Description

Tetrahedron FEA element with 4 nodes.

This is a classical element with linear displacement, hence with constant stress and constant strain. It can be easily used for 3D FEA problems.

#include <ChElementTetraCorot_4.h>

Inheritance diagram for chrono::fea::ChElementTetraCorot_4:

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Collaboration diagram for chrono::fea::ChElementTetraCorot_4:

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Public Types
using	ShapeVector = ChMatrixNM< double, 1, 4 >

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

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

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

double	GetVolume ()

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

virtual std::shared_ptr< ChNodeFEAxyz >	GetTetrahedronNode (unsigned int n) override
	Return the specified tetrahedron node (0 <= n <= 3).

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

virtual void	Update () override
	Update element at each time step.

void	ShapeFunctions (ShapeVector &N, double r, double s, double t)
	Fills the N shape function matrix with the values of shape functions at r,s,t 'volume' coordinates, where r=1 at 2nd vertex, s=1 at 3rd, t = 1 at 4th. More...

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

double	ComputeVolume ()

virtual void	ComputeStiffnessMatrix ()
	Computes the local STIFFNESS MATRIX of the element: K = Volume * [B]' * [D] * [B].

virtual void	UpdateRotation () override
	compute large rotation of element for corotational approach

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	SetMaterial (std::shared_ptr< ChContinuumElastic > my_material)
	Set the material of the element.

std::shared_ptr< ChContinuumElastic >	GetMaterial ()

const ChMatrixDynamic &	GetMatrB () const
	Get the partial derivatives matrix MatrB and the StiffnessMatrix.

const ChMatrixDynamic &	GetStiffnessMatrix () const

ChStrainTensor	GetStrain ()
	Returns the strain tensor (note that the tetrahedron 4 nodes is a linear element, thus the strain is constant in the entire volume). More...

ChStressTensor	GetStress ()
	Returns the stress tensor (note that the tetrahedron 4 nodes is a linear element, thus the stress is constant in the entire volume). More...

void	ComputeNodalMass () override
	This function computes and adds corresponding masses to ElementBase member m_TotalMass.

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

virtual unsigned int	GetLoadableNumCoordsVelLevel () override
	Gets the number of DOFs affected by this element (speed part)

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

virtual void	LoadableGetStateBlockVelLevel (int block_offset, ChStateDelta &mD) override
	Gets all the DOFs packed in a single vector (speed 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 unsigned int	GetNumFieldCoords () override
	Number of coordinates in the interpolated field: here the {x,y,z} displacement.

virtual unsigned int	GetNumSubBlocks () override
	Get the number of DOFs sub-blocks.

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

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

virtual bool	IsSubBlockActive (unsigned int nblock) const override
	Check if the specified sub-block of DOFs is active.

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, 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 0..+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.

virtual bool	IsTetrahedronIntegrationNeeded () override
	If true, use quadrature over u,v,w in [0..1] range as tetrahedron volumetric coords, with z=1-u-v-w otherwise use quadrature over u,v,w in [-1..+1] as box isoparametric coords.

Public Member Functions inherited from chrono::fea::ChElementGeneric
ChKRMBlock &	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	EleIntLoadLumpedMass_Md (ChVectorDynamic<> &Md, double &error, const double c) override
	Adds the lumped mass to a Md vector, representing a mass diagonal matrix. More...

virtual void	EleIntLoadResidual_F_gravity (ChVectorDynamic<> &R, const ChVector3d &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 ChVector3d &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
	Register with the given system descriptor any ChKRMBlock objects associated with this item.

virtual void	LoadKRMMatrices (double Kfactor, double Rfactor, double Mfactor) override
	Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects. 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 unsigned int	GetNumCoordsPosLevelActive ()
	Get the actual number of active degrees of freedom. More...

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

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

Public Member Functions inherited from chrono::fea::ChElementCorotational
ChMatrix33 &	Rotation ()
	Access the cumulative rotation matrix of the element. More...

Public Member Functions inherited from chrono::ChLoadableUVW
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.

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

Protected Attributes inherited from chrono::fea::ChElementCorotational
ChMatrix33	A

Member Function Documentation

◆ ComputeInternalForces()

void chrono::fea::ChElementTetraCorot_4::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::ChElementTetraCorot_4::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.

Implements chrono::fea::ChElementBase.

◆ ComputeNF()

void chrono::fea::ChElementTetraCorot_4::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 0..+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.

◆ GetNodeNumCoordsPosLevel()

virtual unsigned int chrono::fea::ChElementTetraCorot_4::GetNodeNumCoordsPosLevel ( unsigned 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 GetNode(n)->GetNumCoordsVelLevel().

Implements chrono::fea::ChElementBase.

◆ GetNumCoordsPosLevel()

virtual unsigned int chrono::fea::ChElementTetraCorot_4::GetNumCoordsPosLevel ( )

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.

◆ GetStateBlock()

void chrono::fea::ChElementTetraCorot_4::GetStateBlock ( ChVectorDynamic<> & mD )

overridevirtual

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

If the D vector has not the size of this->GetNumCoordsPosLevel(), it will be resized.For corotational elements, field is assumed in local reference!

Implements chrono::fea::ChElementBase.

◆ GetStrain()

ChStrainTensor chrono::fea::ChElementTetraCorot_4::GetStrain ( )

Returns the strain tensor (note that the tetrahedron 4 nodes is a linear element, thus the strain is constant in the entire volume).

The tensor is in the original undeformed unrotated reference.

◆ GetStress()

ChStressTensor chrono::fea::ChElementTetraCorot_4::GetStress ( )

Returns the stress tensor (note that the tetrahedron 4 nodes is a linear element, thus the stress is constant in the entire volume).

The tensor is in the original undeformed unrotated reference.

◆ ShapeFunctions()

void chrono::fea::ChElementTetraCorot_4::ShapeFunctions	(	ShapeVector &	N,
		double	r,
		double	s,
		double	t
	)

Fills the N shape function matrix with the values of shape functions at r,s,t 'volume' coordinates, where r=1 at 2nd vertex, s=1 at 3rd, t = 1 at 4th.

All ranging in [0...1]. The last (u, u=1 at 1st vertex) is computed form the first 3 as 1.0-r-s-t. NOTE! actually N should be a 3row, 12 column sparse matrix, as N = [n1*eye(3) n2*eye(3) n3*eye(3) n4*eye(3)]; , but to avoid wasting zero and repeated elements, here it stores only the n1 n2 n3 n4 values in a 1 row, 4 columns matrix.

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

/builds/uwsbel/chrono/src/chrono/fea/ChElementTetraCorot_4.h
/builds/uwsbel/chrono/src/chrono/fea/ChElementTetraCorot_4.cpp

Description

Public Types

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ ComputeInternalForces()

◆ ComputeKRMmatricesGlobal()

◆ ComputeNF()

◆ GetNodeNumCoordsPosLevel()

◆ GetNumCoordsPosLevel()

◆ GetStateBlock()

◆ GetStrain()

◆ GetStress()

◆ ShapeFunctions()