Description

Load acting on a single ChLoadable item, via ChLoader objects.

There are various ChLoader interfaces ready to use, that can be used as 'building blocks'. These are especially important for creating loads that are distributed on surfaces, lines, volumes, since some ChLoaders implement quadrature.

#include <ChLoad.h>

Inheritance diagram for chrono::ChLoad:
Collaboration diagram for chrono::ChLoad:

Public Member Functions

 ChLoad (std::shared_ptr< ChLoader > loader_object)
 
virtual ChLoadClone () const override
 "Virtual" copy constructor (covariant return type).
 
void SetLoader (std::shared_ptr< ChLoader > loader_object)
 Set the associated ChLoader object.
 
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 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_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 LoadIntLoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, double c) override
 Increment a vector R with the matrix-vector product M*w, scaled by the 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 bool IsStiff () override
 Report if this is load is stiff. More...
 
virtual void CreateJacobianMatrices () override
 Create the Jacobian loads if needed and set the ChVariables referenced by the sparse KRM block.
 
- Public Member Functions inherited from chrono::ChLoadBase
ChLoadJacobiansGetJacobians ()
 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.
 
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 ()
 

Public Attributes

std::shared_ptr< ChLoaderloader
 

Additional Inherited Members

- Protected Member Functions inherited from chrono::ChObj
int GenerateUniqueIdentifier ()
 
- Protected Attributes inherited from chrono::ChLoadBase
ChLoadJacobiansm_jacobians
 
- 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
 

Member Function Documentation

◆ ComputeJacobian()

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

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

This default implementation uses finite differences for computing the K, R, M matrices if the load is stiff. Note the sign that is flipped because we assume equations are written with Q moved to left-hand side.

Parameters
state_xstate position to evaluate Jacobians
state_wstate speed to evaluate Jacobians

Implements chrono::ChLoadBase.

◆ ComputeQ()

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

Compute the generalized load(s).

The generalized force Q is stored in the wrapped ChLoader.

Parameters
state_xstate position to evaluate Q
state_wstate speed to evaluate Q

Implements chrono::ChLoadBase.

◆ IsStiff()

virtual bool chrono::ChLoad::IsStiff ( )
inlineoverridevirtual

Report if this is load is stiff.

By default, the load is declared as stiff if the loader is stiff.

Implements chrono::ChLoadBase.

◆ LoadGetNumFieldCoords()

int chrono::ChLoad::LoadGetNumFieldCoords ( )
overridevirtual

Number of coordinates in the interpolated field.

For example, 3 for a tetrahedron finite element or a cable, 1 for a thermal problem, etc.

Implements chrono::ChLoadBase.

◆ LoadIntLoadLumpedMass_Md()

void chrono::ChLoad::LoadIntLoadLumpedMass_Md ( ChVectorDynamic<> &  Md,
double &  err,
const double  c 
)
overridevirtual

Add the lumped mass to an Md vector, representing a mass diagonal matrix.

In other words, perform the operation: Md += c*diag(M). Used by lumped explicit integrators. If mass lumping is impossible or approximate, adds scalar error to "err" parameter. If no mass matrix M is present (i.e., no inertial effects), implement as no-op. This default implementation uses the computed Jacobians (if available) to extract M = -dQ/da and then calculates Md += c*diag(M). A derived class should override this method if an analytical expressions for c*M*w is available.

Parameters
Mdresult: Md vector, diagonal of the lumped mass matrix
errresult: not touched if lumping does not introduce errors
ca scaling factor

Implements chrono::ChLoadBase.

◆ LoadIntLoadResidual_F()

void chrono::ChLoad::LoadIntLoadResidual_F ( ChVectorDynamic<> &  R,
double  c 
)
overridevirtual

Add the internal loads Q (pasted at global offsets) into a global vector R, multiplied by a scaling factor c.

In other words, perform the operation: R += forces * c

Implements chrono::ChLoadBase.

◆ LoadIntLoadResidual_Mv()

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

Increment a vector R with the matrix-vector product M*w, scaled by the factor c.

In other words, perform the operation: R += c*M*w (i.e., R += c*(-dQ/da)*w). If no mass matrix M is present (i.e., no inertial effects), implement as no-op. This default implementation uses the computed Jacobians (if available) to extract M = -dQ/da and then calculates R += c*M*w. A derived class should override this method if an analytical expressions for c*M*w is available.

Parameters
Rresult: the R residual, R += c*M*w
wthe w vector
cscaling factor

Implements chrono::ChLoadBase.

◆ LoadStateIncrement()

void chrono::ChLoad::LoadStateIncrement ( const ChState x,
const ChStateDelta dw,
ChState x_new 
)
overridevirtual

Increment a packed state (e.g., as obtained by LoadGetStateBlock_x()) by a given packed state-delta.

Compute: x_new = x + dw. This method is used in calculating Jacobians with finite difference approximations (default implementations of ComputeJacobian).

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