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Elasticity Matrix for polycarbonate and Aluminum

Posted Sep 13, 2016, 8:51 p.m. EDT Results & Visualization Version 5.0 8 Replies

Mina Abbasipour
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Hello all,

I wonder would someone be able to shed light on something for me.

The anisotropic elasticity is defined as a 6x6 matrix:
{D11, D21, D31, D41, D51, D61, D12, D21, D22, D23 ... and so on up to D66} .
But Comsol allows only 21 coefficients in the elasticity matrix.

How can I put elasticity matrix in 21 coefficients?
The other question about the elasticity matrix of polycarbonate. What is the elasticity matrix of polycarbonate?

Thanks for reading, hopefully someone can help.

Mina
8 Replies Last Post Sep 14, 2016, 2:23 p.m. EDT
Jeff Hiller COMSOL Employee

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Posted: 8 years ago Sep 13, 2016, 9:15 p.m. EDT
Hi Mina,
That 6x6 matrix is symmetric, so it only has 21 independent coefficients: D12=D21, etc...
Jeff
Hi Mina, That 6x6 matrix is symmetric, so it only has 21 independent coefficients: D12=D21, etc... Jeff
Mina Abbasipour
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Posted: 8 years ago Sep 14, 2016, 9:32 a.m. EDT
Dear Jeff

Thank you so much for your reply.

I have three coeficient : c11: 10.62; C22: 6.13; C44:2.85

How should I put in Comsol parameters?

Thanks a lot and best regards
Mina
Dear Jeff Thank you so much for your reply. I have three coeficient : c11: 10.62; C22: 6.13; C44:2.85 How should I put in Comsol parameters? Thanks a lot and best regards Mina
Jeff Hiller COMSOL Employee

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Posted: 8 years ago Sep 14, 2016, 12:02 p.m. EDT
That does not look right. You cannot have zeros on the diagonal, the problem would be singular.
Please contact COMSOL support if you need further assistance.
Best regards,
Jeff
That does not look right. You cannot have zeros on the diagonal, the problem would be singular. Please contact COMSOL support if you need further assistance. Best regards, Jeff
Edgar J. Kaiser Certified Consultant
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Posted: 8 years ago Sep 14, 2016, 12:44 p.m. EDT
Mina,

are you sure you have c22 and not c12?

for materials with cubic symmetry c11, c12 and c44 are sufficient. Look there: solidmechanics.org/text/Chapter3_2/Chapter3_2.htm

in chapter 3.2.16

If possible use Firefox, the page gets scrambled in IE.
Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Mina, are you sure you have c22 and not c12? for materials with cubic symmetry c11, c12 and c44 are sufficient. Look there: http://solidmechanics.org/text/Chapter3_2/Chapter3_2.htm in chapter 3.2.16 If possible use Firefox, the page gets scrambled in IE. Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com
Mina Abbasipour
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Posted: 8 years ago Sep 14, 2016, 12:54 p.m. EDT
Dear Dr. Edgar J. Kaiser

Thank you so much for your help and reply.

Best Regards
Mina
Dear Dr. Edgar J. Kaiser Thank you so much for your help and reply. Best Regards Mina
Mina Abbasipour
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Posted: 8 years ago Sep 14, 2016, 12:55 p.m. EDT
Dear Jeff

Thank you so much for your help and reply.
Best Regards
Mina
Dear Jeff Thank you so much for your help and reply. Best Regards Mina
Mina Abbasipour
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Posted: 8 years ago Sep 14, 2016, 1:13 p.m. EDT
Dear Edgar J. Kaiser

Polycarbonate is istropic material or anistropic?

Best Reagrds
Mina
Dear Edgar J. Kaiser Polycarbonate is istropic material or anistropic? Best Reagrds Mina
Edgar J. Kaiser Certified Consultant
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Posted: 8 years ago Sep 14, 2016, 2:23 p.m. EDT
Mina,

my best guess is that in most practical cases the pure polymer can be considered mechanically isotropic. Of course things change radically as soon as you consider a composite or you look at microscopic particles when the partial crystallinity of the material shows up.

As frequently, it depends on your specific case ...

Cheers
Edgar

--
Edgar J. Kaiser
emPhys Physical Technology
www.emphys.com
Mina, my best guess is that in most practical cases the pure polymer can be considered mechanically isotropic. Of course things change radically as soon as you consider a composite or you look at microscopic particles when the partial crystallinity of the material shows up. As frequently, it depends on your specific case ... Cheers Edgar -- Edgar J. Kaiser emPhys Physical Technology http://www.emphys.com

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