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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

Field

Contents

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 (See comment 3).

Default = DT (Real > 0)

DTTH

Output time step for time history files. If zero, no output (See comment 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.

NEWT – Modified Newton.

BFGS – BFGS quasi-Newton method.

Default = NEWT (Character = NEWT, or BFGS)

TSCTRL

Time step control.

ARC – Arc-length is used to accelerate and control the convergence. The time step is determined by displacement norm control (arc-length).

SIMP – Simple time step control.

NONE – No time step control. A warning will be issued.  In the case of divergence, the time step will be repeated with half the step size. The run will be terminated according to DTMIN and NCYCLE.

Default = ARC (Character)

DTMIN

Minimum geometric nonlinear implicit time step. If DTMIN is reached, simulation will be terminated (See comment 3).

Default = 1e-5*DT (Real > 0)

DTMAX

Maximum geometric nonlinear implicit time step from which time step is set constant (See comment 3).

Default = 3*DT (Real > 0)

LSMETH

Line search method.

Default = ENERGY (Character = NONE, FORCE, ENERGY, or AUTO)

RREFIF

Special residual force computation with contact interfaces present.

Default = no special treatment (Integer = 0, …, 5)

0 – Aggressive (modified entirely by the out-of-balance value).

1 – Average (modified each time with 200% maximum).

2 – Light (modified each time with 20% maximum).

3 – No change.

4 – No change; except for the first contact.

5 – Modified automatically (for imposed displacement only).

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.

AUTO – Fully automatic time step control.

NLOAD - The time points in all TABLEDi that are referenced by NLOAD1 in one subcase.

Default = AUTO (AUTO or NLOAD)

DYNA

Implicit transient solution methods.

HHT – α-HHT method.

NEWM – General Newmark method.

Default = HHT (Character = HHT or NEWM)

ALFA

Parameter in α-HHT 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.

OFF – Geometric nonlinear analysis.

ON – Small displacements and small rotations analysis.

Default = OFF (Character = ON, OFF)

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 arc-length for TSCTRL = ARC.

Default = automatic computation (Real)