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--- doc:user:integration:general:mim_tim [2013/07/12 15:26] – joris
+++ doc:user:integration:general:mim_tim [2017/06/16 17:50] – papeleux
@@ Line 1: / Line 1: @@
+====== 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)
+where ''meth'' defines the method used to compute the $Residual$.
+=== Method1ResidualComputation(limitNormFactor) ===
+<note important>important : since revision 2946 Method1ResidualComputation is **not anymore** the default value</note>
+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**) ===
+<note important>important : since revision 2946 Method4ResidualComputation is the new **default value**</note>
+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'')|
+| ''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  [[doc:user:integration:scheme:dynimpl#la_famille_alpha-generalisee|alpha-generalized scheme]])  |
+|              |                        | ''EXTRAPOLATION_MRUA'' = method to compute the displacement predictor by MRUA formula (for now only possible for [[doc:user:integration:scheme:dynimpl#la_famille_alpha-generalisee|alpha-generalized algorithms]]) |
+|              |                        | ''EXTRAPOLATION_ZERO'' = New positions are equal to the old ones, speed (and acceleration for dynamic schemes) equal to zero (for now only possible for  [[doc:user:integration:scheme:quasistatique|quasi-static algorithms]] and [[doc:user:integration:scheme:dynimpl#la_famille_alpha-generalisee|alpha-generalized algorithms]]) . |
+| ''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) |
+| ''cpuDep'' | ''False'' | Specify if the criterion for updating the stiffness matrix (irea > 1) depends on the User CPU time. (Metafor Version > 2422). |