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Abaqus UMAT problem

Submitted by yoon on
Hello

I'm a new commer in Abaqus and working on topology shape optimization for dental implantation.
I have two user-defined materials for Jaw bone area, and using the stress-increment-controlled method
Young's modulus of an element is changed according to the following equation (1) with two constraints (2)

E(i+1) = E(i) + k(sigma(i) - sigma_ref)   --- (1)

where k and sigma_ref are constants

E(i+1) = E_min if E(i+1)<E_min
E(i+1) = E_max if E(i+1)>E_max    (2)

If my Young's modulus is changing with two different user-defined materials, 
is it possible for this process to work through Abaqus UMAT?

I've already created the simple input file before I go through the final analysis, 
but kind of stucked with how to define materials in UMAT
and how to implement the above equation if I need some iterations.

For example, I can say E = STATEV(1)


if E > E_min

E = E + k(sig - sig_ref)

elseif E < E_min

E = E_min

elseif E > E_max

E = E_max

end

But do I still need to define the E in the DO-loop?