Description

Simple finite element with two nodes and a bar that connects them.

No bending and torsion stiffness, just like a bar with two spherical joints. In practical terms, this element works a bit like the class ChElementSpring, but also adds mass along the element, hence point-like mass in the two nodes is not needed.

#include <ChElementBar.h>

Inheritance diagram for chrono::fea::ChElementBar:

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Collaboration diagram for chrono::fea::ChElementBar:

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Public Member Functions
virtual int	GetNnodes () override
	Get the number of nodes used by this element.

virtual int	GetNdofs () override
	Get the number of coordinates in the field used by the referenced nodes. More...

virtual int	GetNodeNdofs (int n) override
	Get the number of coordinates from the specified node that are used by this element. More...

virtual std::shared_ptr< ChNodeFEAbase >	GetNodeN (int n) override
	Access the nth node.

virtual void	SetNodes (std::shared_ptr< ChNodeFEAxyz > nodeA, std::shared_ptr< ChNodeFEAxyz > nodeB)

virtual void	GetStateBlock (ChVectorDynamic<> &mD) override
	Fills the D vector with the current field values at the nodes of the element, with proper ordering. More...

virtual void	ComputeKRMmatricesGlobal (ChMatrixRef H, double Kfactor, double Rfactor=0, double Mfactor=0) override
	Sets H as the global stiffness matrix K, scaled by Kfactor. More...

virtual void	ComputeInternalForces (ChVectorDynamic<> &Fi) override
	Computes the internal forces (ex. More...

void	SetBarArea (double ma)
	Set the cross sectional area of the bar (m^2) (also changes stiffness keeping same E modulus)

double	GetBarArea ()

void	SetBarDensity (double md)
	Set the density of the bar (kg/m^3)

double	GetBarDensity ()

void	SetBarYoungModulus (double mE)
	Set the Young elastic modulus (N/m^2) (also sets stiffness)

double	GetBarYoungModulus ()

void	SetBarRaleyghDamping (double mr)
	Set the Rayleigh damping ratio r (as in: R = r * K )

double	GetBarRaleyghDamping ()

double	GetMass ()
	The full mass of the bar.

double	GetRestLength ()
	The rest length of the bar.

double	GetCurrentLength ()
	The current length of the bar (might be after deformation)

double	GetStrain ()
	Get the strain (epsilon), after deformation.

double	GetStress ()
	Get the elastic stress (sigma), after deformation.

virtual double	GetCurrentForce ()
	Get the current force transmitted along the bar direction, including the effect of the damper. More...

Public Member Functions inherited from chrono::fea::ChElementGeneric
ChKblockGeneric &	Kstiffness ()
	Access the proxy to stiffness, for sparse solver.

virtual void	EleIntLoadResidual_F (ChVectorDynamic<> &R, const double c) override
	Add the internal forces (pasted at global nodes offsets) into a global vector R, multiplied by a scaling factor c, as R += forces * c This default implementation is SLIGHTLY INEFFICIENT.

virtual void	EleIntLoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c) override
	Add the product of element mass M by a vector w (pasted at global nodes offsets) into a global vector R, multiplied by a scaling factor c, as R += M * w * c This default implementation is VERY INEFFICIENT.

virtual void	EleIntLoadResidual_F_gravity (ChVectorDynamic<> &R, const ChVector<> &G_acc, const double c) override
	Add the contribution of gravity loads, multiplied by a scaling factor c, as: R += M * g * c This default implementation is VERY INEFFICIENT. More...

virtual void	ComputeGravityForces (ChVectorDynamic<> &Fg, const ChVector<> &G_acc) override
	Compute the gravitational forces. More...

virtual void	ComputeMmatrixGlobal (ChMatrixRef M) override
	Calculate the mass matrix, expressed in global reference. More...

virtual void	InjectKRMmatrices (ChSystemDescriptor &descriptor) override
	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) override
	Add the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...

virtual void	VariablesFbLoadInternalForces (double factor=1.) override
	Add the internal forces, expressed as nodal forces, into the encapsulated ChVariables.

virtual void	VariablesFbIncrementMq () override
	Add M*q (internal masses multiplied current 'qb').

Public Member Functions inherited from chrono::fea::ChElementBase
virtual int	GetNdofs_active ()
	Get the actual number of active degrees of freedom. More...

virtual int	GetNodeNdofs_active (int n)
	Get the actual number of active coordinates from the specified node that are used by this element. More...

virtual void	ComputeNodalMass ()
	Compute element's nodal masses.

virtual void	Update ()
	Update, called at least at each time step. More...

virtual void	EleDoIntegration ()
	This is optionally implemented if there is some internal state that requires integration.

Additional Inherited Members
Protected Attributes inherited from chrono::fea::ChElementGeneric
ChKblockGeneric	Kmatr

Member Function Documentation

◆ ComputeInternalForces()

void chrono::fea::ChElementBar::ComputeInternalForces ( ChVectorDynamic<> & Fi )

overridevirtual

Computes the internal forces (ex.

the actual position of nodes is not in relaxed reference position) and set values in the Fi vector.

Implements chrono::fea::ChElementBase.

◆ ComputeKRMmatricesGlobal()

void chrono::fea::ChElementBar::ComputeKRMmatricesGlobal	(	ChMatrixRef	H,
		double	Kfactor,
		double	Rfactor = `0`,
		double	Mfactor = `0`
	)

overridevirtual

Sets H as the global stiffness matrix K, scaled by Kfactor.

Optionally, also superimposes global damping matrix R, scaled by Rfactor, and global mass matrix M multiplied by Mfactor. (For the spring matrix there is no need to corotate local matrices: we already know a closed form expression.)

Implements chrono::fea::ChElementBase.

◆ GetCurrentForce()

double chrono::fea::ChElementBar::GetCurrentForce ( )

virtual

Get the current force transmitted along the bar direction, including the effect of the damper.

Positive if pulled. (N)

◆ GetNdofs()

virtual int chrono::fea::ChElementBar::GetNdofs ( )

inlineoverridevirtual

Get the number of coordinates in the field used by the referenced nodes.

This is for example the size (number of rows/columns) of the local stiffness matrix.

Implements chrono::fea::ChElementBase.

◆ GetNodeNdofs()

virtual int chrono::fea::ChElementBar::GetNodeNdofs ( int n )

inlineoverridevirtual

Get the number of coordinates from the specified node that are used by this element.

Note that this may be different from the value returned by GetNodeN(n)->GetNdofW().

Implements chrono::fea::ChElementBase.

◆ GetStateBlock()

void chrono::fea::ChElementBar::GetStateBlock ( ChVectorDynamic<> & mD )

overridevirtual

Fills the D vector with the current field values at the nodes of the element, with proper ordering.

If the D vector size is not this->GetNdofs(), it will be resized.

Implements chrono::fea::ChElementBase.

The documentation for this class was generated from the following files:

/builds/uwsbel/chrono/src/chrono/fea/ChElementBar.h
/builds/uwsbel/chrono/src/chrono/fea/ChElementBar.cpp

Description

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ ComputeInternalForces()

◆ ComputeKRMmatricesGlobal()

◆ GetCurrentForce()

◆ GetNdofs()

◆ GetNodeNdofs()

◆ GetStateBlock()