DELTIM
DELTIM, DTIME,
DTMIN, DTMAX,
Carry, ForceKey
Specifies the time step sizes to be used for the current load step.
DTIMETime step size for this step. If automatic time stepping is used (AUTOTS),
DTIMEis the starting time substep.If contact elements (TARGE169, TARGE170, CONTA172, CONTA174, CONTA175, or CONTA177) are used, defaults to
TIMEorTIME/20 (whereTIMEis the time at the end of the load step as set on the TIME command), depending on the physics of the model. If none of these contact elements are used, defaults toTIME.DTMINMinimum time step (if automatic time stepping is used). The program automatically determines the default based on the physics of the model.
DTMAXMaximum time step (if automatic time stepping is used). The program automatically determines the default based on the physics of the model.
CarryTime step carry over key:
OFF
—
Use
DTIMEas time step at start of each load step.ON
—
Use final time step from previous load step as the starting time step (if automatic time stepping is used).
The program automatically determines the default based on the physics of the model.
ForceKeyForce the time increments at the beginning and end of a load step to adhere to user-defined time increments. This option is valid when automatic time incrementation is activated (AUTOTS,ON).
OFF
—
(Default.) Can adjust the beginning and end of load step time increment.
FORCE
—
Strictly adhere to user-specified time incrementation until the last substep of the load step. At this point, the remaining time specified for the load step is used as the time increment (even if it is smaller than the minimum time increment).
Notes
See NSUBST for an alternative input.
Use consistent values for DTIME and TIME (TIME). For example, using
0.9 for DTIME and 1.0 for TIME results in one time step because 1.0 (TIME) is divisible by .9 (DTIME) at most once. If you intend to load in 10 increments over a time
span of 1.0, use 0.1 for DTIME and 1.0
for TIME.
The program calculates the initial incremental time so that
(EndingTime - StartingTime)/DTIME is an integer, which may affect
the initial incremental time that you specify. For example, if the
starting time is 0, the ending time is 1, and the initial incremental
time is 0.4, the program rounds to the nearest integer and adjusts
the time to 0.33333.
If you do not want the program to adjust the initial time increment
and instead prefer to use the time increment you initially specified, use
ForceKey to enforce strict adherence to your time step. If
ForceKey is set to FORCE, the program continues to adhere to the
user specified time increment limit until the last substep. At this point, the remaining time
specified for the load step is used as the time increment.
For solution efficiency, specify values for all fields of this command.
Changing the time step size upon restarting an analysis during a load step is not recommended. You should only change the time step size between load steps.
This command is also valid in PREP7.