Convergence Parameters (Optimization dialog box)

The Convergence Parameters page in the Optimization dialog box controls the percentage by which values are allowed to vary from the specified minimum, maximum, or target in order to achieve a convergence solution.

Design Limits - Max Violation (%)

Specifies as a percent the amount by which the design limit values are allowed to exceed the specified limit value.

The default value is 0.000. The valid range of values is 0 to 100.

Relative convergence (%)

Specifies as a percent a relative amount that the design objective can deviate at convergence. The default value is 2.500. The valid range of values is 0 to 100.

The design is converged when the relative percentage change in the design objective value is less than the specified relative convergence value for two consecutive iterations. Also, when there is no design limit whose maximum violation has been exceeded in the last iteration.

Absolute convergence

Specifies as a fractional number the actual amount that the design objective can deviate at convergence. The default value is 0.001. The value can be any fractional number greater than or equal to zero.

The design is considered converged when there are two consecutive iterations for which the absolute change in the design objective is less than the absolute convergence tolerance. Also, when there is no design limit whose maximum violation has been exceeded in the last iteration.

Note:

Convergence tolerance=(Absolute Convergence Value) x (Initial Design Objective Value).

Perturbation fraction

Defines as a percent a relative amount by which design variables can change during a sampling period in the first few iterations of the optimization. The default value is 0.200 (that is, 20%). There is no restriction on valid values.

The perturbation fraction amount is the difference between the upper and lower limits of the design variable multiplied by the perturbation percentage.

Example:

A design variable has a value equal to 10.

Its upper and lower limits are 11 and 9, respectively.

The Perturbation fraction is 0.200.

Then the optimization can change the design variable value is .20(11–9), or 0.4.

Restore Defaults

Resets the values in the Convergence Parameters dialog box to their default values.

Control Parameters (Optimization dialog box)

Design Limit/Design Variable Rule Editor