Poisson Ratio Input for VTI vertical transverse isotropic

YL 2021-02-03

I need your help again.

I'd like to confirm input of Poisson ratio for VTI(vertical transverse isotropic) material using engineering constants. If vertical direction is 3, then direction 1,2 are in-plane direction and I define local orientation is the same as global direction. There are 5 independent constants, Ep, Et, mu_p,Nu_pt (or Nu_tp), Gt. In engineering constant input, the Poisson ratio is Nu12, Nu13,Nu23. Now questions I have are:

1. in my case, Nu12 is in-plane Poisson ratio, Nu13=Nu23 is transverse Poisson ratio, is it correct?

2. so I don't need to input Nu31. Does abaqus use the relationship of Nu31/E3=Nu13/E1 to back calculate Nu31?

3. any relationship between Nu12 and Nu13? I only know the value of Nu13, for example, 0.35. what is the typical value of Nu12? I know it is best to do lab test. but anyone has some example value I can get some idea with it?

4. G12=Gp=E1/(1+Nu12). If we input E1 and Nu12 already, why we still need to input G12?

Thank you so much for your help again.