Learning Forum

[Shuan-Tai Yeh]

Hi everyone,

I'm currently working on implementing an user defined EOS (Equation of State) using a lookup table similar to SESAME EOS in Autodyn. I've managed to modify the user-defined EOS in the mdeos_user_1.f90 file, but I'm unsure about how to include a table in the EOS. If anyone has any advice or suggestions, I would greatly appreciate your assistance.

Thanks in advance!

[Chris Quan]

You can refer to the Section 7.1. Subroutine MDSTR_USER_1 from Autodyn User's Subroutines Guide: 

7.1. Subroutine MDSTR_USER_1 (ansys.com)

It has an example on how to use one-dimentional array in Autodyn User Subroutines. Below is the definition of array in this example:

        ! FOR EACH REAL INPUT PARAMETER, ASSIGN DATA
        !                ('name    '     L, T,M,H, val, min,max,default,0,required)
        EQ%PAR(1)=PRMT (1,'Shear Modulus',-1,-2,1,0,ZERO,ZERO,BIG,ZERO   ,0,1)  ! THIS LINE MUST ALWAYS EXIST
        EQ%PAR(2)=PRMT (2,'EPS #1'       , 0, 0,0,0,ZERO,ZERO,BIG,ZERO   ,0,0)
        EQ%PAR(3)=PRMT (3,'EPS #2'       , 0, 0,0,0,ZERO,ZERO,BIG,ZERO   ,0,0)
        EQ%PAR(4)=PRMT (4,'EPS #3'       , 0, 0,0,0,ZERO,ZERO,BIG,ZERO   ,0,0)
        EQ%PAR(5)=PRMT (5,'YIELD #1'     ,-1,-2,1,0,ZERO,ZERO,BIG,ZERO   ,0,0)
        EQ%PAR(6)=PRMT (6,'YIELD #2'     ,-1,-2,1,0,ZERO,ZERO,BIG,ZERO   ,0,0)
        EQ%PAR(7)=PRMT (7,'YIELD #3'     ,-1,-2,1,0,ZERO,ZERO,BIG,ZERO   ,0,0)


Be aware that L, T, M, H in the Fortran statements above represent the exponent order of the unit Length, Time, Mass, and Temprature where a parameter has.

For example, shear modulus has the unit of Force/Area = Mass*Acceleration/Area. 

If the system of unit is SI units of mks, the unit of shear modulus = Kg*m/s^2/m^2 = Kg*s^-2*m^-1. Thus, L=-1, T=-2, M=1, and H=0 in the parameter definition of shear modulus.   

 In the user subroutine "mdeos_user_1.f90", you can

1. Define the size of a table in the MODULE EOS_USER_1. 
2. Initialize the table in the SUBROUTINE INIT_EOS_USER_1.
3. Assign values to the table in the SUBROUTINE SET_EOS_USER_1.