LinearPlasticViscoelasticNormalSpecies contains the parameters used to describe a plastic-cohesive normal force (Stefan Ludings plastic-cohesive force model). More...

#include <LinearPlasticViscoelasticNormalSpecies.h>

Inheritance diagram for LinearPlasticViscoelasticNormalSpecies:

Public Types
typedef LinearPlasticViscoelasticInteraction	InteractionType
	The correct Interaction type for this FrictionForceSpecies. More...

Public Member Functions
	LinearPlasticViscoelasticNormalSpecies ()
	The default constructor. More...

	LinearPlasticViscoelasticNormalSpecies (const LinearPlasticViscoelasticNormalSpecies &p)
	The default copy constructor. More...

virtual	~LinearPlasticViscoelasticNormalSpecies ()
	The default destructor. More...

void	read (std::istream &is)
	Reads the species properties from an input stream. More...

void	write (std::ostream &os) const
	Writes the species properties to an output stream. More...

std::string	getBaseName () const
	Used in Species::getName to obtain a unique name for each Species. More...

void	mix (LinearPlasticViscoelasticNormalSpecies const S, LinearPlasticViscoelasticNormalSpecies const T)
	creates default values for mixed species More...

void	setCollisionTimeAndRestitutionCoefficient (Mdouble tc, Mdouble eps, Mdouble mass)
	Set k, disp such that is matches a given tc and eps for a collision of two different masses. More...

void	setStiffnessAndRestitutionCoefficient (Mdouble k_, Mdouble eps, Mdouble mass)
	Sets k, disp such that it matches a given tc and eps for a collision of two copies of P. More...

Mdouble	getCollisionTime (Mdouble mass)
	Calculates collision time for two copies of a particle of given disp, k, mass. More...

void	setPlasticParameters (Mdouble loadingStiffness, Mdouble unloadingStiffnessMax, Mdouble cohesionStiffness, Mdouble penetrationDepthMax)
	Sets all parameters of the linear plastic-viscoelastic normal force at once. More...

Mdouble	getLoadingStiffness () const
	Returns the loading stiffness of the linear plastic-viscoelastic normal force. More...

Mdouble	getUnloadingStiffnessMax () const
	Returns the maximum unloading stiffness of the linear plastic-viscoelastic normal force. More...

Mdouble	getCohesionStiffness () const
	Returns the cohesive stiffness of the linear plastic-viscoelastic normal force. More...

Mdouble	getPenetrationDepthMax () const
	Returns the maximum penetration depth of the linear plastic-viscoelastic normal force. More...

void	setLoadingStiffness (Mdouble loadingStiffness)
	Sets the loading stiffness of the linear plastic-viscoelastic normal force. More...

void	setUnloadingStiffnessMax (Mdouble unloadingStiffnessMax)
	Sets the maximum unloading stiffness of the linear plastic-viscoelastic normal force. More...

void	setCohesionStiffness (Mdouble cohesionStiffness)
	Sets the cohesive stiffness of the linear plastic-viscoelastic normal force. More...

void	setPenetrationDepthMax (Mdouble penetrationDepthMax)
	Sets the maximum penetration depth of the linear plastic-viscoelastic normal force. More...

void	setDissipation (Mdouble dissipation)
	Sets the linear dissipation coefficient of the linear plastic-viscoelastic normal force. More...

MERCURY_DEPRECATED void	setLoadingStiffnessAndDissipation (helpers::KAndDisp new_)
	Allows the spring and dissipation constants to be changed simultaneously. More...

Mdouble	computeTimeStep (Mdouble mass)
	Returns the optimal time step to resolve a collision of two particles of a given mass. More...

Mdouble	getDissipation () const
	Allows the normal dissipation to be accessed. More...

Public Member Functions inherited from BaseSpecies
	BaseSpecies ()
	The default constructor. More...

	BaseSpecies (const BaseSpecies &p)
	The copy constructor. More...

virtual	~BaseSpecies ()
	The default destructor. More...

virtual BaseSpecies *	copy () const =0
	Creates a deep copy of the object from which it is called. More...

void	setHandler (SpeciesHandler *handler)
	Sets the pointer to the handler to which this species belongs. More...

SpeciesHandler *	getHandler () const
	Returns the pointer to the handler to which this species belongs. More...

Mdouble	average (Mdouble a, Mdouble b)
	defines the average of two variables by the harmonic mean. More...

virtual void	mixAll (BaseSpecies const S, BaseSpecies const T)=0
	creates default values for mixed species More...

virtual Mdouble	getInteractionDistance () const =0
	returns the largest separation distance at which adhesive short-range forces can occur. More...

virtual bool	getUseAngularDOFs () const =0
	Returns true if torques (i.e. angular degrees of freedom) have to be calculated. More...

virtual BaseInteraction *	getNewInteraction (BaseInteractable P, BaseInteractable I, Mdouble timeStamp) const =0
	returns new Interaction object. More...

Public Member Functions inherited from BaseObject
	BaseObject ()
	Default constructor. More...

	BaseObject (const BaseObject &p)
	Copy constructor, copies all the objects BaseObject contains. More...

virtual	~BaseObject ()
	virtual destructor More...

virtual std::string	getName () const =0
	A purely virtual function. More...

virtual void	moveInHandler (const unsigned int index)
	Except that it is virtual, it does the same thing as setIndex() does. More...

void	setIndex (const unsigned int index)
	Allows one to assign an index to an object in the handler/container. More...

void	setId (const unsigned int 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...

Private Attributes
Mdouble	loadingStiffness_
	(normal) spring constant (k_1) More...

Mdouble	unloadingStiffnessMax_
	the maximum elastic constant (k_2^max) for plastic deformations More...

Mdouble	cohesionStiffness_
	the adhesive spring constant (k^c) for plastic deformations More...

Mdouble	penetrationDepthMax_
	the depth (relative to the normalized radius) at which k_2^max is used (phi_f) More...

Mdouble	dissipation_
	linear dissipation coefficient More...

Detailed Description

LinearPlasticViscoelasticNormalSpecies contains the parameters used to describe a plastic-cohesive normal force (Stefan Ludings plastic-cohesive force model).

See LinearPlasticViscoelasticNormalInteraction::computeForce for a description of the force law.

Definition at line 36 of file LinearPlasticViscoelasticNormalSpecies.h.

Member Typedef Documentation

typedef LinearPlasticViscoelasticInteraction LinearPlasticViscoelasticNormalSpecies::InteractionType

The correct Interaction type for this FrictionForceSpecies.

Definition at line 40 of file LinearPlasticViscoelasticNormalSpecies.h.

Constructor & Destructor Documentation

LinearPlasticViscoelasticNormalSpecies::LinearPlasticViscoelasticNormalSpecies ( )

The default constructor.

Definition at line 33 of file LinearPlasticViscoelasticNormalSpecies.cc.

References cohesionStiffness_, dissipation_, loadingStiffness_, penetrationDepthMax_, and unloadingStiffnessMax_.

 {
     loadingStiffness_ = 0.0;
     unloadingStiffnessMax_ = 0.0;
     cohesionStiffness_ = 0.0;
     penetrationDepthMax_ = 0.0;
     dissipation_ = 0.0;
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"LinearPlasticViscoelasticNormalSpecies::LinearPlasticViscoelasticNormalSpecies() finished"<<std::endl;
 #endif
 }

LinearPlasticViscoelasticNormalSpecies::LinearPlasticViscoelasticNormalSpecies ( const LinearPlasticViscoelasticNormalSpecies & p )

The default copy constructor.

Parameters

[in] the species that is copied

Definition at line 48 of file LinearPlasticViscoelasticNormalSpecies.cc.

References cohesionStiffness_, dissipation_, loadingStiffness_, penetrationDepthMax_, and unloadingStiffnessMax_.

 {
     loadingStiffness_ = p.loadingStiffness_;
     unloadingStiffnessMax_ = p.unloadingStiffnessMax_;
     cohesionStiffness_ = p.cohesionStiffness_;
     penetrationDepthMax_ = p.penetrationDepthMax_;
     dissipation_ = p.dissipation_;
 #ifdef DEBUG_CONSTRUCTOR
     std::cout<<"LinearPlasticViscoelasticNormalSpecies::LinearPlasticViscoelasticNormalSpecies(const LinearPlasticViscoelasticNormalSpecies &p) finished"<<std::endl;
 #endif
 }

LinearPlasticViscoelasticNormalSpecies::~LinearPlasticViscoelasticNormalSpecies ( )

virtual

The default destructor.

Definition at line 60 of file LinearPlasticViscoelasticNormalSpecies.cc.

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

Member Function Documentation

Mdouble LinearPlasticViscoelasticNormalSpecies::computeTimeStep ( Mdouble mass )

Returns the optimal time step to resolve a collision of two particles of a given mass.

Calculates collision time for stiffest spring constant, divides by 50

Parameters

[in] the optimal time step is computed to resolve a collision of two particles of this mass.

Definition at line 201 of file LinearPlasticViscoelasticNormalSpecies.cc.

References dissipation_, constants::pi, mathsFunc::square(), and unloadingStiffnessMax_.

 {
     return 0.02 * constants::pi / std::sqrt(unloadingStiffnessMax_ / (.5 * mass) - mathsFunc::square(dissipation_ /mass));
 }

std::string LinearPlasticViscoelasticNormalSpecies::getBaseName ( ) const

Used in Species::getName to obtain a unique name for each Species.

Returns: a string containing the name of the species (minus the word "Species")

Definition at line 95 of file LinearPlasticViscoelasticNormalSpecies.cc.

 {
     return "LinearPlasticViscoelastic";
 }

Mdouble LinearPlasticViscoelasticNormalSpecies::getCohesionStiffness ( ) const

Returns the cohesive stiffness of the linear plastic-viscoelastic normal force.

Returns: the cohesive stiffness of the linear plastic-viscoelastic normal force.

Definition at line 152 of file LinearPlasticViscoelasticNormalSpecies.cc.

References cohesionStiffness_.

Referenced by LinearPlasticViscoelasticInteraction::computeLinearPlasticViscoelasticForce(), and mix().

 {
     return cohesionStiffness_;
 }

Mdouble LinearPlasticViscoelasticNormalSpecies::getCollisionTime ( Mdouble mass )

Calculates collision time for two copies of a particle of given disp, k, mass.

Definition at line 276 of file LinearPlasticViscoelasticNormalSpecies.cc.

References dissipation_, loadingStiffness_, constants::pi, and mathsFunc::square().

 {
     if (mass <= 0)
     {
         std::cerr << "Error in getCollisionTime(" << mass << ") mass is not set or has an unexpected value, (getCollisionTime(" << mass << "))" << std::endl;
         exit(-1);
     }
     if (loadingStiffness_ <= 0)
     {
         std::cerr << "Error in getCollisionTime(" << mass << ") stiffness=" << loadingStiffness_ << " is not set or has an unexpected value, (getCollisionTime(" << mass << "), with stiffness=" << loadingStiffness_ << ")" << std::endl;
         exit(-1);
     }
     if (dissipation_ < 0)
     {
         std::cerr << "Error in getCollisionTime(" << mass << ") dissipation=" << dissipation_ << " is not set or has an unexpected value, (getCollisionTime(" << mass << "), with dissipation=" << dissipation_ << ")" << std::endl;
         exit(-1);
     }
     Mdouble tosqrt = loadingStiffness_ / (.5 * mass) - mathsFunc::square(dissipation_ / mass);
     if (tosqrt <= -1e-8*loadingStiffness_ / (.5 * mass))
     {
         std::cerr << "Error in getCollisionTime(" << mass << ") values for mass, stiffness and dissipation would "
         "lead to an overdamped system: reduce dissipation." << std::endl;
         exit(-1);
     }
     return constants::pi / std::sqrt(tosqrt);
 }

Mdouble LinearPlasticViscoelasticNormalSpecies::getDissipation ( ) const

Allows the normal dissipation to be accessed.

Returns: the linear dissipation coefficient

Definition at line 235 of file LinearPlasticViscoelasticNormalSpecies.cc.

References dissipation_.

Referenced by LinearPlasticViscoelasticInteraction::computeLinearPlasticViscoelasticForce(), mix(), and SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficient().

 {
     return dissipation_;
 }

Mdouble LinearPlasticViscoelasticNormalSpecies::getLoadingStiffness ( ) const

Returns the loading stiffness of the linear plastic-viscoelastic normal force.

Returns: the loading stiffness of the linear plastic-viscoelastic normal force.

Definition at line 136 of file LinearPlasticViscoelasticNormalSpecies.cc.

References loadingStiffness_.

Referenced by LinearPlasticViscoelasticInteraction::computeLinearPlasticViscoelasticForce(), LinearPlasticViscoelasticInteraction::getElasticEnergy(), LinearPlasticViscoelasticInteraction::getUnloadingStiffness(), mix(), and SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficient().

 {
     return loadingStiffness_;
 }

Mdouble LinearPlasticViscoelasticNormalSpecies::getPenetrationDepthMax ( ) const

Returns the maximum penetration depth of the linear plastic-viscoelastic normal force.

Returns: the maximum penetration depth of the linear plastic-viscoelastic normal force.

Definition at line 160 of file LinearPlasticViscoelasticNormalSpecies.cc.

References penetrationDepthMax_.

Referenced by LinearPlasticViscoelasticInteraction::computeLinearPlasticViscoelasticForce(), LinearPlasticViscoelasticInteraction::getUnloadingStiffness(), and mix().

 {
     return penetrationDepthMax_;
 }

Mdouble LinearPlasticViscoelasticNormalSpecies::getUnloadingStiffnessMax ( ) const

Returns the maximum unloading stiffness of the linear plastic-viscoelastic normal force.

Returns: the maximum unloading stiffness of the linear plastic-viscoelastic normal force.

Definition at line 144 of file LinearPlasticViscoelasticNormalSpecies.cc.

References unloadingStiffnessMax_.

Referenced by LinearPlasticViscoelasticInteraction::computeLinearPlasticViscoelasticForce(), LinearPlasticViscoelasticInteraction::getUnloadingStiffness(), and mix().

 {
     return unloadingStiffnessMax_;
 }

void LinearPlasticViscoelasticNormalSpecies::mix	(	LinearPlasticViscoelasticNormalSpecies *const	S,
		LinearPlasticViscoelasticNormalSpecies *const	T
	)

creates default values for mixed species

For all parameters we assume that the harmonic mean of the parameters of the original two species is a sensible default.

Parameters

[in] S,T the two species whose properties are mixed to create the new species

Definition at line 105 of file LinearPlasticViscoelasticNormalSpecies.cc.

References BaseSpecies::average(), cohesionStiffness_, dissipation_, getCohesionStiffness(), getDissipation(), getLoadingStiffness(), getPenetrationDepthMax(), getUnloadingStiffnessMax(), loadingStiffness_, penetrationDepthMax_, and unloadingStiffnessMax_.

 {
     loadingStiffness_ = average(S->getLoadingStiffness(), T->getLoadingStiffness());
     unloadingStiffnessMax_ = average(S->getUnloadingStiffnessMax(), T->getUnloadingStiffnessMax());
     cohesionStiffness_ = average(S->getCohesionStiffness(), T->getCohesionStiffness());
     penetrationDepthMax_ = average(S->getPenetrationDepthMax(), T->getPenetrationDepthMax());
     dissipation_ = average(S->getDissipation(), T->getDissipation());
 }

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

virtual

Reads the species properties from an input stream.

Parameters

[in] input stream (typically the restart file)

Implements BaseObject.

Definition at line 82 of file LinearPlasticViscoelasticNormalSpecies.cc.

References cohesionStiffness_, dissipation_, loadingStiffness_, penetrationDepthMax_, and unloadingStiffnessMax_.

 {
     std::string dummy;
     is >> dummy >> loadingStiffness_;
     is >> dummy >> unloadingStiffnessMax_;
     is >> dummy >> cohesionStiffness_;
     is >> dummy >> penetrationDepthMax_;
     is >> dummy >> dissipation_;
 }

void LinearPlasticViscoelasticNormalSpecies::setCohesionStiffness ( Mdouble cohesionStiffness )

Sets the cohesive stiffness of the linear plastic-viscoelastic normal force.

Parameters

[in] cohesionStiffness the cohesive stiffness of the linear plastic-viscoelastic normal force.

Definition at line 184 of file LinearPlasticViscoelasticNormalSpecies.cc.

References cohesionStiffness_.

Referenced by setPlasticParameters().

 {
     cohesionStiffness_ = cohesionStiffness;
 }

void LinearPlasticViscoelasticNormalSpecies::setCollisionTimeAndRestitutionCoefficient	(	Mdouble	tc,
		Mdouble	eps,
		Mdouble	mass
	)

Set k, disp such that is matches a given tc and eps for a collision of two different masses.

Recall the resitution constant is a function of k, disp and the mass of each particle in the collision See also setCollisionTimeAndRestitutionCoefficient(Mdouble tc, Mdouble eps, Mdouble mass)

Sets k, disp such that it matches a given tc and eps for a collision of two copies of equal mass m

Parameters

[in]	tc	collision time
[in]	eps	restitution coefficient
[in]	mass	effective particle mass, $\frac{2}{1/m1+1/m2}$

Todo:: TW: check that the masses are described correctly here (m_eff or m_p?))

Definition at line 247 of file LinearPlasticViscoelasticNormalSpecies.cc.

 {
     if (eps==0.0) {
         loadingStiffness_ = .5 * mass * mathsFunc::square(constants::pi / tc);
         dissipation_ = std::sqrt(2.0 * mass * loadingStiffness_);
     } else {
         dissipation_ = -mass / tc * std::log(eps);
         loadingStiffness_ = .5 * mass * (mathsFunc::square(constants::pi / tc) + mathsFunc::square(dissipation_ / mass));
     }
     unloadingStiffnessMax_ = loadingStiffness_;
 }

void LinearPlasticViscoelasticNormalSpecies::setDissipation ( Mdouble dissipation )

Sets the linear dissipation coefficient of the linear plastic-viscoelastic normal force.

should be non-negative

Parameters

[in] the linear dissipation coefficient of the linear plastic-viscoelastic normal force.

Definition at line 210 of file LinearPlasticViscoelasticNormalSpecies.cc.

References dissipation_.

Referenced by SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficient(), and setLoadingStiffnessAndDissipation().

 {
     if (dissipation >= 0)
     {
         dissipation_ = dissipation;
     }
     else
     {
         std::cerr << "Error in setDissipation(" << dissipation << ")" << std::endl;
         exit(-1);
     }
 }

void LinearPlasticViscoelasticNormalSpecies::setLoadingStiffness ( Mdouble loadingStiffness )

Sets the loading stiffness of the linear plastic-viscoelastic normal force.

Parameters

[in] loadingStiffness the loading stiffness of the linear plastic-viscoelastic normal force.

Definition at line 168 of file LinearPlasticViscoelasticNormalSpecies.cc.

References loadingStiffness_.

Referenced by SlidingFrictionSpecies::setCollisionTimeAndNormalAndTangentialRestitutionCoefficient(), setLoadingStiffnessAndDissipation(), and setPlasticParameters().

 {
     loadingStiffness_ = loadingStiffness;
 }

void LinearPlasticViscoelasticNormalSpecies::setLoadingStiffnessAndDissipation ( helpers::KAndDisp new_ )

Allows the spring and dissipation constants to be changed simultaneously.

Parameters

[in] a helper struct containing both the loading stiffness and the disssipation coefficient.

Definition at line 226 of file LinearPlasticViscoelasticNormalSpecies.cc.

References helpers::KAndDisp::disp, helpers::KAndDisp::k, setDissipation(), and setLoadingStiffness().

 {
     setLoadingStiffness(new_.k);
     setDissipation(new_.disp);
 }

void LinearPlasticViscoelasticNormalSpecies::setPenetrationDepthMax ( Mdouble penetrationDepthMax )

Sets the maximum penetration depth of the linear plastic-viscoelastic normal force.

Parameters

[in] penetrationDepthMax the maximum penetration depth of the linear plastic-viscoelastic normal force.

Definition at line 192 of file LinearPlasticViscoelasticNormalSpecies.cc.

References penetrationDepthMax_.

Referenced by setPlasticParameters().

 {
     penetrationDepthMax_ = penetrationDepthMax;
 }

void LinearPlasticViscoelasticNormalSpecies::setPlasticParameters	(	Mdouble	loadingStiffness,
		Mdouble	unloadingStiffnessMax,
		Mdouble	cohesionStiffness,
		Mdouble	penetrationDepthMax
	)

Sets all parameters of the linear plastic-viscoelastic normal force at once.

Parameters

[in]	loadingStiffness	the loading stiffness of the linear plastic-viscoelastic normal force.
[in]	unloadingStiffnessMax	the maximum unloading stiffness of the linear plastic-viscoelastic normal force.
[in]	cohesionStiffness	the cohesive stiffness of the linear plastic-viscoelastic normal force.
[in]	penetrationDepthMax	the maximum penetration depth of the linear plastic-viscoelastic normal force.

Definition at line 120 of file LinearPlasticViscoelasticNormalSpecies.cc.

References setCohesionStiffness(), setLoadingStiffness(), setPenetrationDepthMax(), and setUnloadingStiffnessMax().

 {
     if (loadingStiffness <= 0 || unloadingStiffnessMax < loadingStiffness || cohesionStiffness < 0 || penetrationDepthMax < 0 || penetrationDepthMax > 1)
     {
         std::cerr << "Error: arguments of setPlasticParameters do not make sense" << std::endl;
         exit(-1);
     }
     setLoadingStiffness(loadingStiffness);
     setUnloadingStiffnessMax(unloadingStiffnessMax);
     setCohesionStiffness(cohesionStiffness);
     setPenetrationDepthMax(penetrationDepthMax);
 }

void LinearPlasticViscoelasticNormalSpecies::setStiffnessAndRestitutionCoefficient	(	Mdouble	stiffness,
		Mdouble	eps,
		Mdouble	mass
	)

Sets k, disp such that it matches a given tc and eps for a collision of two copies of P.

Sets k, disp such that it matches a given tc and eps for a collision of two copies of P

Parameters

[in]	stiffness	stiffness
[in]	eps	restitution coefficient
[in]	mass	effective particle mass, $\frac{2}{1/m1+1/m2}$

Definition at line 265 of file LinearPlasticViscoelasticNormalSpecies.cc.

References dissipation_, loadingStiffness_, mathsFunc::log(), constants::sqr_pi, and mathsFunc::square().

 {
     loadingStiffness_ = stiffness;
     if (eps==0.0) {
         dissipation_ = std::sqrt(2.0 * mass * stiffness);
     } else {
         dissipation_ = -std::sqrt(2.0 * mass * stiffness / (constants::sqr_pi + mathsFunc::square(log(eps)))) * log(eps);
     }
 }

void LinearPlasticViscoelasticNormalSpecies::setUnloadingStiffnessMax ( Mdouble unloadingStiffnessMax )

Sets the maximum unloading stiffness of the linear plastic-viscoelastic normal force.

Parameters

[in] unloadingStiffnessMax the maximum unloading stiffness of the linear plastic-viscoelastic normal force.

Definition at line 176 of file LinearPlasticViscoelasticNormalSpecies.cc.

References unloadingStiffnessMax_.

Referenced by setPlasticParameters().

 {
     unloadingStiffnessMax_ = unloadingStiffnessMax;
 }

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

virtual

Writes the species properties to an output stream.

Parameters

[out] output stream (typically the restart file)

Implements BaseObject.

Definition at line 70 of file LinearPlasticViscoelasticNormalSpecies.cc.

References cohesionStiffness_, dissipation_, loadingStiffness_, penetrationDepthMax_, and unloadingStiffnessMax_.

 {
     os  << " loadingStiffness " << loadingStiffness_;
     os  << " maxUnloadingStiffness " << unloadingStiffnessMax_;
     os  << " cohesionStiffness " << cohesionStiffness_;
     os  << " maxPenetration " << penetrationDepthMax_;
     os  << " dissipation " << dissipation_;
 }