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z direction(out of plane)properties for composites
5

z direction(out of plane)properties for composites

z direction(out of plane)properties for composites

(OP)
For an ansys analysis i need to know z direction(out of plane)material properties of on filament wound carbon/epoxy composite.but in handbooks i saw only the properties in x,y&xy directions.how can i have these properties.any help would be appreciated.

Cheers

alleak

RE: z direction(out of plane)properties for composites

4
What specific material system do you have?  There is some thru-thickness shear data in Mil-Handbook-17.  Other values can be estimated from the im-plane values.

RE: z direction(out of plane)properties for composites

(OP)
Hi SWComposites ;
It is necessary at least to enter Ez & Strenght in Z direction and it is sufficient to enter other modulus and strenghts relating to z direction.

Cheers

alleak

RE: z direction(out of plane)properties for composites

I don't understand your reply.  What material are you analyzing?  What are the in-plane properties that you are using for your analysis?

RE: z direction(out of plane)properties for composites

(OP)
I am analysing a 3d composite(carbon/epoxy) pressure vessel and i want to obtain tsai-wu failure criterian.I have only these properties:(1,2 or x,y are in plane 3 or z is out of plane)
MODULUS: E1,E2,G12
STRENGHT: Xt,Xc,Yt,Yc,S
POISON RATIO:NU12
but there are more properties required by ansys,if i leave other blank ansys shows an error,until i use a value for modulus E3,and strenghts Zt,Zc,now ansys will solve the problem.I think this is because The Tsai-Wu failure criteria used in ansys are 3-D versions of the failure criterion.plus these there are other properties which leaving them blank does not make an error in ansys but this may influnce on the results.these properties are:
G23,G13,NU23,NU13,Zt,Zc,Syz,Sxz


Cheers

alleak

RE: z direction(out of plane)properties for composites

You are obviously using solid elements in your model, therefore you will need to enter a full set of 3D stiffness properties.  You will have to look in the Ansys manual regarding what strength properties for the failure criteria are required, but I suspect that a 3D set is required also.  Now, as to what values to enter, you need to answer the following questions (which I will ask for the third and last time):
- what specific material are you using (fiber, resin, vendor)?
- what values are you entering for the in-plane properties?  I know what the variables are; what is needed is the actual values.

RE: z direction(out of plane)properties for composites

(OP)
I used shell elements(shell 99 which is Linear Layered Structural Shell)and i mentioned that in ansys manual The Tsai-Wu failure criteria used are 3-D versions of the failure criterion .so strenghts in all directions(x,y,z,xy,xz,yz)are required.
your questions:
1-carbon fibers are TC-42 from TAIRYFIL co.
2-epoxy resin is LY5052,and hardener is HY5052,these are from CIBA co.
3-Wf(fiber weight ratio)is 0.625 so Vf(fiber volume ratio)is 0.5
4-values entered first are:
modulus:
Ex=1.103e11 pa
Ey=1.52e10 pa
Gxy=4.9e9 pa
poison ratio:
PRxy=0.25
strenght:
XTenstrs=1.918e9 pa
XComstrs=-1.569e9 pa
YTenstrs=2.74e8 pa
YComstrs=-1.245e9 pa
XYShstrs=6.895e7
by these values ansys shows an error
so i entered :
Ez=Ey
ZTenstrs=YTenstrs
ZComstrs=YComstrs
and i got a result but other values which may affect the final results are left blank:(G23,G13,NU23,NU13,Zt,Zc,Syz,Sxz )

Cheers

alleak

RE: z direction(out of plane)properties for composites

Ok, assuming this is a unidirectional tape material (which it appears to be by the stiffness properties that you listed), I recommend the following based on other typical carbon fiber/epoxy materials (room temperature/ambient properties):

YT and YC appear to be way too high for a carbon/epoxy tape.  I would use something like:

YT = 8 ksi (5.52E7 pa)
YC = -40 ksi (-2.76E8 pa)

for the thru-thickness properties:

EZ = 1.3 msi (8.97E9 pa)
(note your value for EY of 2.2 msi seems too high for an epoxy material at room temperature)
G13 = G12 = 4.9E9 pa
G23 = 0.67*G12 = 3.28E9 pa
NU13 = NU12 = 0.25
NU23 = [EZ/2/G23]-1 = 0.365 (assumes material is isotropic in the 2-3 plane)
ZT = YT = 8 ksi (5.52E9 pa)
ZC = YC = -40 ksi (-2.76E8 pa)
SXZ = SYZ = 5 ksi (3.45E7 pa)

Hope this helps.

RE: z direction(out of plane)properties for composites

(OP)
Thanks a lot for your consideration.The values i mentioned are based on this book:
Hyer M.W.,"Stress Analysis of Fiber Reinforced Composite Materials"McGrawHill 2001
perhaps these are for another kind of carbon/epoxy.
but i want to know how did you guess Ez and other formula,where are they from.are they from a reference or they are from your own experiments.

Cheers

alleak

RE: z direction(out of plane)properties for composites

I did not "guess" anything.  My recommendations are based on 20+ years of experience with composite materials and a lot of test data.  Unfortunately, I do not have data for your specific material system (TC42/5052).  Data published in textbooks is usually of unknown pedigree and of questionable value.  One source of composite material data is Mil-Handbook-17 (copies of which can be purchased at www.astm.org)  Volume 2 contains data for a number of carbon/epoxy material systems, though not your specific material.

RE: z direction(out of plane)properties for composites

Hi Alleak;

Why don't you get your materials tested? You can get the material results in all directions you need. Some materials testing labs (like www.axelproducts.com) can help you out with that quite easily!

Ron

RE: z direction(out of plane)properties for composites

SW: where did you get your 2/3 factor for G23 from? We've seen various values recommended for this over the years, but have not got a "definitive" one. It can have a significant effect on buckling predictions.

RE: z direction(out of plane)properties for composites

RP: there is some thru-thickness shear stiffness data (G13, G23) in Mil-Handbook-17, Volume 2, Rev F for a couple of carbon fiber/epoxy materials.  I based my factor on this data and other proprietary data which I have access to.

RE: z direction(out of plane)properties for composites

Ah. Thanks. I hadn't spotted that snippet in MIL-HDBK-17. I'm always finding stuff in there that I didn't know was there.

RE: z direction(out of plane)properties for composites

you can assume the fiber is isotropic. so the properties you need input are only E and v. The composite will be transversely isotropic in this case.

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