Description

Implementation of the HHT implicit integrator for II order systems.

This timestepper allows use of an adaptive time-step, as well as optional use of a modified Newton scheme for the solution of the resulting nonlinear problem.

#include <ChTimestepperHHT.h>

Inheritance diagram for chrono::ChTimestepperHHT:

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Collaboration diagram for chrono::ChTimestepperHHT:

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Public Member Functions
	ChTimestepperHHT (ChIntegrableIIorder *intgr=nullptr)

virtual Type	GetType () const override
	Return type of the integration method.

void	SetAlpha (double val)
	Set the numerical damping parameter (in the [-1/3, 0] range). More...

double	GetAlpha ()
	Return the current value of the method parameter alpha.

void	SetStepControl (bool enable)
	Turn on/off the internal step size control. More...

void	SetMinStepSize (double step)
	Set the minimum step size. More...

void	SetMaxItersSuccess (int iters)
	Set the maximum allowable number of iterations for counting a step towards a stepsize increase. More...

void	SetRequiredSuccessfulSteps (int num_steps)
	Set the minimum number of (internal) steps that use at most maxiters_success before considering a stepsize increase. More...

void	SetStepIncreaseFactor (double factor)
	Set the multiplicative factor for a stepsize increase (must be larger than 1). More...

void	SetStepDecreaseFactor (double factor)
	Set the multiplicative factor for a stepsize decrease (must be smaller than 1). More...

void	SetModifiedNewton (bool enable)
	Enable/disable modified Newton. More...

virtual void	Advance (const double dt) override
	Perform an integration timestep, by advancing the state by the specified time step.

double	GetEstimatedConvergenceRate () const
	Get the last estimated convergence rate for the internal Newton solver. More...

virtual void	ArchiveOut (ChArchiveOut &archive) override
	Method to allow serialization of transient data to archives.

virtual void	ArchiveIn (ChArchiveIn &archive) override
	Method to allow de-serialization of transient data from archives.

Public Member Functions inherited from chrono::ChTimestepperIIorder
	ChTimestepperIIorder (ChIntegrableIIorder *intgr=nullptr)
	Constructor.

virtual	~ChTimestepperIIorder ()
	Destructor.

virtual ChState &	GetStatePos ()
	Access the state, position part, at current time.

virtual ChStateDelta &	GetStateVel ()
	Access the state, speed part, at current time.

virtual ChStateDelta &	GetStateAcc ()
	Access the acceleration, at current time.

virtual void	SetIntegrable (ChIntegrableIIorder *intgr)
	Set the integrable object.

Public Member Functions inherited from chrono::ChTimestepper
	ChTimestepper (ChIntegrable *intgr=nullptr)
	Constructor.

virtual	~ChTimestepper ()
	Destructor.

virtual ChVectorDynamic &	GetLagrangeMultipliers ()
	Access the lagrangian multipliers, if any.

virtual void	SetIntegrable (ChIntegrable *intgr)
	Set the integrable object.

ChIntegrable *	GetIntegrable ()
	Get the integrable object.

virtual double	GetTime () const
	Get the current time.

virtual void	SetTime (double mt)
	Set the current time.

void	SetVerbose (bool verb)
	Turn on/off logging of messages.

Public Member Functions inherited from chrono::ChImplicitIterativeTimestepper
void	SetMaxIters (int iters)
	Set the max number of iterations using the Newton Raphson procedure.

double	GetMaxIters ()
	Get the max number of iterations using the Newton Raphson procedure.

void	SetRelTolerance (double rel_tol)
	Set the relative tolerance. More...

void	SetAbsTolerances (double abs_tolS, double abs_tolL)
	Set the absolute tolerances. More...

void	SetAbsTolerances (double abs_tol)
	Set the absolute tolerances. More...

unsigned int	GetNumIterations () const
	Return the number of iterations.

unsigned int	GetNumSetupCalls () const
	Return the number of calls to the solver's Setup function.

unsigned int	GetNumSolveCalls () const
	Return the number of calls to the solver's Solve function.

Additional Inherited Members
Public Types inherited from chrono::ChTimestepper
enum	Type { EULER_IMPLICIT_LINEARIZED, EULER_IMPLICIT_PROJECTED, EULER_IMPLICIT, TRAPEZOIDAL, TRAPEZOIDAL_LINEARIZED, HHT, HEUN, RUNGEKUTTA45, EULER_EXPLICIT, LEAPFROG, NEWMARK, CUSTOM }
	Available methods for time integration (time steppers).

Static Public Member Functions inherited from chrono::ChTimestepper
static std::string	GetTypeAsString (Type type)
	Return the integrator type as a string.

Protected Attributes inherited from chrono::ChTimestepperIIorder
ChState	X

ChStateDelta	V

ChStateDelta	A

Protected Attributes inherited from chrono::ChTimestepper
ChIntegrable *	integrable

double	T

ChVectorDynamic	L

bool	verbose

bool	Qc_do_clamp

double	Qc_clamping

Protected Attributes inherited from chrono::ChImplicitIterativeTimestepper
unsigned int	maxiters
	maximum number of iterations

double	reltol
	relative tolerance

double	abstolS
	absolute tolerance (states)

double	abstolL
	absolute tolerance (Lagrange multipliers)

unsigned int	numiters
	number of iterations

unsigned int	numsetups
	number of calls to the solver's Setup function

unsigned int	numsolves
	number of calls to the solver's Solve function

Member Function Documentation

◆ GetEstimatedConvergenceRate()

double chrono::ChTimestepperHHT::GetEstimatedConvergenceRate ( ) const

inline

Get the last estimated convergence rate for the internal Newton solver.

Note that an estimate can only be calculated after the 3rd iteration. For the first 2 iterations, the convergence rate estimate is set to 1.

◆ SetAlpha()

void chrono::ChTimestepperHHT::SetAlpha ( double val )

Set the numerical damping parameter (in the [-1/3, 0] range).

The closer to -1/3, the more damping. The closer to 0, the less damping (for 0, it is the trapezoidal method). The method coefficients gamma and beta are set automatically, based on alpha. Default: -0.2.

◆ SetMaxItersSuccess()

void chrono::ChTimestepperHHT::SetMaxItersSuccess ( int iters )

inline

Set the maximum allowable number of iterations for counting a step towards a stepsize increase.

Default: 3.

◆ SetMinStepSize()

void chrono::ChTimestepperHHT::SetMinStepSize ( double step )

inline

Set the minimum step size.

An exception is thrown if the internal step size decreases below this limit. Default: 1e-10.

◆ SetModifiedNewton()

void chrono::ChTimestepperHHT::SetModifiedNewton ( bool enable )

inline

Enable/disable modified Newton.

If enabled, the Newton matrix is evaluated, assembled, and factorized only once per step or if the Newton iteration does not converge with an out-of-date matrix. If disabled, the Newton matrix is evaluated at every iteration of the nonlinear solver. Default: true.

◆ SetRequiredSuccessfulSteps()

void chrono::ChTimestepperHHT::SetRequiredSuccessfulSteps ( int num_steps )

inline

Set the minimum number of (internal) steps that use at most maxiters_success before considering a stepsize increase.

Default: 5.

◆ SetStepControl()

void chrono::ChTimestepperHHT::SetStepControl ( bool enable )

inline

Turn on/off the internal step size control.

Default: true.

◆ SetStepDecreaseFactor()

void chrono::ChTimestepperHHT::SetStepDecreaseFactor ( double factor )

inline

Set the multiplicative factor for a stepsize decrease (must be smaller than 1).

Default: 0.5.

◆ SetStepIncreaseFactor()

void chrono::ChTimestepperHHT::SetStepIncreaseFactor ( double factor )

inline

Set the multiplicative factor for a stepsize increase (must be larger than 1).

Default: 2.

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

/builds/uwsbel/chrono/src/chrono/timestepper/ChTimestepperHHT.h
/builds/uwsbel/chrono/src/chrono/timestepper/ChTimestepperHHT.cpp

Description

Public Member Functions

Additional Inherited Members

Member Function Documentation

◆ GetEstimatedConvergenceRate()

◆ SetAlpha()

◆ SetMaxItersSuccess()

◆ SetMinStepSize()

◆ SetModifiedNewton()

◆ SetRequiredSuccessfulSteps()

◆ SetStepControl()

◆ SetStepDecreaseFactor()

◆ SetStepIncreaseFactor()