Solution Control

The solution control parameters on the Nonlinear Parameters form differ depending on the type of analysis.  

Note:  When an item is clicked on this form, a description of that item displays in the display area at the bottom of the form.

An excessive number of null steps may indicate that the solution is stalled because of catastrophic failure or numerical sensitivity. If a model is having trouble converging, set the Maximum Null (Zero) Steps so that the solution will terminate early. Set this value equal to the Maximum Total Steps to prevent the analysis from terminating because of null steps.

Tip: The accuracy of direct-integration methods is very sensitive to integration time step, especially for stiff (high-frequency) response. Try decreasing the maximum substep size until consistent results are obtained. Keep the output time step size fixed to prevent storing excessive amounts of data.

Note: The default value of zero means no limit, i.e., use the output time-step size.

Tip: It is unlikely that this parameter will ever need to be changed from its default value.

Tip: The accuracy of modal methods is NOT very sensitive to integration time step. The main reason for limiting the maximum substep size is for comparison with other analyses that have used such limits.

Note: The default value of zero means no limit, i.e., use the output time-step size.

Tip: It is unlikely that this parameter will ever need to be changed from its default value, unless a convergence factor less than one is being used.

Tip: It is unlikely that this parameter will ever need to be changed from its default value.