Nonlinear - Advanced Options

The Advanced tab in the Nonlinear dialog box sets options for controlling the solution method. This tab appears only after clicking the Advanced Options button on the Solution tab. The following are the options to set on this tab (click any of them to get more information).

• Method. Sets the control technique and the iterative method to be used.

• • Control. Choose a control technique . Only Force control is available for dynamic studies.

  • • Force. Use force control.

    • Displacement. Use Displacement control.

    • Arc length. Use Riks Arc-length control.

  • Iterative. Sets the numerical technique to be used for iterations.

  • • Newton-Raphson (NR). Use the Newton-Raphson (NR) iterations.

    • Modified Newton-Raphson (MNR). Use the Modified Newton-Raphson (MNR) iteration scheme.

• Displacement control options.

• • Select a vertex or reference point to control the analysis. Select a vertex or a reference point to drive the solution. If you select a reference point, the program uses the closest node to the specified point.

  • Displacement component for the selected location. Displacement component. Sets the displacement component to be used in the displacement control method. Here is a list of valid components.

  • Displacement variation with time. Click Edit to define a time variation of the displacement using the Time Curve dialog box. After defining the time variation of the selected displacement component, click Graph to view the displacement as a function of time.

• Arc-Length completion options.

• • Maximum load pattern multiplier. The maximum load-pattern multiplier at which the solution is to be terminated (approximate value). Default is 1.0E8.

  • Maximum displacement (for translational DOF). The analysis terminates if any displacement DOF exceeds this value.

  • Maximum number of arc steps. The analysis terminates if the number of arc length steps reaches this limit. Default is 50.

• Step/Tolerance options. Sets convergence and equilibrium parameters.

• • Do equilibrium iteration every ... step. Sets the frequency of performing equilibrium in number of solution steps.

  • Maximum equilibrium iterations. Sets the maximum number of equilibrium iterations for any solution step.

  • Convergence tolerance. Relative displacement tolerance used for equilibrium convergence.

  • Maximum increment strain. Sets tolerance for strain increment for models with creep or plasticity.

  • Singularity elimination factor (0-1). Sets stiffness singularity elimination factor (normal solution if set to 1; if less than 1.0, the program modifies stiffness terms causing singularity  to help convergence). If normal solution fails, trying a different value, for example 0, may help convergence.

Related Topics

Nonlinear - Solution

Flow/Thermal Effects

Remark

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