A stability limit is placed on the time-step size (Zienkiewicz and Cormeau), as an explicit integration procedure is used in which the stresses and strains are referred to time tn-1. (The temperature, however, is at time tn.)
The creep strain rate is calculated using time tn. Use a
time step such that the creep ratio Cmax is less than 0.10.
If the creep ratio exceeds 0.25, the run terminates with the message:
CREEP RATIO OF . . . EXCEEDS STABILITY LIMIT OF
.25.
Automatic Time-Stepping discusses the automatic time-stepping algorithm that can be used with creep to increase or decrease the time step as needed for an accurate, efficient solution.