TSTEPNX
Bulk Data Entry Defines additional parameters for geometric nonlinear implicit dynamic analysis.
Format
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TSTEPNX  ID  TA0  DTA  DTTH  NPRINT  RFILE  
SOLV  TSCTRL  DTMIN  DTMAX  LSMETH  RREFIF  NCYCLE  FIXTID/TOUT  
DYNA  ALFA  BETA  GAMA  SMDISP  
ITW  DTSCI  LDTN  DTSCD  LARC 
Example 1
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TSTEPNL  99  0.01 
Example 2
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TSTEPNL  99  0.01  
TSTEPNX  99  0.1  
NEWT  ARC  1.e4  0.1 
Example 3
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TSTEPNL  99  0.01  3  PW  
0.01  0.01  
TSTEPNX  99  0.1  
NEWT  ARC  1.e4  0.1  
NEWM  0.25  0.5 
Definitions
Field  Contents  SI Unit Example 

ID  An associated
TSTEPNL entry identification number. No default (Integer > 0) 

TA0  Start time for writing
animation files. Default = 0.0 (Real ≥ 0) 

DTA  Output time step for
animation files. If zero, no output. 3 Default = DT (Real ≥ 0) 

DTTH  Output time step for time
history files. If zero, no output. 3 Default = 0.1*DT (Real ≥ 0) 

NPRINT  Print every
NPRINT iterations. If negative, to
.out and standard output; if positive, only
to .out file. Default = 1 (Integer) 

RFILE  Cycle frequency to write
restart file for nonlinear iteration. Default = 5000 (Integer > 0) 

SOLV  Geometric nonlinear
implicit solution method
(Character) 

TSCTRL  Time step control.
(Character) 

DTMIN  Minimum geometric
nonlinear implicit time step. If DTMIN is
reached, simulation will be terminated. 3 Default = 1e5*DT (Real ≥ 0) 

DTMAX  Maximum geometric
nonlinear implicit time step from which time step is set constant.
3 Default = 3*DT (Real > 0) 

LSMETH  Line search method.
(Character) 

RREFIF  Special residual force
computation with contact interfaces present.
Default = no special treatment (Integer) 

NCYCLE  Maximum number of time
steps. If reached, solution will be terminated,
NCYCLE=0 means no
limit. Default = no limit (Integer ≥ 0) 

FIXTID  A
TABLEDi entry identification number. The x
values of the table define fixed time points that the automatic time
step control will adhere to. (Integer > 0) 

TOUT  The method to determine
the fixed time point.


DYNA  Implicit transient
solution methods.
(Character) 

ALFA  Parameter in αHHT Method
(DYNA = HHT). Default = 0.05 (Real, 1/3 < ALFA < 0.0) 

BETA  Parameter in general
Newmark method
(DYNA=NEWM). Default = 0.25 (Real, 2 * BETA ≤ GAMA < 0.5) 

GAMA  Parameter in general
Newmark method
(DYNA=NEWM). Default = 0.5 (Real, 2 * BETA ≤ GAMA ≤ 0.5) 

SMDISP  Perform small displacement
and rotation analysis instead of geometric nonlinear analysis. PARAM, SMDISP,
YES overwrites this definition.


ITW  If the solution of a time
step converges within ITW iterations, the next
time step will be increased by a factor controlled by
DTSCI. Default = 6 for TSCTRL=ARC Default = 2 for TSCTRL=SIMP (Integer > 0) 

DTSCI  Maximum scale factor for
increasing the time step
(TSCTRL=ARC). Scale factor
for TSCTRL=SIMP. Default = 1.1 (Real > 0) 

LDTN  Maximum number of
iterations before resetting and decreasing the time step by a factor
of DTSCD. Default = 20 for TSCTRL=ARC Default = 15 for TSCTRL=SIMP (Integer > 0) 

DTSCD  Scale factor for
decreasing the time step
(TSCTRL=ARC or
SIMP). Default = 0.67 (Real > 0) 

LARC  Input arclength for
TSCTRL=ARC. Default = automatic computation (Real) 
Comments
 The TSTEPNX Bulk Data Entry is selected by the Subcase Information command TSTEP=option. There must also be a TSTEPNL Bulk Data Entry with the same ID. It is only used in geometric nonlinear implicit dynamic analysis (ANALYSIS=IMPDYN); it is ignored in other analyses.
 The solution method for geometric nonlinear implicit analysis is selected by SOLV. The frequency of stiffness matrix updates is controlled by TSTEPNL, KSTEP. For highly nonlinear problems, it is recommended to reduce KSTEP for better performance. KSTEP=1 means full Newton.
 The initial time step DTINI=DT is defined by TSTEPNL.
 For more information about geometric nonlinear analysis, refer to Explicit Dynamic Analysis (Radioss Integration) in the Users Guide.
 This card is represented as a loadcollector in HyperMesh.