Description

Class for defining a torsional spring-damper between two 1D parts; i.e., shafts that can be used to build 1D models of powertrains.

This is more efficient than simulating power trains modeled with full 3D ChBody objects. This supersedes the old ChShaftsTorsionSpring (which cannot handle extremely stiff spring values)

#include <ChShaftsLoads.h>

Inheritance diagram for chrono::ChShaftsElasticGear:

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Collaboration diagram for chrono::ChShaftsElasticGear:

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Public Member Functions
	ChShaftsElasticGear (std::shared_ptr< ChShaft > mbodyA, std::shared_ptr< ChShaft > mbodyB, const double mstiffness, const double mdamping, const double mRa, const double mratio=-1)

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

void	SetTeethStiffness (const double mstiffness)
	Set teeth stiffness, at contact point, in tangent direction to the two primitives. Es. [N/m].

double	GetTeethStiffness () const

void	SetTeethDamping (const double mdamping)
	Set teeth damping, at contact point, in tangent direction to the two primitives. Es. [Ns/m].

double	GetTeethDamping () const

void	SetRestPhase (const double mphase)
	Set the phase shaftA-tau*shaftB for zero compression of the spring (default = 0 [rad])

double	GetRestPhase () const

void	SetTransmissionRatioAndRadiusA (double mt, double mRa)
	Set the transmission ratio t, as in w2=tw1, or t=w2/w1 , or tw1 - w2 = 0. More...

void	SetTransmissionRatioFromRadii (double mRa, double mRb, bool minternal=false)
	Set the transmission ratio t, as in w2=t*w1, using the two primitive radii Ra and Rb. More...

double	GetTransmissionRatio () const
	Get the transmission ratio t, as in w2=t*w1, or t=w2/w1.

double	GetGearRadiusA () const
	Get the primitive radius of the gear wheel of shaftA.

double	GetGearRadiusB () const
	Get the primitive radius of the gear wheel of shaftB.

double	GetContactForce () const
	Get the last computed contact force, for diagnostics. More...

Public Member Functions inherited from chrono::ChLoadCustomMultiple
	ChLoadCustomMultiple (std::vector< std::shared_ptr< ChLoadable >> &mloadables)

	ChLoadCustomMultiple (std::shared_ptr< ChLoadable > mloadableA, std::shared_ptr< ChLoadable > mloadableB)

	ChLoadCustomMultiple (std::shared_ptr< ChLoadable > mloadableA, std::shared_ptr< ChLoadable > mloadableB, std::shared_ptr< ChLoadable > mloadableC)

virtual int	LoadGet_ndof_x () override
	Gets the number of DOFs affected by this load (position part)

virtual int	LoadGet_ndof_w () override
	Gets the number of DOFs affected by this load (speed part)

virtual void	LoadGetStateBlock_x (ChState &mD) override
	Gets all the current DOFs packed in a single vector (position part)

virtual void	LoadGetStateBlock_w (ChStateDelta &mD) override
	Gets all the current DOFs packed in a single vector (speed part)

virtual void	LoadStateIncrement (const ChState &x, const ChStateDelta &dw, ChState &x_new) override
	Increment a packed state (ex. More...

virtual int	LoadGet_field_ncoords () override
	Number of coordinates in the interpolated field, ex=3 for a tetrahedron finite element or a cable, = 1 for a thermal problem, etc.

virtual void	ComputeJacobian (ChState state_x, ChStateDelta state_w, ChMatrixRef mK, ChMatrixRef mR, ChMatrixRef mM) override
	Compute jacobians (default fallback). More...

virtual void	LoadIntLoadResidual_F (ChVectorDynamic<> &R, double c) override
	Adds the internal loads Q (pasted at global nodes offsets) into a global vector R, multiplied by a scaling factor c, as R += forces * c.

virtual void	LoadIntLoadResidual_Mv (ChVectorDynamic<> &R, const ChVectorDynamic<> &w, double c) override
	Default fallback: compute jacobians via ComputeJacobian(), then use M=-dQ/da to do R += cMw. More...

virtual void	CreateJacobianMatrices () override
	Create the jacobian loads if needed, and also set the ChVariables referenced by the sparse KRM block.

virtual ChVectorDynamic &	GetQ ()
	Access the generalized load vector Q.

Public Member Functions inherited from chrono::ChLoadBase
ChLoadJacobians *	GetJacobians ()
	Access the jacobians (if any, i.e. if this is a stiff load)

virtual void	Update (double time)
	Update: this is called at least at each time step. More...

virtual void	InjectKRMmatrices (ChSystemDescriptor &mdescriptor)
	Tell to a system descriptor that there are item(s) of type ChKblock in this object (for further passing it to a solver)

virtual void	KRMmatricesLoad (double Kfactor, double Rfactor, double Mfactor)
	Adds the current stiffness K and damping R and mass M matrices in encapsulated ChKblock item(s), if any. More...

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

int	GetIdentifier () const
	Gets the numerical identifier of the object.

void	SetIdentifier (int id)
	Sets the numerical identifier of the object.

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

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

const char *	GetName () const
	Gets the name of the object as C Ascii null-terminated string -for reading only!

void	SetName (const char myname[])
	Sets the name of this object, as ascii string.

std::string	GetNameString () const
	Gets the name of the object as C Ascii null-terminated string.

void	SetNameString (const std::string &myname)
	Sets the name of this object, as std::string.

void	MFlagsSetAllOFF (int &mflag)

void	MFlagsSetAllON (int &mflag)

void	MFlagSetON (int &mflag, int mask)

void	MFlagSetOFF (int &mflag, int mask)

int	MFlagGet (int &mflag, int mask)

virtual void	ArchiveOUT (ChArchiveOut &marchive)
	Method to allow serialization of transient data to archives.

virtual void	ArchiveIN (ChArchiveIn &marchive)
	Method to allow de-serialization of transient data from archives.

virtual std::string &	ArchiveContainerName ()

Protected Member Functions
virtual bool	IsStiff () override
	Report if this is load is stiff. More...

virtual void	ComputeQ (ChState state_x, ChStateDelta state_w) override
	Compute Q, the generalized load. More...

Protected Attributes
double	stiffness

double	damping

double	rest_phase

double	Ra

double	ratio

double	contact_force

Protected Attributes inherited from chrono::ChLoadBase
ChLoadJacobians *	jacobians

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

Additional Inherited Members
Public Attributes inherited from chrono::ChLoadCustomMultiple
std::vector< std::shared_ptr< ChLoadable > >	loadables

ChVectorDynamic	load_Q

Constructor & Destructor Documentation

◆ ChShaftsElasticGear()

chrono::ChShaftsElasticGear::ChShaftsElasticGear	(	std::shared_ptr< ChShaft >	mbodyA,
		std::shared_ptr< ChShaft >	mbodyB,
		const double	mstiffness,
		const double	mdamping,
		const double	mRa,
		const double	mratio = `-1`
	)

Parameters

mbodyA	shaft A
mbodyB	shaft B
mstiffness	normal stiffness at teeth contact, tangent direction to primitive
mdamping	normal damping at teeth contact, tangent direction to primitive
mRa	primitive radius of the gear on shaft A (the radius of B is not needed)
mratio	transmission ratio (negative for outer gear, positive for inner gears)

Member Function Documentation

◆ ComputeQ()

void chrono::ChShaftsElasticGear::ComputeQ	(	ChState *	state_x,
		ChStateDelta *	state_w
	)

overrideprotectedvirtual

Compute Q, the generalized load.

Called automatically at each Update().

Parameters

state_x	state position to evaluate Q
state_w	state speed to evaluate Q

Implements chrono::ChLoadBase.

◆ GetContactForce()

double chrono::ChShaftsElasticGear::GetContactForce ( ) const

inline

Get the last computed contact force, for diagnostics.

The force is assumed tangent to the primitives of the gear wheels, it can be positive or negative depending on clock/counterclock effect.

◆ IsStiff()

virtual bool chrono::ChShaftsElasticGear::IsStiff ( )

inlineoverrideprotectedvirtual

Report if this is load is stiff.

If so, InjectKRMmatrices will provide the jacobians of the load.

Implements chrono::ChLoadBase.

◆ SetTransmissionRatioAndRadiusA()

void chrono::ChShaftsElasticGear::SetTransmissionRatioAndRadiusA	(	double	mt,
		double	mRa
	)

inline

Set the transmission ratio t, as in w2=t*w1, or t=w2/w1 , or t*w1 - w2 = 0.

For example, t=1 for a rigid joint; t=-0.5 for representing a couple of spur gears with teeth z1=20 & z2=40; t=0.1 for a gear with inner teeth (or epicycloidal reducer), etc. Differently from the ideal ChShaftsGear constraint, this model includes elasticity, so at least the radius of one of the two gear wheels is needed, namely Ra.

◆ SetTransmissionRatioFromRadii()

void chrono::ChShaftsElasticGear::SetTransmissionRatioFromRadii	(	double	mRa,
		double	mRb,
		bool	minternal = `false`
	)

inline

Set the transmission ratio t, as in w2=t*w1, using the two primitive radii Ra and Rb.

It will be computed as t=Ra/Rb by default, otherwise t=-Ra/Rb if the bigger wheel has inner teeth.

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

/builds/uwsbel/chrono/src/chrono/physics/ChShaftsLoads.h
/builds/uwsbel/chrono/src/chrono/physics/ChShaftsLoads.cpp

Description

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ ChShaftsElasticGear()

Member Function Documentation

◆ ComputeQ()

◆ GetContactForce()

◆ IsStiff()

◆ SetTransmissionRatioAndRadiusA()

◆ SetTransmissionRatioFromRadii()