Help in honeycomb composite modeling
Altair EmployeeHello,
my name is Yanni Eleftheriadis and I am new to Optistruct and Hypermesh. I am currently working on a project on Optistruct that has to do with modeling a composite material and I would appreciate any advise on how to model the composite material with the following details:
My compound should be made from three plies of carbon fiber, one ply of honeycomb material and four plies of carbon fiber. What I have to start with is a shell geometry without any thickness. The honeycomb material has a given spec of MAT9 and the carbon fiber a spec of MAT8.
1) I have tried to form a laminate using Hyperlaminate but I can not get MAT9 inside the panel to build the laminate.
2) I checked for MAT9 and I found that I can only use it in 3d elements which I do not have since my geometry is a shell (Can I get from a shell geometry 3d elements?).
3) I tried to form a solid geometry by offsetting 2d elements from my shell but the geometry is so complex that my computer is anable to resolve.
In order to be clear and not to confuse what I mean by shell is that my model ( car seat ) has a complex 3d geometry that has no thickness.
When I use a PCOMPP or PCOMPG property and create the laminate without using the Hyperlaminate panel, it looks ok and I get a visualization on the screen on how the compound should look like but I am not sure if this is the correct proccedure.
My question is: How can I model a honeycomb composite material with MAT9 and MAT8 composites in it when starting from a 2d geometry?
Can someone help me with this? I would be gratefull for any tip and advice.
Thanks in advance
Yanni Eleftheriadis
Answers
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You can model honeycomb with Shell elements using PCOMPP and MAT8 as MAT9 and MAT9ORT are only compatible with 3D elements.
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Hello Mr. Prakash Pagadala,
thank you very much for your reply!
As far as I can understand from your reply, if I do not have 3d elements, I can not use a material MAT9 since it only compatible with 3d elements, correct?
I have already tried to create 3d elements out of my geometry by offseting my 2d elements and to aply in each element level different material but due to complex geometry my pc can not do the job i suppose and it keeps crashing down (maybe it is not possible eather with such complex design...)
The thing is the project has a MAT9 material with all the details ( G11 to G66, RHO, A and TREF) and I have to use it for the composite laminate. It is going to be a sandwitch like material having carbon fibers top and bottom and honeycomb material between.
I am trying to figure out if there should be from the beginning a 3d solid instead a 2d drawing in order for the material to be applicable or if the material characterization of MAT9 is not correct.
I have an other question for anyone that can help me clarify this:
1) Is there an other way to model sandwitch components without having 3d elements and use MAT9 as the midle section of the composite?
Thank you once again for your valuable help
Your answer has been most enlightening for me.
Yanni
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Hi Yanni,
The only way I can see is converting Gij's to Eij's and using the output in MAT8.
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Thank you very much for your answer. It has been very helpfull. I wish the best for 2015
Thanks again
Yanni
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Thank you Yanni, I wish you the same
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Merry Christmas and Happy New Year
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Hello
I also have a doubt about modeling honeycomb in Altair, and since this topic is about the same theme, I hope it is ok to post here.
As Yannis, I am studying a 2D model made of carbon fiber with a honeycomb core and my primary goal is to perform an optimization of this part, so it's out of the question to use 3D elements for the core.
The problem is, the properties of the material that I have available are E1, E2 and E3(this being the compressive modulus) and also Gxy,Gxz and Gzy. And of course the density and Poisson. However, for MAT 8 I can only assign E1 and E2 so I am not sure about which values to assign to the material.
Can anyone help me?
Thank you and I apologize if this is not the appropriate topic for my post
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Hello again!
I have proceed with the primary analysis of the model an want now to do a Optimization simlation.
What is the corect way to proceed in such a case of a sandwich composite with diferen materials top and bottom and honeycomp material in the center?
Is it posible to keep the arranged plies as they are and only do a ply thickness optimization, or should I run a free size optimization first and then do a size and shufle optimization?
The model is a compination of 3 plies - 1 ply - 4 plies of different material from the begining and I am wondering if it is posible to keep the originat arrangement and do a simulation only on the ply thicknesses in order to minimize the mass keeping the total displacement and stress under certain numbers!
Would appreciate any given advise!!
Thank you in advance
Yannis
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Hi,
I have the same propblem: I know I could use MAT9 for honeycomb structure if I had 3D elements, but I have only 2D elements that is why I have to use MAT8. How can I apply the material properties which I can find in any honeycomb material datasheet to the MAT8 material card?
These are the material properties I can get from a honeycomb datasheet:
Compressive strengthCompressive modulusShear strength 1 directionShear modulus 1 directionShear strength 2 directionShear modulus 2 directionThese are the material properties I can use for MAT8:E1E2NU12G12G1ZG2ZXtXcYtYcS
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Hi,
My questions is about the Gij values. I have all 9 properties required to define an anisotropic honeycomb.
That is:
E1 (GPa)
E2 (GPa)
E3 (GPa)
G12 (GPa)
G13 (GPa)
G23 (GPa)
ν12
ν13
ν23
So I am looking at the MAT9 – Material Property Definition, Form 9 found here: https://www.sharcnet.ca/Software/Hyperworks/help/hwsolvers/hwsolvers.htm?mat9.htm
and my confusion arises with the following sentance: 'The subscripts 1 to 6 refer to x, y, z, xy, yz, zx of the material coordinate system defined by the CORDM field on the PSOLID entry.'
Gij is apparently the material property matrix, so I'm assuming my 9 properties should correspond to the matrix of Gij's provided. This would make sense if the Gij matrix subscripts were just numbered 1 - 6 but there are subscripts like G66 and G56 for example which according to the defintion should mean Gzxzx and Gyzzx which doesn't make sense. Could anyone let me know how the values in my table match up with the subscripts please.
Regards
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