Description

ANCF shell element with four nodes.

The coordinates at each node are the position vector and 3 position vector gradients.

The node numbering is in ccw fashion as in the following scheme:

        v
        ^
        |
D o-----+-----o C
  |     |     |
--+-----+-----+----> u
  |     |     |
A o-----+-----o B

#include <ChElementShellANCF_3443.h>

Inheritance diagram for chrono::fea::ChElementShellANCF_3443:

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Collaboration diagram for chrono::fea::ChElementShellANCF_3443:

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Classes
class	Layer
	Definition of a layer. More...

Public Types
enum	IntFrcMethod { IntFrcMethod::ContInt, IntFrcMethod::PreInt }
	Internal force calculation method. More...

using	VectorN = ChVectorN< double, NSF >

using	Vector3N = ChVectorN< double, 3 *NSF >

using	VectorNIP = ChVectorN< double, NIP >

using	Matrix3xN = ChMatrixNM< double, 3, NSF >

using	MatrixNx3 = ChMatrixNM< double, NSF, 3 >

using	MatrixNx3c = ChMatrixNM_col< double, NSF, 3 >

using	MatrixNx6 = ChMatrixNM< double, NSF, 6 >

using	MatrixNxN = ChMatrixNM< double, NSF, NSF >

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.

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

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

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

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

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

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

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

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

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

std::shared_ptr< ChNodeFEAxyzDDD >	GetNodeD () const
	Get a handle to the fourth node of this element.

void	AddLayer (double thickness, double theta, std::shared_ptr< ChMaterialShellANCF > material)
	Add a layer. More...

size_t	GetNumLayers () const
	Get the number of layers.

const Layer &	GetLayer (size_t i) const
	Get a handle to the specified layer.

void	SetMidsurfaceOffset (const double offset)
	Offset the midsurface of the composite shell element. More...

void	SetAlphaDamp (double a)
	Set the structural damping.

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

double	GetLengthY ()
	Get the element length in the Y direction.

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

void	SetIntFrcCalcMethod (IntFrcMethod method)
	Set the calculation method to use for the generalized internal force and its Jacobian calculations. More...

IntFrcMethod	GetIntFrcCalcMethod ()
	Return the type of calculation method currently set for the generalized internal force and its Jacobian calculations.

ChMatrix33	GetGreenLagrangeStrain (const double xi, const double eta, const double zeta)
	Get the Green-Lagrange strain tensor at the normalized element coordinates (xi, eta, zeta) at the current state of the element. More...

ChMatrix33	GetPK2Stress (const double layer, const double xi, const double eta, const double layer_zeta)
	Get the 2nd Piola-Kirchoff stress tensor at the normalized layer coordinates (xi, eta, layer_zeta) at the current state of the element for the specified layer number (0 indexed) since the stress can be discontinuous at the layer boundary. More...

double	GetVonMissesStress (const double layer, const double xi, const double eta, const double layer_zeta)
	Get the von Mises stress value at the normalized layer coordinates (xi, eta, layer_zeta) at the current state of the element for the specified layer number (0 indexed) since the stress can be discontinuous at the layer boundary. More...

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

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

virtual void	ComputeMmatrixGlobal (ChMatrixRef M) override
	Set M equal to the global mass matrix.

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

virtual void	ComputeInternalForces (ChVectorDynamic<> &Fi) override
	Compute the generalized internal force vector for the current nodal coordinates as set the value in the Fi vector.

virtual void	ComputeKRMmatricesGlobal (ChMatrixRef H, double Kfactor, double Rfactor=0, double Mfactor=0) override
	Set H as a linear combination of M, K, and R. More...

virtual void	ComputeGravityForces (ChVectorDynamic<> &Fg, const ChVector3d &G_acc) override
	Compute the generalized force vector due to gravity using the efficient ANCF specific method.

virtual void	EvaluateSectionDisplacement (const double xi, const double eta, ChVector3d &u_displ, ChVector3d &u_rotaz) override
	Gets the xyz displacement of a point on the shell midsurface, and the rotation RxRyRz of section plane, at abscissa '(xi,eta,0)'.

virtual void	EvaluateSectionFrame (const double xi, const double eta, ChVector3d &point, ChQuaternion<> &rot) override
	Gets the absolute xyz position of a point on the shell midsurface, and the absolute rotation of section plane, at abscissa '(xi,eta,0)'. More...

virtual void	EvaluateSectionPoint (const double xi, const double eta, ChVector3d &point) override
	Gets the absolute xyz position of a point on the shell midsurface specified in normalized coordinates.

virtual void	EvaluateSectionVelNorm (const double xi, const double eta, ChVector3d &Result) override
	Gets the absolute xyz velocity of a point on the shell midsurface specified in normalized coordinates.

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 (velocity 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 (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 unsigned int	GetNumFieldCoords () 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 unsigned int	GetNumSubBlocks () override
	Tell the number of DOFs blocks (ex. =1 for a body, =4 for a tetrahedron, etc.)

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

virtual unsigned int	GetSubBlockSize (unsigned int nblock) override
	Get the size of the i-th 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 xi, const double eta, 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 xi,eta coordinates of the midsurface, 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 xi, const double eta, const double zeta, 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 xi,eta,zeta 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...

virtual ChVector3d	ComputeNormal (const double xi, const double eta) override
	Gets the normal to the surface at the parametric coordinate xi,eta. More...

Public Member Functions inherited from chrono::fea::ChElementShell
virtual bool	IsTriangleShell ()
	Return false if quadrilateral shell - hence u,v parametric coordinates assumed in -1..+1, return true if triangular shell - hence u,v are triangle natural coordinates assumed in 0..+1.

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

Public Member Functions inherited from chrono::ChLoadableUV
virtual bool	IsTriangleIntegrationNeeded ()
	If true, use quadrature over u,v in [0..1] range as triangle area coords (with z=1-u-v) otherwise use default quadrature over u,v in [-1..+1] as rectangular isoparametric coords.

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.

Static Public Attributes
static const int	NP = 4
	number of Gauss quadrature points for each midsurface direction

static const int	NT = 2
	number of quadrature points through the thickness

static const int	NIP = NP * NP * NT
	number of Gauss quadrature points

static const int	NSF = 16
	number of shape functions

Additional Inherited Members
Protected Attributes inherited from chrono::fea::ChElementANCF
int	m_element_dof
	actual number of degrees of freedom for the element

bool	m_full_dof
	true if all node variables are active (not fixed)

ChArray< int >	m_mapping_dof
	indices of active DOFs (set only is some are fixed)

Protected Attributes inherited from chrono::fea::ChElementShell
double	mass

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

Member Enumeration Documentation

◆ IntFrcMethod

enum chrono::fea::ChElementShellANCF_3443::IntFrcMethod

strong

Internal force calculation method.

Enumerator
ContInt	"Continuous Integration" style method - Fastest for a small number of layers
PreInt	"Pre-Integration" style method - Fastest for a large number of layers

Member Function Documentation

◆ AddLayer()

void chrono::fea::ChElementShellANCF_3443::AddLayer	(	double	thickness,
		double	theta,
		std::shared_ptr< ChMaterialShellANCF >	material
	)

Add a layer.

Layers should be added prior to the start of the simulation since can be a significant amount of pre-calculation overhead required.

Parameters

thickness	layer thickness
theta	fiber angle (radians)
material	layer material

◆ ComputeKRMmatricesGlobal()

void chrono::fea::ChElementShellANCF_3443::ComputeKRMmatricesGlobal	(	ChMatrixRef	H,
		double	Kfactor,
		double	Rfactor = `0`,
		double	Mfactor = `0`
	)

overridevirtual

Set H as a linear combination of M, K, and R.

H = Mfactor * [M] + Kfactor * [K] + Rfactor * [R], where [M] is the mass matrix, [K] is the stiffness matrix, and [R] is the damping matrix.

Implements chrono::fea::ChElementBase.

◆ ComputeNF() [1/2]

void chrono::fea::ChElementShellANCF_3443::ComputeNF	(	const double	xi,
		const double	eta,
		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 xi,eta coordinates of the midsurface, 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.

For this ANCF element, only the first 6 entries in F are used in the calculation. The first three entries is the applied force in global coordinates and the second 3 entries is the applied moment in global space.

Parameters

xi	parametric coordinate in surface
eta	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::ChLoadableUV.

◆ ComputeNF() [2/2]

void chrono::fea::ChElementShellANCF_3443::ComputeNF	(	const double	xi,
		const double	eta,
		const double	zeta,
		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 xi,eta,zeta 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.

For this ANCF element, only the first 6 entries in F are used in the calculation. The first three entries is the applied force in global coordinates and the second 3 entries is the applied moment in global space.

Parameters

xi	parametric coordinate in volume
eta	parametric coordinate in volume
zeta	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.

◆ ComputeNormal()

ChVector3d chrono::fea::ChElementShellANCF_3443::ComputeNormal	(	const double	xi,
		const double	eta
	)

overridevirtual

Gets the normal to the surface at the parametric coordinate xi,eta.

Each coordinate ranging in -1..+1.

Implements chrono::ChLoadableUV.

◆ EvaluateSectionFrame()

void chrono::fea::ChElementShellANCF_3443::EvaluateSectionFrame	(	const double	xi,
		const double	eta,
		ChVector3d &	point,
		ChQuaternion<> &	rot
	)

overridevirtual

Gets the absolute xyz position of a point on the shell midsurface, and the absolute rotation of section plane, at abscissa '(xi,eta,0)'.

Note, nodeA = (xi=-1, eta=-1) Note, nodeB = (xi=1, eta=-1) Note, nodeC = (xi=1, eta=1) Note, nodeD = (xi=-1, eta=1)

Implements chrono::fea::ChElementShell.

◆ GetDensity()

double chrono::fea::ChElementShellANCF_3443::GetDensity ( )

overridevirtual

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

Density is the average mass per unit volume for the entire shell in the reference state of the element.

Implements chrono::ChLoadableUVW.

◆ GetGreenLagrangeStrain()

ChMatrix33 chrono::fea::ChElementShellANCF_3443::GetGreenLagrangeStrain	(	const double	xi,
		const double	eta,
		const double	zeta
	)

Get the Green-Lagrange strain tensor at the normalized element coordinates (xi, eta, zeta) at the current state of the element.

Normalized element coordinates span from -1 to 1.

◆ GetPK2Stress()

ChMatrix33 chrono::fea::ChElementShellANCF_3443::GetPK2Stress	(	const double	layer,
		const double	xi,
		const double	eta,
		const double	layer_zeta
	)

Get the 2nd Piola-Kirchoff stress tensor at the normalized layer coordinates (xi, eta, layer_zeta) at the current state of the element for the specified layer number (0 indexed) since the stress can be discontinuous at the layer boundary.

"layer_zeta" spans -1 to 1 from the bottom surface to the top surface

◆ GetStateBlock()

void chrono::fea::ChElementShellANCF_3443::GetStateBlock ( ChVectorDynamic<> & mD )

overridevirtual

Fill the D vector (column matrix) 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. {Pos_a Du_a Dv_a Dw_a Pos_b Du_b Dv_b Dw_b Pos_c Du_c Dv_c Dw_c Pos_d Du_d Dv_d Dw_d}

Implements chrono::fea::ChElementBase.

◆ GetVonMissesStress()

double chrono::fea::ChElementShellANCF_3443::GetVonMissesStress	(	const double	layer,
		const double	xi,
		const double	eta,
		const double	layer_zeta
	)

Get the von Mises stress value at the normalized layer coordinates (xi, eta, layer_zeta) at the current state of the element for the specified layer number (0 indexed) since the stress can be discontinuous at the layer boundary.

"layer_zeta" spans -1 to 1 from the bottom surface to the top surface

◆ SetIntFrcCalcMethod()

void chrono::fea::ChElementShellANCF_3443::SetIntFrcCalcMethod ( IntFrcMethod method )

Set the calculation method to use for the generalized internal force and its Jacobian calculations.

This should be set prior to the start of the simulation since can be a significant amount of pre-calculation overhead required.

◆ SetMidsurfaceOffset()

void chrono::fea::ChElementShellANCF_3443::SetMidsurfaceOffset ( const double offset )

Offset the midsurface of the composite shell element.

A positive value shifts the element's midsurface upward along the elements zeta direction. The offset should be provided in model units.

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

/builds/uwsbel/chrono/src/chrono/fea/ChElementShellANCF_3443.h
/builds/uwsbel/chrono/src/chrono/fea/ChElementShellANCF_3443.cpp

Description

Classes

Public Types

Public Member Functions

Static Public Attributes

Additional Inherited Members

Member Enumeration Documentation

◆ IntFrcMethod

Member Function Documentation

◆ AddLayer()

◆ ComputeKRMmatricesGlobal()

◆ ComputeNF() [1/2]

◆ ComputeNF() [2/2]

◆ ComputeNormal()

◆ EvaluateSectionFrame()

◆ GetDensity()

◆ GetGreenLagrangeStrain()

◆ GetPK2Stress()

◆ GetStateBlock()

◆ GetVonMissesStress()

◆ SetIntFrcCalcMethod()

◆ SetMidsurfaceOffset()