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

#include <MindlinInteraction.h>

Inheritance diagram for MindlinInteraction:

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

Public Member Functions
	MindlinInteraction (BaseInteractable P, BaseInteractable I, unsigned timeStamp)
	Constructor. More...

	MindlinInteraction (const MindlinInteraction &p)
	Copy constructor. More...

	MindlinInteraction ()
	Empty constructor. More...

	~MindlinInteraction () 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...

const Vec3D	getTangentialForce () const override
	Returns the sliding friction force vector. More...

const Mdouble	getTangentialForceDirection () const

Mdouble	getAbsoluteNormalForcePrevious () const
	Returns the absolute value of the norm (length) of the previous Normal force vector. More...

void	setAbsoluteNormalForcePrevious (Mdouble absoluteNormalForcePrevious)
	allows the previous normal force to be (re)set from external classes More...

const MindlinSpecies *	getSpecies () const
	Returns a const pointer of type MindlinSpecies*. 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	setTangentialStiffnessZero (Mdouble newKt0)

Mdouble	getTangentialStiffnessZero ()

Mdouble	getTangentialStiffness ()

void	updateTangentialStiffnessZero (Mdouble rad, double shearMod)

void	updateTangentialStiffnessInitial (Mdouble fric)

void	updateTangentialStiffnessInitial2 (Mdouble fric, Vec3D direction)

void	updateTangentialStiffnessUnloading (Mdouble fric, Vec3D direction)

void	updateTangentialStiffnessReloading (Mdouble fric, Vec3D direction)

void	updateTangentialStiffnessReloadingTanUp (Mdouble fric, Vec3D direction)

void	updateTangentialStiffnessUnloadingTanDown (Mdouble fric, Vec3D direction)

void	updateK_t (Mdouble fric, Vec3D direction, bool useTurningPoint, bool isLoading)

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 \(f_t=-k\delta-\nurelVel\). Set in the member function integrate(), used in computeFrictionForce(). More...

Vec3D	slidingSpringPrevious_

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...

Vec3D	tangentialForcePrevious_

Mdouble	tangentialForceDirection_

Vec3D	tangentialForceTurningPointLU_

Vec3D	tangentialForceTurningPointUL_

Vec3D	tangentialForceTurningPointLUTemp_

Vec3D	tangentialForceTurningPointULTemp_

Vec3D	tangentialDisplacementTurningPointUL_

Vec3D	tangentialDisplacementTurningPointLU_

Mdouble	tangentialStiffnessZero_

Mdouble	tangentialStiffnessZeroPrevious_

Mdouble	tangentialStiffness_

bool	priorLoadingFlag_

Vec3D	tangentialForceTemp_

Vec3D	tangentialDisplacementTemp_

Vec3D	tangentialForceTemp2_

Vec3D	tangentialDisplacementTemp2_

Mdouble	tangentialDisplacementSL_

Vec3D	initialTangentialVelocity_

Mdouble	absoluteNormalForcePrevious_

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 MindlinSpecies MindlinInteraction::SpeciesType

An alias name for MindlinSpecies data type.

Constructor & Destructor Documentation

◆ MindlinInteraction() [1/3]

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

Constructor.

Parameters

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

         : BaseInteraction(P, I, timeStamp)
 {
     slidingSpring_.setZero();
     //k_edit
     //setting the "previousSlidingSpring_" initially to zero, as before a contact
     //this parameter should (obviously) not carry a value.
     slidingSpringPrevious_.setZero();
     //similarly, setting the turning point tangential forces to zero, as a "new"
     //interaction will clearly have no such history
     tangentialForceTurningPointLU_.setZero();
     tangentialForceTurningPointUL_.setZero();
     //k_edit
     //setting the K_t0 parameter by default to zero...
     tangentialStiffnessZero_ = 0;
     //...and its previous value...
     tangentialStiffnessZeroPrevious_ = 0;
     
     absoluteNormalForcePrevious_ = 0;
     //k_edit
     //...and, similarly, the "normal" tangential stiffness, K_t
     tangentialStiffness_ = 0;
     //k_edit
     //setting the tangential force direction by default to -1 (i.e. acting against the motion!)
     tangentialForceDirection_ = -1;
     //k_edit
     //setting to zero the temporary 'holders' which store intermediate values of tangential force
     //and displacement during multiple-step force calculations
     tangentialForceTemp_.setZero();
     tangentialForceTemp2_.setZero();
     tangentialDisplacementTemp_.setZero();
     tangentialDisplacementTemp2_.setZero();
     //Similarly for temporary turning point force values...
     tangentialForceTurningPointLUTemp_.setZero();
     tangentialForceTurningPointULTemp_.setZero();
     //...and the turning point displacement values
     tangentialDisplacementTurningPointUL_.setZero();
     tangentialDisplacementTurningPointLU_.setZero();
     //k_edit
     //setting the variable which stores the minimum displacement for simple loading to zero
     tangentialDisplacementSL_ = 0;
     //k_edit
     //setting the priorLoadingFlag to zero as, when an interaction is created for the first time,
     //there will, by definition, have been no prior loading
     priorLoadingFlag_ = false;
     //ensuring that the initial tangential velocity of a new interaction is zero until updated
     initialTangentialVelocity_.setZero();
  
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"MindlinInteraction::MindlinInteraction() finished"<<std::endl;
 #endif
 }

References absoluteNormalForcePrevious_, initialTangentialVelocity_, priorLoadingFlag_, Vec3D::setZero(), slidingSpring_, slidingSpringPrevious_, tangentialDisplacementSL_, tangentialDisplacementTemp2_, tangentialDisplacementTemp_, tangentialDisplacementTurningPointLU_, tangentialDisplacementTurningPointUL_, tangentialForceDirection_, tangentialForceTemp2_, tangentialForceTemp_, tangentialForceTurningPointLU_, tangentialForceTurningPointLUTemp_, tangentialForceTurningPointUL_, tangentialForceTurningPointULTemp_, tangentialStiffness_, tangentialStiffnessZero_, and tangentialStiffnessZeroPrevious_.

◆ MindlinInteraction() [2/3]

MindlinInteraction::MindlinInteraction ( const MindlinInteraction & p )

Copy constructor.

Parameters

[in] p

         : BaseInteraction(p)
 {
     slidingSpring_ = p.slidingSpring_;
     //k_edit
     //setting the K_t0 parameter to that possessed by the interaction
     //to be copied....
     tangentialStiffnessZero_ = p.tangentialStiffnessZero_;
     //...and its previous value...
     tangentialStiffnessZeroPrevious_ = p.tangentialStiffnessZeroPrevious_;
     //...and the same for the "normal" tangential stiffness parameter
     tangentialStiffness_ = p.tangentialStiffness_;
     //k_edit
     //allowing turning point forces to be copied when an interaction is copied
     tangentialForceTurningPointLU_ = p.tangentialForceTurningPointLU_;
     tangentialForceTurningPointUL_ = p.tangentialForceTurningPointUL_;
     //k_edit
     //allowing the direction of the tangential force to be "remembered" also
     //by the copied interaction
     tangentialForceDirection_ = p.tangentialForceDirection_;
     //k_edit
     //copying the temporary 'holders' which store intermediate values of tangential force
     //and displacement during multiple-step force calculations
     tangentialForceTemp_ = p.tangentialForceTemp_;
     tangentialForceTemp2_ = p.tangentialForceTemp2_;
     tangentialDisplacementTemp_ = p.tangentialDisplacementTemp_;
     tangentialDisplacementTemp2_ = p.tangentialDisplacementTemp2_;
     //and similarly for the temporary turning point variables
     tangentialForceTurningPointLUTemp_ = p.tangentialForceTurningPointLUTemp_;
     tangentialForceTurningPointULTemp_ = p.tangentialForceTurningPointULTemp_;
     //...and the displacement equivalents
     tangentialDisplacementTurningPointUL_ = p.tangentialDisplacementTurningPointUL_;
     tangentialDisplacementTurningPointLU_ = p.tangentialDisplacementTurningPointLU_;
     //k_edit
     //copying the variable which stores the minimum displacement for simple loading
     tangentialDisplacementSL_ = p.tangentialDisplacementSL_;
     //k_edit
     priorLoadingFlag_ = p.priorLoadingFlag_;
     //copying the initial tangential velocity
     initialTangentialVelocity_ = p.initialTangentialVelocity_;
     
     absoluteNormalForcePrevious_ = p.absoluteNormalForcePrevious_;
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"MindlinInteraction::MindlinInteraction(const MindlinInteraction& p) finished"<<std::endl;
 #endif
 }

References absoluteNormalForcePrevious_, initialTangentialVelocity_, priorLoadingFlag_, slidingSpring_, tangentialDisplacementSL_, tangentialDisplacementTemp2_, tangentialDisplacementTemp_, tangentialDisplacementTurningPointLU_, tangentialDisplacementTurningPointUL_, tangentialForceDirection_, tangentialForceTemp2_, tangentialForceTemp_, tangentialForceTurningPointLU_, tangentialForceTurningPointLUTemp_, tangentialForceTurningPointUL_, tangentialForceTurningPointULTemp_, tangentialStiffness_, tangentialStiffnessZero_, and tangentialStiffnessZeroPrevious_.

◆ MindlinInteraction() [3/3]

MindlinInteraction::MindlinInteraction ( )

Empty constructor.

 {
     //I don't see why we are restricted in the use of interactions
 //#ifdef MERCURYDPM_USE_MPI
 //    logger(FATAL,"MindlinInteractions are currently not implemented in parallel MercuryDPM");
 //#endif
 }

◆ ~MindlinInteraction()

MindlinInteraction::~MindlinInteraction ( )

override

Destructor.

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

Member Function Documentation

◆ computeFrictionForce()

void MindlinInteraction::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 MindlinSpecies* species = getSpecies();//dynamic_cast
     
     //Checking if the relevant particle species has a non-zero friction coefficient
     if (species->getSlidingFrictionCoefficient() != 0.0)
     {
         //Compute the tangential component of relativeVelocity_
         Vec3D tangentialRelativeVelocity = getRelativeVelocity() - getNormal() * getNormalRelativeVelocity();
         {
             // *************************************************************************************************************************
             // **********************************************GENERAL CALCULATIONS*******************************************************
             // *************************************************************************************************************************
             //used to Integrate the spring
             //Calculating the tangential spring using Luding, S. (2008) eq. (17)
             const Mdouble springLength = slidingSpring_.getLength();
             if (springLength > 1e-10)
             {
                 slidingSpring_ -= Vec3D::dot(slidingSpring_, getNormal()) * getNormal();
                 slidingSpring_ *= springLength / slidingSpring_.getLength();
                 // logger.assert(std::abs(slidingSpring_.getLength() - springLength) < 1e-10, "Spring length not the same after rotation");
             }
  
             //integrate(getHandler()->timeStep_);
             slidingSpringVelocity_ = tangentialRelativeVelocity;
             slidingSpring_ += slidingSpringVelocity_ * getHandler()->getDPMBase()->getTimeStep();
             //logger(INFO,"slidingSpring.normalDirection %",Vec3D::dot(slidingSpring_/slidingSpring_.getLength(),getNormal()));
  
             //1) Calculating the current value of K_t0
             //This is identical for both unloading and loading (under constant normal force) and hence can
             //potentially later be moved for neatness/efficiency
             Mdouble r1 = 1.0 * getEffectiveRadius();
             Mdouble shearModulus = species->getEffectiveShearModulus();
             updateTangentialStiffnessZero(r1, shearModulus);
             
             //2) Calculating the relevant tangential dissipation constant based on the current stiffness (and other relevant parameters)
             Mdouble slidingDissipationCoefficient =
                     species->getSlidingDissipation() * sqrt(getEffectiveMass() * tangentialStiffnessZero_);
             
             //3) Using the parameters determined above, calculating the tangential force as per Di Maio and Di Renzo eqn. (37)
             tangentialForce_ = - 2.0/3.0 * tangentialStiffnessZero_ * slidingSpring_;
             
             //applying the Coulomb criterion (Di Maio and Di Renzo eqn. (36)) to ensure falsely large tangential forces are avoided
             //if all is OK, i.e. if tangential force is smaller than mu*f_n, we simply add the tangential force calculated.
             if (tangentialForce_.getLength() < (species->getSlidingFrictionCoefficient() * getAbsoluteNormalForce()))
             {
                 tangentialForce_ -= slidingDissipationCoefficient * tangentialRelativeVelocity;
                 addForce(tangentialForce_);
             }
                 //otherwise, we take the force as mu*f_n and recalculate the spring length accordingly
             else
             {
                 tangentialForce_ *= species->getSlidingFrictionCoefficient() * getAbsoluteNormalForce() /
                                     tangentialForce_.getLength();
                 //adding the force as mu*f_n
                 addForce(tangentialForce_);
                 //updating the spring length accordingly
                 slidingSpring_ = -(tangentialForce_ / (2.0/3.0 * tangentialStiffnessZero_));
             }
         }
     }
     slidingSpringPrevious_ = slidingSpring_;
 }

References BaseInteraction::addForce(), Vec3D::dot(), BaseInteraction::getAbsoluteNormalForce(), BaseHandler< T >::getDPMBase(), BaseInteraction::getEffectiveMass(), BaseInteraction::getEffectiveRadius(), MindlinSpecies::getEffectiveShearModulus(), BaseInteraction::getHandler(), Vec3D::getLength(), BaseInteraction::getNormal(), BaseInteraction::getNormalRelativeVelocity(), BaseInteraction::getRelativeVelocity(), MindlinSpecies::getSlidingDissipation(), MindlinSpecies::getSlidingFrictionCoefficient(), getSpecies(), DPMBase::getTimeStep(), slidingSpring_, slidingSpringPrevious_, slidingSpringVelocity_, tangentialForce_, tangentialStiffnessZero_, and updateTangentialStiffnessZero().

Referenced by MindlinRollingTorsionInteraction::computeFrictionForce().

◆ getAbsoluteNormalForcePrevious()

Mdouble MindlinInteraction::getAbsoluteNormalForcePrevious ( ) const

Returns the absolute value of the norm (length) of the previous Normal force vector.

Return the absolute normal force. This is the magnitude of the normal force.

Todo:: Ant: Check this comment.

Returns: Mdouble that contains the absolute norm (length) of the normal force.

 {
     return absoluteNormalForcePrevious_;
 }

References absoluteNormalForcePrevious_.

◆ getBaseName()

std::string MindlinInteraction::getBaseName ( ) const

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

Returns: std::string

 {
     return "Mindlin";
 }

◆ getElasticEnergy()

Mdouble MindlinInteraction::getElasticEnergy ( ) const

overridevirtual

Returns the amount of elastic energy stored in sliding spring.

Returns: Mdouble

Reimplemented from BaseInteraction.

Reimplemented in MindlinRollingTorsionInteraction.

 {
     
     //new_edit replacing outdated 'getSlidingStiffness()'
     //return 0.5 * getSpecies()->getSlidingStiffness() * slidingSpring_.getLengthSquared();
     return 0.5 * tangentialStiffness_ * slidingSpring_.getLengthSquared();
 }

References Vec3D::getLengthSquared(), slidingSpring_, and tangentialStiffness_.

Referenced by MindlinRollingTorsionInteraction::getElasticEnergy().

◆ getSpecies()

const MindlinSpecies * MindlinInteraction::getSpecies ( ) const

Returns a const pointer of type MindlinSpecies*.

Returns: const MindlinSpecies*

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

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

Referenced by computeFrictionForce().

◆ getTangentialForce()

const Vec3D MindlinInteraction::getTangentialForce ( ) const

overridevirtual

Returns the sliding friction force vector.

Returns: const Vec3D

Reimplemented from BaseInteraction.

 {
     return tangentialForce_;
 }

References tangentialForce_.

◆ getTangentialForceDirection()

const Mdouble MindlinInteraction::getTangentialForceDirection ( ) const

 {
     return tangentialForceDirection_;
 }

References tangentialForceDirection_.

◆ getTangentialOverlap()

Mdouble MindlinInteraction::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.

 {
     //k_edit Indeed it should - todo done :)
     //k_edit
     //Updating sliding spring to give positive / negative values dependent on the direction of the extension
     return slidingSpring_.getLength() * Vec3D::dot(Vec3D::getUnitVector(slidingSpring_), Vec3D(1.0, 1.0, 1.0));
 }

References Vec3D::dot(), Vec3D::getLength(), Vec3D::getUnitVector(), and slidingSpring_.

◆ getTangentialStiffness()

Mdouble MindlinInteraction::getTangentialStiffness ( )

 {
     return tangentialStiffness_;
 }

References tangentialStiffness_.

◆ getTangentialStiffnessZero()

Mdouble MindlinInteraction::getTangentialStiffnessZero ( )

 {
     return tangentialStiffnessZero_;
 }

References tangentialStiffnessZero_.

◆ integrate()

void MindlinInteraction::integrate ( Mdouble timeStep )

overridevirtual

Increments the amount of compression in sliding spring.

Parameters

[in] timeStep the dt

Reimplemented from BaseInteraction.

Reimplemented in MindlinRollingTorsionInteraction.

 {
     slidingSpring_ += slidingSpringVelocity_ * timeStep;
 }

References slidingSpring_, and slidingSpringVelocity_.

Referenced by MindlinRollingTorsionInteraction::integrate().

◆ read()

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

overridevirtual

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

Parameters

[in,out] is

Reimplemented from BaseInteraction.

Reimplemented in MindlinRollingTorsionInteraction.

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

References slidingSpring_.

Referenced by MindlinRollingTorsionInteraction::read().

◆ reverseHistory()

void MindlinInteraction::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.

Reimplemented in MindlinRollingTorsionInteraction.

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

References slidingSpring_, slidingSpringVelocity_, and tangentialForce_.

Referenced by MindlinRollingTorsionInteraction::reverseHistory().

◆ rotateHistory()

void MindlinInteraction::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.

Reimplemented in MindlinRollingTorsionInteraction.

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

References slidingSpring_, slidingSpringVelocity_, and tangentialForce_.

Referenced by MindlinRollingTorsionInteraction::rotateHistory().

◆ setAbsoluteNormalForcePrevious()

void MindlinInteraction::setAbsoluteNormalForcePrevious ( Mdouble absoluteNormalForcePrevious )

allows the previous normal force to be (re)set from external classes

set absolute normal force.

Parameters

[in] absoluteNormalForce Mdouble contain the value of the absolute normal force.

 {
     absoluteNormalForcePrevious_ = absoluteNormalForcePrevious;
 }

References absoluteNormalForcePrevious_.

◆ setTangentialStiffnessZero()

void MindlinInteraction::setTangentialStiffnessZero ( Mdouble newKt0 )

 {
     tangentialStiffnessZero_ = newKt0;
 }

References tangentialStiffnessZero_.

◆ updateK_t()

void MindlinInteraction::updateK_t	(	Mdouble	fric,
		Vec3D	direction,
		bool	useTurningPoint,
		bool	isLoading
	)

 {
     //creating a simple positive or negative integer 'multiplier', m, whose values are either +1 or -1
     //that can be used to alter the relevant equations depending on if we are loading or unloading
     Mdouble m;
     //A parameter to temporarily hold the relevant turning point so that this function can work both for
     //loading and loading.
     Vec3D turningPoint;
     //Changing the directions and turning points used in calculation depending on if we are loading or unloading
     if (isLoading)
     {
         m = 1;
         turningPoint = tangentialForceTurningPointUL_;
     }
     else
     {
         m = -1;
         turningPoint = tangentialForceTurningPointLU_;
     }
     //if the current part of the interaction can be treated as a virgin loading
     //(i.e. the turning point can be ignored), we simply update K_t in the 'standard' manner
     if (!useTurningPoint)
     {
         //determining the direction of the current tangential force relative to the
         //current direction of motion
         Mdouble forceDirection = Vec3D::dot(Vec3D::getUnitVector(tangentialForceTemp_), direction);
         //finding the scalar ratio f_t1 / (mu f_n1)
         //(note for a first loading f_t1 is simply equal to f_t, and similarly f_n1 f_n = const
         Mdouble forceRatio = tangentialForceTemp_.getLength() / (fric * getAbsoluteNormalForce());
         //changing the direction of the force ratio, if necessary, based on its relative orientation
         //with respect to the current tangential motion.
         if (forceDirection < 0)
             forceRatio = -forceRatio;
         //using the scalar ratio to update tangential stiffness
         tangentialStiffness_ = tangentialStiffnessZero_ * cbrt(1 - forceRatio);
     }
         //alternatively, if we are reloading and within the limits where the turning point force must be considered
     else
     {
         Vec3D resultantForce = m * (tangentialForceTemp_ - turningPoint);
         //QUESTION: Does it make sense to use the total force here? Or should I just use the tangentialForceTemp?
         Mdouble forceDirection = Vec3D::dot(Vec3D::getUnitVector(resultantForce), direction);
         Mdouble forceRatio = resultantForce.getLength() / (2 * fric * getAbsoluteNormalForce());
         //changing the direction of the force ratio, if necessary, based on its relative orientation
         //with respect to the current tangential motion.
         if (forceDirection < 0)
             forceRatio = -forceRatio;
         //using the scalar ratio to update tangential stiffness
         tangentialStiffness_ = tangentialStiffnessZero_ * cbrt(1 - m * forceRatio);
     }
 }

References Vec3D::dot(), BaseInteraction::getAbsoluteNormalForce(), Vec3D::getLength(), Vec3D::getUnitVector(), tangentialForceTemp_, tangentialForceTurningPointLU_, tangentialForceTurningPointUL_, tangentialStiffness_, and tangentialStiffnessZero_.

◆ updateTangentialStiffnessInitial()

void MindlinInteraction::updateTangentialStiffnessInitial ( Mdouble fric )

◆ updateTangentialStiffnessInitial2()

void MindlinInteraction::updateTangentialStiffnessInitial2	(	Mdouble	fric,
		Vec3D	direction
	)

◆ updateTangentialStiffnessReloading()

void MindlinInteraction::updateTangentialStiffnessReloading	(	Mdouble	fric,
		Vec3D	direction
	)

◆ updateTangentialStiffnessReloadingTanUp()

void MindlinInteraction::updateTangentialStiffnessReloadingTanUp	(	Mdouble	fric,
		Vec3D	direction
	)

◆ updateTangentialStiffnessUnloading()

void MindlinInteraction::updateTangentialStiffnessUnloading	(	Mdouble	fric,
		Vec3D	direction
	)

◆ updateTangentialStiffnessUnloadingTanDown()

void MindlinInteraction::updateTangentialStiffnessUnloadingTanDown	(	Mdouble	fric,
		Vec3D	direction
	)

◆ updateTangentialStiffnessZero()

void MindlinInteraction::updateTangentialStiffnessZero	(	Mdouble	rad,
		double	shearMod
	)

 {
     //K_t0 = 8G_eq * sqrt(R_eq * delta_n) (Di Renzo and Di Maio)
     tangentialStiffnessZero_ = 8 * shearMod * sqrt(rad * getOverlap());
 }

References BaseInteraction::getOverlap(), and tangentialStiffnessZero_.

Referenced by computeFrictionForce().

◆ write()

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

overridevirtual

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

Parameters

[in,out] os

Reimplemented from BaseInteraction.

Reimplemented in MindlinRollingTorsionInteraction.

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

References slidingSpring_.

Referenced by MindlinRollingTorsionInteraction::write().

Member Data Documentation

◆ absoluteNormalForcePrevious_

Mdouble MindlinInteraction::absoluteNormalForcePrevious_

protected

Referenced by getAbsoluteNormalForcePrevious(), MindlinInteraction(), and setAbsoluteNormalForcePrevious().

◆ initialTangentialVelocity_

Vec3D MindlinInteraction::initialTangentialVelocity_

protected

Referenced by MindlinInteraction().

◆ priorLoadingFlag_

bool MindlinInteraction::priorLoadingFlag_

protected

Referenced by MindlinInteraction().

◆ slidingSpring_

Vec3D MindlinInteraction::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(), getElasticEnergy(), getTangentialOverlap(), integrate(), MindlinInteraction(), read(), reverseHistory(), rotateHistory(), and write().

◆ slidingSpringPrevious_

Vec3D MindlinInteraction::slidingSpringPrevious_

protected

Referenced by computeFrictionForce(), and MindlinInteraction().

◆ slidingSpringVelocity_

Vec3D MindlinInteraction::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 computeFrictionForce(), integrate(), reverseHistory(), and rotateHistory().

◆ tangentialDisplacementSL_

Mdouble MindlinInteraction::tangentialDisplacementSL_

protected

Referenced by MindlinInteraction().

◆ tangentialDisplacementTemp2_

Vec3D MindlinInteraction::tangentialDisplacementTemp2_

protected

Referenced by MindlinInteraction().

◆ tangentialDisplacementTemp_

Vec3D MindlinInteraction::tangentialDisplacementTemp_

protected

Referenced by MindlinInteraction().

◆ tangentialDisplacementTurningPointLU_

Vec3D MindlinInteraction::tangentialDisplacementTurningPointLU_

protected

Referenced by MindlinInteraction().

◆ tangentialDisplacementTurningPointUL_

Vec3D MindlinInteraction::tangentialDisplacementTurningPointUL_

protected

Referenced by MindlinInteraction().

◆ tangentialForce_

Vec3D MindlinInteraction::tangentialForce_

protected

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

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

◆ tangentialForceDirection_

Mdouble MindlinInteraction::tangentialForceDirection_

protected

Referenced by getTangentialForceDirection(), and MindlinInteraction().

◆ tangentialForcePrevious_

Vec3D MindlinInteraction::tangentialForcePrevious_

protected

◆ tangentialForceTemp2_

Vec3D MindlinInteraction::tangentialForceTemp2_

protected

Referenced by MindlinInteraction().

◆ tangentialForceTemp_

Vec3D MindlinInteraction::tangentialForceTemp_

protected

Referenced by MindlinInteraction(), and updateK_t().

◆ tangentialForceTurningPointLU_

Vec3D MindlinInteraction::tangentialForceTurningPointLU_

protected

Referenced by MindlinInteraction(), and updateK_t().

◆ tangentialForceTurningPointLUTemp_

Vec3D MindlinInteraction::tangentialForceTurningPointLUTemp_

protected

Referenced by MindlinInteraction().

◆ tangentialForceTurningPointUL_

Vec3D MindlinInteraction::tangentialForceTurningPointUL_

protected

Referenced by MindlinInteraction(), and updateK_t().

◆ tangentialForceTurningPointULTemp_

Vec3D MindlinInteraction::tangentialForceTurningPointULTemp_

protected

Referenced by MindlinInteraction().

◆ tangentialStiffness_

Mdouble MindlinInteraction::tangentialStiffness_

protected

Referenced by getElasticEnergy(), getTangentialStiffness(), MindlinInteraction(), and updateK_t().

◆ tangentialStiffnessZero_

Mdouble MindlinInteraction::tangentialStiffnessZero_

protected

Referenced by computeFrictionForce(), MindlinRollingTorsionInteraction::computeFrictionForce(), MindlinRollingTorsionInteraction::getElasticEnergy(), getTangentialStiffnessZero(), MindlinInteraction(), setTangentialStiffnessZero(), updateK_t(), and updateTangentialStiffnessZero().

◆ tangentialStiffnessZeroPrevious_

Mdouble MindlinInteraction::tangentialStiffnessZeroPrevious_

protected

Referenced by MindlinInteraction().

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

Public Types

Public Member Functions

Protected Attributes

Additional Inherited Members

Detailed Description

Member Typedef Documentation

◆ SpeciesType

Constructor & Destructor Documentation

◆ MindlinInteraction() [1/3]

◆ MindlinInteraction() [2/3]

◆ MindlinInteraction() [3/3]

◆ ~MindlinInteraction()

Member Function Documentation

◆ computeFrictionForce()

◆ getAbsoluteNormalForcePrevious()

◆ getBaseName()

◆ getElasticEnergy()

◆ getSpecies()

◆ getTangentialForce()

◆ getTangentialForceDirection()

◆ getTangentialOverlap()

◆ getTangentialStiffness()

◆ getTangentialStiffnessZero()

◆ integrate()

◆ read()

◆ reverseHistory()

◆ rotateHistory()

◆ setAbsoluteNormalForcePrevious()

◆ setTangentialStiffnessZero()

◆ updateK_t()

◆ updateTangentialStiffnessInitial()

◆ updateTangentialStiffnessInitial2()

◆ updateTangentialStiffnessReloading()

◆ updateTangentialStiffnessReloadingTanUp()

◆ updateTangentialStiffnessUnloading()

◆ updateTangentialStiffnessUnloadingTanDown()

◆ updateTangentialStiffnessZero()

◆ write()

Member Data Documentation

◆ absoluteNormalForcePrevious_

◆ initialTangentialVelocity_

◆ priorLoadingFlag_

◆ slidingSpring_

◆ slidingSpringPrevious_

◆ slidingSpringVelocity_

◆ tangentialDisplacementSL_

◆ tangentialDisplacementTemp2_

◆ tangentialDisplacementTemp_

◆ tangentialDisplacementTurningPointLU_

◆ tangentialDisplacementTurningPointUL_

◆ tangentialForce_

◆ tangentialForceDirection_

◆ tangentialForcePrevious_

◆ tangentialForceTemp2_

◆ tangentialForceTemp_

◆ tangentialForceTurningPointLU_

◆ tangentialForceTurningPointLUTemp_

◆ tangentialForceTurningPointUL_

◆ tangentialForceTurningPointULTemp_

◆ tangentialStiffness_

◆ tangentialStiffnessZero_

◆ tangentialStiffnessZeroPrevious_