chrono::ChLoadCustomMultiple Class Referenceabstract

Description

Loads acting on multiple ChLoadable items.

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. Given that multiple ChLoadable objects are referenced here, their sub-forces Q are assumed appended in sequence in the "load_Q" vector, in the same order that has been used in the std::vector "mloadables" for ChLoadCustomMultiple creation. The same applies for the order of the sub-matrices of jacobians K,R etc.

#include <ChLoad.h>

Inheritance diagram for chrono::ChLoadCustomMultiple:
Collaboration diagram for chrono::ChLoadCustomMultiple:

Public Member Functions

 ChLoadCustomMultiple (std::vector< std::shared_ptr< ChLoadable > > &mloadables)
 
 ChLoadCustomMultiple (std::shared_ptr< ChLoadable > mloadableA, std::shared_ptr< ChLoadable > mloadableB)
 
 ChLoadCustomMultiple (std::shared_ptr< ChLoadable > mloadableA, std::shared_ptr< ChLoadable > mloadableB, std::shared_ptr< ChLoadable > mloadableC)
 
virtual int LoadGet_ndof_x ()
 Gets the number of DOFs affected by this load (position part)
 
virtual int LoadGet_ndof_w ()
 Gets the number of DOFs affected by this load (speed part)
 
virtual void LoadGetStateBlock_x (ChState &mD)
 Gets all the current DOFs packed in a single vector (position part)
 
virtual void LoadGetStateBlock_w (ChStateDelta &mD)
 Gets all the current DOFs packed in a single vector (speed part)
 
virtual void LoadStateIncrement (const ChState &x, const ChStateDelta &dw, ChState &x_new)
 Increment a packed state (ex. More...
 
virtual int LoadGet_field_ncoords ()
 Number of coordinates in the interpolated field, ex=3 for a tetrahedron finite element or a cable, = 1 for a thermal problem, etc. More...
 
virtual void ComputeQ (ChState *state_x, ChStateDelta *state_w)=0
 Compute Q, the generalized load. More...
 
virtual void ComputeJacobian (ChState *state_x, ChStateDelta *state_w, ChMatrix<> &mK, ChMatrix<> &mR, ChMatrix<> &mM)
 Compute jacobians (default fallback). More...
 
virtual void LoadIntLoadResidual_F (ChVectorDynamic<> &R, const double c)
 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 bool IsStiff ()=0
 Return true if stiff load. More...
 
virtual void CreateJacobianMatrices ()
 Create the jacobian loads if needed, and also set the ChVariables referenced by the sparse KRM block. More...
 
virtual ChVectorDynamicGetQ ()
 Access the generalized load vector Q.
 
- Public Member Functions inherited from chrono::ChLoadBase
ChLoadJacobiansGetJacobians ()
 Access the jacobians (if any, i.e. if this is a stiff load)
 
virtual void Update ()
 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) Basically does nothing, but inherited classes must specialize this. More...
 
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 Attributes

std::vector< std::shared_ptr
< ChLoadable > > 
loadables
 
ChVectorDynamic load_Q
 

Additional Inherited Members

- Protected Attributes inherited from chrono::ChLoadBase
ChLoadJacobiansjacobians
 

Member Function Documentation

virtual void chrono::ChLoadCustomMultiple::ComputeJacobian ( ChState state_x,
ChStateDelta state_w,
ChMatrix<> &  mK,
ChMatrix<> &  mR,
ChMatrix<> &  mM 
)
virtual

Compute jacobians (default fallback).

Compute the K=-dQ/dx, R=-dQ/dv , M=-dQ/da jacobians. Uses a numerical differentiation for computing K, R, M jacobians, if stiff load. If possible, override this with an analytical jacobian. NOTE: Given that multiple ChLoadable objects are referenced here, sub-matrices of mK,mR are assumed pasted in i,j block-positions where i,j reflect the same order that has been used in the std::vector "mloadables" at ChLoadCustomMultiple creation. Called automatically at each Update().

Parameters
state_xstate position to evaluate jacobians
state_wstate speed to evaluate jacobians
mKresult dQ/dx
mRresult dQ/dv
mMresult dQ/da

Implements chrono::ChLoadBase.

virtual void chrono::ChLoadCustomMultiple::ComputeQ ( ChState state_x,
ChStateDelta state_w 
)
pure virtual

Compute Q, the generalized load.

Called automatically at each Update(). NOTE: The computed Q must be stored in this->load_Q. NOTE: Given that multiple ChLoadable objects are referenced here, their sub-forces Q are assumed appended in sequence in the "load_Q" vector, in the same order that has been used in the std::vector "mloadables" at ChLoadCustomMultiple creation. MUST BE IMPLEMENTED BY CHILDREN CLASSES!!!

Parameters
state_xstate position to evaluate Q
state_wstate speed to evaluate Q

Implements chrono::ChLoadBase.

Implemented in chrono::ChLoadBodyBody.

virtual void chrono::ChLoadCustomMultiple::CreateJacobianMatrices ( )
virtual

Create the jacobian loads if needed, and also set the ChVariables referenced by the sparse KRM block.

Implements chrono::ChLoadBase.

virtual bool chrono::ChLoadCustomMultiple::IsStiff ( )
pure virtual
virtual int chrono::ChLoadCustomMultiple::LoadGet_field_ncoords ( )
virtual

Number of coordinates in the interpolated field, ex=3 for a tetrahedron finite element or a cable, = 1 for a thermal problem, etc.

Implements chrono::ChLoadBase.

virtual void chrono::ChLoadCustomMultiple::LoadStateIncrement ( const ChState x,
const ChStateDelta dw,
ChState x_new 
)
virtual

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.