chrono::modal::ChModalAssembly Class Reference

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:
Collaboration diagram for chrono::modal::ChModalAssembly:

Public Types

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

Public Member Functions

 ChModalAssembly (const ChModalAssembly &other)
 
virtual ChModalAssemblyClone () const override
 "Virtual" copy constructor (covariant return type).
 
ChModalAssemblyoperator= (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 ChVectorDynamicGetConstraintsResidualF ()
 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 ChMatrixDynamicGetModalMassMatrix () const
 Get the modal mass matrix.
 
const ChMatrixDynamicGetModalStiffnessMatrix () const
 Get the modal stiffness matrix.
 
const ChMatrixDynamicGetModalDampingMatrix () const
 Get the modal damping matrix.
 
const ChMatrixDynamicGetModalReductionMatrix () 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 ChVectorDynamicGetDeformedState () const
 Get the deformed configuration of the full modal assembly.
 
const ChVectorDynamicGetInitialState () const
 Get the initial full state of the modal assembly before the modal reduction.
 
ChVectorDynamicGetModalCoordinatesPosLevel ()
 Get the vector of modal coordinates (positions).
 
ChVectorDynamicGetModalCoordinatesVelLevel ()
 Get the vector of time derivative of modal coordinates (velocities).
 
ChVectorDynamicGetModalCoordinatesAccLevel ()
 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 M*v term, multiplying mass by a vector, scale and adds to R at given offset: R += c*M*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 += c*Cq'*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)
 
ChAssemblyoperator= (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< ChBodySearchBody (const std::string &name) const
 Search a body by its name.
 
std::shared_ptr< ChBodySearchBodyID (int id) const
 Search a body by its ID.
 
std::shared_ptr< ChShaftSearchShaft (const std::string &name) const
 Search a shaft by its name.
 
std::shared_ptr< ChLinkBaseSearchLink (const std::string &name) const
 Search a link by its name.
 
std::shared_ptr< fea::ChMeshSearchMesh (const std::string &name) const
 Search a mesh by its name.
 
std::shared_ptr< ChPhysicsItemSearchOtherPhysicsItem (const std::string &name) const
 Search from other ChPhysics items (not bodies, links, or meshes) by name.
 
std::shared_ptr< ChMarkerSearchMarker (const std::string &name) const
 Search a marker by its name.
 
std::shared_ptr< ChMarkerSearchMarker (int id) const
 Search a marker by its unique ID.
 
std::shared_ptr< ChPhysicsItemSearch (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)
 
ChSystemGetSystem () const
 Get the pointer to the parent ChSystem().
 
void AddVisualModel (std::shared_ptr< ChVisualModel > model)
 Add an (optional) visualization model. More...
 
std::shared_ptr< ChVisualModelGetVisualModel () 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< ChVisualShapeGetVisualShape (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< ChVisualShapeFEAGetVisualShapeFEA (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
ChSystemsystem
 parent system
 
std::shared_ptr< ChVisualModelInstancevis_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

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_Mmass matrix of the full assembly (boundary+internal)
full_Kstiffness matrix of the full assembly (boundary+internal)
full_Cqconstraint jacobian matrix of the full assembly (boundary+internal)
n_modes_settingssettings for the modal analysis, such as the number of modes to extract
damping_modeldamping 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_voffset for v
vvector to where the q 'unknowns' term of the variables will be copied
off_Loffset for L
Lvector 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
offoffset in Qc residual
Qcresult: the Qc residual, Qc += c*C
ca scaling factor
do_clampapply clamping to c*C?
recovery_clampvalue 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
offoffset in Qc residual
Qcresult: the Qc residual, Qc += c*Ct
ca 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
offoffset in Md vector
Mdresult: Md vector, diagonal of the lumped mass matrix
errresult: not touched if lumping does not introduce errors
ca 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_Loffset in L multipliers
Rresult: the R residual, R += c*Cq'*L
Lthe L vector
ca 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
offoffset in R residual
Rresult: the R residual, R += c*F
ca 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
offoffset in R residual
Rresult: the R residual, R += c*M*v
wthe w vector
ca 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_xoffset in x state vector
xstate vector, position part
off_voffset in v state vector
vstate vector, speed part
Ttime

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_aoffset in a accel. vector
aacceleration 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_Loffset in L vector
LL 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_xoffset in x state vector
x_newstate vector, final position part
xstate vector, initial position part
off_voffset in v state vector
Dvstate 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_xoffset in x state vector
x_newstate vector, position part, incremented result
xstate vector, initial position part
off_voffset in v state vector
Dvstate 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_xoffset in x state vector
xstate vector, position part
off_voffset in v state vector
vstate vector, speed part
Ttime
full_updateperform 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_aoffset in a accel. vector
aacceleration 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_Loffset in L vector
LL 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_voffset for v and R
vvector copied into the q 'unknowns' term of the variables
Rvector copied into the F 'force' term of the variables
off_Loffset for L and Qc
Lvector copied into the L 'lagrangian ' term of the constraints
Qcvector 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