Solution Step dialog box (Simcenter Samcef Structure Nonlinear Analysis)

Solution
Name	Sets a name for the step.
Solver TypeAnalysis TypeSolution	Displays the solver, analysis, and solution type of the parent solution.
Step	Specifies the type of step to create.
Steps to Create	Sets the number of steps to create.
Relative Position	Specifies the position of this step in the Simulation Navigator (relative to the other steps in this solution) and the sequence in which it is processed during the solve.
Properties
Description	Sets a description for the solution step. Click Description to open an editor that lets you type or paste a longer description.
Subcase Analysis Type
Analysis Type (.SUB MECA)	Specifies the type of subcase time response to perform:DynamicAll the inertia, damping, and friction data are taken into account.KinematicThe velocity-dependent phenomena (such as friction or viscous damping) are taken into account, but the inertia forces are omitted.StaticAll the inertia, damping, and friction data are omitted.For more information, see the MECA parameter of the Samcef .SUBCASE command.
Boundary Condition Control Variables
Evaluation Time	Lets you define the time at which the loads will be evaluated for the Mechanical Loads Summary.

Time page

Properties
Subcase Definition (.SUB TYPE)	Specifies whether the subcase depends on time.Time DependentThe subcase time begins with the end time of the previous subcase and continues to increment.Load IncrementThe subcase time begins with the end time of the previous subcase. Time, load, and temperature remain constant, and no time options are taken into account. This is useful when enabling or disabling contact elements or special elements, or when preloading a bolt.For more information, see Structural nonlinear solution step (Simcenter Samcef) and the NCAS parameter of the Samcef .SUBCASE command.
Number of Load Increment (.SUB NCAS)	Appears when Subcase Definition (.SUB TYPE) is set to Load Increment.Sets the load increment you want this subcase to use.
Initial Subcase State (.SUB RSUB)	Specifies the subcase to use as a starting point for the current subcase.End Of Previous SubcaseUses the starting state of the subcase that precedes the one you are creating.**Initial Time (After Initial Static Computation if Defined)**Does not use a computation state from a previous subcase for its starting state.End of Specified SubcaseLets you enter the number of the subcase you want to use as the starting state.For more information, see Structural nonlinear solution step (Simcenter Samcef) and the RSUB parameter of the Samcef .SUBCASE command.
Specified Subcase	Appears when Initial Subcase State (.SUB RSUB) is set to End Of Specified Subcase.Sets the number of the subcase to use to set the initial state of the subcase you are creating. The ending time and boundary condition values of this subcase are used as the initial state of the new subcase.
Time Interval
From****To	Sets the starting and ending computation time for the step.For more information, see the T1, T2 or TIMP, A sets of parameters of the Samcef .SUBCASE command.
Imposed Time Step
Imposed Time Step	When the Automatic Time Step check box is selected, selecting this check box manually adds a time step mode to the automatic scheme. By adding a time step, you can force the solver to compute results for some specific times.When the Automatic Time Step check box is cleared, selecting this check box lets you manually impose your own time step value, or you can select the Number of Timesteps check box to impose the number of time steps. For more information, see the PAS parameter of the Samcef .SUBCASE command.
Imposed Time Step Value	Appears when the Imposed Time Step check box is selected.Sets the time step value. The nonlinear solver uses this time step value except when solving iterations requires a lower value to ensure convergence.For more information, see the PAS parameter of the Samcef .SUBCASE command.
Automatic Time Step
Automatic Time Step	Select this check box to let Samcef handle time steps automatically, or clear it to manually impose time steps.For more information, see the CIBL parameter of the Samcef .SUBCASE command.
Minimal Time Step****Maximal Time Step	Appears when the Automatic Time Step check box is selected.Sets the allowable range for the time step when running the automatic time step computation.Depending on the computation workflow, the nonlinear solver can automatically modify at any iteration the value of the time step, but always in the given range.For more information, see the HMIN and HMAX parameters of the Samcef .SUBCASE command.
Initial Time Step (.SUB DTI0)	Sets the size of the initial time step.When the Automatic Time Step check box is selected, the initial time step is automatically computed from the selected computation times interval. Changing the initial time step can be helpful in a model that fails to converge at the very beginning of the computation. We recommend specifying an initial time step in most situations.For more information, see the DTI0 parameter of the Samcef .SUBCASE command.

Integration Scheme page

Integration Scheme
Time Integration scheme (.SUB IMPL)	Appears when Analysis Type (.SUB MECA) is set to Dynamic.Specifies the integration scheme:NewmarkEnables the Newmark implicit predictor-corrector scheme.Hilber-Hughes-TaylorEnables the Hilber-Hughes-Taylor implicit predictor-corrector scheme.Generalized alphaEnables the generalized alpha scheme.For more information, see the IMPL parameter of the Samcef .SUBCASE command and the integration schema page of the Samcef documentation.
**1st Newmark Parameter (.SUB BETA)**2nd Newmark Parameter (.SUB GAMA)	Appears when Time Integration scheme (.SUB IMPL) is set to Newmark.Sets the two Newmark scheme parameters.For more information, see the BETA and GAMA parameters of the Samcef .SUBCASE command.
Numerical Damping (.SUB ALFA)	Appears when Time Integration scheme (.SUB IMPL) is set to Hilber-Hughes-Taylor.Sets the numerical damping of the Hilber-Hughes-Taylor integration scheme.For more information, see the ALFA parameter of the Samcef .SUBCASE command.
Spectral Radius at Infinity (.SUB TETA)	Appears when Time Integration scheme (.SUB IMPL) is set to Generalized alpha.Sets the spectral radius of the Generalized alpha integration scheme.For more information, see the TETA parameter of the Samcef .SUBCASE command.
Time Integration Error Check (.SUB IMPL)	Enables integration error checks. This is useful only when the Automatic Time Step check box is selected on the Time page.For more information, see the IMPL parameter of the Samcef .SUBCASE command.
Precision Threshold (.SUB PRCO)	Appears when the Time Integration Error Check (.SUB IMPL) check box is selected.Sets the precision threshold.For more information, see the PRCO parameter of the Samcef .SUBCASE command.
Min. Timestep for Precision Threshold (.SUB HPRCO)	Appears when the Time Integration Error Check (.SUB IMPL) check box is selected.Sets the minimum time step value for which integration errors are checked. Any time steps under this value are not checked for integration errors.For more information, see the HPRCO parameter of the Samcef .SUBCASE command.
Time Step Criterion based on Error of Disp. Change (.SUB ERCD)	Lets you activate the time step criterion based on the absolute error of the displacement change.For more information, see the ERCD parameter of the Samcef .SUBCASE command.
The following options appear when the Time Step Criterion based on Error of Disp. Change (.SUB ERCD) check box is selected.
Maximum Displacement Variation (.SUB PRED)	Lets you define the displacement variation level.For more information, see the PRED parameter of the Samcef .SUBCASE command.

Storage page

Storage
Parameters	Specifies how you want to set the extra times at which results must be saved.To select from the list of Storage modeling objects that you defined in other subcases, or to create a new Storage modeling object, select Link.To manually define extra times that are valid only for the current subcase, select Edit.For information on the Storage Time Step, Storage Frequency, Storage State Variable, and Chaining Parameter options, see Storage dialog box (Simcenter Samcef).
Storage	Appears when the Parameters list is set to Link.Specifies the modeling object that contains the set of storage times.To select an existing set, click More Options . The following options are available.FindLets you search for an object by entering the full name of the object.For example, to find a region named ABC_region, type ABC_region in the search box and press Enter or click Find . If the object is found, it will be selected automatically.Filter by NameLets you filter the list by the names of the objects. This filter supports wildcards. The default wildcard is the asterisk (), and it displays all entries in the list.For example, to filter the list to display every object with a name starting with the letter "a," enter a as the filter string.Filter by LabelLets you filter the list by the label of the objects.To create a new set, click Create Modeling Object .

Solver Parameters page

Parameters
Linear Prediction (.SUB DIPR)	Enables the linear prediction of the displacements at the first iteration of each time step.For more information, see the DIPR parameter of the Samcef .SUBCASE command.
Thresholds
Internal Force Norm (.SUB NORM)	Specifies when the solver has to compute the norm of the internal forces:Calculation after AssemblyCalculation is performed after the assembly of forces.Calculation before AssemblyCalculation is performed before the assembly of forces.For more information, see the NORM parameter of the Samcef .SUBCASE command.
**Energy Threshold (.SUB PRCE)**Allowed Relative Energy Residual (.SUB PRDE)	Specifies the energy and relative energy residual thresholds. For more information, see the PRCE and PRDE parameters of the Samcef .SUBCASE command.
**Force Threshold (.SUB PRCR)**Allowed Relative Force Residual (.SUB PRDR)	Specifies the power and relative power residual thresholds.For more information, see the PRCR and PRDR parameters of the Samcef .SUBCASE command.
**Displacement Threshold (.SUB PRCQ)**Allowed Relative Displacement Residual (.SUB PRDR)	Specifies the displacement and relative displacement residual thresholds.For more information, see the PRCQ and PRDQ parameters of the Samcef .SUBCASE command.
Iterations
Maximum Iteration Number (.SUB ITMA)	Sets the maximum number of iterations to compute for an individual time step. For more information, see the ITMA parameter of the Samcef .SUBCASE command.
Optimum Number of Iterations (.SUB ITEREF)	Sets the optimum number of iterations.For more information, see the ITEREF parameter of the Samcef .SUBCASE command.
Stabilization of Initial Rigid Body Motion
Stiffness Stabilization (.SUB STAB)	Lets you define the stiffness stabilization factor.For more information, see Structural nonlinear solution step (Simcenter Samcef) and the STAB parameter of the Samcef .SUBCASE command.
Max Variation of Displacement by Iteration (.SUB MADI)	Lets you define the maximum displacements variation by iteration.For more information, see Structural nonlinear solution step (Simcenter Samcef) and the MADI parameter of the Samcef .SUBCASE command.
Pivots
Option on Negative Pivot (.SUB RJPN/RJPV)	Lets you define the behavior of the solution when zero pivots are detected:NoNothing is done.Reject Time StepThe converged time step is rejected.Non Rejected Time StepThe time step is not rejected and the number of negative pivots are printed out in the computation .res file.Iterations Are StoppedThe iteration is stopped and the time step is rejected.Automatic Switch Static/DynamicAn automatic switch between static and dynamic analysis is performed:When you select this option, the analysis always starts as a static analysis.If negative pivots are detected for a converged time step, the time step is rejected. The analysis switches to a dynamic analysis.The rejected time step is restarted in this dynamic analysis.If during the computation that follows the kinetic energy of a time step goes under 1/100 of the kinetic energy value computed at the moment of the switch above, the analysis reverts to static.For more information, see the RJPN and RJPV parameters of the Samcef .SUBCASE command.
Option on Zero Pivot (.SUB RJPZ/RJPV)	Lets you define the behavior of the solution when zero pivots are detected.Select No to do nothing or select Iterations Are Stopped to stop the iterations when zero pivots are detected.For more information, see the RJPZ and RJPV parameters of the Samcef .SUBCASE command.
Line Search
Line Search Activation (.SUB ILNS)	Lest you activate the line search algorithm:NoNo line search is activated.Minimizing the Energy ErrorActivates the line search algorithm that minimizes the energy.Minimizing the Energy ResidueActivates the line search algorithm that minimizes the energy residue.For more information, see the INLS parameter of the Samcef .SUBCASE command.For more information on the line search method, see Line search (Simcenter Samcef).
Activated at Iteration	Lets you select at which Newton iteration you want to activate the line search algorithm.
Relaxation
Relaxation Factor (.SUB RELX	Specifies the relaxation factor. This factor can be used to help the convergence of the Newton-Raphson algorithm but can lead to more iterations.For more information, see the RELX parameter of the Samcef .SUBCASE command.
Material
Activation of Material Time Stepping (.SUB VISC)	Activates the material time stepping integrationFor more information, see the VISC parameter of the Samcef .SUBCASE command.
Threshold for the Integration Error of the Viscous Material (.SUB PRCV)	Appears when the Activation of Material Time Stepping (.SUB VISC) check box is selected.Lets you define the threshold to use when viscous material properties are integrated.For more information, see the PRCV parameter of the Samcef .SUBCASE command.
Characteristic Stress (.SUB SREF)	Lets you define the characteristic stress.For more information, see the SREF parameter of the Samcef .SUBCASE command.
Maximum Equivalent Plastic Strain Increment (.SUB PLLIM)	Sets the maximum equivalent plastic strain that can occur in a time step (time increment or load increment). At the end of each iteration of a time step, the solver evaluates the plastic strain. If the plastic strain is too high, that is, the plastic increment is greater than the value you set, the solver bisects the time step and restarts with a smaller time step.For more information, see the PLLIM parameter of the Samcef .SUBCASE command.

Continuation Methods page

Use this page to set corrector methods for unstable problems.

For more information, see Arc-length corrector methods (Simcenter Samcef).

Corrector Methods

Methods (.SUB CONT)

Lets you select the arc-length corrector method:NoNo corrector method is applied.Riks Arc-Length MethodThe Riks method, which is also known as the hyper-plane method.Crisfield Arc-Length MethodCrisfield method, which is the hyper-plane method that is linearized by iteration.Fried Arc-Length MethodFried method, which is the hyper-plane method that uses orthogonal trajectories.For more information, see the CONT parameter of the Samcef .SUBCASE command.

The following options appear when you select a corrector method from the Methods (.SUB CONT) list.
Predictor (First Iteration
Type pf Predictor (.SUB PRST)	Lets you select the type of predictor schema you want to apply. You can choose between a Tangent Predictor Vector or a Secant Predictor Vector.For more information, see the PRST parameter of the Samcef .SUBCASE command.
Min Radius for Arc-Length Increment Relative to Initial Value (.SUB RADINF)	Lets you specify the minimum radius value for the arc-length method.For more information, see the RADINF parameter of the Samcef .SUBCASE command.
Max Radius for Arc-Length Increment Relative to Initial Value (.SUB RADSUP)	Lets you specify the maximum radius value for the arc-length method.For more information, see the RADSUP parameter of the Samcef .SUBCASE command.
Stop Continuation
Maximum Number of Controlled Load Increments (.SUP NPAMAX)	Lets you define the number of increments to compute.For more information, see the NPAMAX parameter of the Samcef .SUBCASE command.
Stop Time Offset (.SUB TDEC)	Lets you define the stop time offset.For more information, see the TDEC parameter of the Samcef .SUBCASE command.

User page

User Parameters
User Parameters	Sets parameters for the .SUBCASE command that were not available on the other pages.Separate each extra parameter and its related value with a space. For example, to add the specific thresholds for the iteration matrix (PRCK and PRCC), type PRCK 1E-10 PRCC 1E-09.

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Solution Step dialog box (Simcenter Samcef Structure Nonlinear Analysis), Simcenter 3D 2021.1 Series

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