Managing N.-R. Iterations
Mechanical iterations parameters are imposed by functions associated to metafor.getMechanicalIterationManager(), when thermal iterations parameters are imposed by functions associated to metafor.getThermalIterationManager().
mim = metafor.getMechanicalIterationManager() tim = metafor.getThermalIterationManager() mim/tim.setResidualComputationMethod(meth) mim/tim.setVerbose() mim/tim.setResidualTolerance(prec) mim/tim.setMaxNbOfIterations(itma) mim/tim.setNbOfIterationsForStiffUpdate(irea) mim/tim.setMaxNbOfLineSearchIterations(lsma) mim/tim.setLineSearchTolerance1(lsp1) mim/tim.setLineSearchTolerance2(lsp2) mim.setPredictorComputationMethod(predMeth) mim.setConstrainedDofsVAComputationMethod(VACMeth) mim/tim.setPreviousResidualsDecreaseCriterion() mim/tim.setCpuDependency(cpuDep) mim/tim.setForceOneIte(bool)
where meth defines the method used to compute the $Residual$.
Method1ResidualComputation(limitNormFactor)
The residual is adimensionalized by the norm of external forces and internal reactions . First :
$$Rmin = \frac{||FreeExternalForces|| + ||CstrInternalForces||+||CstrInertialForces||}{nreac} $$
If $$ Rmin < limitNormFactor $$
$Rmin$ is set to $$ Rmin = limitNormFactor $$
and the residual is adimensionalized :
$$Residual = \frac{||FreeResidual||}{ndofs*Rmin}$$
where
$ndofs$ : total number of degrees of freedom
$nreac$ : number of fixed degrees of freedom (having an associated reaction)
Method2ResidualComputation(limitNormFactor)
The residual is adimensionalized by the square of the norm of external forces and internal reactions. First:
$$Rmin = \frac{\sqrt{||FreeExternalForces||^2 + ||CstrInternalForces||^2+||CstrInertialForces||^2}}{nreac}$$
If $$ Rmin < limitNormFactor $$ then $$ Rmin = limitNormFactor $$
and the residual is adimensionalized :
$$Residual = \frac{||FreeResidual||}{ndofs*Rmin}$$
where
$ndofs$ : total number of degrees of freedom
$nreac$ : number of fixed degrees of freedom (having an associated reaction)
Method3ResidualComputation(limitNormFactor)
The residual is adimensionalized by the norm of external and inertial forces, and internal reactions (value to use preferentially for thermal simulations. Careful, the user must define it).
If $$ ||FreeExternalForces|| < limitNormFactor $$ then $$ Residual = max(|FreeResidual|) $$ Else, $$Rmin = ||FreeExternalForces|| + ||CstrInternalForces||+||CstrInertialForces|| $$ and $$Residual = \frac{||FreeResidual||}{ndofs*Rmin}$$
Method4ResidualComputation(limitNormFactor) (**default value**)
This method is the same as Method1ResidualComputation() but without dividing by the number of dofs nor nreac, so
$$Rmin = ||FreeExternalForces|| + ||CstrInternalForces||+||CstrInertialForces|| $$
If $$ Rmin < limitNormFactor$$ then $$ Rmin = limitNormFactor $$
and the residual is adimensionalized :
$$Residual = \frac{||FreeResidual||}{Rmin}$$
Method5ResidualComputation(adimFactor)
The residual is adimensionalized by the factor adimFactor, given by the user, without dividing by the number of dofs.
$$Residual = \frac{||FreeResidual||}{adimFactor }$$
Method6ResidualComputation(adimFactor)
The residual is adimensionalized by the factor adimFactor, given by the user, and by the number of dofs.
$$Residual = \frac{||FreeResidual||}{ndofs * adimFactor }$$
where
$ndofs$ : total number of dofs
Parameters
| Parameter | Default value | Description |
|---|---|---|
limitNormFactor | 1.0 | Value from which the residual is no longer divided by $$Rmin$$ (to adjust as a function of the loading using verbose output) |
adimFactor | - | Fixed adimensionalization factor for methods #5 and 6 (no default value, the factor must be defined for these methods) |
prec | 1.0E-4 | accuracy that the residual must reach |
itma | 7 | maximal number of Newton-Raphson iterations (this number if corrected internally if the automatic criterion is used to update the matrix). Iterations are stopped if the residual does not decrease over 6 iterations |
irea | 1 | = 1 : stiffness matrix updated for each iteration |
> 1 : stiffness matrix is updated automatically if the iteration number is lower than irea. The criterion is based on a convergence speed and a CPU time ratio (requires MDE_ICPU=1) |
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lsma | 0 | maximal line-search iteration number |
lsp1 | 1.0 | accuracy that the line-search residual must reach |
lsp2 | 1.E-8 | stop criterion when the line search parameter is not updated enough |
predMeth | EXTRAPOLATION_DEFAULT | EXTRAPOLATION_DEFAULT = Extrapolation of the scheme by default (for example method to compute the displacement predictor by Newmark formula in the case of alpha-generalized scheme) |
EXTRAPOLATION_MRUA = method to compute the displacement predictor by MRUA formula (for now only possible for alpha-generalized algorithms) |
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EXTRAPOLATION_ZERO = New positions are equal to the old ones, speed (and acceleration for dynamic schemes) equal to zero (for now only possible for quasi-static algorithms and alpha-generalized algorithms) . |
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VACMeth | VAC_SCHEMECONSISTANT | VAC_SCHEMECONSISTANT : Calculation of speed and acceleration with Newmark formula |
VAC_BACKWARDEULER : Calculation of speed and acceleration using Backward Euler (to stabilize Newmark with dofs with a non zero fixed displacement. See JPP's thesis pg VIII.28) |
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cpuDep | False | Specify if the criterion for updating the stiffness matrix (irea > 1) depends on the User CPU time. (Metafor Version > 2422). |
forceOneIte | False | If True, Force the resolution of at least one iteration (mechanical or thermal according to the iteration manager even if the tolerance is allready met at iteration 0. |