Learning Forum

[Sahil Daswani]

AUTOSPC detected very large entries in the           *
     *  assembled matrix.  These are probably caused         *
     *  by overflow during elemental matrix computations.    *
     *  This could be caused by an energy explosion.         *
     *  Recommend switching to the REAL*8 version of LS-DYNA

i get this error while trying to simulate my file 

I'm new to LS Dyna

Problem statement:

i'm trying to simulate forces on a single element block which is placed between rigid walls.

  

[Reno Genest]

Hello,

It looks like you are doing an implicit simulation. AUTOSPC constraints are added to an implicit model to prevent rigid body motion which is not allowed in implicit. Here is what you can try:

1. Fully constrain the parts in your model so that they don't move as a rigid body. Then run the implicit model again.
2. Do an explicit simulation. It is okay to have rigid body motion in an explicit simulation.

Also, the error message recommends to switch to REAL 8 version of LS-DYNA. This means using a double precision solver. You can download one here:

LSDYNA » Downloader (ansys.com)

username: user

password: computer

 

If you are new the LS-DYNA, it would be good to go through some training. Do you have access to the Ansys Learning Hub (ALH)?

You will find the WB LS-DYNA course here:

https://jam8.sapjam.com/groups/aMA6tQ2siKgaRc9waZYwd0/overview_page/h1E4U3fDPcHQL0JtegqTV8

And many LS-DYNA courses here:

https://jam8.sapjam.com/home/bRkQVuQCyaRN2s3K5mv5yM

 

Reno.

[Andreas Koutras]

Hello Sahil,

You'll also find plenty of information and examples online if you search for "ls-dyna implicit guidelines" and "ls-dyna implicit examples".

Regarding the behavior of rigid walls in implicit, see the field RWPNAL of *CONTROL_CONTACT.