chrono::ChStaticNonLinearRheonomicAnalysis Class Reference

## Description

Nonlinear static analysis for a mechanism that is rotating/moving in steady state.

If SetAutomaticSpeedAndAccelerationComputation(true), the rotation/movement, if any, is automaticlally assigned via rheonomic constraints. Example, an elastic turbine blade that rotates via a ChLinkMotorRotationAngle: the motor will impose a steady state rotation that creates centrifugal forces, so the analysis will generate an elongated blade (the ChStaticNonLinearAnalysis cannot capture centrifugal and gyroscopical effects because it resets all speeds/acceleration to zero during its iteration). WARNING at the moment this is ok only for undeformed finite elements! If SetAutomaticSpeedAndAccelerationComputation(false), it is up to you to provide an iteration callback that keeps the speeds and accelerations updated as needed.

#include <ChStaticAnalysis.h>

Inheritance diagram for chrono::ChStaticNonLinearRheonomicAnalysis:
Collaboration diagram for chrono::ChStaticNonLinearRheonomicAnalysis:

## Classes

class  IterationCallback
Class to be used as a callback interface for updating the system at each iteration, for example for incrementing the load or for updating the speeds and accelerations of the parts. More...

## Public Member Functions

ChStaticNonLinearRheonomicAnalysis (ChIntegrableIIorder &integrable)

virtual void StaticAnalysis () override
Performs the static analysis, doing a non-linear solve.

void SetVerbose (bool verbose)
Enable/disable verbose output (default: false)

void SetMaxIterations (int max_iters)
Set the max number of iterations for the Newton Raphson procedure (default: 10).

void SetIncrementalSteps (int incr_steps)
Set the number of steps that, for the first iterations, make the residual grow linearly (default: 6). More...

void SetCorrectionTolerance (double reltol, double abstol)
Set stopping criteria based on WRMS norm of correction and the specified relative and absolute tolerances. More...

void SetResidualTolerance (double tol)
Set stopping criteria based on norm of residual and the specified tolerance. More...

int GetMaxIterations () const
Get the max number of iterations for the Newton Raphson procedure.

int GetIncrementalSteps () const
Set the number of steps that, for the first iterations, make the residual grow linearly.

void SetCallbackIterationBegin (std::shared_ptr< IterationCallback > my_callback)
Set the callback to be called at each iteration.

void SetAutomaticSpeedAndAccelerationComputation (bool mv)
If enabled, the algorithm automatically computes the speed and accelerations of the system by using the rheonomic constraints. More...

Public Member Functions inherited from chrono::ChStaticAnalysis
ChStaticAnalysis (ChIntegrableIIorder &integrable)

ChIntegrableGetIntegrable ()
Get the integrable object.

const ChStateGetX () const
Access the state, position part, at current analysis.

const ChVectorDynamicGetL () const
Access the Lagrange multipliers, if any.

Protected Attributes inherited from chrono::ChStaticAnalysis
ChIntegrableIIorderm_integrable

ChState X

ChVectorDynamic L

## ◆ SetAutomaticSpeedAndAccelerationComputation()

 void chrono::ChStaticNonLinearRheonomicAnalysis::SetAutomaticSpeedAndAccelerationComputation ( bool mv )
inline

If enabled, the algorithm automatically computes the speed and accelerations of the system by using the rheonomic constraints.

WARNING!!! this is working only for non-stretched finite elements at the moment! If not enabled, as by default, you can use an IterationCallback to update the speeds and accelerations using your c++ code.

## ◆ SetCorrectionTolerance()

 void chrono::ChStaticNonLinearRheonomicAnalysis::SetCorrectionTolerance ( double reltol, double abstol )

Set stopping criteria based on WRMS norm of correction and the specified relative and absolute tolerances.

This is the default, with reltol = 1e-4, abstol = 1e-8. The Newton Raphson procedure is stopped if the WRMS norm of the correction vector (based on the current state) is less than 1.

## ◆ SetIncrementalSteps()

 void chrono::ChStaticNonLinearRheonomicAnalysis::SetIncrementalSteps ( int incr_steps )

Set the number of steps that, for the first iterations, make the residual grow linearly (default: 6).

If =0, no incremental application of residual, so it is a classic Newton Raphson iteration, otherwise acts as a continuation strategy. For values > 0 , it might help convergence. Must be less than maxiters.

## ◆ SetResidualTolerance()

 void chrono::ChStaticNonLinearRheonomicAnalysis::SetResidualTolerance ( double tol )

Set stopping criteria based on norm of residual and the specified tolerance.

The Newton Raphson is stopped when the infinity norm of the residual is below the tolerance.

The documentation for this class was generated from the following files:
• /builds/uwsbel/chrono/src/chrono/timestepper/ChStaticAnalysis.h
• /builds/uwsbel/chrono/src/chrono/timestepper/ChStaticAnalysis.cpp