Impact Analysis.......
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Impact Analysis......Object not rebounding after impact

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Posts: 2
Topic starter
Joined: 3 years ago

I have a rigid wall, shell object (steel) and a stiff ram. The ram strikes the shell object which is constrained by the wall. I ran the job from 0.1 to 1 sec. The ram keeps moving forward even after impact. The shell behaves like rubber and stretches due to the impact. 

Automatic surface to surface contacts used. I used FEMAP to build the model.

What am I doing wrong?

2 Replies

Negative Volume
Posts: 641
Joined: 6 years ago

Hi @jesner1981

Sorry for the late response. Your issue seems to be with your material densities. The tube mass is 70 (units), head of the tube mass is 35304 (units), and ram is 285955 (units). So your ram is just plowing through the lightweight tube. 

What units are you working with? Double-check that everything is consistent. 

Other suggestions for your simulation:

The distance between your tube and rigid plate is approximately 0.018 (units) while both of these parts have a thickness of 0.4388 and 0.5 (units) respectively. Using an NLOC=0.0 in your section means that this thickness is split in half, half one side of the shell, half on the other. So you need to try moving the shell away from the rigid plate to have an approximate initial distance of around 0.47 (units). 

You should also add *Control_Contact and change IGNORE=1. This will allow you to have some initial penetration (shell thickness overlap between two parts in contact). Normally this is set at 0 which moves the nodes of the part that is penetrating to eliminate the penetration. 

You can also try making segment sets for both the rigid wall and the tube and changing the entity types of your contact to both be 0. Segment sets usually work best for contacts if you are having issues. 


Posts: 61
Lab Tech
Joined: 3 years ago

This issue was resolved in another forum (eng-tips).