ()
	Access the jacobians (if any, i.e. if this is a stiff load)

virtual void	CreateJacobianMatrices ()=0
	Create the jacobian loads if needed, and also set the ChVariables referenced by the sparse KRM block.

virtual void	Update (double time)
	Update: this is called at least at each time step. More...

virtual bool	IsStiff ()=0
	Report if this is load is stiff. More...

virtual void	LoadIntLoadResidual_F (ChVectorDynamic<> &R, double c)=0
	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)=0
	Increment a vector R with a term that has M multiplied a given vector w: R += cMw also R += c(-dQ/da)w Not needed (ex. More...

virtual void	InjectKRMmatrices (ChSystemDescriptor &mdescriptor)
	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)
	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::ChObj
	ChObj (const ChObj &other)

virtual ChObj *	Clone () const =0
	"Virtual" copy constructor. More...

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 ()

Protected Attributes
ChLoadJacobians *	jacobians

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

Member Function Documentation

◆ ComputeJacobian()

virtual void chrono::ChLoadBase::ComputeJacobian	(	ChState *	state_x,
		ChStateDelta *	state_w,
		ChMatrixRef	mK,
		ChMatrixRef	mR,
		ChMatrixRef	mM
	)

pure virtual

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

If possible, override this with an analytical jacobian. Note the sign that is flipped because assuming Q a right hand side, and dQ/d... at left hand side! Called automatically at each Update().

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

Implemented in chrono::ChLoadCustomMultiple, chrono::ChLoadCustom, chrono::ChLoadBodyInertia, chrono::ChLoad< Tloader >, chrono::ChLoad< ChLoaderBeamWrench >, chrono::ChLoad< ChLoaderXYZnode >, chrono::ChLoad< ChLoaderBeamWrenchDistributed >, chrono::fea::ChLoadContactSurfaceMesh, and chrono::ChLoadBodyMesh.

◆ ComputeQ()

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

pure virtual

Compute Q, the generalized load(s).

Where Q is stored depends on children classes. Called automatically at each Update().

Parameters

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

Implemented in chrono::fea::ChLoadXYZROTnodeBody, chrono::ChLoadXYZnodeBody, chrono::ChLoadBodyBody, chrono::ChLoadBodyInertia, chrono::ChLoadXYZnodeXYZnode, chrono::ChShaftsElasticGear, chrono::ChLoad< Tloader >, chrono::ChLoad< ChLoaderBeamWrench >, chrono::ChLoad< ChLoaderXYZnode >, chrono::ChLoad< ChLoaderBeamWrenchDistributed >, chrono::fea::ChLoadXYZROTnodeXYZROTnode, chrono::ChLoadBodyTorque, chrono::ChLoadXYZnodeForce, chrono::fea::ChLoadContactSurfaceMesh, chrono::ChLoadBodyForce, chrono::ChLoadBodyMesh, chrono::fea::ChLoadXYZROTnode, and chrono::ChShaftsLoad.

◆ IsStiff()

virtual bool chrono::ChLoadBase::IsStiff ( )

pure virtual

Report if this is load is stiff.

If so, InjectKRMmatrices will provide the jacobians of the load.

Implemented in chrono::fea::ChLoadXYZROTnodeBodyBushingGeneric, chrono::ChLoadBodyBodyBushingGeneric, chrono::fea::ChLoadXYZROTnodeBodyBushingSpherical, chrono::ChLoadXYZnodeBodyBushing, chrono::ChLoadXYZnodeBodySpring, chrono::ChLoadBodyBodyBushingSpherical, chrono::fea::ChLoadXYZROTnodeXYZROTnodeBushingGeneric, chrono::ChLoadXYZnodeXYZnodeBushing, chrono::ChLoadXYZnodeXYZnodeSpring, chrono::fea::ChLoadXYZROTnodeXYZROTnodeBushingSpherical, chrono::ChLoadXYZnodeXYZnode, chrono::ChLoad< Tloader >, chrono::ChLoad< ChLoaderBeamWrench >, chrono::ChLoad< ChLoaderXYZnode >, chrono::ChLoad< ChLoaderBeamWrenchDistributed >, chrono::ChShaftsElasticGear, chrono::ChLoadXYZnodeForceAbsolute, chrono::fea::ChLoadXYZROTnodeForceAbsolute, chrono::ChLoadXYZnodeForce, chrono::fea::ChLoadContactSurfaceMesh, chrono::ChShaftsTorsionSpringDamper, chrono::ChLoadBodyMesh, and chrono::fea::ChLoadXYZROTnode.

◆ KRMmatricesLoad()

void chrono::ChLoadBase::KRMmatricesLoad	(	double	Kfactor,
		double	Rfactor,
		double	Mfactor
	)

virtual

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 in chrono::fea::ChLoadContactSurfaceMesh, and chrono::ChLoadBodyMesh.

◆ LoadIntLoadResidual_Mv()

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

pure virtual

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

R	result: the R residual, R += cMv
w	the w vector
c	scaling factor

Implemented in chrono::ChLoadCustomMultiple, chrono::ChLoadCustom, chrono::ChLoad< Tloader >, chrono::ChLoad< ChLoaderBeamWrench >, chrono::ChLoad< ChLoaderXYZnode >, chrono::ChLoad< ChLoaderBeamWrenchDistributed >, chrono::fea::ChLoadContactSurfaceMesh, chrono::ChLoadBodyMesh, and chrono::ChLoadBodyInertia.

◆ LoadStateIncrement()

virtual void chrono::ChLoadBase::LoadStateIncrement	(	const ChState &	x,
		const ChStateDelta &	dw,
		ChState &	x_new
	)

pure virtual

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.

Implemented in chrono::ChLoadCustomMultiple, chrono::ChLoadCustom, chrono::ChLoad< Tloader >, chrono::ChLoad< ChLoaderBeamWrench >, chrono::ChLoad< ChLoaderXYZnode >, chrono::ChLoad< ChLoaderBeamWrenchDistributed >, chrono::fea::ChLoadContactSurfaceMesh, and chrono::ChLoadBodyMesh.

◆ Update()

void chrono::ChLoadBase::Update ( double time )

virtual

Update: this is called at least at each time step.

It recomputes the generalized load Q vector(s)
It recomputes the jacobian(s) K,R,M in case of stiff load Q and jacobians assumed evaluated at the current state. Jacobian structures are automatically allocated if needed.

Reimplemented in chrono::ChLoadXYZnodeXYZnode, chrono::ChLoadXYZnodeForceAbsolute, chrono::fea::ChLoadXYZROTnodeForceAbsolute, chrono::ChLoadXYZnodeForce, and chrono::fea::ChLoadXYZROTnode.

The documentation for this class was generated from the following files:

/builds/uwsbel/chrono/src/chrono/physics/ChLoad.h
/builds/uwsbel/chrono/src/chrono/physics/ChLoad.cpp

Description

Public Member Functions

Protected Attributes

Member Function Documentation

◆ ComputeJacobian()

◆ ComputeQ()

◆ IsStiff()

◆ KRMmatricesLoad()

◆ LoadIntLoadResidual_Mv()

◆ LoadStateIncrement()

◆ Update()