chrono::fea::ChElementHexa_20 Class Reference

Description

Class for FEA elements of hexahedron type (isoparametric 3D bricks) with 20 nodes.

#include <ChElementHexa_20.h>

Inheritance diagram for chrono::fea::ChElementHexa_20:
Collaboration diagram for chrono::fea::ChElementHexa_20:

Public Member Functions

virtual int GetNnodes () override
 Gets the number of nodes used by this element.
 
virtual int GetNdofs () override
 Gets 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 n-th 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, std::shared_ptr< ChNodeFEAxyz > nodeC, std::shared_ptr< ChNodeFEAxyz > nodeD, std::shared_ptr< ChNodeFEAxyz > nodeE, std::shared_ptr< ChNodeFEAxyz > nodeF, std::shared_ptr< ChNodeFEAxyz > nodeG, std::shared_ptr< ChNodeFEAxyz > nodeH, std::shared_ptr< ChNodeFEAxyz > nodeI, std::shared_ptr< ChNodeFEAxyz > nodeJ, std::shared_ptr< ChNodeFEAxyz > nodeK, std::shared_ptr< ChNodeFEAxyz > nodeL, std::shared_ptr< ChNodeFEAxyz > nodeM, std::shared_ptr< ChNodeFEAxyz > nodeN, std::shared_ptr< ChNodeFEAxyz > nodeO, std::shared_ptr< ChNodeFEAxyz > nodeP, std::shared_ptr< ChNodeFEAxyz > nodeQ, std::shared_ptr< ChNodeFEAxyz > nodeR, std::shared_ptr< ChNodeFEAxyz > nodeS, std::shared_ptr< ChNodeFEAxyz > nodeT)
 
virtual void SetDefaultIntegrationRule ()
 
virtual void SetReducedIntegrationRule ()
 
virtual void SetIntegrationRule (int nPoints)
 
virtual void ShapeFunctions (ChMatrix<> &N, double r, double s, double t)
 Fills the N shape function matrix with the values of shape functions at r,s,t parametric coordinates, where each parameter is in [-1...+1] range. More...
 
virtual void GetStateBlock (ChMatrixDynamic<> &mD) override
 Fills the D vector (displacement) column matrix with the current field values at the nodes of the element, with proper ordering. More...
 
virtual void ComputeJacobian (ChMatrixDynamic<> &Jacobian, ChMatrixDynamic<> &J1, ChVector<> coord)
 Puts inside 'Jacobian' and 'J1' the Jacobian matrix and the shape functions derivatives matrix of the element The vector "coord" contains the natural coordinates of the integration point in case of hexahedral elements natural coords vary in the classical range -1 ... More...
 
virtual void ComputeMatrB (ChMatrixDynamic<> &MatrB, double zeta1, double zeta2, double zeta3, double &JacobianDet)
 Computes the matrix of partial derivatives and puts data in "MatrB" evaluated at natural coordinates zeta1,...,zeta4 . More...
 
virtual void ComputeMatrB (ChGaussPoint *GaussPt, double &JacobianDet)
 Computes the matrix of partial derivatives and puts data in "GaussPt" Stores the determinant of the jacobian in "JacobianDet".
 
virtual void ComputeStiffnessMatrix ()
 Computes the global STIFFNESS MATRIX of the element: K = Volume * [B]' * [D] * [B] The number of Gauss Point is defined by SetIntegrationRule function (default: 27 Gp)
 
virtual void SetupInitial (ChSystem *system) override
 *** OLD METHOD (before GaussIntegrationRule) *** ////////////////////// Computes the global STIFFNESS MATRIX of the element: K = Volume * [B]' * [D] * [B]
 
virtual void UpdateRotation () override
 Given the actual position of the nodes, recompute the cumulative rotation matrix A. More...
 
ChStrainTensor GetStrain (double z1, double z2, double z3)
 Returns the strain tensor at given parameters. More...
 
ChStressTensor GetStress (double z1, double z2, double z3)
 Returns the stress tensor at given parameters. More...
 
virtual void ComputeKRMmatricesGlobal (ChMatrix<> &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 (ChMatrixDynamic<> &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 ()
 
ChMatrixGetStiffnessMatrix ()
 Get the StiffnessMatrix.
 
ChGaussPointGetGaussPoint (int N)
 Get the Nth gauss point.
 
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 (speed 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 (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 int Get_field_ncoords () override
 Number of coordinates in the interpolated field: here the {x,y,z} displacement.
 
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.
 
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 -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.
 
- Public Member Functions inherited from chrono::fea::ChElementHexahedron
virtual void Update ()
 Update: this is called at least at each time step. More...
 
- Public Member Functions inherited from chrono::fea::ChElement3D
double GetVolume ()
 
- Public Member Functions inherited from chrono::fea::ChElementGeneric
ChKblockGenericKstiffness ()
 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 ComputeMmatrixGlobal (ChMatrix<> &M) override
 Returns the global mass matrix. More...
 
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 ComputeNodalMass ()
 Compute element's nodal masses.
 
- Public Member Functions inherited from chrono::fea::ChElementCorotational
ChMatrix33Rotation ()
 Access the cumulative rotation matrix of the element, The rotation is expressed relative to initial reference position of element. More...
 
- 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 quadrature over u,v,w in [-1..+1] as box isoparametric coords. More...
 

Protected Attributes

std::vector< std::shared_ptr
< ChNodeFEAxyz > > 
nodes
 
std::shared_ptr
< ChContinuumElastic
Material
 
ChMatrixDynamic StiffnessMatrix
 
- Protected Attributes inherited from chrono::fea::ChElementHexahedron
ChGaussIntegrationRuleir
 
std::vector< ChGaussPoint * > GpVector
 
- Protected Attributes inherited from chrono::fea::ChElement3D
double Volume
 
- Protected Attributes inherited from chrono::fea::ChElementGeneric
ChKblockGeneric Kmatr
 
- Protected Attributes inherited from chrono::fea::ChElementCorotational
ChMatrix33 A
 

Additional Inherited Members

- Public Attributes inherited from chrono::fea::ChElementHexahedron
int ID
 

Member Function Documentation

virtual void chrono::fea::ChElementHexa_20::ComputeInternalForces ( ChMatrixDynamic<> &  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.

virtual void chrono::fea::ChElementHexa_20::ComputeJacobian ( ChMatrixDynamic<> &  Jacobian,
ChMatrixDynamic<> &  J1,
ChVector<>  coord 
)
virtual

Puts inside 'Jacobian' and 'J1' the Jacobian matrix and the shape functions derivatives matrix of the element The vector "coord" contains the natural coordinates of the integration point in case of hexahedral elements natural coords vary in the classical range -1 ...

+1

virtual void chrono::fea::ChElementHexa_20::ComputeKRMmatricesGlobal ( ChMatrix<> &  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.

virtual void chrono::fea::ChElementHexa_20::ComputeMatrB ( ChMatrixDynamic<> &  MatrB,
double  zeta1,
double  zeta2,
double  zeta3,
double &  JacobianDet 
)
virtual

Computes the matrix of partial derivatives and puts data in "MatrB" evaluated at natural coordinates zeta1,...,zeta4 .

Also computes determinant of jacobian. note: in case of hexahedral elements natural coord. vary in the range -1 ... +1

virtual void chrono::fea::ChElementHexa_20::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
Uparametric coordinate in volume
Vparametric coordinate in volume
Wparametric coordinate in volume
QiReturn result of N'*F here, maybe with offset block_offset
detJReturn det[J] here
FInput F vector, size is = n.field coords.
state_xif != 0, update state (pos. part) to this, then evaluate Q
state_wif != 0, update state (speed part) to this, then evaluate Q

Implements chrono::ChLoadableUVW.

virtual int chrono::fea::ChElementHexa_20::GetNdofs ( )
overridevirtual

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

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

Implements chrono::fea::ChElementBase.

virtual int chrono::fea::ChElementHexa_20::GetNodeNdofs ( int  n)
overridevirtual

Get the number of coordinates from the n-th node that are used by this element.

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

Implements chrono::fea::ChElementBase.

virtual void chrono::fea::ChElementHexa_20::GetStateBlock ( ChMatrixDynamic<> &  mD)
overridevirtual

Fills the D vector (displacement) 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->GetNdofs(), it will be resized. For corotational elements, field is assumed in local reference!

Implements chrono::fea::ChElementBase.

ChStrainTensor chrono::fea::ChElementHexa_20::GetStrain ( double  z1,
double  z2,
double  z3 
)

Returns the strain tensor at given parameters.

The tensor is in the original undeformed unrotated reference.

ChStressTensor chrono::fea::ChElementHexa_20::GetStress ( double  z1,
double  z2,
double  z3 
)

Returns the stress tensor at given parameters.

The tensor is in the original undeformed unrotated reference.

virtual void chrono::fea::ChElementHexa_20::ShapeFunctions ( ChMatrix<> &  N,
double  r,
double  s,
double  t 
)
virtual

Fills the N shape function matrix with the values of shape functions at r,s,t parametric coordinates, where each parameter is in [-1...+1] range.

It stores the Ni(r,s,t) values in a 1 row, 20 columns matrix N.

virtual void chrono::fea::ChElementHexa_20::UpdateRotation ( )
overridevirtual

Given the actual position of the nodes, recompute the cumulative rotation matrix A.

CHLDREN CLASSES MUST IMPLEMENT THIS!!!

Implements chrono::fea::ChElementCorotational.