Description

Loads acting on a single ChLoadable item.

Differently form ChLoad, this does not use the ChLoader interface, so one must inherit from this and implement ComputeQ() directly. The ComputeQ() must write the generalized forces Q into the "load_Q" vector of this object.

#include <ChLoad.h>

Inheritance diagram for chrono::ChLoadCustom:

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Collaboration diagram for chrono::ChLoadCustom:

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Public Member Functions
	ChLoadCustom (std::shared_ptr< ChLoadable > mloadable)

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	ComputeJacobian (ChState state_x, ChStateDelta state_w, ChMatrixRef mK, ChMatrixRef mR, ChMatrixRef mM) override
	Compute jacobians (default fallback). More...

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
	Default fallback: compute jacobians via ComputeJacobian(), then use M=-dQ/da to do R += cMw. More...

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

virtual ChVectorDynamic &	GetQ ()
	Access the generalized load vector Q.

Public Member Functions inherited from chrono::ChLoadBase
virtual void	ComputeQ (ChState state_x, ChStateDelta state_w)=0
	Compute Q, the generalized load(s). More...

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...

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

Public Attributes
std::shared_ptr< ChLoadable >	loadable

ChVectorDynamic	load_Q

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::ChLoadCustom::ComputeJacobian	(	ChState *	state_x,
		ChStateDelta *	state_w,
		ChMatrixRef	mK,
		ChMatrixRef	mR,
		ChMatrixRef	mM
	)

overridevirtual

Compute jacobians (default fallback).

Uses a numerical differentiation for computing K, R, M jacobians, if stiff load. If possible, override this with an analytical jacobian. Compute the K=-dQ/dx, R=-dQ/dv , M=-dQ/da jacobians. 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

Implements chrono::ChLoadBase.

Reimplemented in chrono::ChLoadBodyInertia.

◆ LoadIntLoadResidual_Mv()

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

overridevirtual

Default fallback: compute jacobians via ComputeJacobian(), then use M=-dQ/da to do R += c*M*w.

If possible, override this to bypass jacobian computation, if analytical expression c*M*w is known. Not needed (ex. override to {} ) if no M is involved, ex. no inertial effects.

Parameters

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

Implements chrono::ChLoadBase.

Reimplemented in chrono::ChLoadBodyInertia.

◆ LoadStateIncrement()

void chrono::ChLoadCustom::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.

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

Public Attributes

Additional Inherited Members

Member Function Documentation

◆ ComputeJacobian()

◆ LoadIntLoadResidual_Mv()

◆ LoadStateIncrement()