Description

Class for assemblies of items, for example ChBody, ChLink, ChMesh, etc.

This supports component mode synthesis (CMS) to do substructuring, hence an assembly becomes a "modal body" where many "internal" DOFs of finite elements will be reduced to few modal modes that are superimposed to the motion of a floating frame (for small deflections). Some nodes can be selected as "boundary nodes" to allow connecting this modal assembly to external joints and forces.

The development of this modal reduction procedure has been inspired by the research paper: Sonneville, V., Scapolan, M., Shan, M. et al. Modal reduction procedures for flexible multibody dynamics. Multibody Syst Dyn 51, 377–418 (2021).

#include <ChModalAssembly.h>

Inheritance diagram for chrono::modal::ChModalAssembly:

[legend]

Collaboration diagram for chrono::modal::ChModalAssembly:

[legend]

Public Types
enum	ReductionType { ReductionType::HERTING, ReductionType::CRAIG_BAMPTON }
	Modal reduction methods. More...

Public Member Functions
	ChModalAssembly (const ChModalAssembly &other)

virtual ChModalAssembly *	Clone () const override
	"Virtual" copy constructor (covariant return type).

ChModalAssembly &	operator= (ChModalAssembly other)
	Assignment operator for ChModalAssembly.

void	SetReductionType (ReductionType type)
	Set the type of modal reduction to be used.

ReductionType	GetReductionType () const
	Get the type of modal reduction used.

bool	ComputeModes (const ChModalSolveUndamped &n_modes_settings)
	Compute the undamped modes for the current assembly. More...

bool	ComputeModesExternalData (const ChSparseMatrix &full_M, const ChSparseMatrix &full_K, const ChSparseMatrix &full_Cq, const ChModalSolveUndamped &n_modes_settings)
	Compute the undamped modes from M and K matrices. More...

bool	ComputeModesDamped (const ChModalSolveDamped &n_modes_settings)
	Compute the damped modes for the entire modal assembly. More...

void	DoModalReduction (const ChModalSolveUndamped &n_modes_settings, const ChModalDamping &damping_model=ChModalDampingNone())
	Perform modal reduction on this modal assembly, from the current "full" ("boundary"+"internal") assembly. More...

void	DoModalReduction (ChSparseMatrix &full_M, ChSparseMatrix &full_K, ChSparseMatrix &full_Cq, const ChModalSolveUndamped &n_modes_settings, const ChModalDamping &damping_model=ChModalDampingNone())
	Perform modal reduction on this modal assembly that contains only the "boundary" nodes, whereas the "internal" nodes have been modeled only in an external FEA software with the full ("boundary"+"internal") modes. More...

ChFrameMoving	GetFloatingFrameOfReference ()
	Get the floating frame F of the reduced modal assembly.

const ChVectorDynamic &	GetConstraintsResidualF ()
	Get the residual of constraint equations on the floating frame F. More...

void	SetVerbose (bool verbose)
	Set verbose output.

void	SetUseStaticCorrection (bool flag)
	Set whether the static correction is used. More...

bool	GetUsetStaticCorrection ()
	Get the flag whether the static correction is used.

void	SetUseLinearInertialTerm (bool flag)
	A rigorous mathematical manipulation can be employed to derive the inertial forces and the consequent inertial damping matrix, or a linear assumption is applied to obtain quite concise expressions. More...

void	UpdateFullStateWithModeOverlay (unsigned int n_mode, double phase, double amplitude)
	For displaying modes, you can use the following function. More...

void	UpdateInternalStateWithModes (bool full_update)
	For displaying the deformation using internal nodes, you can use the following function. More...

void	SetFullStateReset ()
	Resets the state of this modal assembly (both boundary and internal items) to the state snapshot in the initial configuration.

void	SetInternalNodesUpdate (bool flag)
	Optimization flag. More...

void	SetModalAutomaticGravity (bool gravity)
	If true, as by default, this modal assembly will add automatically a gravity load to all contained boundary and internal bodies/nodes (that support gravity) in the modal reduced state using the G value from the ChSystem. More...

bool	GetModalAutomaticGravity ()
	Tell if this modal assembly will add automatically a gravity load to all contained boundary and internal bodies/nodes.

const ChMatrixDynamic &	GetModalMassMatrix () const
	Get the modal mass matrix.

const ChMatrixDynamic &	GetModalStiffnessMatrix () const
	Get the modal stiffness matrix.

const ChMatrixDynamic &	GetModalDampingMatrix () const
	Get the modal damping matrix.

const ChMatrixDynamic &	GetModalReductionMatrix () const
	Get the modal reduction transformation matrix 'Psi'. More...

const ChMatrixDynamic< std::complex< double > > &	GetEigenVectors () const
	Get the modal eigenvectors, if previously computed. More...

const ChVectorDynamic< std::complex< double > > &	GetEigenValues () const
	Get the modal eigenvalues, if previously computed. More...

const ChVectorDynamic< double > &	GetUndampedFrequencies () const
	Get a vector of (undamped) modal natural frequencies [Hz], if previously computed. More...

const ChVectorDynamic< double > &	GetDampingRatios () const
	Get a vector of modal damping ratios = damping/critical_damping, if previously computed. More...

const ChVectorDynamic &	GetDeformedState () const
	Get the deformed configuration of the full modal assembly.

const ChVectorDynamic &	GetInitialState () const
	Get the initial full state of the modal assembly before the modal reduction.

ChVectorDynamic &	GetModalCoordinatesPosLevel ()
	Get the vector of modal coordinates (positions).

ChVectorDynamic &	GetModalCoordinatesVelLevel ()
	Get the vector of time derivative of modal coordinates (velocities).

ChVectorDynamic &	GetModalCoordinatesAccLevel ()
	Get the vector of 2nd time derivative of modal coordinates (accelerations).

void	Clear ()
	Removes all inserted items: bodies, links, etc., both boundary and internal.

void	AddInternalBody (std::shared_ptr< ChBody > body)
	Attach an internal body to this modal assembly.

void	AddInternalLink (std::shared_ptr< ChLinkBase > link)
	Attach an internal link to this modal assembly. More...

void	AddInternalMesh (std::shared_ptr< fea::ChMesh > mesh)
	Attach an internal mesh to this modal assembly.

void	AddInternalOtherPhysicsItem (std::shared_ptr< ChPhysicsItem > item)
	Attach an internal ChPhysicsItem object that is not a body, link, or mesh.

void	AddInternal (std::shared_ptr< ChPhysicsItem > item)
	Attach an arbitrary internal ChPhysicsItem (e.g. More...

void	RemoveInternalBody (std::shared_ptr< ChBody > body)
	Remove an internal body from this modal assembly.

void	RemoveInternalLink (std::shared_ptr< ChLinkBase > link)
	Remove an internal link from this modal assembly.

void	RemoveInternalMesh (std::shared_ptr< fea::ChMesh > mesh)
	Remove an internal mesh from this modal assembly.

void	RemoveInternalOtherPhysicsItem (std::shared_ptr< ChPhysicsItem > item)
	Remove an internal ChPhysicsItem object that is not a body or a link.

void	RemoveInternal (std::shared_ptr< ChPhysicsItem > item)
	Remove an internal arbitrary ChPhysicsItem that was.

void	RemoveAllInternalBodies ()
	Remove all internal bodies from this modal assembly.

void	RemoveAllInternalLinks ()
	Remove all internal links from this modal assembly.

void	RemoveAllInternalMeshes ()
	Remove all meshes from this modal assembly.

void	RemoveAllInternalOtherPhysicsItems ()
	Remove all physics items not in the body, link, or mesh lists.

const std::vector< std::shared_ptr< ChBody > > &	GetBodiesInternal () const
	Get the list of internal bodies.

const std::vector< std::shared_ptr< ChLinkBase > > &	GetLinksInternal () const
	Get the list of internal links.

const std::vector< std::shared_ptr< fea::ChMesh > > &	GetMeshesInternal () const
	Get the list of internal meshes.

const std::vector< std::shared_ptr< ChPhysicsItem > > &	GetOtherPhysicsItemsInternal () const
	Get the list of internal physics items that are not in the body or link lists.

unsigned int	GetNumBodiesInternal () const
	Get the number of internal bodies.

unsigned int	GetNumLinksInternal () const
	Get the number of internal links.

unsigned int	GetNumMeshesInternal () const
	Get the number of internal meshes.

unsigned int	GetNumOtherPhysicsItemsInternal () const
	Get the number of other internal physics items (other than bodies, links, or meshes).

unsigned int	GetNumCoordinatesPosInternal () const
	Get the number of internal coordinates at the position level. More...

unsigned int	GetNumCoordinatesVelInternal () const
	Get the number of internal coordinates at the velocity level. More...

unsigned int	GetNumConstraintsInternal () const
	Get the number of internal scalar constraints.

unsigned int	GetNumConstraintsBilateralInternal () const
	Get the number of internal bilateral scalar constraints.

unsigned int	GetNumConstraintsUnilateralInternal () const
	Get the number of internal unilateral scalar constraints.

unsigned int	GetNumBodiesBoundary () const
	Get the number of boundary bodies.

unsigned int	GetNumLinksBoundary () const
	Get the number of boundary links.

unsigned int	GetNumMeshesBoundary () const
	Get the number of boundary meshes.

unsigned int	GetNumOtherPhysicsItemsBoundary () const
	Get the number of other boundary physics items (other than bodies, links, or meshes).

unsigned int	GetNumCoordinatesPosBoundary () const
	Get the number of boundary coordinates at the position level. More...

unsigned int	GetNumCoordinatesVelBoundary () const
	Get the number of boundary coordinates at the velocity level. More...

unsigned int	GetNumConstraintsBoundary () const
	Get the number of boundary scalar constraints.

unsigned int	GetNumConstraintsBilateralBoundary () const
	Get the number of boundary scalar bilateral constraints (only bilaterals).

unsigned int	GetNumConstraintsUnilateralBoundary () const
	Get the number of boundary scalar constraints (only unilaterals).

int	GetNumCoordinatesModal ()
	Get the number of modal coordinates. Use DoModalReduction() to change it.

void	WriteSubassemblyMatrices (bool save_M, bool save_K, bool save_R, bool save_Cq, const std::string &path, bool one_indexed=true)
	Write the mass (M), damping (K), damping (R), and constraint Jacobian (C) matrices at current configuration. More...

void	GetSubassemblyMassMatrix (ChSparseMatrix *M)
	Compute the mass matrix of the modal assembly. More...

void	GetSubassemblyStiffnessMatrix (ChSparseMatrix *K)
	Compute the stiffness matrix of the modal assembly, i.e. More...

void	GetSubassemblyDampingMatrix (ChSparseMatrix *R)
	Compute the stiffness matrix of the modal assembly, i.e. More...

void	GetSubassemblyConstraintJacobianMatrix (ChSparseMatrix *Cq)
	Compute the constraint Jacobian matrix of the modal assembly, i.e. More...

virtual void	SetSystem (ChSystem *m_system) override
	Set the pointer to the parent ChSystem() and also add to new collision system / remove from old coll.system.

virtual void	SyncCollisionModels () override
	Synchronize collision models for all physics items in this assembly.

virtual void	Setup () override
	Counts the number of bodies, links, and meshes. More...

virtual void	Update (bool update_assets=true) override
	Updates all the auxiliary data and children of bodies, forces, links, given their current state.

virtual void	ForceToRest () override
	Set zero speed (and zero accelerations) in state, without changing the position.

virtual unsigned int	GetNumCoordsPosLevel () override
	Get the number of scalar coordinates (ex. dim of position vector)

virtual unsigned int	GetNumCoordsVelLevel () override
	Get the number of scalar coordinates of variables derivatives (ex. dim of speed vector)

virtual unsigned int	GetNumConstraints () override
	Get the number of scalar constraints, if any, in this item.

virtual unsigned int	GetNumConstraintsBilateral () override
	Get the number of scalar constraints, if any, in this item (only bilateral constr.)

virtual unsigned int	GetNumConstraintsUnilateral () override
	Get the number of scalar constraints, if any, in this item (only unilateral constr.)

virtual void	IntStateGather (const unsigned int off_x, ChState &x, const unsigned int off_v, ChStateDelta &v, double &T) override
	From item's state to global state vectors y={x,v} pasting the states at the specified offsets. More...

virtual void	IntStateScatter (const unsigned int off_x, const ChState &x, const unsigned int off_v, const ChStateDelta &v, const double T, bool full_update) override
	From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets. More...

virtual void	IntStateGatherAcceleration (const unsigned int off_a, ChStateDelta &a) override
	From item's state acceleration to global acceleration vector. More...

virtual void	IntStateScatterAcceleration (const unsigned int off_a, const ChStateDelta &a) override
	From global acceleration vector to item's state acceleration. More...

virtual void	IntStateGatherReactions (const unsigned int off_L, ChVectorDynamic<> &L) override
	From item's reaction forces to global reaction vector. More...

virtual void	IntStateScatterReactions (const unsigned int off_L, const ChVectorDynamic<> &L) override
	From global reaction vector to item's reaction forces. More...

virtual void	IntStateIncrement (const unsigned int off_x, ChState &x_new, const ChState &x, const unsigned int off_v, const ChStateDelta &Dv) override
	Computes x_new = x + Dt , using vectors at specified offsets. More...

virtual void	IntStateGetIncrement (const unsigned int off_x, const ChState &x_new, const ChState &x, const unsigned int off_v, ChStateDelta &Dv) override
	Computes Dt = x_new - x, using vectors at specified offsets. More...

virtual void	IntLoadResidual_F (const unsigned int off, ChVectorDynamic<> &R, const double c) override
	Takes the F force term, scale and adds to R at given offset: R += c*F. More...

virtual void	IntLoadResidual_Mv (const unsigned int off, ChVectorDynamic<> &R, const ChVectorDynamic<> &w, const double c) override
	Takes the Mv term, multiplying mass by a vector, scale and adds to R at given offset: R += cM*w. More...

virtual void	IntLoadLumpedMass_Md (const unsigned int off, ChVectorDynamic<> &Md, double &err, const double c) override
	Adds the lumped mass to a Md vector, representing a mass diagonal matrix. More...

virtual void	IntLoadResidual_CqL (const unsigned int off_L, ChVectorDynamic<> &R, const ChVectorDynamic<> &L, const double c) override
	Takes the term Cq'L, scale and adds to R at given offset: R += cCq'*L. More...

virtual void	IntLoadConstraint_C (const unsigned int off, ChVectorDynamic<> &Qc, const double c, bool do_clamp, double recovery_clamp) override
	Takes the term C, scale and adds to Qc at given offset: Qc += c*C. More...

virtual void	IntLoadConstraint_Ct (const unsigned int off, ChVectorDynamic<> &Qc, const double c) override
	Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct. More...

virtual void	IntToDescriptor (const unsigned int off_v, const ChStateDelta &v, const ChVectorDynamic<> &R, const unsigned int off_L, const ChVectorDynamic<> &L, const ChVectorDynamic<> &Qc) override
	Prepare variables and constraints to accommodate a solution: More...

virtual void	IntFromDescriptor (const unsigned int off_v, ChStateDelta &v, const unsigned int off_L, ChVectorDynamic<> &L) override
	After a solver solution, fetch values from variables and constraints into vectors: More...

virtual void	InjectVariables (ChSystemDescriptor &descriptor) override
	Register with the given system descriptor any ChVariable objects associated with this item.

virtual void	InjectConstraints (ChSystemDescriptor &descriptor) override
	Register with the given system descriptor any ChConstraint objects associated with this item.

virtual void	LoadConstraintJacobians () override
	Compute and load current Jacobians in encapsulated ChConstraint objects.

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...

double	GetTimeMatrixAssembly () const
	Get cumulative time for matrix assembly.

double	GetTimeSetup () const
	Get cumulative time for setup.

double	GetTimeModalSolver () const
	Get cumulative time for modal solver.

virtual void	ArchiveOut (ChArchiveOut &archive_out) override
	Method to allow serialization of transient data to archives.

virtual void	ArchiveIn (ChArchiveIn &archive_in) override
	Method to allow deserialization of transient data from archives.

Public Member Functions inherited from chrono::ChAssembly
	ChAssembly (const ChAssembly &other)

ChAssembly &	operator= (ChAssembly other)
	Assignment operator for ChAssembly.

void	Clear ()
	Removes all inserted items: bodies, links, etc.

void	AddBody (std::shared_ptr< ChBody > body)
	Attach a body to this assembly.

void	AddShaft (std::shared_ptr< ChShaft > shaft)
	Attach a shaft to this assembly.

void	AddLink (std::shared_ptr< ChLinkBase > link)
	Attach a link to this assembly.

void	AddMesh (std::shared_ptr< fea::ChMesh > mesh)
	Attach a mesh to this assembly.

void	AddOtherPhysicsItem (std::shared_ptr< ChPhysicsItem > item)
	Attach a ChPhysicsItem object that is not a body, link, or mesh.

void	Add (std::shared_ptr< ChPhysicsItem > item)
	Attach an arbitrary ChPhysicsItem (e.g. More...

void	AddBatch (std::shared_ptr< ChPhysicsItem > item)
	Items added in this way are added like in the Add() method, but not instantly, they are simply queued in a batch of 'to add' items, that are added automatically at the first Setup() call. More...

void	FlushBatch ()
	If some items are queued for addition in the assembly, using AddBatch(), this will effectively add them and clean the batch. More...

void	RemoveBody (std::shared_ptr< ChBody > body)
	Remove a body from this assembly.

void	RemoveShaft (std::shared_ptr< ChShaft > shaft)
	Remove a shaft from this assembly.

void	RemoveLink (std::shared_ptr< ChLinkBase > link)
	Remove a link from this assembly.

void	RemoveMesh (std::shared_ptr< fea::ChMesh > mesh)
	Remove a mesh from the assembly.

void	RemoveOtherPhysicsItem (std::shared_ptr< ChPhysicsItem > item)
	Remove a ChPhysicsItem object that is not a body or a link.

void	Remove (std::shared_ptr< ChPhysicsItem > item)
	Remove arbitrary ChPhysicsItem that was added to the assembly.

void	RemoveAllBodies ()
	Remove all bodies from this assembly.

void	RemoveAllShafts ()
	Remove all shafts from this assembly.

void	RemoveAllLinks ()
	Remove all links from this assembly.

void	RemoveAllMeshes ()
	Remove all meshes from this assembly.

void	RemoveAllOtherPhysicsItems ()
	Remove all physics items not in the body, link, or mesh lists.

const std::vector< std::shared_ptr< ChBody > > &	GetBodies () const
	Get the list of bodies.

const std::vector< std::shared_ptr< ChShaft > > &	GetShafts () const
	Get the list of shafts.

const std::vector< std::shared_ptr< ChLinkBase > > &	GetLinks () const
	Get the list of links.

const std::vector< std::shared_ptr< fea::ChMesh > > &	GetMeshes () const
	Get the list of meshes.

const std::vector< std::shared_ptr< ChPhysicsItem > > &	GetOtherPhysicsItems () const
	Get the list of physics items that are not in the body or link lists.

std::shared_ptr< ChBody >	SearchBody (const std::string &name) const
	Search a body by its name.

std::shared_ptr< ChBody >	SearchBodyID (int id) const
	Search a body by its ID.

std::shared_ptr< ChShaft >	SearchShaft (const std::string &name) const
	Search a shaft by its name.

std::shared_ptr< ChLinkBase >	SearchLink (const std::string &name) const
	Search a link by its name.

std::shared_ptr< fea::ChMesh >	SearchMesh (const std::string &name) const
	Search a mesh by its name.

std::shared_ptr< ChPhysicsItem >	SearchOtherPhysicsItem (const std::string &name) const
	Search from other ChPhysics items (not bodies, links, or meshes) by name.

std::shared_ptr< ChMarker >	SearchMarker (const std::string &name) const
	Search a marker by its name.

std::shared_ptr< ChMarker >	SearchMarker (int id) const
	Search a marker by its unique ID.

std::shared_ptr< ChPhysicsItem >	Search (const std::string &name) const
	Search an item (body, link or other ChPhysics items) by name.

unsigned int	GetNumBodies () const
	Get the total number of bodies added to the assembly, including fixed and sleeping bodies.

unsigned int	GetNumBodiesActive () const
	Get the number of active bodies, excluding sleeping or fixed.

unsigned int	GetNumBodiesSleeping () const
	Get the number of sleeping bodies.

unsigned int	GetNumBodiesFixed () const
	Get the number of bodies fixed to ground.

unsigned int	GetNumShafts () const
	Get the number of shafts.

unsigned int	GetNumShaftsSleeping () const
	Get the number of shafts that are in sleeping mode (excluding fixed shafts).

unsigned int	GetNumShaftsFixed () const
	Get the number of shafts that are fixed to ground.

unsigned int	GetNumShaftsTotal () const
	Get the total number of shafts added to the assembly, including the grounded and sleeping shafts.

unsigned int	GetNumLinks () const
	Get the number of links (including non active).

unsigned int	GetNumLinksActive () const
	Get the number of active links.

unsigned int	GetNumMeshes () const
	Get the number of meshes.

unsigned int	GetNumOtherPhysicsItems () const
	Get the number of other active physics items (including non active).

unsigned int	GetNumOtherPhysicsItemsActive () const
	Get the number of other active physics items.

virtual void	AddCollisionModelsToSystem (ChCollisionSystem *coll_sys) const override
	Add collision models (if any) for all items in the assembly to the provided collision system.

virtual void	RemoveCollisionModelsFromSystem (ChCollisionSystem *coll_sys) const override
	Remove the collision models (if any) for all items in the assembly from the provided collision system.

virtual void	Update (double mytime, bool update_assets=true) override
	Updates all the auxiliary data and children of bodies, forces, links, given their current state.

virtual void	VariablesFbReset () override
	Sets the 'fb' part (the known term) of the encapsulated ChVariables to zero.

virtual void	VariablesFbLoadForces (double factor=1) override
	Adds the current forces (applied to item) into the encapsulated ChVariables, in the 'fb' part: qf+=forces*factor.

virtual void	VariablesQbLoadSpeed () override
	Initialize the 'qb' part of the ChVariables with the current value of speeds. More...

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

virtual void	VariablesQbSetSpeed (double step=0) override
	Fetches the item speed (ex. More...

virtual void	VariablesQbIncrementPosition (double step) override
	Increment item positions by the 'qb' part of the ChVariables, multiplied by a 'step' factor. More...

virtual void	ConstraintsBiReset () override
	Sets to zero the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsBiLoad_C (double factor=1, double recovery_clamp=0.1, bool do_clamp=false) override
	Adds the current C (constraint violation) to the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsBiLoad_Ct (double factor=1) override
	Adds the current Ct (partial t-derivative, as in C_dt=0-> [Cq]*q_dt=-Ct) to the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsBiLoad_Qc (double factor=1) override
	Adds the current Qc (the vector of C_dtdt=0 -> [Cq]*q_dtdt=Qc ) to the known term (b_i) of encapsulated ChConstraints.

virtual void	ConstraintsFbLoadForces (double factor=1) override
	Adds the current link-forces, if any, (caused by springs, etc.) to the 'fb' vectors of the ChVariables referenced by encapsulated ChConstraints.

virtual void	ConstraintsFetch_react (double factor=1) override
	Fetches the reactions from the lagrangian multiplier (l_i) of encapsulated ChConstraints. More...

void	ShowHierarchy (std::ostream &outstream, int level=0) const
	Writes the hierarchy of contained bodies, markers, etc. More...

Public Member Functions inherited from chrono::ChPhysicsItem
	ChPhysicsItem (const ChPhysicsItem &other)

ChSystem *	GetSystem () const
	Get the pointer to the parent ChSystem().

void	AddVisualModel (std::shared_ptr< ChVisualModel > model)
	Add an (optional) visualization model. More...

std::shared_ptr< ChVisualModel >	GetVisualModel () const
	Access the visualization model (if any). More...

void	AddVisualShape (std::shared_ptr< ChVisualShape > shape, const ChFrame<> &frame=ChFrame<>())
	Add the specified visual shape to the visualization model. More...

std::shared_ptr< ChVisualShape >	GetVisualShape (unsigned int i) const
	Access the specified visualization shape in the visualization model (if any). More...

void	AddVisualShapeFEA (std::shared_ptr< ChVisualShapeFEA > shapeFEA)
	Add the specified FEA visualization object to the visualization model. More...

std::shared_ptr< ChVisualShapeFEA >	GetVisualShapeFEA (unsigned int i) const
	Access the specified FEA visualization object in the visualization model (if any). More...

virtual ChFrame	GetVisualModelFrame (unsigned int nclone=0) const
	Get the reference frame (expressed in and relative to the absolute frame) of the visual model. More...

virtual unsigned int	GetNumVisualModelClones () const
	Return the number of clones of the visual model associated with this physics item. More...

void	AddCamera (std::shared_ptr< ChCamera > camera)
	Attach a ChCamera to this physical item. More...

std::vector< std::shared_ptr< ChCamera > >	GetCameras () const
	Get the set of cameras attached to this physics item.

virtual bool	IsActive () const
	Return true if the object is active and included in dynamics.

virtual bool	IsCollisionEnabled () const
	Tell if the object is subject to collision. More...

virtual ChAABB	GetTotalAABB ()
	Get the entire AABB axis-aligned bounding box of the object. More...

virtual void	GetCenter (ChVector3d &mcenter)
	Get a symbolic 'center' of the object. More...

unsigned int	GetOffset_x ()
	Get offset in the state vector (position part)

unsigned int	GetOffset_w ()
	Get offset in the state vector (speed part)

unsigned int	GetOffset_L ()
	Get offset in the lagrangian multipliers.

void	SetOffset_x (const unsigned int moff)
	Set offset in the state vector (position part) Note: only the ChSystem::Setup function should use this.

void	SetOffset_w (const unsigned int moff)
	Set offset in the state vector (speed part) Note: only the ChSystem::Setup function should use this.

void	SetOffset_L (const unsigned int moff)
	Set offset in the lagrangian multipliers Note: only the ChSystem::Setup function should use this.

Public Member Functions inherited from chrono::ChObj
	ChObj (const ChObj &other)

int	GetIdentifier () const
	Get the unique integer identifier of this object. More...

void	SetTag (int tag)
	Set an object integer tag (default: -1). More...

int	GetTag () const
	Get the tag of this object.

void	SetName (const std::string &myname)
	Set the name of this object.

const std::string &	GetName () const
	Get the name of this object.

double	GetChTime () const
	Gets the simulation time of this object.

void	SetChTime (double m_time)
	Sets the simulation time of this object.

virtual std::string &	ArchiveContainerName ()

Friends
class	ChSystem

class	ChSystemMulticore

void	swap (ChModalAssembly &first, ChModalAssembly &second)
	Swap the contents of the two provided ChAssembly objects. More...

Additional Inherited Members
Protected Member Functions inherited from chrono::ChObj
int	GenerateUniqueIdentifier ()

Protected Attributes inherited from chrono::ChAssembly
std::vector< std::shared_ptr< ChBody > >	bodylist
	list of rigid bodies

std::vector< std::shared_ptr< ChShaft > >	shaftlist
	list of 1-D shafts

std::vector< std::shared_ptr< ChLinkBase > >	linklist
	list of joints (links)

std::vector< std::shared_ptr< fea::ChMesh > >	meshlist
	list of meshes

std::vector< std::shared_ptr< ChPhysicsItem > >	otherphysicslist
	list of other physics objects

std::vector< std::shared_ptr< ChPhysicsItem > >	batch_to_insert
	list of items to insert at once

unsigned int	m_num_bodies_active
	number of active bodies

unsigned int	m_num_bodies_sleep
	number of sleeping bodies

unsigned int	m_num_bodies_fixed
	number of fixed bodies

unsigned int	m_num_shafts
	number of active shafts

unsigned int	m_num_shafts_sleep
	number of sleeping shafts

unsigned int	m_num_shafts_fixed
	number of fixed shafts

unsigned int	m_num_links_active
	number of active links

unsigned int	m_num_meshes
	number of meshes

unsigned int	m_num_otherphysicsitems_active
	number of other active physics items

unsigned int	m_num_coords_pos
	number of scalar position-level coordinates for all active bodies

unsigned int	m_num_coords_vel
	number of scalar velocity-level coordinates for all active bodies

unsigned int	m_num_constr
	number of scalar constraints

unsigned int	m_num_constr_bil
	number of scalar bilateral constraints

unsigned int	m_num_constr_uni
	number of scalar unilateral constraints

Protected Attributes inherited from chrono::ChPhysicsItem
ChSystem *	system
	parent system

std::shared_ptr< ChVisualModelInstance >	vis_model_instance
	instantiated visualization model

std::vector< std::shared_ptr< ChCamera > >	cameras
	set of cameras

unsigned int	offset_x
	offset in vector of state (position part)

unsigned int	offset_w
	offset in vector of state (speed part)

unsigned int	offset_L
	offset in vector of lagrangian multipliers

Protected Attributes inherited from chrono::ChObj
double	ChTime
	object simulation time

std::string	m_name
	object name

int	m_identifier
	object unique identifier

int	m_tag
	user-supplied tag

Member Enumeration Documentation

◆ ReductionType

enum chrono::modal::ChModalAssembly::ReductionType

strong

Modal reduction methods.

Enumerator
HERTING	free-free modes are used as the modal basis, more suitable for subsystems with free boundary conditions, such as helicopter blades or wind turbine blades.
CRAIG_BAMPTON	clamped-clamped modes are used as the modal basis.

Constructor & Destructor Documentation

◆ ChModalAssembly()

chrono::modal::ChModalAssembly::ChModalAssembly ( const ChModalAssembly & other )

TODO: deep copy of the object lists (internal_bodylist, internal_linklist, internal_meshlist, internal_otherphysicslist)

Member Function Documentation

◆ AddInternal()

void chrono::modal::ChModalAssembly::AddInternal ( std::shared_ptr< ChPhysicsItem > item )

Attach an arbitrary internal ChPhysicsItem (e.g.

ChBody, ChParticles, ChLink, etc.) to the modal assembly. It will take care of adding it to the proper list of internal bodies, links, meshes, or generic physic item.

◆ AddInternalLink()

void chrono::modal::ChModalAssembly::AddInternalLink ( std::shared_ptr< ChLinkBase > link )

Attach an internal link to this modal assembly.

AddInternalLink(): to link "boundary nodes" with "internal nodes", or "internal nodes" with "internal nodes", which will be reduced;
AddLink(): to link "boundary nodes" with "boundary nodes", which will be computed and updated in the full state.

◆ ComputeModes()

bool chrono::modal::ChModalAssembly::ComputeModes ( const ChModalSolveUndamped & n_modes_settings )

Compute the undamped modes for the current assembly.

Later you can fetch results via GetEigenVectors(), GetUndampedFrequencies() etc. Usually done for the assembly in full state, not available in reduced state.

◆ ComputeModesDamped()

bool chrono::modal::ChModalAssembly::ComputeModesDamped ( const ChModalSolveDamped & n_modes_settings )

Compute the damped modes for the entire modal assembly.

Expect complex eigenvalues/eigenvectors if damping is used. Later you can fetch results via GetEigenVectors(), GetUndampedFrequencies(), GetDampingRatios() etc. Usually done for the assembly in full state, not available in reduced state.

◆ ComputeModesExternalData()

bool chrono::modal::ChModalAssembly::ComputeModesExternalData	(	const ChSparseMatrix &	full_M,
		const ChSparseMatrix &	full_K,
		const ChSparseMatrix &	full_Cq,
		const ChModalSolveUndamped &	n_modes_settings
	)

Compute the undamped modes from M and K matrices.

Later you can fetch results via GetEigenVectors() etc.

◆ DoModalReduction() [1/2]

void chrono::modal::ChModalAssembly::DoModalReduction	(	ChSparseMatrix &	full_M,
		ChSparseMatrix &	full_K,
		ChSparseMatrix &	full_Cq,
		const ChModalSolveUndamped &	n_modes_settings,
		const ChModalDamping &	damping_model = `ChModalDampingNone()`
	)

Perform modal reduction on this modal assembly that contains only the "boundary" nodes, whereas the "internal" nodes have been modeled only in an external FEA software with the full ("boundary"+"internal") modes.

with an external FEA software, the full assembly is modeled with "boundary"+"internal" nodes.
with an external FEA software, the M mass matrix and the K stiffness matrix are saved to disk.
in Chrono, M and K and Cq constraint jacobians (if any) are load from disk and stored in ChSparseMatrix objects.
in Chrono, only boundary nodes are added to a ChModalAssembly.
in Chrono, run this function passing such M and K matrices: a modal analysis will be done on K and M Note that the size of M (and K) must be at least > m_num_coords_vel_boundary.

Parameters

full_M	mass matrix of the full assembly (boundary+internal)
full_K	stiffness matrix of the full assembly (boundary+internal)
full_Cq	constraint jacobian matrix of the full assembly (boundary+internal)
n_modes_settings	settings for the modal analysis, such as the number of modes to extract
damping_model	damping model

◆ DoModalReduction() [2/2]

void chrono::modal::ChModalAssembly::DoModalReduction	(	const ChModalSolveUndamped &	n_modes_settings,
		const ChModalDamping &	damping_model = `ChModalDampingNone()`
	)

Perform modal reduction on this modal assembly, from the current "full" ("boundary"+"internal") assembly.

An undamped modal analysis will be done on the full assembly, followed by a modal reduction transformation.
The "boundary" nodes will be retained.
The "internal" nodes will be replaced by n_modes modal coordinates.

◆ GetConstraintsResidualF()

const ChVectorDynamic& chrono::modal::ChModalAssembly::GetConstraintsResidualF ( )

inline

Get the residual of constraint equations on the floating frame F.

The configuration of the floating frame F is determined by the six constraint equations using a Newton-Raphson iteration. The residual of constraint equations is an indicator to check the convergence of the modal method.

◆ GetDampingRatios()

const ChVectorDynamic<double>& chrono::modal::ChModalAssembly::GetDampingRatios ( ) const

inline

Get a vector of modal damping ratios = damping/critical_damping, if previously computed.

Use one of the ComputeModes() functions to set it.

◆ GetEigenValues()

const ChVectorDynamic<std::complex<double> >& chrono::modal::ChModalAssembly::GetEigenValues ( ) const

inline

Get the modal eigenvalues, if previously computed.

These are the eigenvalues of the original assembly with applied boundary conditions, depending on reduction type. Use one of the ComputeModes() functions to set it.

◆ GetEigenVectors()

const ChMatrixDynamic<std::complex<double> >& chrono::modal::ChModalAssembly::GetEigenVectors ( ) const

inline

Get the modal eigenvectors, if previously computed.

These are the eigenvectors of the original assembly with applied boundary conditions, depending on reduction type. Use one of the ComputeModes() functions to set it.

◆ GetModalReductionMatrix()

const ChMatrixDynamic& chrono::modal::ChModalAssembly::GetModalReductionMatrix ( ) const

inline

Get the modal reduction transformation matrix 'Psi'.

'Psi' as in v_full = Psi * v_reduced, also {v_boundary; v_internal} = Psi * {v_boundary; v_modes}. Hence Psi contains the "static modes", the selected "dynamic modes" and the "static correction mode", as Psi = [ I 0 0 ] [ Psi_S Psi_D Psi_Cor ] [ Psi_S_LambdaI Psi_D_LambdaI Psi_Cor_LambdaI ] where Psi_D is the matrix of the selected eigenvectors after DoModalReduction(), Psi_Cor is the static correction mode which depends on the external forces imposed on the internal bodies and nodes.

◆ GetNumCoordinatesPosBoundary()

unsigned int chrono::modal::ChModalAssembly::GetNumCoordinatesPosBoundary ( ) const

inline

Get the number of boundary coordinates at the position level.

Might differ from GetNumCoordinatesPosInternal in case of quaternions.

◆ GetNumCoordinatesPosInternal()

unsigned int chrono::modal::ChModalAssembly::GetNumCoordinatesPosInternal ( ) const

inline

Get the number of internal coordinates at the position level.

Might differ from GetNumCoordinatesPosInternal in case of quaternions.

◆ GetNumCoordinatesVelBoundary()

unsigned int chrono::modal::ChModalAssembly::GetNumCoordinatesVelBoundary ( ) const

inline

Get the number of boundary coordinates at the velocity level.

Might differ from GetNumCoordinatesPosInternal in case of quaternions.

◆ GetNumCoordinatesVelInternal()

unsigned int chrono::modal::ChModalAssembly::GetNumCoordinatesVelInternal ( ) const

inline

Get the number of internal coordinates at the velocity level.

Might differ from GetNumCoordinatesPosInternal in case of quaternions.

◆ GetSubassemblyConstraintJacobianMatrix()

void chrono::modal::ChModalAssembly::GetSubassemblyConstraintJacobianMatrix ( ChSparseMatrix * Cq )

Compute the constraint Jacobian matrix of the modal assembly, i.e.

the jacobian Cq=-dC/dq where C are constraints (the lower left part of the KKT matrix). Assumes the columns of the matrix are ordered as the ChVariable objects used in this modal assembly, i.e. first the all the "boundary" variables then all the "internal" variables (or modal variables if switched to modal reduced state), and assumes the rows of the matrix are ordered as the constraints used in this modal assembly, i.e. first the boundary and then the internal. fill this system constraint Jacobian matrix

◆ GetSubassemblyDampingMatrix()

void chrono::modal::ChModalAssembly::GetSubassemblyDampingMatrix ( ChSparseMatrix * R )

Compute the stiffness matrix of the modal assembly, i.e.

the jacobian -dF/dv where F are stiff loads. Assumes the rows/columns of the matrix are ordered as the ChVariable objects used in this modal assembly, first the all the "boundary" variables then all the "internal" variables (or modal variables if switched to modal reduced state). Note that not all loads provide a jacobian, as this is optional in their implementation. fill this system damping matrix

◆ GetSubassemblyMassMatrix()

void chrono::modal::ChModalAssembly::GetSubassemblyMassMatrix ( ChSparseMatrix * M )

Compute the mass matrix of the modal assembly.

Assumes the rows/columns of the matrix are ordered as the ChVariable objects used in this modal assembly, first the all the "boundary" itvariablesems then all the "internal" variables (or modal variables if switched to modal reduced state). fill this system mass matrix

◆ GetSubassemblyStiffnessMatrix()

void chrono::modal::ChModalAssembly::GetSubassemblyStiffnessMatrix ( ChSparseMatrix * K )

Compute the stiffness matrix of the modal assembly, i.e.

the jacobian -dF/dq where F are stiff loads. Assumes the rows/columns of the matrix are ordered as the ChVariable objects used in this modal assembly, first the all the "boundary" variables then all the "internal" variables (or modal variables if switched to modal reduced state). Note that not all loads provide a jacobian, as this is optional in their implementation. fill this system stiffness matrix

◆ GetUndampedFrequencies()

const ChVectorDynamic<double>& chrono::modal::ChModalAssembly::GetUndampedFrequencies ( ) const

inline

Get a vector of (undamped) modal natural frequencies [Hz], if previously computed.

These are the frequencies of the original assembly with applied boundary conditions, depending on reduction type. Use one of the ComputeModes() functions to set it.

◆ IntFromDescriptor()

void chrono::modal::ChModalAssembly::IntFromDescriptor	(	const unsigned int	off_v,
		ChStateDelta &	v,
		const unsigned int	off_L,
		ChVectorDynamic<> &	L
	)

overridevirtual

After a solver solution, fetch values from variables and constraints into vectors:

Parameters

off_v	offset for v
v	vector to where the q 'unknowns' term of the variables will be copied
off_L	offset for L
L	vector to where L 'lagrangian ' term of the constraints will be copied

Reimplemented from chrono::ChAssembly.

◆ IntLoadConstraint_C()

void chrono::modal::ChModalAssembly::IntLoadConstraint_C	(	const unsigned int	off,
		ChVectorDynamic<> &	Qc,
		const double	c,
		bool	do_clamp,
		double	recovery_clamp
	)

overridevirtual

Takes the term C, scale and adds to Qc at given offset: Qc += c*C.

Parameters

off	offset in Qc residual
Qc	result: the Qc residual, Qc += c*C
c	a scaling factor
do_clamp	apply clamping to c*C?
recovery_clamp	value for min/max clamping of c*C

Reimplemented from chrono::ChAssembly.

◆ IntLoadConstraint_Ct()

void chrono::modal::ChModalAssembly::IntLoadConstraint_Ct	(	const unsigned int	off,
		ChVectorDynamic<> &	Qc,
		const double	c
	)

overridevirtual

Takes the term Ct, scale and adds to Qc at given offset: Qc += c*Ct.

Parameters

off	offset in Qc residual
Qc	result: the Qc residual, Qc += c*Ct
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntLoadLumpedMass_Md()

void chrono::modal::ChModalAssembly::IntLoadLumpedMass_Md	(	const unsigned int	off,
		ChVectorDynamic<> &	Md,
		double &	err,
		const double	c
	)

overridevirtual

Adds the lumped mass to a Md vector, representing a mass diagonal matrix.

Used by lumped explicit integrators. If mass lumping is impossible or approximate, adds scalar error to "error" parameter. Md += c*diag(M)

Parameters

off	offset in Md vector
Md	result: Md vector, diagonal of the lumped mass matrix
err	result: not touched if lumping does not introduce errors
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntLoadResidual_CqL()

void chrono::modal::ChModalAssembly::IntLoadResidual_CqL	(	const unsigned int	off_L,
		ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	L,
		const double	c
	)

overridevirtual

Takes the term Cq'*L, scale and adds to R at given offset: R += c*Cq'*L.

Parameters

off_L	offset in L multipliers
R	result: the R residual, R += cCq'L
L	the L vector
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntLoadResidual_F()

void chrono::modal::ChModalAssembly::IntLoadResidual_F	(	const unsigned int	off,
		ChVectorDynamic<> &	R,
		const double	c
	)

overridevirtual

Takes the F force term, scale and adds to R at given offset: R += c*F.

g_quadvel: the quadratic velocity term of the reduced modal superelement

Parameters

off	offset in R residual
R	result: the R residual, R += c*F
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntLoadResidual_Mv()

void chrono::modal::ChModalAssembly::IntLoadResidual_Mv	(	const unsigned int	off,
		ChVectorDynamic<> &	R,
		const ChVectorDynamic<> &	w,
		const double	c
	)

overridevirtual

Takes the M*v term, multiplying mass by a vector, scale and adds to R at given offset: R += c*M*w.

Parameters

off	offset in R residual
R	result: the R residual, R += cMv
w	the w vector
c	a scaling factor

Reimplemented from chrono::ChAssembly.

◆ IntStateGather()

void chrono::modal::ChModalAssembly::IntStateGather	(	const unsigned int	off_x,
		ChState &	x,
		const unsigned int	off_v,
		ChStateDelta &	v,
		double &	T
	)

overridevirtual

From item's state to global state vectors y={x,v} pasting the states at the specified offsets.

Parameters

off_x	offset in x state vector
x	state vector, position part
off_v	offset in v state vector
v	state vector, speed part
T	time

Reimplemented from chrono::ChAssembly.

◆ IntStateGatherAcceleration()

void chrono::modal::ChModalAssembly::IntStateGatherAcceleration	(	const unsigned int	off_a,
		ChStateDelta &	a
	)

overridevirtual

From item's state acceleration to global acceleration vector.

Parameters

off_a	offset in a accel. vector
a	acceleration part of state vector derivative

Reimplemented from chrono::ChAssembly.

◆ IntStateGatherReactions()

void chrono::modal::ChModalAssembly::IntStateGatherReactions	(	const unsigned int	off_L,
		ChVectorDynamic<> &	L
	)

overridevirtual

From item's reaction forces to global reaction vector.

Parameters

off_L	offset in L vector
L	L vector of reaction forces

Reimplemented from chrono::ChAssembly.

◆ IntStateGetIncrement()

void chrono::modal::ChModalAssembly::IntStateGetIncrement	(	const unsigned int	off_x,
		const ChState &	x_new,
		const ChState &	x,
		const unsigned int	off_v,
		ChStateDelta &	Dv
	)

overridevirtual

Computes Dt = x_new - x, using vectors at specified offsets.

By default, when DOF = DOF_w, it does just the difference of two state vectors, but in some cases (ex when using quaternions for rotations) it could do more complex stuff, and children classes might overload it.

Parameters

off_x	offset in x state vector
x_new	state vector, final position part
x	state vector, initial position part
off_v	offset in v state vector
Dv	state vector, increment. Here gets the result

Reimplemented from chrono::ChAssembly.

◆ IntStateIncrement()

void chrono::modal::ChModalAssembly::IntStateIncrement	(	const unsigned int	off_x,
		ChState &	x_new,
		const ChState &	x,
		const unsigned int	off_v,
		const ChStateDelta &	Dv
	)

overridevirtual

Computes x_new = x + Dt , using vectors at specified offsets.

By default, when DOF = DOF_w, it does just the sum, but in some cases (ex when using quaternions for rotations) it could do more complex stuff, and children classes might overload it.

Parameters

off_x	offset in x state vector
x_new	state vector, position part, incremented result
x	state vector, initial position part
off_v	offset in v state vector
Dv	state vector, increment

Reimplemented from chrono::ChAssembly.

◆ IntStateScatter()

void chrono::modal::ChModalAssembly::IntStateScatter	(	const unsigned int	off_x,
		const ChState &	x,
		const unsigned int	off_v,
		const ChStateDelta &	v,
		const double	T,
		bool	full_update
	)

overridevirtual

From global state vectors y={x,v} to item's state (and update) fetching the states at the specified offsets.

Parameters

off_x	offset in x state vector
x	state vector, position part
off_v	offset in v state vector
v	state vector, speed part
T	time
full_update	perform complete update

Reimplemented from chrono::ChAssembly.

◆ IntStateScatterAcceleration()

void chrono::modal::ChModalAssembly::IntStateScatterAcceleration	(	const unsigned int	off_a,
		const ChStateDelta &	a
	)

overridevirtual

From global acceleration vector to item's state acceleration.

Parameters

off_a	offset in a accel. vector
a	acceleration part of state vector derivative

Reimplemented from chrono::ChAssembly.

◆ IntStateScatterReactions()

void chrono::modal::ChModalAssembly::IntStateScatterReactions	(	const unsigned int	off_L,
		const ChVectorDynamic<> &	L
	)

overridevirtual

From global reaction vector to item's reaction forces.

Parameters

off_L	offset in L vector
L	L vector of reaction forces

Reimplemented from chrono::ChAssembly.

◆ IntToDescriptor()

void chrono::modal::ChModalAssembly::IntToDescriptor	(	const unsigned int	off_v,
		const ChStateDelta &	v,
		const ChVectorDynamic<> &	R,
		const unsigned int	off_L,
		const ChVectorDynamic<> &	L,
		const ChVectorDynamic<> &	Qc
	)

overridevirtual

Prepare variables and constraints to accommodate a solution:

Parameters

off_v	offset for v and R
v	vector copied into the q 'unknowns' term of the variables
R	vector copied into the F 'force' term of the variables
off_L	offset for L and Qc
L	vector copied into the L 'lagrangian ' term of the constraints
Qc	vector copied into the Qb 'constraint' term of the constraints

Reimplemented from chrono::ChAssembly.

◆ LoadKRMMatrices()

void chrono::modal::ChModalAssembly::LoadKRMMatrices	(	double	Kfactor,
		double	Rfactor,
		double	Mfactor
	)

overridevirtual

Compute and load current stiffnes (K), damping (R), and mass (M) matrices in encapsulated ChKRMBlock objects.

The resulting KRM blocks represent linear combinations of the K, R, and M matrices, with the specified coefficients Kfactor, Rfactor,and Mfactor, respectively. Note: signs are flipped from the term dF/dx in the integrator: K = -dF/dq and R = -dF/dv.

Reimplemented from chrono::ChAssembly.

◆ SetInternalNodesUpdate()

void chrono::modal::ChModalAssembly::SetInternalNodesUpdate ( bool flag )

Optimization flag.

Default true: when in modal reduced mode, during simulations the internal (discarded) nodes are updated anyway by superposition of modal shapes etc., for visualization or postprocessing purposes. In sake of high CPU performance, if no interest in visualization/postprocessing, one can disable this by setting to false, then automatically set m_num_coords_static_correction = 0 to disable the static correction mode.

◆ SetModalAutomaticGravity()

void chrono::modal::ChModalAssembly::SetModalAutomaticGravity ( bool gravity )

inline

If true, as by default, this modal assembly will add automatically a gravity load to all contained boundary and internal bodies/nodes (that support gravity) in the modal reduced state using the G value from the ChSystem.

In modal reduced state, this flag will overwrite mesh->SetAutomaticGravity() for both boundary and internal meshes.
In full state, this flap does NOT affect, and mesh->SetAutomaticGravity() is used for both boundary and internal meshes. It is recommended to use a same boolean value to ensure a consistent setting in both full and reduced state, for example:
modal_assembly->SetModalAutomaticGravity(USE_GRAVITY);
mesh_internal->SetAutomaticGravity(USE_GRAVITY);
mesh_boundary->SetAutomaticGravity(USE_GRAVITY);

◆ Setup()

void chrono::modal::ChModalAssembly::Setup ( )

overridevirtual

Counts the number of bodies, links, and meshes.

Computes the offsets of object states in the global state. Assumes that this->offset_x this->offset_w this->offset_L are already set as starting point for offsetting all the contained sub objects.

Reimplemented from chrono::ChAssembly.

◆ SetUseLinearInertialTerm()

void chrono::modal::ChModalAssembly::SetUseLinearInertialTerm ( bool flag )

inline

A rigorous mathematical manipulation can be employed to derive the inertial forces and the consequent inertial damping matrix, or a linear assumption is applied to obtain quite concise expressions.

True: default option, the linear assumption is used.
False: rigorous deviation is used, only for internal test.

◆ SetUseStaticCorrection()

void chrono::modal::ChModalAssembly::SetUseStaticCorrection ( bool flag )

Set whether the static correction is used.

By default, it is false. When some external forces are imposed on the internal bodies and nodes, the static correction is important to obtain a reasonable accurary of the elastic deformation and internal forces of finite elements, and reaction forces of constriants in the modal assembly. In this case, it is strongly recommended to set true. Note: only available to SetUseStaticCorrection(true) when m_internal_nodes_update = true.

◆ UpdateFullStateWithModeOverlay()

void chrono::modal::ChModalAssembly::UpdateFullStateWithModeOverlay	(	unsigned int	n_mode,
		double	phase,
		double	amplitude
	)

For displaying modes, you can use the following function.

It sets the state of this modal assembly (both boundary and internal items) using the n-th eigenvector multiplied by an "amplitude" factor * sin(phase). If you increment the phase during an animation, you will see the n-th mode oscillating on the screen. The modal shapes are animated based on the initial full state of the modal assembly. It works only in full state.

◆ UpdateInternalStateWithModes()

void chrono::modal::ChModalAssembly::UpdateInternalStateWithModes ( bool full_update )

For displaying the deformation using internal nodes, you can use the following function.

Works only if FlagModelAsReduced(). It sets the state of the internal nodes of this modal assembly using the current state of the modal coordinates q given the computed eigenvectors: s = V * q , then it overlays s to the state snapshot x0 stored last time one called a modal reduction. This is not necessary, but useful during animations, in fact the internal nodes would be completely neglected if m_internal_nodes_update == false; but calling this function one can update their changing positions for visualization, stress recovery, etc.

◆ WriteSubassemblyMatrices()

void chrono::modal::ChModalAssembly::WriteSubassemblyMatrices	(	bool	save_M,
		bool	save_K,
		bool	save_R,
		bool	save_Cq,
		const std::string &	path,
		bool	one_indexed = `true`
	)

Write the mass (M), damping (K), damping (R), and constraint Jacobian (C) matrices at current configuration.

Assumes the rows/columns of the matrices are ordered as the ChVariable objects used in this modal assembly, first all the "boundary" variables then all the "internal" variables (or modal variables if switched to modal reduced state). The sparse matrices are saved in COO format in [path]_M.dat [path]_K.dat [path]_R.dat, and [path]_Cq.dat. By default, uses 1-based indices (as in Matlab).

Friends And Related Function Documentation

◆ swap

void swap	(	ChModalAssembly &	first,
		ChModalAssembly &	second
	)

friend

Swap the contents of the two provided ChAssembly objects.

Implemented as a friend (as opposed to a member function) so classes with a ChModalAssembly member can use ADL when implementing their own swap.

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

/builds/uwsbel/chrono/src/chrono_modal/ChModalAssembly.h
/builds/uwsbel/chrono/src/chrono_modal/ChModalAssembly.cpp

Description

Public Types

Public Member Functions

Friends

Additional Inherited Members

Member Enumeration Documentation

◆ ReductionType

Constructor & Destructor Documentation

◆ ChModalAssembly()

Member Function Documentation

◆ AddInternal()

◆ AddInternalLink()

◆ ComputeModes()

◆ ComputeModesDamped()

◆ ComputeModesExternalData()

◆ DoModalReduction() [1/2]

◆ DoModalReduction() [2/2]

◆ GetConstraintsResidualF()

◆ GetDampingRatios()

◆ GetEigenValues()

◆ GetEigenVectors()

◆ GetModalReductionMatrix()

◆ GetNumCoordinatesPosBoundary()

◆ GetNumCoordinatesPosInternal()

◆ GetNumCoordinatesVelBoundary()

◆ GetNumCoordinatesVelInternal()

◆ GetSubassemblyConstraintJacobianMatrix()

◆ GetSubassemblyDampingMatrix()

◆ GetSubassemblyMassMatrix()

◆ GetSubassemblyStiffnessMatrix()

◆ GetUndampedFrequencies()

◆ IntFromDescriptor()

◆ IntLoadConstraint_C()

◆ IntLoadConstraint_Ct()

◆ IntLoadLumpedMass_Md()

◆ IntLoadResidual_CqL()

◆ IntLoadResidual_F()

◆ IntLoadResidual_Mv()

◆ IntStateGather()

◆ IntStateGatherAcceleration()

◆ IntStateGatherReactions()

◆ IntStateGetIncrement()

◆ IntStateIncrement()

◆ IntStateScatter()

◆ IntStateScatterAcceleration()

◆ IntStateScatterReactions()

◆ IntToDescriptor()

◆ LoadKRMMatrices()

◆ SetInternalNodesUpdate()

◆ SetModalAutomaticGravity()

◆ Setup()

◆ SetUseLinearInertialTerm()

◆ SetUseStaticCorrection()

◆ UpdateFullStateWithModeOverlay()

◆ UpdateInternalStateWithModes()

◆ WriteSubassemblyMatrices()

Friends And Related Function Documentation

◆ swap