SlidingFrictionInteraction Class Reference

Computes the forces corresponding to sliding friction. More...

#include <SlidingFrictionInteraction.h>

Inheritance diagram for SlidingFrictionInteraction:

Public Types
typedef SlidingFrictionSpecies	SpeciesType
	An alias name for SlidingFrictionSpecies data type. More...

Public Member Functions
	SlidingFrictionInteraction (BaseInteractable *P, BaseInteractable *I, unsigned timeStamp)
	Constructor. More...
	SlidingFrictionInteraction ()
	SlidingFrictionInteraction (const SlidingFrictionInteraction &p)
	Copy constructor. More...
	~SlidingFrictionInteraction () override
	Destructor. More...
void	computeFrictionForce ()
	Computes the tangential force generated due to compression in the sliding spring. Does take into account if the interaction is between particle-particle or particle-wall. More...
void	read (std::istream &is) override
	Interaction read function, which accepts an std::istream as input. More...
void	write (std::ostream &os) const override
	Interaction write function, which accepts an std::ostream as input. More...
void	integrate (Mdouble timeStep) override
	Increments the amount of compression in sliding spring. More...
Mdouble	getElasticEnergy () const override
	Returns the amount of elastic energy stored in sliding spring. More...
Mdouble	getTangentialOverlap () const override
	Returns the amount of tangential overlap which is needed by BaseInteraction::writeToFstat(). More...
std::string	getBaseName () const
	Returns the type/name of interaction (sliding friction interaction) More...
void	setSlidingSpring (Vec3D slidingSpring)
Vec3D	getSlidingSpring () const
const Vec3D	getTangentialForce () const override
	Returns the sliding friction force vector. More...
void	addTangentialForce (Vec3D force)
	adds an extra tangential force, mainly for the tangential lubrication force from LiquidMigrationLS model. More...
const SlidingFrictionSpecies *	getSpecies () const
	Returns a const pointer of type SlidingFrictionSpecies*. More...
void	reverseHistory () override
	A useful feature if one wants to return to the initial state of the spring. However, reverse history decrements the current state to the state corresponding to previous time step. Decrements the value of slidingSpring_. More...
void	rotateHistory (Matrix3D &rotationMatrix) override
	When periodic particles are used, some interactions need certain history properties rotated (e.g. tangential springs). This is the function for that. More...
void	moveSlidingSpring (Vec3D displacement)
void	computeSlidingSpring (const Vec3D &tangentialRelativeVelocity)
void	computeSlidingSpringSuperQuadric (const Vec3D &tangentialRelativeVelocity)
void	setIsSuperQuadricInteraction (bool isSuperQuadricInteraction)
Public Member Functions inherited from BaseInteraction
	BaseInteraction (BaseInteractable *P, BaseInteractable *I, unsigned timeStamp)
	A constructor takes the BaseInteractable objects which are interacting (come into contact) and time the interaction starts. More...
	BaseInteraction ()
	BaseInteraction (const BaseInteraction &p)
	Copy constructor. More...
	~BaseInteraction () override
	The destructor. It removes this interactions from the objects that were interacting, and writes the time to a file when needed. More...
virtual void	actionsOnErase ()
	If an interaction needs to do something before it gets erased, add it here. E.g. Liquid bridges rupture at the end of their lifetime, and the liquid bridge volume has to be redistributed. The reason this action is not done in the destructor is that this action should not be taken when erasing ghost interactions. More...
virtual void	computeForce ()
	Virtual function that contains the force law between the two objects interacting. More...
void	writeToFStat (std::ostream &os, Mdouble time) const
	Writes forces data to the FStat file. More...
std::string	getName () const override
	Virtual function which allows interactions to be named. More...
void	setDistance (Mdouble distance)
	Sets the interaction distance between the two interacting objects. More...
void	setNormal (Vec3D normal)
	Sets the normal vector between the two interacting objects. More...
void	setOverlap (Mdouble overlap)
	Set the overlap between the two interacting object. More...
void	setContactPoint (Vec3D contactPoint)
	Set the location of the contact point between the two interacting objects. More...
void	setTimeStamp (unsigned timeStamp)
	Updates the time step of the interacting. Note, time steps used to find completed interactions. More...
void	setSpecies (const BaseSpecies *species)
	Set the Species of the interaction; note this can either be a Species or MixedSpecies. More...
void	setP (BaseInteractable *P)
	Sets the first object involved in the interaction (normally a particle). More...
void	setI (BaseInteractable *I)
	Sets the second object involved in the interaction (often particle or wall). More...
void	importP (BaseInteractable *P)
	Sets the first object involved in the interaction (normally a particle). More...
void	importI (BaseInteractable *I)
	Sets the second object involved in the interaction (often particle or wall). More...
Vec3D	getIP () const
Vec3D	getIC () const
Vec3D	getCP () const
void	setLagrangeMultiplier (Mdouble multiplier)
Mdouble	getLagrangeMultiplier ()
void	setHandler (InteractionHandler *handler)
	Sets the pointer to the interaction hander which is storing this interaction. More...
InteractionHandler *	getHandler () const
	Gets a point to the interaction handlers to which this interaction belongs. More...
const Vec3D &	getForce () const
	Gets the current force (vector) between the two interacting objects. More...
const Vec3D &	getTorque () const
	Gets the current torque (vector) between the two interacting objects. More...
const Vec3D &	getNormal () const
	Gets the normal vector between the two interacting objects. More...
const Vec3D &	getContactPoint () const
	Gets constant reference to contact point (vector). More...
Mdouble	getOverlap () const
	Returns a Mdouble with the current overlap between the two interacting objects. More...
Mdouble	getOverlapVolume () const
	Returns the overlap volume between two interacting objects. More...
Mdouble	getContactRadius () const
	Returns a Mdouble with the current contact between the two interacting objects. More...
void	removeFromHandler ()
	Removes this interaction from its interaction hander. More...
void	copySwitchPointer (const BaseInteractable *original, BaseInteractable *ghost) const
	This copies the interactions of the original particle and replaces the original with the ghost copy. More...
void	gatherContactStatistics ()
BaseInteractable *	getP ()
	Returns a pointer to first object involved in the interaction (normally a particle). More...
BaseInteractable *	getI ()
	Returns a pointer to the second object involved in the interaction (often a wall or a particle). More...
const BaseInteractable *	getP () const
	Returns a constant pointer to the first object involved in the interaction. More...
const BaseInteractable *	getI () const
	Returns a constant pointer to the second object involved in the interaction. More...
Mdouble	getTimeStamp () const
	Returns an Mdouble which is the time stamp of the interaction. More...
Mdouble	getDistance () const
	Returns an Mdouble which is the norm (length) of distance vector. More...
const Vec3D &	getRelativeVelocity () const
	Returns a constant reference to a vector of relative velocity. More...
Mdouble	getNormalRelativeVelocity () const
	Returns a double which is the norm (length) of the relative velocity vector. More...
Mdouble	getAbsoluteNormalForce () const
	Returns the absolute value of the norm (length) of the Normal force vector. More...
virtual BaseInteraction *	copy () const =0
	Makes a copy of the interaction and returns a pointer to the copy. More...
void	setFStatData (std::fstream &fstat, BaseParticle *P, BaseWall *I)
void	setFStatData (std::fstream &fstat, BaseParticle *P, BaseParticle *I)
unsigned int	getMultiContactIdentifier () const
void	setMultiContactIdentifier (unsigned int multiContactIdentifier_)
virtual void	actionsAfterTimeStep ()
virtual unsigned	getNumberOfFieldsVTK () const
virtual std::string	getTypeVTK (unsigned i) const
virtual std::string	getNameVTK (unsigned i) const
virtual std::vector< Mdouble >	getFieldVTK (unsigned i) const
void	addForce (Vec3D force)
	add an force increment to the total force. More...
void	addTorque (Vec3D torque)
	add a torque increment to the total torque. More...
void	setForce (Vec3D force)
	set total force (this is used by the normal force, tangential forces are added use addForce) More...
void	setTorque (Vec3D torque)
	set the total force (this is used by the normal force, tangential torques are added use addTorque) More...
const BaseSpecies *	getBaseSpecies () const
	Return a constant point to BaseSpecies of the interaction. More...
virtual void	createMPIType ()
virtual void *	createMPIInteractionDataArray (unsigned int numberOfInteractions) const
virtual void	deleteMPIInteractionDataArray (void *dataArray)
virtual void	getMPIInteraction (void *historyDataArray, unsigned int index) const
	copies the history interactions into the data array More...
virtual void	getInteractionDetails (void *interactionDataArray, unsigned int index, unsigned int &identificationP, unsigned int &identificationI, bool &isWallInteraction, unsigned &timeStamp)
virtual void	setMPIInteraction (void *interactionDataArray, unsigned int index, bool resetPointers)
void	setBasicMPIInteractionValues (int P, int I, unsigned timeStamp, Vec3D force, Vec3D torque, bool isWallInteraction, bool resetPointers)
void	setIdentificationP (unsigned int identification)
void	setIdentificationI (int identification)
void	setWallInteraction (bool flag)
unsigned int	getIdentificationP ()
int	getIdentificationI ()
bool	isWallInteraction ()
virtual bool	isBonded () const
Public Member Functions inherited from BaseObject
	BaseObject ()=default
	Default constructor. More...
	BaseObject (const BaseObject &p)=default
	Copy constructor, copies all the objects BaseObject contains. More...
virtual	~BaseObject ()=default
	virtual destructor More...
virtual void	moveInHandler (unsigned int index)
	Except that it is virtual, it does the same thing as setIndex() does. More...
void	setIndex (unsigned int index)
	Allows one to assign an index to an object in the handler/container. More...
void	setId (unsigned long id)
	Assigns a unique identifier to each object in the handler (container) which remains constant even after the object is deleted from the container/handler. More...
unsigned int	getIndex () const
	Returns the index of the object in the handler. More...
unsigned int	getId () const
	Returns the unique identifier of any particular object. More...
void	setGroupId (unsigned groupId)
unsigned	getGroupId () const

Protected Attributes
Vec3D	slidingSpring_
	Stores the amount of sliding spring ( \(\delta\)) compression from the expression \(f_t=-k*\delta-\nu*relVel\). Set in the member function integrate(), used in computeFrictionForce(). More...
Vec3D	slidingSpringVelocity_
	Stores the rate at which the sliding spring compressed or relaxed. Set in the member function computeFrictionForce() and used in integrate(). More...
Vec3D	tangentialForce_
	Computes the tangential force such that \(|f_t|=\mu*|f_n|\). Set and computed in computeFrictionForce(). More...
bool	isSuperQuadricInteraction_

Additional Inherited Members
Protected Member Functions inherited from BaseInteraction
Mdouble	getEffectiveRadius () const
	Returns a Mdouble to the effective radius of the interaction. (Not corrected for the overlap) More...
Mdouble	getEffectiveMass () const
	Returns a Mdouble to the effective radius of the interaction. (Not corrected for the overlap) More...
void	setRelativeVelocity (Vec3D relativeVelocity)
	set the relative velocity of the current of the interactions. More...
void	setNormalRelativeVelocity (Mdouble normalRelativeVelocit)
	set the normal component of the relative velocity. More...
void	setAbsoluteNormalForce (Mdouble absoluteNormalForce)
	the absolute values of the norm (length) of the normal force More...
virtual Mdouble	getElasticEnergyAtEquilibrium (Mdouble adhesiveForce) const
void	writeInteraction (std::ostream &os, bool created) const
	Writes information about a interaction to the interaction file. More...

Detailed Description

Computes the forces corresponding to sliding friction.

Member Typedef Documentation

SpeciesType

typedef SlidingFrictionSpecies SlidingFrictionInteraction::SpeciesType

An alias name for SlidingFrictionSpecies data type.

Constructor & Destructor Documentation

SlidingFrictionInteraction() [1/3]

SlidingFrictionInteraction::SlidingFrictionInteraction	(	BaseInteractable *	P,
		BaseInteractable *	I,
		unsigned	timeStamp
	)

Constructor.

Parameters

[in]	P
[in]	I
[in]	timeStamp

        : BaseInteraction(P, I, timeStamp)
{
    slidingSpring_.setZero();
    isSuperQuadricInteraction_ = false;
#ifdef DEBUG_CONSTRUCTOR
    std::cout<<"SlidingFrictionInteraction::SlidingFrictionInteraction() finished"<<std::endl;
#endif
}

References isSuperQuadricInteraction_, Vec3D::setZero(), and slidingSpring_.

SlidingFrictionInteraction() [2/3]

SlidingFrictionInteraction::SlidingFrictionInteraction

(

)

        : BaseInteraction()
{
    slidingSpring_.setZero();
    isSuperQuadricInteraction_ = false;
#ifdef DEBUG_CONSTRUCTOR
    std::cout<<"SlidingFrictionInteraction::SlidingFrictionInteraction() finished"<<std::endl;
#endif
}

References isSuperQuadricInteraction_, Vec3D::setZero(), and slidingSpring_.

SlidingFrictionInteraction() [3/3]

SlidingFrictionInteraction::SlidingFrictionInteraction

(

const SlidingFrictionInteraction &

p

)

Copy constructor.

Parameters

[in]

p

        : BaseInteraction(p)
{
    slidingSpring_ = p.slidingSpring_;
    isSuperQuadricInteraction_ = p.isSuperQuadricInteraction_;
#ifdef DEBUG_CONSTRUCTOR
    std::cout<<"SlidingFrictionInteraction::SlidingFrictionInteraction(const SlidingFrictionInteraction& p) finished"<<std::endl;
#endif
}

References isSuperQuadricInteraction_, and slidingSpring_.

~SlidingFrictionInteraction()

SlidingFrictionInteraction::~SlidingFrictionInteraction ( )

override

Destructor.

{
#ifdef DEBUG_DESTRUCTOR
    std::cout<<"SlidingFrictionInteraction::~SlidingFrictionInteraction() finished"<<std::endl;
#endif
}

Member Function Documentation

addTangentialForce()

void SlidingFrictionInteraction::addTangentialForce ( Vec3D  force )

inline

adds an extra tangential force, mainly for the tangential lubrication force from LiquidMigrationLS model.

                                         {
        tangentialForce_ = Vec3D(0.0,0.0,0.0);
        tangentialForce_ += force;
    }

References tangentialForce_.

Referenced by LiquidMigrationLSInteraction::computeAdhesionForce().

computeFrictionForce()

void SlidingFrictionInteraction::computeFrictionForce

(

)

Computes the tangential force generated due to compression in the sliding spring. Does take into account if the interaction is between particle-particle or particle-wall.

{
    //If tangential forces are absent
    if (getAbsoluteNormalForce() == 0.0) return;
    
    const SlidingFrictionSpecies* species = getSpecies();//dynamic_cast
    isSuperQuadricInteraction_ = species->getIsSuperquadricSpecies();
    
    if (species->getSlidingFrictionCoefficient() != 0.0)
    {
        //Compute the tangential component of relativeVelocity_
        // relativeVelocity = [v_p + (r_p-c) x w_p] - [v_i + (r_i-c) x w_i]
        // tangentialRelativeVelocity = relativeVelocity - (relativeVelocity . n) n
        Vec3D tangentialRelativeVelocity = getRelativeVelocity() - getNormal() * getNormalRelativeVelocity();
        
        if (species->getSlidingStiffness() != 0.0)
        {
            if (!isSuperQuadricInteraction_)
            {
                computeSlidingSpring(tangentialRelativeVelocity);
            }
            else
            {
                computeSlidingSpringSuperQuadric(tangentialRelativeVelocity);
            }
            
            //Calculate test force acting on P including viscous force
            tangentialForce_ = -species->getSlidingStiffness() * slidingSpring_ -
                               species->getSlidingDissipation() * tangentialRelativeVelocity;
            if (getBaseSpecies()->getNormalForce()->getConstantRestitution()) tangentialForce_ *=2.0*getEffectiveMass();
            
            //tangential forces are modelled by a spring-damper of elasticity kt and viscosity dispt (sticking),
            //but the force is limited by Coulomb friction (sliding):
            Mdouble tangentialForceSquared = tangentialForce_.getLengthSquared();
            if (tangentialForceSquared <=
                mathsFunc::square(species->getSlidingFrictionCoefficientStatic() * getAbsoluteNormalForce()))
            {
                //if sticking (|ft|<=mu*|fn|), apply the force
                addForce(tangentialForce_);
            }
            else
            {
                //if sliding, resize the tangential force such that |ft|=mu*|fn|
                tangentialForce_ *= species->getSlidingFrictionCoefficient() * getAbsoluteNormalForce() /
                                    std::sqrt(tangentialForceSquared);
                addForce(tangentialForce_);
                //resize the tangential spring accordingly such ft=-k*delta-nu*relVel
                slidingSpring_ = -(tangentialForce_ + species->getSlidingDissipation() * tangentialRelativeVelocity) /
                                 species->getSlidingStiffness();
            }
        }
        else //if no spring stiffness is set
        {
//            if (species->getSlidingDissipation()==0.0)
//            {
//                std::cerr << "SlidingFrictionInteraction::getForce(): warning:  both sliding stiffness and dissipation are zero" << std::endl;
//            }
            Mdouble tangentialRelativeVelocitySquared = tangentialRelativeVelocity.getLengthSquared();
            if (tangentialRelativeVelocitySquared * mathsFunc::square(species->getSlidingDissipation()) <=
                mathsFunc::square(species->getSlidingFrictionCoefficientStatic() * getAbsoluteNormalForce()))
                tangentialForce_ = -species->getSlidingDissipation() * tangentialRelativeVelocity;
            else //if sliding, set force to Coulomb limit
                tangentialForce_ = -(species->getSlidingFrictionCoefficient() * getAbsoluteNormalForce() /
                                     std::sqrt(tangentialRelativeVelocitySquared)) * tangentialRelativeVelocity;
            
            addForce(tangentialForce_);
        }
    }
 
    /* And if species->getSlidingFrictionCoefficient() == 0.0, then there is no
     * friction force at all. */
}

References BaseInteraction::addForce(), computeSlidingSpring(), computeSlidingSpringSuperQuadric(), BaseInteraction::getAbsoluteNormalForce(), BaseInteraction::getBaseSpecies(), BaseInteraction::getEffectiveMass(), SlidingFrictionSpecies::getIsSuperquadricSpecies(), Vec3D::getLengthSquared(), BaseInteraction::getNormal(), BaseInteraction::getNormalRelativeVelocity(), BaseInteraction::getRelativeVelocity(), SlidingFrictionSpecies::getSlidingDissipation(), SlidingFrictionSpecies::getSlidingFrictionCoefficient(), SlidingFrictionSpecies::getSlidingFrictionCoefficientStatic(), SlidingFrictionSpecies::getSlidingStiffness(), getSpecies(), isSuperQuadricInteraction_, slidingSpring_, mathsFunc::square(), and tangentialForce_.

Referenced by FrictionInteraction::computeFrictionForce().

computeSlidingSpring()

void SlidingFrictionInteraction::computeSlidingSpring

(

const Vec3D &

tangentialRelativeVelocity

)

{
    //used to Integrate the spring
    if (dynamic_cast<BaseParticle*>(getI()) == nullptr)  //if particle-wall
    {
        slidingSpringVelocity_ = tangentialRelativeVelocity;
    }
    else //if particle-particle
    {
        slidingSpringVelocity_ = (tangentialRelativeVelocity -
                                  Vec3D::dot(slidingSpring_, getP()->getVelocity() - getI()->getVelocity()) *
                                  getNormal() / getDistance());
    }
    // v_s = v_t - [xi . (v_p-v_i)/|r_pi|] n
    
    
    //integrate(getHandler()->timeStep_);
    // xi = xi' + dt v_s
    slidingSpring_ += slidingSpringVelocity_ * getHandler()->getDPMBase()->getTimeStep();
    // Stefan does [EJECE-12/2008] sth. like xi = xi' - (xi . n) n + dt*v_t, see SlidingFrictionSuperQuadricInteraction
}

References Vec3D::dot(), BaseInteraction::getDistance(), BaseHandler< T >::getDPMBase(), BaseInteraction::getHandler(), BaseInteraction::getI(), BaseInteraction::getNormal(), BaseInteraction::getP(), DPMBase::getTimeStep(), slidingSpring_, and slidingSpringVelocity_.

Referenced by computeFrictionForce().

computeSlidingSpringSuperQuadric()

void SlidingFrictionInteraction::computeSlidingSpringSuperQuadric

(

const Vec3D &

tangentialRelativeVelocity

)

{
    //used to Integrate the spring
    if (dynamic_cast<BaseParticle*>(getI()) == nullptr)  //if particle-wall
    {
        slidingSpringVelocity_ = tangentialRelativeVelocity;
    }
    else //if particle-particle
    {
        slidingSpringVelocity_ = tangentialRelativeVelocity;
    }
    
    // From Stefan [EJECE-12/2008]:
    // xi = xi' - (xi . n) n and renormalising, then add v_t * dt
    logger(DEBUG, "sliding spring, normal before rotation-step: %, %", slidingSpring_, getNormal());
    if (slidingSpring_.getLength() > 1e-10)
    {
        const Mdouble springLength = slidingSpring_.getLength();
        slidingSpring_ -= Vec3D::dot(slidingSpring_, getNormal()) * getNormal();
        slidingSpring_.normalise();
        slidingSpring_ *= springLength;
        logger.assert_debug(std::abs(slidingSpring_.getLength() - springLength) < 1e-10, "Spring length not the same after rotation");
    }
    logger(DEBUG, "sliding spring after rotation-step: %\n", slidingSpring_);
    slidingSpring_ += slidingSpringVelocity_ * getHandler()->getDPMBase()->getTimeStep();
    logger.assert_debug(std::abs(Vec3D::dot(slidingSpring_, getNormal())) < 1e-10, "sliding spring not perpendicular to normal");
}

References DEBUG, Vec3D::dot(), BaseHandler< T >::getDPMBase(), BaseInteraction::getHandler(), BaseInteraction::getI(), Vec3D::getLength(), BaseInteraction::getNormal(), DPMBase::getTimeStep(), logger, Vec3D::normalise(), slidingSpring_, and slidingSpringVelocity_.

Referenced by computeFrictionForce().

getBaseName()

std::string SlidingFrictionInteraction::getBaseName

(

)

const

Returns the type/name of interaction (sliding friction interaction)

Returns

std::string

{
    return "SlidingFriction";
}

getElasticEnergy()

Mdouble SlidingFrictionInteraction::getElasticEnergy ( ) const

overridevirtual

Returns the amount of elastic energy stored in sliding spring.

Returns

Mdouble

Reimplemented from BaseInteraction.

{
    if (getBaseSpecies()->getNormalForce()->getConstantRestitution()) {
        return getEffectiveMass() * getSpecies()->getSlidingStiffness() * slidingSpring_.getLengthSquared();
    } else {
        return 0.5 * getSpecies()->getSlidingStiffness() * slidingSpring_.getLengthSquared();
    }
}

References BaseInteraction::getBaseSpecies(), BaseInteraction::getEffectiveMass(), Vec3D::getLengthSquared(), SlidingFrictionSpecies::getSlidingStiffness(), getSpecies(), and slidingSpring_.

Referenced by FrictionInteraction::getElasticEnergy().

getSlidingSpring()

Vec3D SlidingFrictionInteraction::getSlidingSpring

(

)

const

{
    return slidingSpring_;
}

References slidingSpring_.

getSpecies()

const SlidingFrictionSpecies * SlidingFrictionInteraction::getSpecies

(

)

const

Returns a const pointer of type SlidingFrictionSpecies*.

Returns

const SlidingFrictionSpecies*

{
    return static_cast<const SlidingFrictionSpecies*>(getBaseSpecies()->getFrictionForce());
;
}

References BaseInteraction::getBaseSpecies(), and BaseSpecies::getFrictionForce().

Referenced by computeFrictionForce(), and getElasticEnergy().

getTangentialForce()

const Vec3D SlidingFrictionInteraction::getTangentialForce ( ) const

overridevirtual

Returns the sliding friction force vector.

Returns

const Vec3D

Reimplemented from BaseInteraction.

{
    return tangentialForce_;
}

References tangentialForce_.

Referenced by TwoParticleElasticCollisionInteraction::printTime().

getTangentialOverlap()

Mdouble SlidingFrictionInteraction::getTangentialOverlap ( ) const

overridevirtual

Returns the amount of tangential overlap which is needed by BaseInteraction::writeToFstat().

Returns

Mdouble

Todo:

TWnow this should be positive

Reimplemented from BaseInteraction.

{
    return -slidingSpring_.getLength();
}

References Vec3D::getLength(), and slidingSpring_.

integrate()

void SlidingFrictionInteraction::integrate ( Mdouble timeStep  )

overridevirtual

Increments the amount of compression in sliding spring.

Parameters

[in]

timeStep

the dt

Reimplemented from BaseInteraction.

{
    slidingSpring_ += slidingSpringVelocity_ * timeStep;
}

References slidingSpring_, and slidingSpringVelocity_.

Referenced by FrictionInteraction::integrate().

moveSlidingSpring()

void SlidingFrictionInteraction::moveSlidingSpring

(

Vec3D

displacement

)

{
    slidingSpring_ += displacement;
}

References slidingSpring_.

read()

void SlidingFrictionInteraction::read ( std::istream &  is )

overridevirtual

Interaction read function, which accepts an std::istream as input.

Parameters

[in,out]

is

Reimplemented from BaseInteraction.

{
    //BaseInteraction::read(is);
    std::string dummy;
    is >> dummy >> slidingSpring_;
}

References slidingSpring_.

Referenced by FrictionInteraction::read().

reverseHistory()

void SlidingFrictionInteraction::reverseHistory ( )

overridevirtual

A useful feature if one wants to return to the initial state of the spring. However, reverse history decrements the current state to the state corresponding to previous time step. Decrements the value of slidingSpring_.

Reimplemented from BaseInteraction.

{
    slidingSpring_ = -slidingSpring_;
    slidingSpringVelocity_ = -slidingSpringVelocity_;
    tangentialForce_ = -tangentialForce_;
}

References slidingSpring_, slidingSpringVelocity_, and tangentialForce_.

Referenced by FrictionInteraction::reverseHistory().

rotateHistory()

void SlidingFrictionInteraction::rotateHistory ( Matrix3D &  rotationMatrix )

overridevirtual

When periodic particles are used, some interactions need certain history properties rotated (e.g. tangential springs). This is the function for that.

Todo:

some of these might be unneccesary

Reimplemented from BaseInteraction.

{
    slidingSpring_ = rotationMatrix * slidingSpring_;
    slidingSpringVelocity_ = rotationMatrix * slidingSpringVelocity_;
    tangentialForce_ = rotationMatrix * tangentialForce_;
}

References slidingSpring_, slidingSpringVelocity_, and tangentialForce_.

Referenced by FrictionInteraction::rotateHistory().

setIsSuperQuadricInteraction()

void SlidingFrictionInteraction::setIsSuperQuadricInteraction

(

bool

isSuperQuadricInteraction

)

{
    isSuperQuadricInteraction_ = isSuperQuadricInteraction;
}

References isSuperQuadricInteraction_.

setSlidingSpring()

void SlidingFrictionInteraction::setSlidingSpring

(

Vec3D

slidingSpring

)

Bug:

may need to remove the consts

{
    slidingSpring_ = slidingSpring;
}

References slidingSpring_.

write()

void SlidingFrictionInteraction::write ( std::ostream &  os ) const

overridevirtual

Interaction write function, which accepts an std::ostream as input.

Parameters

[in,out]

os

Reimplemented from BaseInteraction.

{
    //BaseInteraction::write(os);
    os << " slidingSpring " << slidingSpring_;
}

References slidingSpring_.

Referenced by FrictionInteraction::write().

Member Data Documentation

isSuperQuadricInteraction_

bool SlidingFrictionInteraction::isSuperQuadricInteraction_

protected

Referenced by computeFrictionForce(), setIsSuperQuadricInteraction(), and SlidingFrictionInteraction().

slidingSpring_

Vec3D SlidingFrictionInteraction::slidingSpring_

protected

Stores the amount of sliding spring ( \(\delta\)) compression from the expression \(f_t=-k*\delta-\nu*relVel\). Set in the member function integrate(), used in computeFrictionForce().

Referenced by computeFrictionForce(), computeSlidingSpring(), computeSlidingSpringSuperQuadric(), getElasticEnergy(), getSlidingSpring(), getTangentialOverlap(), integrate(), moveSlidingSpring(), read(), reverseHistory(), rotateHistory(), setSlidingSpring(), SlidingFrictionInteraction(), and write().

slidingSpringVelocity_

Vec3D SlidingFrictionInteraction::slidingSpringVelocity_

protected

Stores the rate at which the sliding spring compressed or relaxed. Set in the member function computeFrictionForce() and used in integrate().

Referenced by computeSlidingSpring(), computeSlidingSpringSuperQuadric(), integrate(), reverseHistory(), and rotateHistory().

tangentialForce_

Vec3D SlidingFrictionInteraction::tangentialForce_

protected

Computes the tangential force such that \(|f_t|=\mu*|f_n|\). Set and computed in computeFrictionForce().

Referenced by addTangentialForce(), computeFrictionForce(), getTangentialForce(), reverseHistory(), and rotateHistory().

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

• SlidingFrictionInteraction.h
• SlidingFrictionInteraction.cc