Error 40509 negative volume in solid elements in Elform -1,-2 and 2 and many buffers in tetra second order elform16

[Hamza Güngör]

Hi Folks, 

I am trying drop test simulation in LS-DYNA. When I run my simulation with elform1, I am facing with hourglass. I used many hourglass type, I couldnt overcome it. For this purpose, I tried fully integration elforms. I faced error 40509 negative volume. I tried to do tetra. I did second degree tetra and I used elfrom 16. I faced many buffers, after many buffers, there is no d3plot. Do you have any advice to me.

My model has 2 automatic_surface_to_surface,speciman material is mat181 simplified foam/rubber. A table with 0.001 strain rate compression and tension, 1300 strain rate just compression. 

Best Regards.

[l...@schwer.net]

An easy thing to try is reducing the time step via the parameter TSSFAC on *CONTROL_TIMESTEP. Perhaps try TSSFAC=0.5                     --len

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[James Kennedy]

Dear Hamza,

 

See if the following is of some help:

 

Finite element models of quasi-static material characterization processes were developed to assess hyperelastic material models available in LS-DYNA and ensure proper user input of data and parameters. Two material models were investigated: *MAT_77_O and *MAT_181:

 

Bondy, M., "Development of Procedures for Accurate Finite Element Modeling of the Dynamic and Quasi-Static Performance of Automotive Chassis Components Incorporating Hyperelastic Materials", Master's Thesis, Department of Mechanical, Automotive, and Materials Engineering, University of Windsor, Windsor, Ontario, Canada, January, 2013

 

http://scholar.uwindsor.ca/cgi/viewcontent.cgi?article=5756&context=etd

 

Cyclic loading using *MAT_SIMPLIFIED_RUBBER (*MAT_181) with elastic damage. Data is tabulated hyperelasticity with direct input of experimental results (no time-consuming parameter identification):

 

Sygusch, N., Kolling, S., Staudt, Y., Kuntsche, J., and Schneider, J., "Characterization and Modeling of Elastomers", 13th German LS-DYNA Forum, Bamberg, Germany, October, 2014.

 

http://www.dynamore.de/de/download/papers/2014-ls-dyna-forum/documents/material-ii/characterization-and-modeling-of-elastomers

 

simple example

 

Bird strike analysis using a rubber projectile with rate effects impacting a rigid plate. The rubber projectile is used to represent the "bird material" and is modeled using *MAT_SIMPLIFIED_RUBBER (MAT_181). Gelatin rebounds elastically (until tension failure). Gelatin appears to soften at higher strain rates. These effects are included in the model. Two types of force vs. change in gauge length at different strain rates are tested.

http://awg.lstc.com/tiki/tiki-index.php?page=QA+test+example

 

*MAT_SIMPLIFIED_RUBBER/FOAM

 

This is Material Type 181. This material model provides a rubber and foam model specified with a single uniaxial load curve or a family of uniaxial curves at discrete strain rates. Hysteretic unloading may optionally be modeled through a single uniaxial unloading curve or a two-parameter formulation. Specifying a Poisson’s ratio greater than 0.0 and less than 0.49 activates the foam formulation. This material may be used with both shell and solid elements.

 

Sincerely,

James M. Kennedy

KBS2 Inc.

March 26, 2024

 

From: ls-d...@googlegroups.com [mailto:ls-d...@googlegroups.com] On Behalf Of Hamza Güngör
Sent: Tuesday, March 26, 2024 2:02 AM
To: LS-DYNA2 <ls-d...@googlegroups.com>
Subject: [LS-DYNA2] Error 40509 negative volume in solid elements in Elform -1,-2 and 2 and many buffers in tetra second order elform16

 

Hi Folks, 

--

[James Kennedy]

Simple example:

 

QA test example 3 | LS-DYNA Aerospace Working Group (ansys.com)