This data entry area is visible for the crack growth simulations.

Initial Increment

Enter the requested values for the increment increment, or step size, in years. This value is required.

If the simulation takes a long time, the initial increment can be increased, for example from 1 to 100 years to speed up calculation.

Delta KI limit

Enter the limit for the change in ΔKI in % from one time step to the next. The percent change in the load case KI from one increment to the next is computed beginning with the 2nd increment. This value is used as described below to determine the next step size. This value is required.

A default value of 2% is suggested.

Increase Constant

Enter the increase constant in %. The increase constant must be > 1. This value is required.

If the computed KI for a given increment is less than the delta K limit entered, then the subsequent increment size will be scaled by the increase constant.

A default value of 1.1 is suggested. If the crack is growing slowly (less than entered ΔKI limit), then the time increment will be increased by 10% in the subsequent increment.

Decrease Constant

Enter the decrease constant in %. The decrease constant must be > 0 and < 1. This value is required

If the computed percent change in load case KI for a given increment is greater than the delta K limit entered, then the subsequent increment size will be scaled by the decrease constant. 

A default value of 0.9 is suggested. If the crack is growing quickly (greater than the entered ΔKI limit), then the time increment will be decreased to 90% of the current time step for the subsequent increment.