question regarding the updating a user variable

[vinnuram]

hey all,
i am trying to update my own variable with the help of strain.I need to update own variable in every step of the analysis.
these are my equations: I am considering 2D symmetry equations and i want to calcuate my own variable XT=sqrt(2/3(E(1)^2+E(2)^2+E(3)^2))
epsilon11=E(1)=E(1)+delta(epsilon11)
epsilon22=E(2)=E(2)+delta(epsilon22)
epsilon12=E(3)=E(3)+delta(epsilon12)
I want to know whether abaqus directly takes E(1)as strain in 11 direction and E(2)as 22 and E(3) as 12direction.
I guess i can give the loop from 1 to NTENS as i want have the strain increments.
one more last question :
I want to update my variable XT in every step of abaqus analysis.If i intialize the E(1),E(2) and E(3)equal to zero before the loop i guess it does not get the updated value in the next step of analysis.
So is there any command to control the step that it should take th updated values of E(1)...... every time and get the updated value of XT.

thanks to everybody in helping me in linking the abaqus with the subroutine.

Thankyou
Vinnu S.Arige[/list]

[Jorgen]

Hello Vinnu,

Let's see if I can understand what you are after. You want to update your own variable, OK that can be done. Does your variable depend on its previous values? If so, then you need to make it a state (history) variable, if not, then you can simply make it a local variable in your material subroutine.

Hmm, it looks like your variable XT is some type of effective strain. I don't quite understand, however, that you mean by E(1). Where do you get E(1) from? Is E(1) simply the total (current) strain in the 11-direction? If so then you have two options:
(1) make E(1) a state variable and update it by [TeX:3617958f11]\Delta\epsilon_{11}[/TeX:3617958f11].
(2) calculate E(1) from the deformation gradient.

Best of luck,
Jorgen