Creep subroutine

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Creep subroutine

tabassum
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Dear Abaqus Users,

I have written creep subroutine for the set of constitutive equations .Before writing the subroutine I have written an integration code for the equations in Plato IDE and obtained the desired integration curve(Stress vs strain).
Now using the same constitutive equation I have written a creep subroutine with an aim to get same stress-strain(as from the integration code) curve for one element model using Visco step in Abaqus.
Please see attachments for subroutine .f file, an input file and also the integration code file.
Now the problem is that the stress-strain curve in the subroutine never goes beyond the elastic limit    
The following portion is from the creep subroutine(can be seen in attachment).According to which if D1 is less than zero, it means the stress-strain curve is in the elastic region so DyDt(1) is zero but after some time when the QTILD value increases this D1 value should have positive values and so the material deformation should enter in the plastic region and I should get some value of CEEQ from the Visco step of Abaqus.

 
  !plastic strain rate
            D1= (QTILD-STATEV(1)-SMETAL(1))
               IF ((D1).LE.1.0D-15) THEN
            DyDt(1)=0
                   else
            DyDt(1)=(((D1)/(SMETAL(2)))**SMETAL(3))*(1/(1-STATEV(3)))
                   END IF

I am working on this for the last 2 months.Could any please help.

Best Regards
Tabassam

creeepfrommatlab.f (4K) Download Attachment
Jobinmeters.inp (21K) Download Attachment
integration code.f95 (5K) Download Attachment
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