I have a product made by 3d printer with material of ABS and I need to define its properties.
Thank you very much Dr Sergei,
I read them and I found 4 elastic constants (Ex =2016 MPa, Vxy = 0.43; Ey = 1530 MPa, Vyx = 0.41)
To get the other elastic constants , I searched on relations between Gxy,Gxz,Gyz and the other constants and found some relation but used for orthotropic fibers in a matrix ,
such as :
E33 = E22, G13 = G12, ν13 = ν12,
and
E22 = 2(1 + ν23)G23
source:http://www.kayelaby.npl.co.uk/general_physics/2_2/2_2_2.html
My question :
Can I depend on such relations considering the ABS as fibers in a polymeric matrix of ABS also ?
Or how can I get other constants?
Thank you in advance very much for your help :)
I am afraid you can't completely trust such relations obtained for fibers. For your sample you need all the 9 constants. If I come across such information, I let you know.
As I expected, the above relations between elastic constants are valid only for the so-called transversely isotropic material, Your printed ABS sample is of different type. However, in your case there may exist a special symmetry which allows to reduce 9 constants to just 6. According to the attached master thesis (see page 25 for discussion), this is a natural outcome of the crisscross type deposition. The independent 6 constants for 3D printed ASB are as follows (see page 67 of the thesis):
E2 = E1 = 1636 MPa,
E3 = 1197 MPa,
n21 = 0.39,
n31 = n32 = 0.37,
G13 = G23 = 645 MPa,
G12 = 676 MPa.
Of course, you need to find an independent way to check these estimates for your sample. I hope the attached thesis will provide you with some help.
Dear Dr Sergei,
Can I use 2 constants from tests and they are E1 and E2 and use the other 7 elastic constants from the thesis ?
Because the values of E1 and E2 in the thesis shifted my results in Ansys away from the calculated ones !
As the 9 elastic constants are independent and I need to characterize them through tests (shear and tension) tests.
Is it scientific way?
or I have to test specimens in shear to get shear modulus in the three planes?
Dear Ahmed,
like I said before, the best way is to test your own sample (using shear and tension tests). You should realize that all the estimates are always sample sensitive. There are no (and can't be) any universal values of the elastic constants. So, it's quite normal if some of your estimates differ from any given pattern. Simply try to minimize the differences. Clearly, for any realistic 3D prepared sample, E1 would be different from E2 (n31 from n32 etc). The only question is how much? This is for you to find out.
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