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What's the main difference between /mat/law38 and /mat/law70?

Altair Forum User

Hi all,

Which material model should be used for a package foam when doing package dropping simulation? From the help manual, both /mat/law38 and /mat/law70 are visco-elastic Foam Tabulated material. What's the difference between this two models? Is there any example about package dropping simulation?

Best Wishes

Roy

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Radioss

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Altair Forum User

Hi Roy,

/MAT/LAW 38 and /MAT/LAW70 can be used to model visco-elastic foam tabulated materials. Based on the input user has a material law can be selected.

/MAT/LAW70 generally works stable. For /MAT/LAW38 time step can reduce significantly for high deformations.

I suggest you to try with /MAT/LAW70.

Altair Forum User

Hi Roy,

/MAT/LAW 38 and /MAT/LAW70 can be used to model visco-elastic foam tabulated materials. Based on the input user has a material law can be selected.

/MAT/LAW70 generally works stable. For /MAT/LAW38 time step can reduce significantly for high deformations.

I suggest you to try with /MAT/LAW70.

Hi George,

Could you provide some example about using this foam material? Thank you.

Roy

Altair Forum User

Is there any example about using /mat/law70?

Altair Forum User

Hi Roy,

Unfortunately we don't have any example files on this material law as of now. Very soon we will release a tutorial/webinar on foam modelling in RADIOSS.

Altair Forum User

Hi Roy,

Unfortunately we don't have any example files on this material law as of now. Very soon we will release a tutorial/webinar on foam modelling in RADIOSS.

Hi George,

I'm glad to hear that. I'm looking forward to the tutorial or webinar on foam.

Roy

Altair Forum User

Hi George,

Is there any information about tutorial/webinar on foam modelling in RADIOSS?

Roy

Altair Forum User

Hi Roy,

This tutorial is still on the anvil.

Meanwhile you can go through http://altairatc.com/europe/presentations/session10/session10_ford_schilling.pdf which is a case study on Numerical simulation of polymeric foams under impact loading. If possible, I will share a foam material model for your reference.

Altair Forum User

Hi Roy,

This tutorial is still on the anvil.

Meanwhile you can go through http://altairatc.com/europe/presentations/session10/session10_ford_schilling.pdf which is a case study on Numerical simulation of polymeric foams under impact loading. If possible, I will share a foam material model for your reference.

Hi George,

How about the tutorial about foam in Radioss?

Roy

Altair Forum User

Hi Roy,

I'm sharing you a model file for /MAT/LAW70. Please go through the same.

Unable to find an attachment - read this blog

Altair Forum User

Hi George,

How about the tutorial about foam in Radioss? I'm waiting for it all the time.

Roy

Altair Forum User

Hi Roy,

The above shared file is an example file on /MAT/LAW70 which is only available as of now.

I'm also not sure about the tutorial/webinar on the same but I'll try to get some information on this.

Hi, still no tutorial about foam in Radioss? I'm waiting for it also

Thanks!

JM

Altair Forum User

Hi JM,

Unfortunately no tutorials are still yet released on foam materials. In this same discussion thread I have shared a model file where foam material is used.

Please review the same so that you will get an idea on this material card. Also please go through the Help Menu on this material card.

Hi George,

Thanks for the fast response! I did download the model and it helped me understand a couple of things. I was just wondering, if the model is the exact same that the one in the case study that you provided (http://altairatc.com/europe/presentations/session10/session10_ford_schilling.pdf). In fact, the geometry looks different, but if everything else is the same, it's perfect for me. More precisely, if the model has the same material, the EPP, it's even better.

Also, I have an additional question. I was wondering if in law 70, there were parameters to change the shear behavior of the foam. I ''played'' with some of them, but I don't have what I expected. In fact, in pure compression the model behaves like the experimental tests that are obviously in pure compression. However, when I run combined or oblique loading simulations (pure compression and shear), the forces are not the same.

If you want more precision on my problem, I'll share it to you. So, if you know some parameters that I can play with to get more of what i want or another tabulated law like 38 maybe, let me know!

Thanks!

JM

Altair Forum User

HI JM,

The model is not exact the sam e as in the case study and it's a customer model which contains the material information which they don't share. But the material model is same, /MAT/LAW70.

Law 70 is a simple material model for visco-elastic foam tabulated material where the viscosity is defined by stress-strain curves for different strain rate.

For the shear behavior you can try with Law 42 which contains parameters for shear hyperelastic modulus. Please go through the Help menu on the same.

Allright thanks! I'll take a look!

JM

Altair Forum User

Hi,

I have worked in FOAM Material using LAW 70 in one of my project.

I tried validating LAW 70 for different scenarios.

Attaching some sample validation case for reference.

Hope it may help you.

Thanks.

Unable to find an attachment - read this blog

Altair Forum User

Hi Roy,

The above shared file is an example file on /MAT/LAW70 which is only available as of now.

I'm also not sure about the tutorial/webinar on the same but I'll try to get some information on this.

Hi George,

How about the tutorial about foam in Radioss or OptiStruct? I'm waiting for it all the time.

Thank you!

Roy

George P Johnson

Could you share model file for /MAT/LAW70. Again please.

Unable to find an attachment - read this blog

Altair Forum User

@EDUARDO AMARO CALDERON

PFA

Unable to find an attachment - read this blog

Thank you Prakash Pagadala

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