Nonlinear Analysis Algorithm Options

Use this dialog to define the algorithm options of a nonlinear analysis.

Access

1. Click Analysis Analysis Types.
2. Select a case, and then click Parameters.
3. Select a Non-linearity option, and then click Parameters.

Incremental method

Additional criterions to stop analysis

Opens the Criterions to stop analysis dialog which allows you to define the conditions under which the analysis must be stopped.

Parameters of the Incremental method

• Load increment number - The number of calculation iterations when dividing a load into smaller segments. For complex structures where the impact of non-linear effects is considerable, calculations may not converge if the analysis for the value of a load is applied in one step. The greater the number of increments, the greater the probability for the calculations to reach the point of convergence.
• Maximum iteration number for one increment - The number of iterations during one load increment. This parameter controls the calculation process.
• Increment length reduction number (modification) - Defines how many times the number of load increments can be changed when calculations do not reach convergence (refer to the increment length reduction factor below).
• Increment length reduction factor - Modifies the required number of load increments. This is the conditional option, used only when calculations do not reach convergence for the currently defined parameters. If convergence is not achieved, the size of load increment is reduced (depending on the value of the coefficient) and calculations continue. This is repeated until convergence is achieved or the iteration process exceeds the allowable number of step length reductions.
• Maximum number of line searches.
• Control parameter for line-search method.
• Maximum number of BFGS corrections.

Arc-length method

Parameters of the Arc-length method

• Load increment number - The number of calculation iterations when dividing a load into smaller segments. For complex structures where the impact of non-linear effects is considerable, calculations may not converge if the analysis for the value of a load is applied in one step. The greater the number of increments, the greater the probability for the calculations to reach the point of convergence.
• Maximum iteration number for one increment - The number of iterations during one load increment. This parameter controls the calculation process.
• Maximum load factor λmax - The maximum value of the load parameter.
• Node number - Specify a node number on a structure roof.
• Degree of freedom - Specify a displacement direction.
• Maximum displacement for selected degree of freedom Dmax - The maximum value of a displacement at a selected node.

Algorithms

Matrix update

Use the Matric update options to select a resolution method for the analysis.

Algorithm	Matrix update after each subdivision	Matrix update after each iteration
Initial Stress	Off	Off
Modified Newton-Raphson	On	Off
Full Newton-Raphson	On	On