Rate-independent associative mean-cap tensile AND compressive failure with hardening/softening of the tensile and compressive strength. More...

#include <TensorMechanicsPlasticMeanCapTC.h>

Inheritance diagram for TensorMechanicsPlasticMeanCapTC:

[legend]

Public Member Functions
	TensorMechanicsPlasticMeanCapTC (const InputParameters &parameters)

virtual void	activeConstraints (const std::vector< Real > &f, const RankTwoTensor &stress, Real intnl, const RankFourTensor &Eijkl, std::vector< bool > &act, RankTwoTensor &returned_stress) const override
	The active yield surfaces, given a vector of yield functions. More...

virtual bool	useCustomReturnMap () const override
	Returns false. You will want to override this in your derived class if you write a custom returnMap function. More...

virtual bool	useCustomCTO () const override
	Returns false. You will want to override this in your derived class if you write a custom consistent tangent operator function. More...

virtual bool	returnMap (const RankTwoTensor &trial_stress, Real intnl_old, const RankFourTensor &E_ijkl, Real ep_plastic_tolerance, RankTwoTensor &returned_stress, Real &returned_intnl, std::vector< Real > &dpm, RankTwoTensor &delta_dp, std::vector< Real > &yf, bool &trial_stress_inadmissible) const override
	Performs a custom return-map. More...

virtual RankFourTensor	consistentTangentOperator (const RankTwoTensor &trial_stress, Real intnl_old, const RankTwoTensor &stress, Real intnl, const RankFourTensor &E_ijkl, const std::vector< Real > &cumulative_pm) const override
	Calculates a custom consistent tangent operator. More...

virtual std::string	modelName () const override

void	initialize ()

void	execute ()

void	finalize ()

virtual unsigned int	numberSurfaces () const
	The number of yield surfaces for this plasticity model. More...

virtual void	yieldFunctionV (const RankTwoTensor &stress, Real intnl, std::vector< Real > &f) const
	Calculates the yield functions. More...

virtual void	dyieldFunction_dstressV (const RankTwoTensor &stress, Real intnl, std::vector< RankTwoTensor > &df_dstress) const
	The derivative of yield functions with respect to stress. More...

virtual void	dyieldFunction_dintnlV (const RankTwoTensor &stress, Real intnl, std::vector< Real > &df_dintnl) const
	The derivative of yield functions with respect to the internal parameter. More...

virtual void	flowPotentialV (const RankTwoTensor &stress, Real intnl, std::vector< RankTwoTensor > &r) const
	The flow potentials. More...

virtual void	dflowPotential_dstressV (const RankTwoTensor &stress, Real intnl, std::vector< RankFourTensor > &dr_dstress) const
	The derivative of the flow potential with respect to stress. More...

virtual void	dflowPotential_dintnlV (const RankTwoTensor &stress, Real intnl, std::vector< RankTwoTensor > &dr_dintnl) const
	The derivative of the flow potential with respect to the internal parameter. More...

virtual void	hardPotentialV (const RankTwoTensor &stress, Real intnl, std::vector< Real > &h) const
	The hardening potential. More...

virtual void	dhardPotential_dstressV (const RankTwoTensor &stress, Real intnl, std::vector< RankTwoTensor > &dh_dstress) const
	The derivative of the hardening potential with respect to stress. More...

virtual void	dhardPotential_dintnlV (const RankTwoTensor &stress, Real intnl, std::vector< Real > &dh_dintnl) const
	The derivative of the hardening potential with respect to the internal parameter. More...

bool	KuhnTuckerSingleSurface (Real yf, Real dpm, Real dpm_tol) const
	Returns true if the Kuhn-Tucker conditions for the single surface are satisfied. More...

Static Public Member Functions
static InputParameters	validParams ()

Public Attributes
const Real	_f_tol
	Tolerance on yield function. More...

const Real	_ic_tol
	Tolerance on internal constraint. More...

Protected Member Functions
Real	yieldFunction (const RankTwoTensor &stress, Real intnl) const override
	The following functions are what you should override when building single-plasticity models. More...

RankTwoTensor	dyieldFunction_dstress (const RankTwoTensor &stress, Real intnl) const override
	The derivative of yield function with respect to stress. More...

Real	dyieldFunction_dintnl (const RankTwoTensor &stress, Real intnl) const override
	The derivative of yield function with respect to the internal parameter. More...

RankTwoTensor	flowPotential (const RankTwoTensor &stress, Real intnl) const override
	The flow potential. More...

RankFourTensor	dflowPotential_dstress (const RankTwoTensor &stress, Real intnl) const override
	The derivative of the flow potential with respect to stress. More...

RankTwoTensor	dflowPotential_dintnl (const RankTwoTensor &stress, Real intnl) const override
	The derivative of the flow potential with respect to the internal parameter. More...

Real	hardPotential (const RankTwoTensor &stress, Real intnl) const override
	The hardening potential. More...

virtual RankTwoTensor	dhardPotential_dstress (const RankTwoTensor &stress, Real intnl) const override
	The derivative of the hardening potential with respect to stress. More...

virtual Real	dhardPotential_dintnl (const RankTwoTensor &stress, Real intnl) const override
	The derivative of the hardening potential with respect to the internal parameter. More...

RankTwoTensor	df_dsig (const RankTwoTensor &stress, Real intnl) const
	Derivative of the yield function with respect to stress. More...

virtual Real	tensile_strength (const Real internal_param) const
	tensile strength as a function of residual value, rate, and internal_param More...

virtual Real	dtensile_strength (const Real internal_param) const
	d(tensile strength)/d(internal_param) as a function of residual value, rate, and internal_param More...

virtual Real	compressive_strength (const Real internal_param) const
	compressive strength as a function of residual value, rate, and internal_param More...

virtual Real	dcompressive_strength (const Real internal_param) const
	d(compressive strength)/d(internal_param) as a function of residual value, rate, and internal_param More...

Protected Attributes
const unsigned	_max_iters
	max iters for custom return map loop More...

const bool	_use_custom_returnMap
	Whether to use the custom return-map algorithm. More...

const bool	_use_custom_cto
	Whether to use the custom consistent tangent operator algorithm. More...

const TensorMechanicsHardeningModel &	_strength
	the tensile strength More...

const TensorMechanicsHardeningModel &	_c_strength
	the compressive strength More...

Detailed Description

Rate-independent associative mean-cap tensile AND compressive failure with hardening/softening of the tensile and compressive strength.

The key point here is that the internal parameter is equal to the volumetric plastic strain. This means that upon tensile failure, the compressive strength can soften (using a TensorMechanicsHardening object) which physically means that a subsequent compressive stress can easily squash the material

Definition at line 29 of file TensorMechanicsPlasticMeanCapTC.h.

Constructor & Destructor Documentation

◆ TensorMechanicsPlasticMeanCapTC()

TensorMechanicsPlasticMeanCapTC::TensorMechanicsPlasticMeanCapTC ( const InputParameters & parameters )

Definition at line 49 of file TensorMechanicsPlasticMeanCapTC.C.

   : TensorMechanicsPlasticModel(parameters),
     _max_iters(getParam<unsigned>("max_iterations")),
     _use_custom_returnMap(getParam<bool>("use_custom_returnMap")),
     _use_custom_cto(getParam<bool>("use_custom_cto")),
     _strength(getUserObject<TensorMechanicsHardeningModel>("tensile_strength")),
     _c_strength(getUserObject<TensorMechanicsHardeningModel>("compressive_strength"))
 {
   // cannot check the following for all values of the internal parameter, but this will catch most
   // errors
   if (_strength.value(0) <= _c_strength.value(0))
     mooseError("MeanCapTC: tensile strength (which is usually positive) must not be less than "
                "compressive strength (which is usually negative)");
 }

Member Function Documentation

◆ activeConstraints()

void TensorMechanicsPlasticMeanCapTC::activeConstraints	(	const std::vector< Real > &	f,
		const RankTwoTensor &	stress,
		Real	intnl,
		const RankFourTensor &	Eijkl,
		std::vector< bool > &	act,
		RankTwoTensor &	returned_stress
	)		const

overridevirtual

The active yield surfaces, given a vector of yield functions.

This is used by FiniteStrainMultiPlasticity to determine the initial set of active constraints at the trial (stress, intnl) configuration. It is up to you (the coder) to determine how accurate you want the returned_stress to be. Currently it is only used by FiniteStrainMultiPlasticity to estimate a good starting value for the Newton-Rahson procedure, so currently it may not need to be super perfect.

Parameters

	f	values of the yield functions
	stress	stress tensor
	intnl	internal parameter
	Eijkl	elasticity tensor (stress = Eijkl*strain)
[out]	act	act[i] = true if the i_th yield function is active
[out]	returned_stress	Approximate value of the returned stress

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 247 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   act.assign(1, false);
  
   if (f[0] <= _f_tol)
   {
     returned_stress = stress;
     return;
   }
  
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   Real str;
   Real dirn;
   if (tr >= t_str)
   {
     str = t_str;
     dirn = 1.0;
   }
   else
   {
     str = compressive_strength(intnl);
     dirn = -1.0;
   }
  
   RankTwoTensor n; // flow direction
   for (unsigned i = 0; i < 3; ++i)
     for (unsigned j = 0; j < 3; ++j)
       for (unsigned k = 0; k < 3; ++k)
         n(i, j) += dirn * Eijkl(i, j, k, k);
  
   // returned_stress = stress - gamma*n
   // and taking the trace of this and using
   // Tr(returned_stress) = str, gives
   // gamma = (Tr(stress) - str)/Tr(n)
   Real gamma = (stress.trace() - str) / n.trace();
  
   for (unsigned i = 0; i < 3; ++i)
     for (unsigned j = 0; j < 3; ++j)
       returned_stress(i, j) = stress(i, j) - gamma * n(i, j);
  
   act[0] = true;
 }

◆ compressive_strength()

Real TensorMechanicsPlasticMeanCapTC::compressive_strength ( const Real internal_param ) const

protectedvirtual

compressive strength as a function of residual value, rate, and internal_param

Definition at line 235 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return _c_strength.value(internal_param);
 }

Referenced by activeConstraints(), df_dsig(), dflowPotential_dintnl(), dflowPotential_dstress(), dhardPotential_dintnl(), dhardPotential_dstress(), dyieldFunction_dintnl(), hardPotential(), returnMap(), and yieldFunction().

◆ consistentTangentOperator()

RankFourTensor TensorMechanicsPlasticMeanCapTC::consistentTangentOperator	(	const RankTwoTensor &	trial_stress,
		Real	intnl_old,
		const RankTwoTensor &	stress,
		Real	intnl,
		const RankFourTensor &	E_ijkl,
		const std::vector< Real > &	cumulative_pm
	)		const

overridevirtual

Calculates a custom consistent tangent operator.

You may choose to over-ride this in your derived TensorMechanicsPlasticXXXX class.

(Note, if you over-ride returnMap, you will probably want to override consistentTangentOpertor too, otherwise it will default to E_ijkl.)

Parameters

stress_old	trial stress before returning
intnl_old	internal parameter before returning
stress	current returned stress state
intnl	internal parameter
E_ijkl	elasticity tensor
cumulative_pm	the cumulative plastic multipliers

Returns: the consistent tangent operator: E_ijkl if not over-ridden

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 399 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   if (!_use_custom_cto)
     return TensorMechanicsPlasticModel::consistentTangentOperator(
         trial_stress, intnl_old, stress, intnl, E_ijkl, cumulative_pm);
  
   Real df_dq;
   Real alpha;
   if (trial_stress.trace() >= tensile_strength(intnl_old))
   {
     df_dq = -dtensile_strength(intnl);
     alpha = 1.0;
   }
   else
   {
     df_dq = dcompressive_strength(intnl);
     alpha = -1.0;
   }
  
   RankTwoTensor elas;
   for (unsigned int i = 0; i < 3; ++i)
     for (unsigned int j = 0; j < 3; ++j)
       for (unsigned int k = 0; k < 3; ++k)
         elas(i, j) += E_ijkl(i, j, k, k);
  
   const Real hw = -df_dq + alpha * elas.trace();
  
   return E_ijkl - alpha / hw * elas.outerProduct(elas);
 }

◆ dcompressive_strength()

Real TensorMechanicsPlasticMeanCapTC::dcompressive_strength ( const Real internal_param ) const

protectedvirtual

d(compressive strength)/d(internal_param) as a function of residual value, rate, and internal_param

Definition at line 241 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return _c_strength.derivative(internal_param);
 }

Referenced by consistentTangentOperator(), dflowPotential_dintnl(), dhardPotential_dintnl(), dyieldFunction_dintnl(), and returnMap().

◆ df_dsig()

RankTwoTensor TensorMechanicsPlasticMeanCapTC::df_dsig	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

protected

Derivative of the yield function with respect to stress.

This is also the flow potential.

Parameters

stress	the stress at which to calculate the hardening potentials
intnl	internal parameter

Returns: the derivative

Definition at line 110 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   if (tr >= t_str)
     return stress.dtrace();
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return -stress.dtrace();
  
   return -std::cos(libMesh::pi * (tr - c_str) / (t_str - c_str)) * stress.dtrace();
 }

Referenced by dyieldFunction_dstress(), and flowPotential().

◆ dflowPotential_dintnl()

RankTwoTensor TensorMechanicsPlasticMeanCapTC::dflowPotential_dintnl	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The derivative of the flow potential with respect to the internal parameter.

Parameters

stress	the stress at which to calculate the flow potential
intnl	internal parameter

Returns: dr_dintnl(i, j) = dr(i, j)/dintnl

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 148 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   if (tr >= t_str)
     return RankTwoTensor();
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return RankTwoTensor();
  
   const Real dt = dtensile_strength(intnl);
   const Real dc = dcompressive_strength(intnl);
   return std::sin(libMesh::pi * (tr - c_str) / (t_str - c_str)) * stress.dtrace() * libMesh::pi /
          Utility::pow<2>(t_str - c_str) * ((tr - t_str) * dc - (tr - c_str) * dt);
 }

◆ dflowPotential_dintnlV()

void TensorMechanicsPlasticModel::dflowPotential_dintnlV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< RankTwoTensor > &	dr_dintnl
	)		const

virtualinherited

The derivative of the flow potential with respect to the internal parameter.

Parameters

	stress	the stress at which to calculate the flow potential
	intnl	internal parameter
[out]	dr_dintnl	dr_dintnl[alpha](i, j) = dr[alpha](i, j)/dintnl

Reimplemented in TensorMechanicsPlasticMohrCoulombMulti, and TensorMechanicsPlasticTensileMulti.

Definition at line 139 of file TensorMechanicsPlasticModel.C.

 {
   return dr_dintnl.assign(1, dflowPotential_dintnl(stress, intnl));
 }

◆ dflowPotential_dstress()

RankFourTensor TensorMechanicsPlasticMeanCapTC::dflowPotential_dstress	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The derivative of the flow potential with respect to stress.

Parameters

stress	the stress at which to calculate the flow potential
intnl	internal parameter

Returns: dr_dstress(i, j, k, l) = dr(i, j)/dstress(k, l)

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 131 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   if (tr >= t_str)
     return RankFourTensor();
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return RankFourTensor();
  
   return libMesh::pi / (t_str - c_str) * std::sin(libMesh::pi * (tr - c_str) / (t_str - c_str)) *
          stress.dtrace().outerProduct(stress.dtrace());
 }

◆ dflowPotential_dstressV()

void TensorMechanicsPlasticModel::dflowPotential_dstressV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< RankFourTensor > &	dr_dstress
	)		const

virtualinherited

The derivative of the flow potential with respect to stress.

Parameters

	stress	the stress at which to calculate the flow potential
	intnl	internal parameter
[out]	dr_dstress	dr_dstress[alpha](i, j, k, l) = dr[alpha](i, j)/dstress(k, l)

Reimplemented in TensorMechanicsPlasticMohrCoulombMulti, and TensorMechanicsPlasticTensileMulti.

Definition at line 125 of file TensorMechanicsPlasticModel.C.

 {
   return dr_dstress.assign(1, dflowPotential_dstress(stress, intnl));
 }

◆ dhardPotential_dintnl()

Real TensorMechanicsPlasticMeanCapTC::dhardPotential_dintnl	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The derivative of the hardening potential with respect to the internal parameter.

Parameters

stress	the stress at which to calculate the hardening potentials
intnl	internal parameter

Returns: the derivative

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 204 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   if (tr >= t_str)
     return 0.0;
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return 0.0;
  
   const Real dt = dtensile_strength(intnl);
   const Real dc = dcompressive_strength(intnl);
   return -std::sin(libMesh::pi * (tr - c_str) / (t_str - c_str)) * libMesh::pi /
          Utility::pow<2>(t_str - c_str) * ((tr - t_str) * dc - (tr - c_str) * dt);
 }

◆ dhardPotential_dintnlV()

void TensorMechanicsPlasticModel::dhardPotential_dintnlV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< Real > &	dh_dintnl
	)		const

virtualinherited

The derivative of the hardening potential with respect to the internal parameter.

Parameters

	stress	the stress at which to calculate the hardening potentials
	intnl	internal parameter
[out]	dh_dintnl	dh_dintnl[alpha] = dh[alpha]/dintnl

Definition at line 180 of file TensorMechanicsPlasticModel.C.

 {
   dh_dintnl.resize(numberSurfaces(), dhardPotential_dintnl(stress, intnl));
 }

◆ dhardPotential_dstress()

RankTwoTensor TensorMechanicsPlasticMeanCapTC::dhardPotential_dstress	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The derivative of the hardening potential with respect to stress.

Parameters

stress	the stress at which to calculate the hardening potentials
intnl	internal parameter

Returns: dh_dstress(i, j) = dh/dstress(i, j)

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 187 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   if (tr >= t_str)
     return RankTwoTensor();
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return RankTwoTensor();
  
   return -std::sin(libMesh::pi * (tr - c_str) / (t_str - c_str)) * libMesh::pi / (t_str - c_str) *
          stress.dtrace();
 }

◆ dhardPotential_dstressV()

void TensorMechanicsPlasticModel::dhardPotential_dstressV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< RankTwoTensor > &	dh_dstress
	)		const

virtualinherited

The derivative of the hardening potential with respect to stress.

Parameters

	stress	the stress at which to calculate the hardening potentials
	intnl	internal parameter
[out]	dh_dstress	dh_dstress[alpha](i, j) = dh[alpha]/dstress(i, j)

Definition at line 166 of file TensorMechanicsPlasticModel.C.

 {
   dh_dstress.assign(numberSurfaces(), dhardPotential_dstress(stress, intnl));
 }

◆ dtensile_strength()

Real TensorMechanicsPlasticMeanCapTC::dtensile_strength ( const Real internal_param ) const

protectedvirtual

d(tensile strength)/d(internal_param) as a function of residual value, rate, and internal_param

Definition at line 229 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return _strength.derivative(internal_param);
 }

Referenced by consistentTangentOperator(), dflowPotential_dintnl(), dhardPotential_dintnl(), dyieldFunction_dintnl(), and returnMap().

◆ dyieldFunction_dintnl()

Real TensorMechanicsPlasticMeanCapTC::dyieldFunction_dintnl	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The derivative of yield function with respect to the internal parameter.

Parameters

stress	the stress at which to calculate the yield function
intnl	internal parameter

Returns: the derivative

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 90 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   if (tr >= t_str)
     return -dtensile_strength(intnl);
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return dcompressive_strength(intnl);
  
   const Real dt = dtensile_strength(intnl);
   const Real dc = dcompressive_strength(intnl);
   return (dc - dt) / libMesh::pi * std::sin(libMesh::pi * (tr - c_str) / (t_str - c_str)) +
          1.0 / (t_str - c_str) * std::cos(libMesh::pi * (tr - c_str) / (t_str - c_str)) *
              ((tr - c_str) * dt - (tr - t_str) * dc);
 }

◆ dyieldFunction_dintnlV()

void TensorMechanicsPlasticModel::dyieldFunction_dintnlV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< Real > &	df_dintnl
	)		const

virtualinherited

The derivative of yield functions with respect to the internal parameter.

Parameters

	stress	the stress at which to calculate the yield function
	intnl	internal parameter
[out]	df_dintnl	df_dintnl[alpha] = df[alpha]/dintnl

Reimplemented in TensorMechanicsPlasticMohrCoulombMulti, and TensorMechanicsPlasticTensileMulti.

Definition at line 98 of file TensorMechanicsPlasticModel.C.

 {
   return df_dintnl.assign(1, dyieldFunction_dintnl(stress, intnl));
 }

◆ dyieldFunction_dstress()

RankTwoTensor TensorMechanicsPlasticMeanCapTC::dyieldFunction_dstress	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The derivative of yield function with respect to stress.

Parameters

stress	the stress at which to calculate the yield function
intnl	internal parameter

Returns: df_dstress(i, j) = dyieldFunction/dstress(i, j)

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 83 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return df_dsig(stress, intnl);
 }

◆ dyieldFunction_dstressV()

void TensorMechanicsPlasticModel::dyieldFunction_dstressV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< RankTwoTensor > &	df_dstress
	)		const

virtualinherited

The derivative of yield functions with respect to stress.

Parameters

	stress	the stress at which to calculate the yield function
	intnl	internal parameter
[out]	df_dstress	df_dstress[alpha](i, j) = dyieldFunction[alpha]/dstress(i, j)

Reimplemented in TensorMechanicsPlasticMohrCoulombMulti, and TensorMechanicsPlasticTensileMulti.

Definition at line 84 of file TensorMechanicsPlasticModel.C.

 {
   df_dstress.assign(1, dyieldFunction_dstress(stress, intnl));
 }

◆ execute()

void TensorMechanicsPlasticModel::execute ( )

inherited

Definition at line 47 of file TensorMechanicsPlasticModel.C.

48 {

49 }

◆ finalize()

void TensorMechanicsPlasticModel::finalize ( )

inherited

Definition at line 52 of file TensorMechanicsPlasticModel.C.

53 {

54 }

◆ flowPotential()

RankTwoTensor TensorMechanicsPlasticMeanCapTC::flowPotential	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The flow potential.

Parameters

stress	the stress at which to calculate the flow potential
intnl	internal parameter

Returns: the flow potential

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 125 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return df_dsig(stress, intnl);
 }

◆ flowPotentialV()

void TensorMechanicsPlasticModel::flowPotentialV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< RankTwoTensor > &	r
	)		const

virtualinherited

The flow potentials.

Parameters

	stress	the stress at which to calculate the flow potential
	intnl	internal parameter
[out]	r	r[alpha] is the flow potential for the "alpha" yield function

Reimplemented in TensorMechanicsPlasticMohrCoulombMulti, and TensorMechanicsPlasticTensileMulti.

Definition at line 111 of file TensorMechanicsPlasticModel.C.

 {
   return r.assign(1, flowPotential(stress, intnl));
 }

◆ hardPotential()

Real TensorMechanicsPlasticMeanCapTC::hardPotential	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The hardening potential.

Note that it is -1 for stress.trace() > _strength, and +1 for stress.trace() < _c_strength. This implements the idea that tensile failure will cause a massive reduction in compressive strength

Parameters

stress	the stress at which to calculate the hardening potential
intnl	internal parameter

Returns: the hardening potential

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 167 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   // This is the key for this whole class!
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
  
   if (tr >= t_str)
     return -1.0; // this will serve to *increase* the internal parameter (so internal parameter will
                  // be a measure of volumetric strain)
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return 1.0; // this will serve to *decrease* the internal parameter (so internal parameter will
                 // be a measure of volumetric strain)
  
   return std::cos(libMesh::pi * (tr - c_str) /
                   (t_str - c_str)); // this interpolates C2 smoothly between 1 and -1
 }

◆ hardPotentialV()

void TensorMechanicsPlasticModel::hardPotentialV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< Real > &	h
	)		const

virtualinherited

The hardening potential.

Parameters

	stress	the stress at which to calculate the hardening potential
	intnl	internal parameter
[out]	h	h[alpha] is the hardening potential for the "alpha" yield function

Definition at line 152 of file TensorMechanicsPlasticModel.C.

 {
   h.assign(numberSurfaces(), hardPotential(stress, intnl));
 }

◆ initialize()

void TensorMechanicsPlasticModel::initialize ( )

inherited

Definition at line 42 of file TensorMechanicsPlasticModel.C.

43 {

44 }

◆ KuhnTuckerSingleSurface()

bool TensorMechanicsPlasticModel::KuhnTuckerSingleSurface	(	Real	yf,
		Real	dpm,
		Real	dpm_tol
	)		const

inherited

Returns true if the Kuhn-Tucker conditions for the single surface are satisfied.

Parameters

yf	Yield function value
dpm	plastic multiplier
dpm_tol	tolerance on plastic multiplier: viz dpm>-dpm_tol means "dpm is non-negative"

Definition at line 248 of file TensorMechanicsPlasticModel.C.

 {
   return (dpm == 0 && yf <= _f_tol) || (dpm > -dpm_tol && yf <= _f_tol && yf >= -_f_tol);
 }

Referenced by TensorMechanicsPlasticMohrCoulombMulti::KuhnTuckerOK(), TensorMechanicsPlasticTensileMulti::KuhnTuckerOK(), and TensorMechanicsPlasticModel::returnMap().

◆ modelName()

std::string TensorMechanicsPlasticMeanCapTC::modelName ( ) const

overridevirtual

Implements TensorMechanicsPlasticModel.

Definition at line 448 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return "MeanCapTC";
 }

◆ numberSurfaces()

unsigned TensorMechanicsPlasticModel::numberSurfaces ( ) const

virtualinherited

The number of yield surfaces for this plasticity model.

Reimplemented in TensorMechanicsPlasticMohrCoulombMulti, and TensorMechanicsPlasticTensileMulti.

Definition at line 57 of file TensorMechanicsPlasticModel.C.

 {
   return 1;
 }

Referenced by TensorMechanicsPlasticModel::activeConstraints(), TensorMechanicsPlasticModel::dhardPotential_dintnlV(), TensorMechanicsPlasticModel::dhardPotential_dstressV(), TensorMechanicsPlasticModel::hardPotentialV(), and TensorMechanicsPlasticModel::returnMap().

◆ returnMap()

bool TensorMechanicsPlasticMeanCapTC::returnMap	(	const RankTwoTensor &	trial_stress,
		Real	intnl_old,
		const RankFourTensor &	E_ijkl,
		Real	ep_plastic_tolerance,
		RankTwoTensor &	returned_stress,
		Real &	returned_intnl,
		std::vector< Real > &	dpm,
		RankTwoTensor &	delta_dp,
		std::vector< Real > &	yf,
		bool &	trial_stress_inadmissible
	)		const

overridevirtual

Performs a custom return-map.

You may choose to over-ride this in your derived TensorMechanicsPlasticXXXX class, and you may implement the return-map algorithm in any way that suits you. Eg, using a Newton-Raphson approach, or a radial-return, etc. This may also be used as a quick way of ascertaining whether (trial_stress, intnl_old) is in fact admissible.

For over-riding this function, please note the following.

(1) Denoting the return value of the function by "successful_return", the only possible output values should be: (A) trial_stress_inadmissible=false, successful_return=true. That is, (trial_stress, intnl_old) is in fact admissible (in the elastic domain). (B) trial_stress_inadmissible=true, successful_return=false. That is (trial_stress, intnl_old) is inadmissible (outside the yield surface), and you didn't return to the yield surface. (C) trial_stress_inadmissible=true, successful_return=true. That is (trial_stress, intnl_old) is inadmissible (outside the yield surface), but you did return to the yield surface. The default implementation only handles case (A) and (B): it does not attempt to do a return-map algorithm.

(2) you must correctly signal "successful_return" using the return value of this function. Don't assume the calling function will do Kuhn-Tucker checking and so forth!

(3) In cases (A) and (B) you needn't set returned_stress, returned_intnl, delta_dp, or dpm. This is for computational efficiency.

(4) In cases (A) and (B), you MUST place the yield function values at (trial_stress, intnl_old) into yf so the calling function can use this information optimally. You will have already calculated these yield function values, which can be quite expensive, and it's not very optimal for the calling function to have to re-calculate them.

(5) In case (C), you need to set: returned_stress (the returned value of stress) returned_intnl (the returned value of the internal variable) delta_dp (the change in plastic strain) dpm (the plastic multipliers needed to bring about the return) yf (yield function values at the returned configuration)

(Note, if you over-ride returnMap, you will probably want to override consistentTangentOpertor too, otherwise it will default to E_ijkl.)

Parameters

	trial_stress	The trial stress
	intnl_old	Value of the internal parameter
	E_ijkl	Elasticity tensor
	ep_plastic_tolerance	Tolerance defined by the user for the plastic strain
[out]	returned_stress	In case (C): lies on the yield surface after returning and produces the correct plastic strain (normality condition). Otherwise: not defined
[out]	returned_intnl	In case (C): the value of the internal parameter after returning. Otherwise: not defined
[out]	dpm	In case (C): the plastic multipliers needed to bring about the return. Otherwise: not defined
[out]	delta_dp	In case (C): The change in plastic strain induced by the return process. Otherwise: not defined
[out]	yf	In case (C): the yield function at (returned_stress, returned_intnl). Otherwise: the yield function at (trial_stress, intnl_old)
[out]	trial_stress_inadmissible	Should be set to false if the trial_stress is admissible, and true if the trial_stress is inadmissible. This can be used by the calling prorgram

Returns: true if a successful return (or a return-map not needed), false if the trial_stress is inadmissible but the return process failed

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 297 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   if (!(_use_custom_returnMap))
     return TensorMechanicsPlasticModel::returnMap(trial_stress,
                                                   intnl_old,
                                                   E_ijkl,
                                                   ep_plastic_tolerance,
                                                   returned_stress,
                                                   returned_intnl,
                                                   dpm,
                                                   delta_dp,
                                                   yf,
                                                   trial_stress_inadmissible);
  
   yf.resize(1);
  
   Real yf_orig = yieldFunction(trial_stress, intnl_old);
  
   yf[0] = yf_orig;
  
   if (yf_orig < _f_tol)
   {
     // the trial_stress is admissible
     trial_stress_inadmissible = false;
     return true;
   }
  
   trial_stress_inadmissible = true;
  
   // In the following we want to solve
   // trial_stress - stress = E_ijkl * dpm * r   ...... (1)
   // and either
   // stress.trace() = tensile_strength(intnl)  ...... (2a)
   // intnl = intnl_old + dpm                   ...... (3a)
   // or
   // stress.trace() = compressive_strength(intnl) ... (2b)
   // intnl = intnl_old - dpm                   ...... (3b)
   // The former (2a and 3a) are chosen if
   // trial_stress.trace() > tensile_strength(intnl_old)
   // while the latter (2b and 3b) are chosen if
   // trial_stress.trace() < compressive_strength(intnl_old)
   // The variables we want to solve for are stress, dpm
   // and intnl.  We do this using a Newton approach, starting
   // with stress=trial_stress and intnl=intnl_old and dpm=0
   const bool tensile_failure = (trial_stress.trace() >= tensile_strength(intnl_old));
   const Real dirn = (tensile_failure ? 1.0 : -1.0);
  
   RankTwoTensor n; // flow direction, which is E_ijkl * r
   for (unsigned i = 0; i < 3; ++i)
     for (unsigned j = 0; j < 3; ++j)
       for (unsigned k = 0; k < 3; ++k)
         n(i, j) += dirn * E_ijkl(i, j, k, k);
   const Real n_trace = n.trace();
  
   // Perform a Newton-Raphson to find dpm when
   // residual = trial_stress.trace() - tensile_strength(intnl) - dpm * n.trace()  [for
   // tensile_failure=true]
   // or
   // residual = trial_stress.trace() - compressive_strength(intnl) - dpm * n.trace()  [for
   // tensile_failure=false]
   Real trial_trace = trial_stress.trace();
   Real residual;
   Real jac;
   dpm[0] = 0;
   unsigned int iter = 0;
   do
   {
     if (tensile_failure)
     {
       residual = trial_trace - tensile_strength(intnl_old + dpm[0]) - dpm[0] * n_trace;
       jac = -dtensile_strength(intnl_old + dpm[0]) - n_trace;
     }
     else
     {
       residual = trial_trace - compressive_strength(intnl_old - dpm[0]) - dpm[0] * n_trace;
       jac = -dcompressive_strength(intnl_old - dpm[0]) - n_trace;
     }
     dpm[0] += -residual / jac;
     if (iter > _max_iters) // not converging
       return false;
     iter++;
   } while (residual * residual > _f_tol * _f_tol);
  
   // set the returned values
   yf[0] = 0;
   returned_intnl = intnl_old + dirn * dpm[0];
   returned_stress = trial_stress - dpm[0] * n;
   delta_dp = dpm[0] * dirn * returned_stress.dtrace();
  
   return true;
 }

◆ tensile_strength()

Real TensorMechanicsPlasticMeanCapTC::tensile_strength ( const Real internal_param ) const

protectedvirtual

tensile strength as a function of residual value, rate, and internal_param

Definition at line 223 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return _strength.value(internal_param);
 }

Referenced by activeConstraints(), consistentTangentOperator(), df_dsig(), dflowPotential_dintnl(), dflowPotential_dstress(), dhardPotential_dintnl(), dhardPotential_dstress(), dyieldFunction_dintnl(), hardPotential(), returnMap(), and yieldFunction().

◆ useCustomCTO()

bool TensorMechanicsPlasticMeanCapTC::useCustomCTO ( ) const

overridevirtual

Returns false. You will want to override this in your derived class if you write a custom consistent tangent operator function.

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 442 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return _use_custom_cto;
 }

◆ useCustomReturnMap()

bool TensorMechanicsPlasticMeanCapTC::useCustomReturnMap ( ) const

overridevirtual

Returns false. You will want to override this in your derived class if you write a custom returnMap function.

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 436 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   return _use_custom_returnMap;
 }

◆ validParams()

InputParameters TensorMechanicsPlasticMeanCapTC::validParams ( )

static

Definition at line 19 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   InputParameters params = TensorMechanicsPlasticModel::validParams();
   params.addRangeCheckedParam<unsigned>("max_iterations",
                                         10,
                                         "max_iterations>0",
                                         "Maximum iterations for custom MeanCapTC return map");
   params.addParam<bool>(
       "use_custom_returnMap", true, "Whether to use the custom MeanCapTC returnMap algorithm.");
   params.addParam<bool>("use_custom_cto",
                         true,
                         "Whether to use the custom consistent tangent operator computations.");
   params.addRequiredParam<UserObjectName>("tensile_strength",
                                           "A TensorMechanicsHardening UserObject that defines "
                                           "hardening of the mean-cap tensile strength (it will "
                                           "typically be positive).  Yield function = trace(stress) "
                                           "- tensile_strength for trace(stress)>tensile_strength.");
   params.addRequiredParam<UserObjectName>(
       "compressive_strength",
       "A TensorMechanicsHardening UserObject that defines hardening of the "
       "mean-cap compressive strength.  This should always be less than "
       "tensile_strength (it will typically be negative).  Yield function = "
       "- (trace(stress) - compressive_strength) for "
       "trace(stress)<compressive_strength.");
   params.addClassDescription(
       "Associative mean-cap tensile and compressive plasticity with hardening/softening");
  
   return params;
 }

◆ yieldFunction()

Real TensorMechanicsPlasticMeanCapTC::yieldFunction	(	const RankTwoTensor &	stress,
		Real	intnl
	)		const

overrideprotectedvirtual

The following functions are what you should override when building single-plasticity models.

The yield function

Parameters

stress	the stress at which to calculate the yield function
intnl	internal parameter

Returns: the yield function

Reimplemented from TensorMechanicsPlasticModel.

Definition at line 65 of file TensorMechanicsPlasticMeanCapTC.C.

 {
   const Real tr = stress.trace();
   const Real t_str = tensile_strength(intnl);
   if (tr >= t_str)
     return tr - t_str;
  
   const Real c_str = compressive_strength(intnl);
   if (tr <= c_str)
     return -(tr - c_str);
   // the following is zero at tr = t_str, and at tr = c_str
   // it also has derivative = 1 at tr = t_str, and derivative = -1 at tr = c_str
   // it also has second derivative = 0, at these points.
   // This makes the complete yield function C2 continuous.
   return (c_str - t_str) / libMesh::pi * std::sin(libMesh::pi * (tr - c_str) / (t_str - c_str));
 }

Referenced by returnMap().

◆ yieldFunctionV()

void TensorMechanicsPlasticModel::yieldFunctionV	(	const RankTwoTensor &	stress,
		Real	intnl,
		std::vector< Real > &	f
	)		const

virtualinherited

Calculates the yield functions.

Note that for single-surface plasticity you don't want to override this - override the private yieldFunction below

Parameters

	stress	the stress at which to calculate the yield function
	intnl	internal parameter
[out]	f	the yield functions

Reimplemented in TensorMechanicsPlasticMohrCoulombMulti, and TensorMechanicsPlasticTensileMulti.

Definition at line 69 of file TensorMechanicsPlasticModel.C.

 {
   f.assign(1, yieldFunction(stress, intnl));
 }

Referenced by TensorMechanicsPlasticModel::returnMap().

Member Data Documentation

◆ _c_strength

const TensorMechanicsHardeningModel& TensorMechanicsPlasticMeanCapTC::_c_strength

protected

the compressive strength

Definition at line 82 of file TensorMechanicsPlasticMeanCapTC.h.

Referenced by compressive_strength(), dcompressive_strength(), and TensorMechanicsPlasticMeanCapTC().

◆ _f_tol

const Real TensorMechanicsPlasticModel::_f_tol

inherited

Tolerance on yield function.

Definition at line 175 of file TensorMechanicsPlasticModel.h.

◆ _ic_tol

const Real TensorMechanicsPlasticModel::_ic_tol

inherited

Tolerance on internal constraint.

Definition at line 178 of file TensorMechanicsPlasticModel.h.

◆ _max_iters

const unsigned TensorMechanicsPlasticMeanCapTC::_max_iters

protected

max iters for custom return map loop

Definition at line 70 of file TensorMechanicsPlasticMeanCapTC.h.

Referenced by returnMap().

◆ _strength

const TensorMechanicsHardeningModel& TensorMechanicsPlasticMeanCapTC::_strength

protected

the tensile strength

Definition at line 79 of file TensorMechanicsPlasticMeanCapTC.h.

Referenced by dtensile_strength(), tensile_strength(), and TensorMechanicsPlasticMeanCapTC().

◆ _use_custom_cto

const bool TensorMechanicsPlasticMeanCapTC::_use_custom_cto

protected

Whether to use the custom consistent tangent operator algorithm.

Definition at line 76 of file TensorMechanicsPlasticMeanCapTC.h.

Referenced by consistentTangentOperator(), and useCustomCTO().

◆ _use_custom_returnMap

const bool TensorMechanicsPlasticMeanCapTC::_use_custom_returnMap

protected

Whether to use the custom return-map algorithm.

Definition at line 73 of file TensorMechanicsPlasticMeanCapTC.h.

Referenced by returnMap(), and useCustomReturnMap().

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

tensor_mechanics/include/userobjects/TensorMechanicsPlasticMeanCapTC.h
tensor_mechanics/src/userobjects/TensorMechanicsPlasticMeanCapTC.C

Public Member Functions

Static Public Member Functions

Public Attributes

Protected Member Functions

Protected Attributes

Detailed Description

Constructor & Destructor Documentation

◆ TensorMechanicsPlasticMeanCapTC()

Member Function Documentation

◆ activeConstraints()

◆ compressive_strength()

◆ consistentTangentOperator()

◆ dcompressive_strength()

◆ df_dsig()

◆ dflowPotential_dintnl()

◆ dflowPotential_dintnlV()

◆ dflowPotential_dstress()

◆ dflowPotential_dstressV()

◆ dhardPotential_dintnl()

◆ dhardPotential_dintnlV()

◆ dhardPotential_dstress()

◆ dhardPotential_dstressV()

◆ dtensile_strength()

◆ dyieldFunction_dintnl()

◆ dyieldFunction_dintnlV()

◆ dyieldFunction_dstress()

◆ dyieldFunction_dstressV()

◆ execute()

◆ finalize()

◆ flowPotential()

◆ flowPotentialV()

◆ hardPotential()

◆ hardPotentialV()

◆ initialize()

◆ KuhnTuckerSingleSurface()

◆ modelName()

◆ numberSurfaces()

◆ returnMap()

◆ tensile_strength()

◆ useCustomCTO()

◆ useCustomReturnMap()

◆ validParams()

◆ yieldFunction()

◆ yieldFunctionV()

Member Data Documentation

◆ _c_strength

◆ _f_tol

◆ _ic_tol

◆ _max_iters

◆ _strength

◆ _use_custom_cto

◆ _use_custom_returnMap