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# anisotropic material

## anisotropic material

(OP)
I know that this question may sound very stupid , but if I know the Young modulus in the X,Y and Z directions of an anisotropic material, how can I get the elastic matrix (G) ? (XX YY ZZ XY YZ ZX)
For example : Young modulus in X = 39 GPa , Y= 12 GPa, Z= 12 GPa.

thank you .

### RE: anisotropic material

What do you mean by the "elastic matrix (G)"? A stiffness matrix for a ply will have nine terms if it is a Q matrix.

If the XX, YY, ZZ, are just the direct ply stiffnesses in the X, Y and Z directions then XY is in-plane shear and YZ and ZX are out-of-plane shear. These are independent and must be measured. They can be (very) roughly estimated by micromechanics but cannot be deduced from the X, Y and Z properties.

See NASA Technical Memorandum 83696, "Simplified Composite Micromechanics Equations for Strength, Fracture Toughness, Impact Resistance and Environmental Effects" by C. C. Chamis. (Just googling for NASA TM 83696 should give a suitable ref.) You could also try NASA TM 2007-214673 "Composite Nanomechanics: A Mechanistic Properties Prediction".

Or you could try http://www.mse.mtu.edu/~drjohn/my4150/index.html .

NASA RP 1351, "Basic Mechanics of Laminate Composite Plates", by A.T. Nettles, is also very useful.

From the look of it your X, Y and Z properties are for a unidirectional glass fiber/polymer composite (possibly a high fiber volume fraction of E-glass or a low volume fraction of S-glass). I'd expect the shears all to be about 4000 or 5000 MPa.

### RE: anisotropic material

(OP)
@RPstress thank you very much for your help.You are absolutely right it's a unidirectional glass fiber.
I'm trying to model a ring made of a unidirectional glass fiber, and I only have the Young modulus in X Y and Z.Does this fall under the "ply" modeling ?
And as you were able to see I'm totally new to this field.
Thank you for your time !

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