## 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:
Collaboration diagram for chrono::ChLoadBodyInertia:

## Public Member Functions

ChLoadBodyInertia (std::shared_ptr< ChBody > body, const ChVector3d &offset, const double m, const ChVector3d &IXX=VNULL, const ChVector3d &IXY=VNULL)

virtual ChLoadBodyInertiaClone () 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 ChMatrix33GetInertia () const
Set the inertia tensor of the body, assumed in the body reference basis, with body reference as center. More...

void SetInertiaXX (const ChVector3d &iner)
Set the diagonal part of the inertia tensor (Ixx, Iyy, Izz values). More...

ChVector3d GetInertiaXX () const
Get the diagonal part of the inertia tensor (Ixx, Iyy, Izz values). More...

void SetInertiaXY (const ChVector3d &iner)
Set the off-diagonal part of the inertia tensor (Ixy, Ixz, Iyz values). More...

ChVector3d 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 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 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

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 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 LoadIntLoadLumpedMass_Md (ChVectorDynamic<> &Md, double &err, const double c) override
Add the lumped mass to an Md vector, representing a mass diagonal matrix. More...

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

virtual ChVectorDynamicGetQ ()
Access the generalized load vector Q.

Public Member Functions inherited from chrono::ChLoadBase
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...

virtual void InjectKRMMatrices (ChSystemDescriptor &descriptor)
Register with the given system descriptor any ChKRMBlock objects associated with this item.

virtual void LoadKRMMatrices (double Kfactor, double Rfactor, double Mfactor)
Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects. 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

Public Attributes inherited from chrono::ChLoadCustom

Protected Member Functions inherited from chrono::ChObj
int GenerateUniqueIdentifier ()

Protected Attributes inherited from chrono::ChLoadBase

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

## Constructor & Destructor Documentation

 chrono::ChLoadBodyInertia::ChLoadBodyInertia ( std::shared_ptr< ChBody > body, const ChVector3d & offset, const double m, const ChVector3d & IXX = VNULL, const ChVector3d & IXY = VNULL )
Parameters
 body object to apply additional inertia to offset offset of the center of mass, in body coordinate system m added mass [kg] IXX added moments of inertia (in body frame, centered in body) IXY added products of inertia values (in body frame, centered in body)

## ◆ ComputeJacobian()

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

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

Implementation in a derived class should load the Jacobian matrices K, R, M in the structure 'm_jacobians'. Note the sign that is flipped because we assume equations are written with Q moved to left-hand side. This override uses analytic expressions (for example, R is the gyroscopic damping matrix).

Parameters
 state_x state position to evaluate Jacobians state_w state speed to evaluate Jacobians

## ◆ ComputeQ()

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

Compute the generalized load(s).

In this case, computes the quadratic (centrifugal, gyroscopic) terms. Signs are negative as Q assumed at right hand side, so Q= -Fgyro -Fcentrifugal 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

## ◆ 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()

 ChVector3d 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()

 ChVector3d 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 ]


 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 += c*M*w w the w vector c scaling factor

## ◆ 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 ChVector3d & 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 ChVector3d & 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: