Description

Load representing a concentrated force acting on a ChNodeXYZ, as a constant force, or it provides a function to modulate it with time.

As it is constant in space, IsStiff() is false, as default.

#include <ChLoadsXYZROTnode.h>

Public Member Functions

ChLoadXYZROTnodeForceAbsolute (std::shared_ptr< ChNodeFEAxyzrot > node, const ChVector<> &force)

"Virtual" copy constructor (covariant return type).

virtual void ComputeForceTorque (const ChFrameMoving<> &node_frame_abs_pos_vel, ChVector<> &abs_force, ChVector<> &abs_torque) override
Compute the force on the node, in absolute coordsystem, given absolute position and speed of node passed via node_frame_abs_pos_vel. More...

void SetForceBase (const ChVector<> &force)
Set the applied force vector: it is assumed constant, unless a non-constant scaling time function is provided. More...

ChVector GetForce () const
Return the current force vector (scaled by the current modulation value).

void SetModulationFunction (std::shared_ptr< ChFunction > modulation)
Set modulation function. More...

Public Member Functions inherited from chrono::fea::ChLoadXYZROTnode

virtual void ComputeQ (ChState *state_x, ChStateDelta *state_w) override
Compute Q, the generalized load. More...

ChVector GetForce () const
For diagnosis purposes, this can return the actual last computed value of the applied force, expressed in absolute coordinate system, assumed applied to node.

ChVector GetTorque () const
For diagnosis purposes, this can return the actual last computed value of the applied torque, expressed in absolute coordinate system, assumed applied to node.

Public Member Functions inherited from chrono::ChLoadCustom

Gets the number of DOFs affected by this load (position part)

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...

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 ComputeJacobian (ChState *state_x, ChStateDelta *state_w, ChMatrixRef mK, ChMatrixRef mR, ChMatrixRef mM) override
Compute jacobians (default fallback). More...

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.

Default fallback: compute jacobians via ComputeJacobian(), then use M=-dQ/da to do R += c*M*w. More...

virtual void CreateJacobianMatrices () override
Create the jacobian loads if needed, and also 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 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 ()

Protected Member Functions

virtual bool IsStiff () override
Inherited classes could override this and return true, if the load benefits from a jacobian when using implicit integrators.

virtual void Update (double time) override
Update: this is called at least at each time step. More...

Protected Attributes

ChVector m_force_base
base force value

std::shared_ptr< ChFunctionm_modulation
modulation function of time

double m_scale
scaling factor (current modulation value)

ChVector computed_abs_force

ChVector computed_abs_torque

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

Constructor & Destructor Documentation

Parameters
 node node to apply load to force force to apply, assumed in absolute coordsys,

◆ ComputeForceTorque()

 void chrono::fea::ChLoadXYZROTnodeForceAbsolute::ComputeForceTorque ( const ChFrameMoving<> & node_frame_abs_pos_vel, ChVector<> & abs_force, ChVector<> & abs_torque )
overridevirtual

Compute the force on the node, in absolute coordsystem, given absolute position and speed of node passed via node_frame_abs_pos_vel.

Compute the force on the node, in absolute coordsystem, given position of node as abs_pos.

◆ SetForceBase()

 void chrono::fea::ChLoadXYZROTnodeForceAbsolute::SetForceBase ( const ChVector<> & force )

Set the applied force vector: it is assumed constant, unless a non-constant scaling time function is provided.

It is expressed in absolute coordinates.

◆ SetModulationFunction()

 void chrono::fea::ChLoadXYZROTnodeForceAbsolute::SetModulationFunction ( std::shared_ptr< ChFunction > modulation )
inline

Set modulation function.

This is a function of time which (optionally) modulates the specified applied force. By default the modulation is a constant function, always returning a value of 1.

◆ Update()

 void chrono::fea::ChLoadXYZROTnodeForceAbsolute::Update ( double time )
overrideprotectedvirtual

Update: this is called at least at each time step.

• It recomputes the generalized load Q vector(s)
• It recomputes the jacobian(s) K,R,M in case of stiff load Q and jacobians assumed evaluated at the current state. Jacobian structures are automatically allocated if needed.