Learning Forum

[jwang416]

Hello,

I am new to LS-Dyna. I created an input file and set the ENDTIM to be 1. However, the simulation only runs to t=0.8353. I did not set any other stopping criteria. What could be the reason the job is ending early?

Thanks!

Keyword: CONTROL_TERMINATION

[tslavik]

Make sure you're using a consistent set of units - read the UNITS section of the Getting Started chapter in the Vol I users manual which can be downloaded here: https://www.lstc.com/download/manuals Use good engineering judgement when selecting that unit system.
Search the d3hsp file for the string "smallest timesteps" and study the table following that.Make sure the element governing the time step is not too small or misshapen.Many impact/penetration events are complete in about 100 millliseconds and most LS-DYNA models have an explicit time step around one microsecond.Strive for a model which meets those conditions within its unit system.Use good engineering judgement to build a sound model:think about loads, boundary conditions, simple material models (e.g., *MAT_ELASTIC for starters) and a simple mesh which effectively captures the topology.Choose robust, computationally inexpensive elements to develop a good baseline model - ELFORM=2 for shells and ELFORM=1 for solids in their respective *SECTION definitions.At first, don't use *CONTACT - add that after everything else is working as expected.Is everything moving as expected under the loads and BCs?Does the energy bookkeeping make sense (use *DATABASE_MATSUM and *DATBASE_GLSTAT)?
Carefully investigate all Warning messages in the d3hsp and messag file (mes**** if MPP).Most simulations which end before the desired termination time will leave an Error message in the d3hsp andmessag/mes**** files.If there are no error messages then there was probably a segmentation fault or floating point exception which appeared lastly in the window where the simulation was executed.If it ended abruptly in that manner, re-run it with higher output frequency just before the abrupt termination - use sense switch SW4 repeatedly, LCUR in *DATABASE, or LCDT in *DATABASE_BINARY.