Description

ANCF beam element with 3 nodes.

This class implements a continuum-based elastic force formulation.

The node numbering, as follows:

              v
              ^
              |
A o-----+-----o-----+-----o B -> u
             /C
            w

where C is the third and central node.

#include <ChElementBeamANCF.h>

Inheritance diagram for chrono::fea::ChElementBeamANCF:

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Collaboration diagram for chrono::fea::ChElementBeamANCF:

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Public Types
enum	StrainFormulation { CMPoisson, CMNoPoisson }
	Poisson effect selection. More...

using	ShapeVector = ChMatrixNM< double, 1, 9 >

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.

virtual int	GetNodeNdofs (int n) override
	Get the number of coordinates from the n-th node used by this element.

void	SetNodes (std::shared_ptr< ChNodeFEAxyzDD > nodeA, std::shared_ptr< ChNodeFEAxyzDD > nodeB, std::shared_ptr< ChNodeFEAxyzDD > nodeC)
	Specify the nodes of this element.

void	SetDimensions (double lenX, double beam_h, double beam_w)
	Specify the element dimensions.

void	SetMaterial (std::shared_ptr< ChMaterialBeamANCF > beam_mat)
	Specify the element material.

virtual std::shared_ptr< ChNodeFEAbase >	GetNodeN (int n) override
	Access the n-th node of this element.

std::shared_ptr< ChNodeFEAxyzDD >	GetNodeA () const
	Get a handle to the first node of this element.

std::shared_ptr< ChNodeFEAxyzDD >	GetNodeB () const
	Get a handle to the second node of this element.

std::shared_ptr< ChNodeFEAxyzDD >	GetNodeC () const
	Get a handle to the third node of this element.

std::shared_ptr< ChMaterialBeamANCF >	GetMaterial () const
	Return the material.

void	SetGravityOn (bool val)
	Turn gravity on/off.

void	SetAlphaDamp (double a)
	Set the structural damping.

double	GetLengthX () const
	Get the element length in the X direction.

double	GetThicknessY ()
	Get the total thickness of the beam element.

double	GetThicknessZ ()
	Get the total thickness of the beam element.

void	ShapeFunctions (ShapeVector &N, double x, double y, double z)
	Fills the N shape function matrix. More...

void	ShapeFunctionsDerivativeX (ShapeVector &Nx, double x, double y, double z)
	Fills the Nx shape function derivative matrix with respect to X.

void	ShapeFunctionsDerivativeY (ShapeVector &Ny, double x, double y, double z)
	Fills the Ny shape function derivative matrix with respect to Y.

void	ShapeFunctionsDerivativeZ (ShapeVector &Nz, double x, double y, double z)
	Fills the Nz shape function derivative matrix with respect to Z.

ChVector	EvaluateBeamSectionStrains ()
	Return a vector with three strain components. More...

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 stiffness matrix K, scaled by Kfactor. More...

virtual void	ComputeMmatrixGlobal (ChMatrixRef M) override
	Returns the global mass matrix. More...

virtual void	ComputeNodalMass () override
	Add contribution of element inertia to total nodal masses. More...

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

virtual void	Update () override
	Update the state of this element.

virtual void	EvaluateSectionStrain (const double, chrono::ChVector< double > &) override

virtual void	EvaluateSectionForceTorque (const double, chrono::ChVector< double > &, chrono::ChVector< double > &) override

virtual void	EvaluateSectionDisplacement (const double eta, ChVector<> &u_displ, ChVector<> &u_rotaz) override
	Gets the xyz displacement of a point on the beam line, and the rotation RxRyRz of section plane, at abscissa 'eta'. More...

virtual void	EvaluateSectionFrame (const double eta, ChVector<> &point, ChQuaternion<> &rot) override
	Gets the absolute xyz position of a point on the beam line, and the absolute rotation of section plane, at abscissa 'eta'. More...

void	ComputeInternalJacobians (double Kfactor, double Rfactor)
	Compute Jacobians of the internal forces. More...

void	ComputeMassMatrix ()
	Compute the mass matrix of the element. More...

void	ComputeGravityForce (const ChVector<> &g_acc)
	Compute the gravitational forces.

double	Calc_detJ0 (double x, double y, double z)

double	Calc_detJ0 (double x, double y, double z, ShapeVector &Nx, ShapeVector &Ny, ShapeVector &Nz, ChMatrixNM< double, 1, 3 > &Nx_d0, ChMatrixNM< double, 1, 3 > &Ny_d0, ChMatrixNM< double, 1, 3 > &Nz_d0)

void	CalcCoordMatrix (ChMatrixNM< double, 9, 3 > &d)

void	CalcCoordDerivMatrix (ChVectorN< double, 27 > &dt)

void	SetStrainFormulation (StrainFormulation model)
	Set the strain formulation.

StrainFormulation	GetStrainFormulation () const
	Get the strain formulation.

virtual int	LoadableGet_ndof_x () override
	Gets the number of DOFs affected by this element (position part).

virtual int	LoadableGet_ndof_w () override
	Gets the number of DOFs affected by this element (velocity part).

virtual void	LoadableGetStateBlock_x (int block_offset, ChState &mD) override
	Gets all the DOFs packed in a single vector (position part).

virtual void	LoadableGetStateBlock_w (int block_offset, ChStateDelta &mD) override
	Gets all the DOFs packed in a single vector (velocity part).

virtual void	LoadableStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv) override
	Increment all DOFs using a delta.

virtual int	Get_field_ncoords () override
	Number of coordinates in the interpolated field, ex=3 for a tetrahedron finite element or a cable, = 1 for a thermal problem, etc.

virtual int	GetSubBlocks () override
	Tell the number of DOFs blocks (ex. =1 for a body, =4 for a tetrahedron, etc.)

virtual unsigned int	GetSubBlockOffset (int nblock) override
	Get the offset of the i-th sub-block of DOFs in global vector.

virtual unsigned int	GetSubBlockSize (int nblock) override
	Get the size of the i-th sub-block of DOFs in global vector.

void	EvaluateSectionVelNorm (double U, ChVector<> &Result)

virtual void	LoadableGetVariables (std::vector< ChVariables * > &mvars) override
	Get the pointers to the contained ChVariables, appending to the mvars vector.

virtual void	ComputeNF (const double U, ChVectorDynamic<> &Qi, double &detJ, const ChVectorDynamic<> &F, ChVectorDynamic<> state_x, ChVectorDynamic<> state_w) override
	Evaluate N'F , where N is some type of shape function evaluated at U,V coordinates of the surface, each ranging in -1..+1 F is a load, N'F is the resulting generalized load Returns also det[J] with J=[dx/du,..], that might be useful in gauss quadrature. More...

virtual void	ComputeNF (const double U, const double V, const double W, ChVectorDynamic<> &Qi, double &detJ, const ChVectorDynamic<> &F, ChVectorDynamic<> state_x, ChVectorDynamic<> state_w) override
	Evaluate N'F , where N is some type of shape function evaluated at U,V,W coordinates of the volume, each ranging in -1..+1 F is a load, N'F is the resulting generalized load Returns also det[J] with J=[dx/du,..], that might be useful in gauss quadrature. More...

virtual double	GetDensity () override
	This is needed so that it can be accessed by ChLoaderVolumeGravity. More...

ChVector	ComputeTangent (const double U)
	Gets the tangent to the centerline at the parametric coordinate U. More...

Public Member Functions inherited from chrono::fea::ChElementBeam
virtual void	EvaluateSectionForceTorque (const double eta, ChVector<> &Fforce, ChVector<> &Mtorque)=0
	Gets the force (traction x, shear y, shear z) and the torque (torsion on x, bending on y, on bending on z) at a section along the beam line, at abscissa 'eta'. More...

virtual void	EvaluateSectionStrain (const double eta, ChVector<> &StrainV)=0
	Gets the axial and bending strain of the ANCF "cable" element.

double	GetMass ()
	The full mass of the beam, (with const. section, density, etc.)

double	GetRestLength ()
	The rest length of the bar.

void	SetRestLength (double ml)
	Set the rest length of the bar (usually this should be automatically done when SetupInitial is called on beams element, given the current state, but one might need to override this, ex for precompressed beams etc).

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
	(This is a default (a bit unoptimal) book keeping so that in children classes you can avoid implementing this EleIntLoadResidual_F function, unless you need faster code)

virtual void	EleIntLoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c) override
	(This is a default (VERY UNOPTIMAL) book keeping so that in children classes you can avoid implementing this EleIntLoadResidual_Mv function, unless you need faster code.)

virtual void	EleIntLoadResidual_F_gravity (ChVectorDynamic<> &R, const ChVector<> &G_acc, const double c) override
	(This is a default (VERY UNOPTIMAL) book keeping so that in children classes you can avoid implementing this EleIntLoadResidual_F_gravity function, unless you need faster code. More...

virtual void	ComputeGravityForces (ChVectorDynamic<> &Fg, const ChVector<> &G_acc) override
	(This is the default implementation (POTENTIALLY INEFFICIENT) so that in children classes you can avoid implementing this ComputeGravityForces() function, unless you need faster code.) This fallback implementation uses a temp ChLoaderGravity that applies the load to elements only if they are inherited by ChLoadableUVW so it can use GetDensity() and Gauss quadrature.

virtual void	InjectKRMmatrices (ChSystemDescriptor &mdescriptor) 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
	Adds 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
	Adds the internal forces, expressed as nodal forces, into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor (This is a default (a bit unoptimal) book keeping so that in children classes you can avoid implementing this VariablesFbLoadInternalForces function, unless you need faster code)

virtual void	VariablesFbIncrementMq () override
	Adds M*q (internal masses multiplied current 'qb') to Fb, ex. More...

Public Member Functions inherited from chrono::fea::ChElementBase
virtual void	EleDoIntegration ()
	This is optionally implemented if there is some internal state that requires integration.

Public Member Functions inherited from chrono::ChLoadableUVW
virtual bool	IsTetrahedronIntegrationNeeded ()
	If true, use quadrature over u,v,w in [0..1] range as tetrahedron volumetric coords (with z=1-u-v-w) otherwise use default quadrature over u,v,w in [-1..+1] as box isoparametric coords.

virtual bool	IsTrianglePrismIntegrationNeeded ()
	If true, use quadrature over u,v in [0..1] range as triangle natural coords (with z=1-u-v), and use linear quadrature over w in [-1..+1], otherwise use default quadrature over u,v,w in [-1..+1] as box isoparametric coords.

Friends
class	BeamANCF_Mass

class	BeamANCF_Gravity

class	BeamANCF_Force

class	BeamANCF_ForceNu

class	BeamANCF_Jacobian

class	BeamANCF_JacobianNu

Additional Inherited Members
Protected Attributes inherited from chrono::fea::ChElementBeam
double	mass

double	length

Protected Attributes inherited from chrono::fea::ChElementGeneric
ChKblockGeneric	Kmatr

Member Enumeration Documentation

◆ StrainFormulation

enum chrono::fea::ChElementBeamANCF::StrainFormulation

Poisson effect selection.

Enumerator
CMPoisson	Continuum-Mechanics formulation, including Poisson effects.
CMNoPoisson	Continuum-Mechanics formulation, disregarding Poisson effects.

Member Function Documentation

◆ ComputeInternalForces()

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

overridevirtual

Computes the internal forces.

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

Implements chrono::fea::ChElementBase.

◆ ComputeInternalJacobians()

void chrono::fea::ChElementBeamANCF::ComputeInternalJacobians	(	double	Kfactor,
		double	Rfactor
	)

Compute Jacobians of the internal forces.

This function calculates a linear combination of the stiffness (K) and damping (R) matrices, J = Kfactor * K + Rfactor * R for given coefficients Kfactor and Rfactor. This Jacobian will be further combined with the global mass matrix M and included in the global stiffness matrix H in the function ComputeKRMmatricesGlobal().

◆ ComputeKRMmatricesGlobal()

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

overridevirtual

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

Optionally, also superimposes global damping matrix R, scaled by Rfactor, and mass matrix M, scaled by Mfactor. Matrices are expressed in global reference. Corotational elements can take the local Kl & Rl matrices and rotate them.

Implements chrono::fea::ChElementBase.

◆ ComputeMassMatrix()

void chrono::fea::ChElementBeamANCF::ComputeMassMatrix ( )

Compute the mass matrix of the element.

Note: in this 'basic' implementation, constant section and constant material are assumed

◆ ComputeMmatrixGlobal()

void chrono::fea::ChElementBeamANCF::ComputeMmatrixGlobal ( ChMatrixRef M )

overridevirtual

Returns the global mass matrix.

This is the default implementation, POTENTIALLY VERY INEFFICIENT. Children classes may need to override this with a more efficient version.

Reimplemented from chrono::fea::ChElementGeneric.

◆ ComputeNF() [1/2]

void chrono::fea::ChElementBeamANCF::ComputeNF	(	const double	U,
		ChVectorDynamic<> &	Qi,
		double &	detJ,
		const ChVectorDynamic<> &	F,
		ChVectorDynamic<> *	state_x,
		ChVectorDynamic<> *	state_w
	)

overridevirtual

Evaluate N'*F , where N is some type of shape function evaluated at U,V coordinates of the surface, each ranging in -1..+1 F is a load, N'*F is the resulting generalized load Returns also det[J] with J=[dx/du,..], that might be useful in gauss quadrature.

Parameters

U	parametric coordinate in surface
Qi	Return result of Q = N'*F here
detJ	Return det[J] here
F	Input F vector, size is =n. field coords.
state_x	if != 0, update state (pos. part) to this, then evaluate
state_w	if != 0, update state (speed part) to this, then evaluate

Implements chrono::ChLoadableU.

◆ ComputeNF() [2/2]

void chrono::fea::ChElementBeamANCF::ComputeNF	(	const double	U,
		const double	V,
		const double	W,
		ChVectorDynamic<> &	Qi,
		double &	detJ,
		const ChVectorDynamic<> &	F,
		ChVectorDynamic<> *	state_x,
		ChVectorDynamic<> *	state_w
	)

overridevirtual

Evaluate N'*F , where N is some type of shape function evaluated at U,V,W coordinates of the volume, each ranging in -1..+1 F is a load, N'*F is the resulting generalized load Returns also det[J] with J=[dx/du,..], that might be useful in gauss quadrature.

Parameters

U	parametric coordinate in volume
V	parametric coordinate in volume
W	parametric coordinate in volume
Qi	Return result of N'*F here, maybe with offset block_offset
detJ	Return det[J] here
F	Input F vector, size is = n.field coords.
state_x	if != 0, update state (pos. part) to this, then evaluate Q
state_w	if != 0, update state (speed part) to this, then evaluate Q

Implements chrono::ChLoadableUVW.

◆ ComputeNodalMass()

void chrono::fea::ChElementBeamANCF::ComputeNodalMass ( )

overridevirtual

Add contribution of element inertia to total nodal masses.

This class computes and adds corresponding masses to ElementGeneric member m_TotalMass.

Reimplemented from chrono::fea::ChElementBase.

◆ ComputeTangent()

ChVector chrono::fea::ChElementBeamANCF::ComputeTangent ( const double U )

Gets the tangent to the centerline at the parametric coordinate U.

Each coordinate ranging in -1..+1.

◆ EvaluateBeamSectionStrains()

ChVector chrono::fea::ChElementBeamANCF::EvaluateBeamSectionStrains ( )

Return a vector with three strain components.

Beta

◆ EvaluateSectionDisplacement()

void chrono::fea::ChElementBeamANCF::EvaluateSectionDisplacement	(	const double	eta,
		ChVector<> &	u_displ,
		ChVector<> &	u_rotaz
	)

overridevirtual

Gets the xyz displacement of a point on the beam line, and the rotation RxRyRz of section plane, at abscissa 'eta'.

Note, eta=-1 at node1, eta=+1 at node2. Note, 'displ' is the displ.state of 2 nodes, ex. get it as GetStateBlock() Results are not corotated.

Implements chrono::fea::ChElementBeam.

◆ EvaluateSectionFrame()

void chrono::fea::ChElementBeamANCF::EvaluateSectionFrame	(	const double	eta,
		ChVector<> &	point,
		ChQuaternion<> &	rot
	)

overridevirtual

Gets the absolute xyz position of a point on the beam line, and the absolute rotation of section plane, at abscissa 'eta'.

Note, eta=-1 at node1, eta=+1 at node2. Note, 'displ' is the displ.state of 2 nodes, ex. get it as GetStateBlock() Results are corotated (expressed in world reference)

Implements chrono::fea::ChElementBeam.

◆ GetDensity()

double chrono::fea::ChElementBeamANCF::GetDensity ( )

overridevirtual

This is needed so that it can be accessed by ChLoaderVolumeGravity.

Density is mass per unit surface.

Implements chrono::ChLoadableUVW.

◆ GetStateBlock()

void chrono::fea::ChElementBeamANCF::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. For corotational elements, field is assumed in local reference!

Implements chrono::fea::ChElementBase.

◆ ShapeFunctions()

void chrono::fea::ChElementBeamANCF::ShapeFunctions	(	ShapeVector &	N,
		double	x,
		double	y,
		double	z
	)

Fills the N shape function matrix.

NOTE! actually N should be a 3row, 27 column sparse matrix, as N = [s1*eye(3) s2*eye(3) s3*eye(3) s4*eye(3)...]; , but here we only store the s1...s9 values in a vector.

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

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

Description

Public Types

Public Member Functions

Friends

Additional Inherited Members

Member Enumeration Documentation

◆ StrainFormulation

Member Function Documentation

◆ ComputeInternalForces()

◆ ComputeInternalJacobians()

◆ ComputeKRMmatricesGlobal()

◆ ComputeMassMatrix()

◆ ComputeMmatrixGlobal()

◆ ComputeNF() [1/2]

◆ ComputeNF() [2/2]

◆ ComputeNodalMass()

◆ ComputeTangent()

◆ EvaluateBeamSectionStrains()

◆ EvaluateSectionDisplacement()

◆ EvaluateSectionFrame()

◆ GetDensity()

◆ GetStateBlock()

◆ ShapeFunctions()