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TIME

Solution control and techniques
*TIME
$t_{term}$, $sf_{\Delta t}$, $\Delta t_{\mathrm{min}}$, $\Delta t_{\mathrm{max}}$, $ms_{\mathrm{max}}$, $t_{start}$
Parameter definition
VariableDescription
$t_{term}$ Termination time or termination FUNCTION
options: constant, fcn
$sf_{\Delta t}$ Time step scale factor. It should range between 0 and 1
default: 0.9
$\Delta t_{\mathrm{min}}$ Minimum time step size or time step FUNCTION
default: 0
$\Delta t_{\mathrm{max}}$ Maximum allowed time step size
default: 1.0e10
$ms_{\mathrm{max}}$ Maximum allowed mass scaling factor on element level
default: 1.0e10
$t_{start}$ Start time
default: 0
Description

This command is used to define the duration of the simulated event and to specify parameters controlling the time step size. If defining a termination FUNCTION the simulation will run until the FUNCTION obtains a positive value.

Mass scaling is activated if the critical time step size drops below $\Delta t_{\mathrm{min}}$. Note that it is possible to define $\Delta t_{\mathrm{min}}$ as a function of time with a CURVE or as a more general expression using a FUNCTION.

$ms_{\mathrm{max}}$ is optional and defines maximum allowed element mass scaling factor.

Example
Trigger termination with a function

The following example is a complete model of a dynamically deforming rubber block. FUNCTION 222 signals for termination when the kinetic energy has reduced to less than one percent of its initial value.

*UNIT_SYSTEM
SI
*PARAMETER
dens = 1000.0, "rubber density"
L = 0.1, "rubber block size"
v0 = 100.0, "initial velocity"
wk0 = 0.5*%dens*%L^3*%v0^2, "initial kinetic energy"
*TIME
fcn(222)
*FUNCTION
"termination function"
222
0.01*%wk0 - wkp(1)
*OUTPUT
1.0e-4, 1.0e-5
*COMPONENT_BOX
"rubber block"
1, 1, 5, 5, 5
[-%L/2], [-%L/2], 0, [%L/2], [%L/2], [%L]
*MAT_MOONEY_RIVLIN
"rubber"
1, [%dens], 1.0e9
1.0e6, 1.0e6, 1.0e3
*PART
"rubber block"
1, 1
*INITIAL_VELOCITY
P, 1, 0, 0, [-%v0]
*BC_SYMMETRY
Z
Minimum allowed time step size

A simple example where the minimum allowed time step sized is defined as a function of time. If necessary, mass scaling will be activated in order to maintain the specified minimum time step size.

*UNIT_SYSTEM
SI
*TIME
0.01, 0, fcn(333)
*CURVE
"minimum allowed time step size"
333
0.0, 1.0e-6
0.001, 1.0e-6
0.002, 1.0e-5
0.01, 1.0e-5