/DT/Eltyp/Keyword3/Iflag
Engine Keyword Element time step control.
Format
/DT/Eltyp/Keyword3/Iflag
$\text{\Delta}{T}_{sca}$ $\text{\Delta}{T}_{\mathrm{min}}$
If using /DT/BRICK/CST/1, insert the next line:
ASP_min VDEF_min
Definition
Field  Contents  SI Unit Example 

Eltyp  Entity selection:


Keyword3  Time step control type.
1
If Keyword3 is not specified, that is, /DT/Eltyp, then the default Keyword3 option for each Eltyp is used. 2 

$\text{\Delta}{T}_{sca}$  Scale factor on critical
time step for the option defined by
Eltyp. Default = 0.9 

$\text{\Delta}{T}_{\mathrm{min}}$  Minimum time step  
Iflag  Number of additional
(optional) cards. Only used for /DT/BRICK/CST/1.


ASP_min  Minimum Aspect ratio (Tet
collapse); Solid elements for which aspect ratio ≤
ASP_min will be switched to small strain
formulation to keep constant time step. 6
Default = 0 

VDEF_min  Minimum Volume ratio
(V/Vo); Solid element for which Volume change ≤
VDEF_min will be switched to small strain
formulation to keep constant time step. 6
Default = 0 
Comments
 For all
Keyword3 options, the time step control will be activated
when the time step of the element controlling the time step of the simulation
becomes less than:
$\frac{\text{\Delta}{T}_{\mathrm{min}}}{\text{\Delta}{T}_{sca}}$
 The table below lists
the different available combinations of Eltyp and
Keyword3. The default options are used when
Keyword3 is not specified such as
/DT/BRICK or /DT/SHELL.
STOP DEL CST QUAD Default Optional BRICK Default Optional Optional SHELL, SH_3N Optional Default Optional BEAM, TRUSS, SPRING Optional Optional  For each Eltyp value, only one /DT/Eltyp/Keyword3 option can be used in a simulation.
 /DT/Eltyp/Keyword3 can be used with /DT/NODA/Keyword3.
 /DT/BRICK/CST is only active when I_{smstr}=2 or 12 is defined in /PROP/SOLID. It is compatible with /TETRA4 with I_{tetra}=0, /TETRA10, and /BRICK solid elements with I_{solid}=1, 2, 14, 17, or 24.
 When using /DT/BRICK/CST/1, elements will be switched to small strain formulation when one of the two minimum values for ASP_min or VDEF_min have been reached. ASP_min uses the same tet collapse calculation as HyperMesh element quality check. Elements failing the ASP_min criteria will be switched to the small strain formulation at the beginning or during a simulation. VDEF_min can be used to switch highly deformed or compressed elements to the small strain formulation during the simulation thus avoiding negative volume issues that can arise.
 A more conservative and thus lower time step calculation for shell elements can be activated by using, /DT1/SHELL.