Glassfiber Reinforced Epoxy Pipe - Poisson's ratio

[Arline]

Hello,
I am doing deflection analysis of a pipe using GRE (Glass reinforced epoxy) pipe for which i ahve the following properties @ 21 Deg. C from material supplier

Hoop Tensile modulus = 23250 MPa
Poisson's ratio axial/hoop = 0.93
Axial Tensile Modulus = 10000 MPa
Poisson's ratio hoop/axial = 0.40

In FEA when i enter the poisson's ratios i get a message that the values ae not practical or with these values strain energy will be negative. I am using transvere isotropic format for GRE in FEA.

Will you suggest me on how to correct the problem of poissonss ratio.

 

[40818]

Not sure if i have read your post correctly, but i wouldnt use an isotropic material for your composite.
Where did you determine your youngs modulus from, it seems high?

 

[Arline]

I got the young's modulus from supplier. I am using transverse isotropic i.e E2=E3 (hoop plane).

ANSYS is showing an error in poisson's ratio. I was thinking that poisson's ratio of 0.93 is not correct. but i am not sure.

Please suggest.

Arline

 

[40818]

Did i say youngs modulus?? I meant to say Mr Poisson's was very high (0.93)

 

[jedward]

when the poisson ratio approaches 0.5 most results are expected to explode. incompressible materials (those maintaining volum under load) have values of about 0.49

check for more appropriate values

 

[Arline]

Hoop Tensile modulus = 25200 MPa
Poisson's ratio axial/hoop = 0.65
Axial Tensile Modulus = 12500 MPa
Poisson's ratio hoop/axial = 0.40

Above are the revised properties after speaking material supplier.
Can somebody help in understanding the "Poisson's Ratio AXIAL/HOOP". I typically always seen as just poisson's ratio but why they are saying that Axial/hoop and Hoop/Axial.

Assume the pipe axis in Z-direction, then what will be PR(Poisson's ratio ) in XY, YZ & ZX directions from above given values.

Which formula i need to use to calculate shear modulus for transverse isotropic materials.

Please help me in my learnings about composite.