Explicit method in LS-Dyna

Mahmood Moosavizadeh

unread,

Sep 17, 2021, 11:33:59 AM9/17/21

to LS-DYNA2

Hi,

How can I analyze a quasi-static problem with the explicit method in Ls-Dyna? Any guidance would be appreciated.

Thanks

l...@schwer.net

unread,

Sep 17, 2021, 12:56:07 PM9/17/21

to Mahmood Moosavizadeh, LS-DYNA2

1\ Apply the loading slowly over a period of time such that the total kinetic energy remains less than 10% of the internal energy. Some users also add damping -- see the options under *DAMPING in the User Manual.

2\ Use dynamic relaxation – see *CONTROL_DYNAMIC_RELAXATION in the User Manual.

--len

--
You received this message because you are subscribed to the Google Groups "LS-DYNA2" group.
To unsubscribe from this group and stop receiving emails from it, send an email to ls-dyna2+u...@googlegroups.com.
To view this discussion on the web visit https://groups.google.com/d/msgid/ls-dyna2/8c3d9f3f-2f56-45d5-8f12-40623c99bbfbn%40googlegroups.com.

James M. Kennedy

unread,

Sep 18, 2021, 12:41:37 PM9/18/21

to L...@schwer.net, Mahmood Moosavizadeh, LS-DYNA2

Dear Mahmood,

This analysis particular focused on the sensitivity of the results concerning element type and hourglass control versus fully integrated elements, loading velocity and mesh refinements:

Schweizerhof, K., Walz, M., Rust, W., Franz, U., and Krichner, M., "Quasi-static Structural Analysis with LS-DYNA - Merits and Limits", 2nd European LS-DYNA Users Conference, Gothenburg, Sweden, June, 1999.

https://www.researchgate.net/publication/250916882_Quasi-Static_Analyses_Using_Explicit_Time_Integration_-_Applications_of_LS-DYNA

The simulation of the quasi static compression test was successfully performed using LS-DYNA. LS-DYNA provides many material models for different types of foams. However, based on previous work by Ozturk and Anlas [2011], the best candidate for modeling EPS crushable foam was *MAT_063 (*MAT_CRUSHABLE_FOAM). This material model requires the input of five parameters: density of material, modulus of elasticity, Poisson’s ratio, stress strain curve, tensile stress cutoff, and damping coefficient:

Shah, Q.M., and Topa, A., "Modeling Large Deformation and Failure of Expanded Polystyrene Crushable Foam Using LS-DYNA", Modelling and Simulation in Engineering, Vol. 2014, Article ID 292647, 7 pages, January, 2014.

http://www.hindawi.com/journals/mse/2014/292647/

---------------------------------------

Several presentations discussing quasi-static and mass-scaling features:

https://www.dynasupport.com/howtos/general/quasistatic-simulation

https://www.dynasupport.com/howtos/general/mass-scaling

https://www.researchgate.net/publication/250916882_Quasi-Static_Analyses_Using_Explicit_Time_Integration_-_Applications_of_LS-DYNA

https://www.d3view.com/overview-of-mass-scaling/

https://www.dynalook.com/conferences/14th-international-ls-dyna-conference/simulation/quasi-static-simulations-using-implicit-ls-dyna-r

https://imechanica.org/files/l5-quasi-static.pdf

http://www.diva-portal.org/smash/get/diva2:1022033/FULLTEXT01.pdf

https://skill-lync.com/projects/week-8-mass-scaling-33

https://www.youtube.com/watch?v=te6mvXF_TjU