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polymer tear test

Altair Forum User

Hi,

I want to tear a polymer, so set up the model and run it.

Material is defined for particular test by MAT LAW 2.

Its running but after some time elements get deleted.

Analysis not completed and stopped.

Herewith shared the output file and deck file.

Please suggest the solution.

Unable to find an attachment - read this blog

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Altair Forum User

Hi Tushar,

Are all the material parameters correct?. Especially a, b and n values.

Which is the unit system you have followed for this analysis?.

Altair Forum User

Hi,

I am using HDPE and a,b, n values are correct.

Unit system: mm,msec, Mpa, N,gram

Now trying the same with MAT LAW 27 as the model is flexible type.

Altair Forum User

Hi Tushar,

LAW 27 is for brittle models, I believe. So tearing may not suite to this material model.

Can you check with LAW 34?

Altair Forum User

Hi,

MAT LAW 34 is only for solid elements and our model is flexible which almost flexible polymer(2D meshing).

So, I am using MAT LAW 27 for flexible material from the reference of following post.

Kindly suggest me the proper material law for flexible polymer.

Altair Forum User

Hi Tushar,

I was just going through the material card. LAW 27 is similar to LAW 2 with an additional space for modeling brittle failure/material damage.

Altair Forum User

In the out file it says Normal termination.

Can you share the animation file?

Altair Forum User

Hi,

I run the analysis with LAW 27 and consider the Aluminium properties from Help example as follows;

#RADIOSS STARTER

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/BEGIN

LAW27_void Aluminum

110 0

Mg mm ms

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

/MAT/PLAS_BRIT/3

Aluminum

# Init. dens.

0.0027

# E NU

60400 0.33

# A B N SIGMAX

90.266 223.14 0.375 177

# C EPS0 ICC

0 0 0

# EPST1 EPSM1 D_MAX1 EPSF1

0.16 0.72 0.999 1

# EPST2 EPSM2 D_MAX2 EPSF2

0 0 0 0

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

#ENDDATA

/END

#---1----|----2----|----3----|----4----|----5----|----6----|----7----|----8----|----9----|---10----|

Herewith shared the output file and animation file.

Please check it and suggest whether LAW 27 is appropriate for flexible polymer or not.

Unable to find an attachment - read this blog

Altair Forum User

I am unable to open the h3d file at my end. HV crashes as soon as I open it.

anyways, can you atleast paste a .gif image of the animation?

Altair Forum User

Hi,

There is a normal termination.

Please check the tear1.gif image.

Unable to find an attachment - read this blog

Altair Forum User

Hi Thushar,

Can you check the material law 35 (/MAT/LAW35 ). This law is applicable only for shell and solid elements and can be used polymers, elastomers, seat cushions....etc.

Altair Forum User

Hi,

I believe MAT LAW 35 is not suitable for my requirement because it works air enclosed in material, also it works only till elastic region.

Whereas plastics generally do not have enclosed air, and show elasto-plastic behavior.

I want to simulate tear strength or tear propagation in plastic laminate.

Altair Forum User

Tushar,

Most of the material is teared and there is no load transfer happening beyond which complete tear down will be seen.

I think this is the reason analysis terminates.

If you have a stress strain curve for your model try with LAW 36 and check if you see a similar behavior.

jsk459

Hi All,

In RADIOSS which material card is best to apply For a super tough, high viscosity acetal homopolymer grade with superior impact resistance - Derlin material ?

I have tried with MATL36(Full solid brick elements) and it is not working properly

Thanks,

Senthilkumar

Altair Forum User

Hi,

What kind of analysis you are trying to perform?.

For impact simulations, if interested in energy absorbtion, and evaluate risk of cracks, LAW36 is sufficient.

Or are you interested in permanent strains after unloading or creep/relaxation effects?.

Please let me know the type of analysis and objective so that we can guide you.

jsk459

Hi ,

Its a high velocity dynamic analysis. When i used LAW36 the component is deforming severely and element spike was happening.

The same model was worked properly in Dyna with MATL24 card.

Altair Forum User

Hi,

/MAT/LAW36 is the equivalent material law in RADIOSS for Law24 in Dyna.

Which element formulation you are using and also for material law is it only a single curve or multiple curves with strain rate dependency?.

If possible please share the model file and h3d file through my secure dropbox link.

jsk459

Hi,

Please find the below formulation and it is single curve strain rate

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

Altair Forum User

Hi,

The solid formulation seems fine.

Can you please share the model file so that we can review and can suggest the possible workarounds.

jsk459

Unfortunately we cant able to share the model. Please find the below details of the material. Is there any RADOIOSS material model to exactly capture the high viscosity with superior impact resistance property ?

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

Altair Forum User

HI @jsk459

Do you want to include thermal properties as well?