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Imed
2004-10-28, 06:06
I want to write a constitutive law of an AISI material,
I found all necessary Data in Bibliography; the constitutive law is as follows:
********* n***** m
S=S0.(E/E0).(ER/ER0).F(T*)
////////////////////////////////////////////////
Where
S=Stress
E=Strain
ER=Strain rate
S0, E0, ER0 are given reference values
m,n given coefficients (Exposants)
TEMP=Temperature
And
T*=TEMP/Melting TEMP
This is defined as:


F(T*)= -1,23.T*+1,27 for TEMP<=600C

/////////////////3
F(T*)=72,3.T* -137,5.T* +80,4.T*-13,9 for 600<TEMP<=900C


Some properties are temperature dependant,



1. Thermal conductivity: Kp=53,56-0,00266.T W/m/C


2. Specific Heat: Cp=398,8+0,8273.T-0,00055.T J/Kg/C
3. Thermal expansion coefficient: 1,6E-5 m/mC
4. Young's modulus 75 GPa
5. Poisson's Ratio 0,3
6. Density: 7882 kg/m3
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My main objective is to write a subroutine that considers all above data, Can any one help me to do this?and what are the necessary options. I am using the ABAQUS/Standard 6.3 version. If any one has a similar subroutine, please send it. With lot of thanks

Jorgen
2004-10-28, 18:22
Although AISI 1020 is a carbon steel and not polymer :o
your question is still interesting.

As you probably have noticed, there are very few public UMATs available. I recommend that you carefully study the ABAQUS manuals, they have an exemplar UMAT for a J2-plasticity model.

Also, for your information, the ABAQUS manuals state that writing a UMAT takes considerable experties, and I agree with this. If you have a good background in solid mechanics and computer programming, then you should be able to write the UMAT that you are describing.

Best of luck,
Jorgen