Description

Load for adding mass and inertia to a body.

Note that a ChBody already has a mass an inertia tensor, however for speed optimization reasons the ChBody mass is limited to zero offset of center of mass, moreover it does not generate a gyroscopical damping matrix. Therefore, you can use this load if you need:

an offset between the body and its center of mass
a gyroscopic damping matrix (and inertial stiffness matrix), ex. it may affect for advanced aeroelastic modal analysis. Note that you must use the solvers for finite elements in order to exploit this feature.

#include <ChLoadsBody.h>

Inheritance diagram for chrono::ChLoadBodyInertia:

[legend]

Collaboration diagram for chrono::ChLoadBodyInertia:

[legend]

Public Member Functions
	ChLoadBodyInertia (std::shared_ptr< ChBody > body, const ChVector<> &m_offset, const double m_mass, const ChVector<> &m_IXX=VNULL, const ChVector<> &m_IXY=VNULL)

virtual ChLoadBodyInertia *	Clone () const override
	"Virtual" copy constructor (covariant return type).

void	SetInertia (const ChMatrix33<> &newXInertia)
	Set the inertia tensor of the body, assumed in the body reference basis, with body reference as center. More...

const ChMatrix33 &	GetInertia () const
	Set the inertia tensor of the body, assumed in the body reference basis, with body reference as center. More...

void	SetInertiaXX (const ChVector<> &iner)
	Set the diagonal part of the inertia tensor (Ixx, Iyy, Izz values). More...

ChVector	GetInertiaXX () const
	Get the diagonal part of the inertia tensor (Ixx, Iyy, Izz values). More...

void	SetInertiaXY (const ChVector<> &iner)
	Set the off-diagonal part of the inertia tensor (Ixy, Ixz, Iyz values). More...

ChVector	GetInertiaXY () const
	Get the extra-diagonal part of the inertia tensor (Ixy, Ixz, Iyz values). More...

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
	For efficiency reasons, do not let the parent class do automatic differentiation to compute the R, K matrices. More...

virtual void	LoadIntLoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c) override
	Just for efficiency, override the default LoadIntLoadResidual_Mv, because we can do this in a simplified way. More...

Public Member Functions inherited from chrono::ChLoadCustom
	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	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	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
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 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)

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
Public Attributes inherited from chrono::ChLoadCustom
std::shared_ptr< ChLoadable >	loadable

ChVectorDynamic	load_Q

Protected Attributes inherited from chrono::ChLoadBase
ChLoadJacobians *	jacobians

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

Constructor & Destructor Documentation

◆ ChLoadBodyInertia()

chrono::ChLoadBodyInertia::ChLoadBodyInertia	(	std::shared_ptr< ChBody >	body,
		const ChVector<> &	m_offset,
		const double	m_mass,
		const ChVector<> &	m_IXX = `VNULL`,
		const ChVector<> &	m_IXY = `VNULL`
	)

Parameters

body	object to apply additional inertia to
m_offset	offset of the center of mass, in body coordinate system
m_mass	added mass [kg]
m_IXX	added diag. inertia values Ixx, Iyy, Izz (in body coordinate system, centered in body)
m_IXY	added off.diag. inertia values Ixy, Ixz, Iyz including the "-"sign (in body coordinate system, centered in body)

Member Function Documentation

◆ ComputeJacobian()

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

overridevirtual

For efficiency reasons, do not let the parent class do automatic differentiation to compute the R, K matrices.

Use analytic expressions instead. For example, R is the well known gyroscopic damping matrix. Also, compute the M matrix.

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

Reimplemented from chrono::ChLoadCustom.

◆ ComputeQ()

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

overridevirtual

Compute Q, the generalized load.

In this case, it computes the quadratic (centrifugal, gyroscopic) terms. Signs are negative as Q assumed at right hand side, so Q= -Fgyro -Fcentrifugal Called automatically at each Update(). The M*a term is not added: to this end one could use LoadIntLoadResidual_Mv afterward.

Parameters

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

Implements chrono::ChLoadBase.

◆ GetInertia()

const ChMatrix33& chrono::ChLoadBodyInertia::GetInertia ( ) const

inline

Set the inertia tensor of the body, assumed in the body reference basis, with body reference as center.

The return 3x3 symmetric matrix contains the following values:

 [ int{y^2+z^2}dm    -int{xy}dm    -int{xz}dm    ]
 [                  int{x^2+z^2}   -int{yz}dm    ]
 [       (symm.)                  int{x^2+y^2}dm ]

◆ GetInertiaXX()

ChVector chrono::ChLoadBodyInertia::GetInertiaXX ( ) const

Get the diagonal part of the inertia tensor (Ixx, Iyy, Izz values).

The vector contains these values, assumed in the body reference basis, with body reference as center:

[  int{y^2+z^2}dm   int{x^2+z^2}   int{x^2+y^2}dm ]

◆ GetInertiaXY()

ChVector chrono::ChLoadBodyInertia::GetInertiaXY ( ) const

Get the extra-diagonal part of the inertia tensor (Ixy, Ixz, Iyz values).

The vector contains these values, assumed in the body reference basis, with body reference as center:

[ -int{xy}dm   -int{xz}dm   -int{yz}dm ]

◆ LoadIntLoadResidual_Mv()

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

overridevirtual

Just for efficiency, override the default LoadIntLoadResidual_Mv, because we can do this in a simplified way.

Parameters

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

Reimplemented from chrono::ChLoadCustom.

◆ SetInertia()

void chrono::ChLoadBodyInertia::SetInertia ( const ChMatrix33<> & newXInertia )

Set the inertia tensor of the body, assumed in the body reference basis, with body reference as center.

The provided 3x3 matrix should be symmetric and contain the inertia tensor as: system:

              [ int{y^2+z^2}dm    -int{xy}dm    -int{xz}dm    ]
newXInertia = [                  int{x^2+z^2}   -int{yz}dm    ]
              [     (symm.)                    int{x^2+y^2}dm ]

◆ SetInertiaXX()

void chrono::ChLoadBodyInertia::SetInertiaXX ( const ChVector<> & iner )

Set the diagonal part of the inertia tensor (Ixx, Iyy, Izz values).

The vector should contain these moments of inertia, assumed in the body reference basis, with body reference as center:

iner = [  int{y^2+z^2}dm   int{x^2+z^2}   int{x^2+y^2}dm ]

◆ SetInertiaXY()

void chrono::ChLoadBodyInertia::SetInertiaXY ( const ChVector<> & iner )

Set the off-diagonal part of the inertia tensor (Ixy, Ixz, Iyz values).

The vector contains these values, assumed in the body reference basis, with body reference as center:

iner = [ -int{xy}dm   -int{xz}dm   -int{yz}dm ]

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

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

Description

Public Member Functions

Additional Inherited Members

Constructor & Destructor Documentation

◆ ChLoadBodyInertia()

Member Function Documentation

◆ ComputeJacobian()

◆ ComputeQ()

◆ GetInertia()

◆ GetInertiaXX()

◆ GetInertiaXY()

◆ LoadIntLoadResidual_Mv()

◆ SetInertia()

◆ SetInertiaXX()

◆ SetInertiaXY()