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Did I setup my M33_FOAM_PLAS correctly?

Hi everyone,
I just finished running a simulation of a FSAE impact attenuator but the results didn't seem to match the test we did in real life. The 4130 steel tubes didn't bend very much and the foam compressed a lot more than it did in real life. I think I didn't setup the foam material correctly but I am not sure.
Did I set my simulation up correctly?

Here is the setup file and video of the results.
Thanks in advance.

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Radioss

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Simon Križnik

Hi,

There are initial penetrations; check and resolve using:
-in Hypercrash: Quality>Check all Solver Contact Interfaces
-in Hypermesh: Tool>penetration check

The issue is due to the yield stress vs. volumetric strain curve. Because the curve has a negative last slope Radioss extrapolates negative stress, which is not valid (The input stress should be positive for both tension and compression). As a workaround, define an additional curve segment with a zero or positive slope.

Yield stress vs. volumetric strain curve should look like:

<?xml version="1.0" encoding="UTF-8"?>

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puffin

Hi Simon,

I'm still new to hypermesh and I don't understand a few things.
How does radioss use the the yield stress vs volumetric strain curve and youngs modulus? Wouldn't youngs modulus be dependent on the slope of stress vs strain curve?

Simon Križnik

This material law initially follows the Maxwell-Kelvin-Voight viscoelastic model until it intersects the defined yield curve, which limits the visco-elastic stress in tension and compression.

For more details refer to the attached documentation (from Radioss help):

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