FEA for Thermoplastics

[richg1]

Hi,

Has anyone any good introductory references for FEA of Thermoplastics. I'm familiar with standard linear FEA and contact analysis but not so much so for non-linear.

My current problem is the analysis of an assembly of parts made from a glass reinforced, carbon fiber nylon dupont resin. (Zytel CDV805 BK409)

I saw this eseminar from Aug 2006 and was wondering if anyone had seen it or knew whether an copy was available?

http://polymerfem.com/modules.php?name=News&file=article&sid=71

Cheers,

Rich

 

[gfbotha]

Rich, you might find the following interesting/useful:

http://kbam.geampod.com/KBAM/Reflection/Assets/11850.pdf

Regards
Gert

 

[gfbotha]

Just realised you might encounter access problems (?) using the above direct link - I actually got to it via

http://www.geplastics.com,

then see under LITERATURE AND TOOLS > Technical Papers,...

 

[GBor]

I haven't read the article, but it looks pretty interesting. When you say you are

familiar with standard linear FEA and contact analysis

is that familiarity with Thermoplastics, or just with the analysis techniques used in homogeneous materials?

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[richg1]

Hi GBor,

As you said, whilst I'm vaguely familiar with the requirements for modelling thermoplastics, most of my fea work to date (note - not a regular part of my work) has been with homogeneous materials.

To some degree it's one of those areas that I want to learn more about so I can converse with those with greater expertise, and therefore be in a better position to judge outsourced work...

Rich

 

[jerzy]

Hello Rich,

A book I have found useful is:
"Structural Analysis Of Thermoplastic Components", by Gerry Trantina and Ron Nimmer, McGraw-Hill, Inc. 1994.
ISBN 0-07-065202-3. It is currently in stock at Amazon.com and at Barnes and Noble.


Jerzy

 

[GBor]

Good reference. There are several books out there on Fiber-reinforced composite materials. Thomas Hahn has put out a couple. Understand the additional complexity when you go from a 1x1 stiffness matrix to a 9x9...or even 36 x 36! Once you see how the various angles are designated in the basic analysis, learning the FEA is just a matter of figuring out how to input that information into your chosen software.

Oh, yeah, and the endless testing that you have to do to get the proper physical properties and potential failure modes. Matching that to your analysis techniques...etc. etc. etc.

Most of the failure analysis methods out there today fall short in at least a mode or two (they are willing to admit that...not my assessment). Spend a great deal of time thinking in terms of "strain" (most of us have been taught to think in terms of "stress"). We don't have a great feel for failure stress in composites because it depends on specific materials used, fiber orientation...generally requires a GREAT amount of testing with VERY specific witness coupons.

It's a fun field to be in...ENJOY!

Garland

Garland E. Borowski, PE
Borowski Engineering & Analytical Services, Inc.
Lower Alabama SolidWorks Users Group

 

[torpen]

Hello,

The main difference is the behavior of the material.
The law can be a viscoelastic or viscoplastic law in case of a glass-fiber-reinforced polyamide.
The behavior depends on the loading (effect of temperature and strain rate).

You have to choose a behavior law in the materials library of your FEA software, a strain measure and to apply the loading step by step to follow the nonlinear material law (even if it's a static analysis).

One difficulty is to find the properties of the polyamide.

You can begin with a elastic linear law to check your model.

Regards,

Torpen.