MindlinSpecies Class Reference

MindlinSpecies contains the parameters used to describe sliding friction. More...

#include <MindlinSpecies.h>

Inheritance diagram for MindlinSpecies:

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

Public Member Functions
	MindlinSpecies ()
	The default constructor. More...
	MindlinSpecies (const MindlinSpecies &s)
	The default copy constructor. More...
	~MindlinSpecies ()
	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...
virtual std::string	getBaseName () const
	Used in Species::getName to obtain a unique name for each Species. More...
void	setSlidingDissipation (Mdouble new_dispt)
	Allows the tangential viscosity to be changed. More...
Mdouble	getSlidingDissipation () const
	Allows the tangential viscosity to be accessed. More...
void	setSlidingFrictionCoefficient (Mdouble new_mu)
	Allows the (dynamic) Coulomb friction coefficient to be changed; also sets mu_s by default. More...
Mdouble	getSlidingFrictionCoefficient () const
	Allows the (dynamic) Coulomb friction coefficient to be accessed. More...
void	setSlidingFrictionCoefficientStatic (Mdouble new_mu)
	Allows the static Coulomb friction coefficient to be changed. More...
Mdouble	getSlidingFrictionCoefficientStatic () const
	Allows the static Coulomb friction coefficient to be accessed. More...
MERCURYDPM_DEPRECATED void	setPoissonRatio (Mdouble poissonRatio)
	Allows the poisson ratio to be changed. More...
void	setEffectiveShearModulus (Mdouble shearModulus)
	allows the shear modulus to be changed More...
Mdouble	getEffectiveShearModulus () const
	Allows the shear modulus to be accessed. More...
bool	getUseAngularDOFs () const override
	Returns true if torques have to be calculated. More...
void	mix (MindlinSpecies *S, MindlinSpecies *T)
	creates default values for mixed species More...
Public Member Functions inherited from BaseForce
BaseSpecies *	getBaseSpecies () const
void	setBaseSpecies (BaseSpecies *baseSpecies)

Private Attributes
Mdouble	slidingDissipation_
	tangential dissipation coefficient. More...
Mdouble	slidingFrictionCoefficient_
	(dynamic) Coulomb friction coefficient More...
Mdouble	slidingFrictionCoefficientStatic_
	static Coulomb friction coefficient (by default set equal to mu) More...
Mdouble	shearModulus_
	tangential spring constant More...

Detailed Description

MindlinSpecies contains the parameters used to describe sliding friction.

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

Member Typedef Documentation

InteractionType

typedef MindlinInteraction MindlinSpecies::InteractionType

The correct Interaction type for this FrictionForceSpecies.

Constructor & Destructor Documentation

MindlinSpecies() [1/2]

MindlinSpecies::MindlinSpecies

(

)

The default constructor.

{
    slidingDissipation_ = 0;
    slidingFrictionCoefficient_ = 0;
    slidingFrictionCoefficientStatic_ = 0;
    shearModulus_ = 0;
#ifdef DEBUG_CONSTRUCTOR
    std::cout<<"MindlinSpecies::MindlinSpecies() finished"<<std::endl;
#endif
}

References shearModulus_, slidingDissipation_, slidingFrictionCoefficient_, and slidingFrictionCoefficientStatic_.

MindlinSpecies() [2/2]

MindlinSpecies::MindlinSpecies

(

const MindlinSpecies &

s

)

The default copy constructor.

Parameters

[in]

s

the species that is copied

{
    slidingDissipation_ = s.slidingDissipation_;
    slidingFrictionCoefficient_ = s.slidingFrictionCoefficient_;
    slidingFrictionCoefficientStatic_ = s.slidingFrictionCoefficientStatic_;
    shearModulus_ = s.shearModulus_;
#ifdef DEBUG_CONSTRUCTOR
    std::cout<<"MindlinSpecies::MindlinSpecies(const MindlinSpecies &p) finished"<<std::endl;
#endif
}

References shearModulus_, slidingDissipation_, slidingFrictionCoefficient_, and slidingFrictionCoefficientStatic_.

~MindlinSpecies()

MindlinSpecies::~MindlinSpecies

(

)

The default destructor.

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

Member Function Documentation

getBaseName()

std::string MindlinSpecies::getBaseName ( ) const

virtual

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")

Reimplemented in MindlinRollingTorsionSpecies.

{
    return "Mindlin";
}

getEffectiveShearModulus()

Mdouble MindlinSpecies::getEffectiveShearModulus

(

)

const

Allows the shear modulus to be accessed.

{
    return shearModulus_;
}

References shearModulus_.

Referenced by MindlinInteraction::computeFrictionForce(), mix(), and setPoissonRatio().

getSlidingDissipation()

Mdouble MindlinSpecies::getSlidingDissipation

(

)

const

Allows the tangential viscosity to be accessed.

{
    return slidingDissipation_;
}

References slidingDissipation_.

Referenced by MindlinInteraction::computeFrictionForce(), and mix().

getSlidingFrictionCoefficient()

Mdouble MindlinSpecies::getSlidingFrictionCoefficient

(

)

const

Allows the (dynamic) Coulomb friction coefficient to be accessed.

{
    return slidingFrictionCoefficient_;
}

References slidingFrictionCoefficient_.

Referenced by MindlinInteraction::computeFrictionForce(), and mix().

getSlidingFrictionCoefficientStatic()

Mdouble MindlinSpecies::getSlidingFrictionCoefficientStatic

(

)

const

Allows the static Coulomb friction coefficient to be accessed.

{
    return slidingFrictionCoefficientStatic_;
}

References slidingFrictionCoefficientStatic_.

Referenced by mix().

getUseAngularDOFs()

bool MindlinSpecies::getUseAngularDOFs ( ) const

overridevirtual

Returns true if torques have to be calculated.

Returns true for any FrictionForceSpecies except EmptyFrictionSpecies, because for spherical particles, torques are only caused by tangential forces. See SpeciesHandler::useAngularDOFs for more details

Returns

true

Implements BaseFrictionForce.

{
    return true;
}

mix()

void MindlinSpecies::mix	(	MindlinSpecies *	S,
		MindlinSpecies *	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]	SFrictional	the first species whose properties are mixed to create the new species
[in]	TFrictional	the second species whose properties are mixed to create the new species

{
    slidingDissipation_ = BaseSpecies::average(SFrictional->getSlidingDissipation(),TFrictional->getSlidingDissipation());
    slidingFrictionCoefficient_ = BaseSpecies::average(SFrictional->getSlidingFrictionCoefficient(),TFrictional->getSlidingFrictionCoefficient());
    slidingFrictionCoefficientStatic_ = BaseSpecies::average(SFrictional->getSlidingFrictionCoefficientStatic(),TFrictional->getSlidingFrictionCoefficientStatic());
    shearModulus_ = BaseSpecies::average(SFrictional->getEffectiveShearModulus(), TFrictional->getEffectiveShearModulus());
}

References BaseSpecies::average(), getEffectiveShearModulus(), getSlidingDissipation(), getSlidingFrictionCoefficient(), getSlidingFrictionCoefficientStatic(), shearModulus_, slidingDissipation_, slidingFrictionCoefficient_, and slidingFrictionCoefficientStatic_.

read()

void MindlinSpecies::read

(

std::istream &

is

)

Reads the species properties from an input stream.

Parameters

[in]

is

input stream (typically the restart file)

{
    //BaseSpecies::read(is);
    std::string dummy;
    is >> dummy >> slidingDissipation_;
    is >> dummy >> slidingFrictionCoefficient_;
    is >> dummy >> slidingFrictionCoefficientStatic_;
    is >> dummy >> shearModulus_;
}

References shearModulus_, slidingDissipation_, slidingFrictionCoefficient_, and slidingFrictionCoefficientStatic_.

Referenced by MindlinRollingTorsionSpecies::read().

setEffectiveShearModulus()

void MindlinSpecies::setEffectiveShearModulus

(

Mdouble

shearModulus

)

allows the shear modulus to be changed

Allows the shear modulus to be changed.

{
    logger.assert_debug(shearModulus > 0,
                  "setEffectiveShearModulus(%): value needs to be positive",shearModulus);
    shearModulus_ = shearModulus;
}

References logger, and shearModulus_.

setPoissonRatio()

void MindlinSpecies::setPoissonRatio

(

Mdouble

poissonRatio

)

Allows the poisson ratio to be changed.

{
    auto hertz = dynamic_cast<HertzianViscoelasticNormalSpecies*>(getBaseSpecies());
    logger.assert_debug(hertz, "setPoissonRatio only works with HertzianViscoelastic*Species.");
    shearModulus_ = hertz->getEffectiveElasticModulus() / 2 * (1 + poissonRatio);
    logger(INFO, "Effective shear modulus set to %, based on effective elastic modulus % and Poisson's ratio %",
           getEffectiveShearModulus(),
           hertz->getEffectiveElasticModulus(), poissonRatio);
}

References BaseForce::getBaseSpecies(), getEffectiveShearModulus(), INFO, logger, and shearModulus_.

setSlidingDissipation()

void MindlinSpecies::setSlidingDissipation

(

Mdouble

new_dispt

)

Allows the tangential viscosity to be changed.

{
    if (new_dispt >= 0)
        slidingDissipation_ = new_dispt;
    else
    {
        logger(ERROR, "Error in setSlidingDissipation");
    }
}

References ERROR, logger, and slidingDissipation_.

setSlidingFrictionCoefficient()

void MindlinSpecies::setSlidingFrictionCoefficient

(

Mdouble

new_mu

)

Allows the (dynamic) Coulomb friction coefficient to be changed; also sets mu_s by default.

{
    if (new_mu >= 0)
    {
        slidingFrictionCoefficient_ = new_mu;
        slidingFrictionCoefficientStatic_ = slidingFrictionCoefficient_;
    }
    else
    {
        logger(ERROR, "Error in setSlidingFrictionCoefficient");
    }
}

References ERROR, logger, slidingFrictionCoefficient_, and slidingFrictionCoefficientStatic_.

setSlidingFrictionCoefficientStatic()

void MindlinSpecies::setSlidingFrictionCoefficientStatic

(

Mdouble

new_mu

)

Allows the static Coulomb friction coefficient to be changed.

{
    if (new_mu >= 0)
    {
        slidingFrictionCoefficientStatic_ = new_mu;
    }
    else
    {
        logger(ERROR, "Error in setSlidingFrictionCoefficientStatic");
    }
}

References ERROR, logger, and slidingFrictionCoefficientStatic_.

write()

void MindlinSpecies::write

(

std::ostream &

os

)

const

Writes the species properties to an output stream.

Parameters

[out]

os

output stream (typically the restart file)

{
    //BaseSpecies::write(os);
    os << " slidingDissipation " << slidingDissipation_;
    os << " slidingFrictionCoefficient " << slidingFrictionCoefficient_;
    os << " slidingFrictionCoefficientStatic " << slidingFrictionCoefficientStatic_;
    os << " shearModulus " << shearModulus_;
}

References shearModulus_, slidingDissipation_, slidingFrictionCoefficient_, and slidingFrictionCoefficientStatic_.

Referenced by MindlinRollingTorsionSpecies::write().

Member Data Documentation

shearModulus_

Mdouble MindlinSpecies::shearModulus_

private

tangential spring constant

Referenced by getEffectiveShearModulus(), MindlinSpecies(), mix(), read(), setEffectiveShearModulus(), setPoissonRatio(), and write().

slidingDissipation_

Mdouble MindlinSpecies::slidingDissipation_

private

tangential dissipation coefficient.

Typically set to 2/7 of the normal force dissipation, as both the tangential and the normal spring have the same restitution coefficients (if the tangential and normal stiffnesses also have a ratio of 2/7). should always satisfy \(4*dispt*dt<mass, dispt \approx disp\), otherwise the restitution is zero and the particles stick.

Referenced by getSlidingDissipation(), MindlinSpecies(), mix(), read(), setSlidingDissipation(), and write().

slidingFrictionCoefficient_

Mdouble MindlinSpecies::slidingFrictionCoefficient_

private

(dynamic) Coulomb friction coefficient

Referenced by getSlidingFrictionCoefficient(), MindlinSpecies(), mix(), read(), setSlidingFrictionCoefficient(), and write().

slidingFrictionCoefficientStatic_

Mdouble MindlinSpecies::slidingFrictionCoefficientStatic_

private

static Coulomb friction coefficient (by default set equal to mu)

Referenced by getSlidingFrictionCoefficientStatic(), MindlinSpecies(), mix(), read(), setSlidingFrictionCoefficient(), setSlidingFrictionCoefficientStatic(), and write().

---

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

• MindlinSpecies.h
• MindlinSpecies.cc