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Roy Duan

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

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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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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.

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On 2017/9/11 at 0:56 PM, George P Johnson said:

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

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2 hours ago, George P Johnson said:

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

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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. 

 

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On 2017/10/10 at 7:05 PM, George P Johnson said:

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

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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.

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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

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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.

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