Hi Everyone,

I've couple of quick questions:

1) I am planning to use ABAQUS 2D shell formulation (S4R) to estimate
3D state of stress (to reduce the computational cost). I've read several articles to estimate the
transverse shear stresses once the in-plane stresses are known by
integrating the 3D equilibrium equations. This is, of course, easily
done, if we have closed form solutions for in-plane stresses:

sigma_xz,z = - (sigma_xx,x + sigma_xy,y)
sigma_yz,z = - (sigma_xy,x + sigma_yy,y)

How do I estimate transverse shear stresses using ABAUAS VUMAT, when I
only know the in-plane stresses at one integration point in the element
(in case of S4R) in VUMAT? Else, is there any possibility to transfer/estimate the transverse shear strains within the VUMAT?

2) In my analysis, I will use progressive failure analysis, where
transverse stiffness cannot be kept constant in the analysis (I read in
ABAQUS manual, we cannot change the transverse stiffness. Is there any
possibility to control transverse stiffness, within VUMAT, in case of shell elements?

Thank you for your help,
Nagesh