chrono::ChNodeBase Class Referenceabstract

Description

Class for a node, that has some degrees of freedom and that contain a proxy to the solver.

It is like a lightweight version of a ChPhysicsItem, often a ChPhysicsItem is used as a container for a cluster of these ChNodeBase.

#include <ChNodeBase.h>

Inheritance diagram for chrono::ChNodeBase:

Public Member Functions

 ChNodeBase (const ChNodeBase &other)
 
ChNodeBaseoperator= (const ChNodeBase &other)
 
virtual int Get_ndof_x () const =0
 Get the number of degrees of freedom.
 
virtual int Get_ndof_w () const
 Get the number of degrees of freedom, derivative This might be different from ndof if quaternions are used for rotations, as derivative might be angular velocity. More...
 
unsigned int NodeGetOffset_x ()
 Get offset in the state vector (position part)
 
unsigned int NodeGetOffset_w ()
 Get offset in the state vector (speed part)
 
void NodeSetOffset_x (const unsigned int moff)
 Set offset in the state vector (position part)
 
void NodeSetOffset_w (const unsigned int moff)
 Set offset in the state vector (speed part)
 
virtual void NodeIntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T)
 
virtual void NodeIntStateScatter (const unsigned int off_x, const ChState &x, const unsigned int off_v, const ChStateDelta &v, const double T)
 
virtual void NodeIntStateGatherAcceleration (const unsigned int off_a, ChStateDelta &a)
 
virtual void NodeIntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a)
 
virtual void NodeIntStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv)
 
virtual void NodeIntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c)
 
virtual void NodeIntLoadResidual_Mv (const unsigned int off, ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c)
 
virtual void NodeIntToDescriptor (const unsigned int off_v, const ChStateDelta &v, const ChVectorDynamic<> &R)
 
virtual void NodeIntFromDescriptor (const unsigned int off_v, ChStateDelta &v)
 
virtual void InjectVariables (ChSystemDescriptor &mdescriptor)
 Tell to a system descriptor that there are variables of type ChVariables in this object (for further passing it to a solver)
 
virtual void VariablesFbReset ()
 Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero.
 
virtual void VariablesFbLoadForces (double factor=1)
 Adds the current forces (applied to node) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor.
 
virtual void VariablesQbLoadSpeed ()
 Initialize the 'qb' part of the ChVariables with the current value of speeds. More...
 
virtual void VariablesFbIncrementMq ()
 Adds M*q (masses multiplied current 'qb') to Fb, ex. More...
 
virtual void VariablesQbSetSpeed (double step=0)
 Fetches the item speed (ex. More...
 
virtual void VariablesQbIncrementPosition (double step)
 Increment node positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor. More...
 
virtual void ArchiveOUT (ChArchiveOut &marchive)
 
virtual void ArchiveIN (ChArchiveIn &marchive)
 Method to allow de serialization of transient data from archives.
 

Protected Attributes

unsigned int offset_x
 offset in vector of state (position part)
 
unsigned int offset_w
 offset in vector of state (speed part)
 

Member Function Documentation

virtual int chrono::ChNodeBase::Get_ndof_w ( ) const
virtual

Get the number of degrees of freedom, derivative This might be different from ndof if quaternions are used for rotations, as derivative might be angular velocity.

Reimplemented in chrono::fea::ChNodeFEAcurv, and chrono::fea::ChNodeFEAxyzrot.

virtual void chrono::ChNodeBase::VariablesFbIncrementMq ( )
virtual

Adds M*q (masses multiplied current 'qb') to Fb, ex.

if qb is initialized with v_old using VariablesQbLoadSpeed, this method can be used in timestepping schemes that do: M*v_new = M*v_old + forces*dt

Reimplemented in chrono::fea::ChNodeFEAxyz, chrono::fea::ChNodeFEAcurv, chrono::fea::ChNodeFEAxyzrot, chrono::fea::ChNodeFEAxyzP, chrono::fea::ChNodeFEAxyzDD, and chrono::fea::ChNodeFEAxyzD.

virtual void chrono::ChNodeBase::VariablesQbIncrementPosition ( double  step)
virtual

Increment node positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor.

pos+=qb*step

If qb is a speed, this behaves like a single step of 1-st order numerical integration (Eulero integration).

Reimplemented in chrono::fea::ChNodeFEAxyz, chrono::fea::ChNodeFEAcurv, chrono::fea::ChNodeFEAxyzrot, chrono::fea::ChNodeFEAxyzP, chrono::fea::ChNodeFEAxyzDD, and chrono::fea::ChNodeFEAxyzD.

virtual void chrono::ChNodeBase::VariablesQbLoadSpeed ( )
virtual
virtual void chrono::ChNodeBase::VariablesQbSetSpeed ( double  step = 0)
virtual

Fetches the item speed (ex.

linear velocity, in xyz nodes) from the 'qb' part of the ChVariables and sets it as the current item speed. If 'step' is not 0, also should compute the approximate acceleration of the item using backward differences, that is accel=(new_speed-old_speed)/step. Mostly used after the solver provided the solution in ChVariables.

Reimplemented in chrono::fea::ChNodeFEAxyz, chrono::fea::ChNodeFEAcurv, chrono::fea::ChNodeFEAxyzrot, chrono::fea::ChNodeFEAxyzP, chrono::fea::ChNodeFEAxyzDD, and chrono::fea::ChNodeFEAxyzD.