Use ABAQUS USDFLD to define thermoplastic behaviours, please check my code

[kuangyu]

Hi,all.
Recently I have to define nonlinear behaviours of thermoplastic by USDFLD in ABAQUS. However i am quite new in coding. Could you please help me checking my code? Thanks a lot for your help. Some details about my model are listed below.

The nonlinear behaviors of thermoplastic is demonstrated by the equation
E= E0*[1-exp(-k*e)]/(k*e)
In the equation, k=46.1, E0=802, e is the strain from the analysis. The Young's modulus E depends on the strain e.
Before the USDFLD code, I add a SDVINI code to define the initia young's modulus which equals to E0. Unfortunately I am not sure about the SDVINI code also.

Codes

 SUBROUTINE SDVINI(STATEV,COORDS,NSTATV,NCRDS,NOEL,NPT,LAYER,KSPT)
C
      INCLUDE 'ABA_PARAM.INC' 
C
      DIMENSION STATEV(NSTATV),COORDS(NCRDS)
C
      STATEV(1)=802
C
      RETURN
      END
      SUBROUTINE USDFLD(FIELD,STATEV,PNEWDT,DIRECT,T,CELENT,
     1 TIME,DTIME,CMNAME,ORNAME,NFIELD,NSTATV,NOEL,NPT,LAYER,
     2 KSPT,KSTEPKINC,NDI,NSHR,COORD,JMAC,JMATYP,MATLAYO,
     3 LACCFLA)
c
     INCLUDE 'ABA_PARAM.INC'
c
     cHARACTER*80 CMNAME,ORNAME
     CHARACTER*3 FLGRAY(15)
     DIMENSION FIELD(NFIELD),sTATEV(NSTATV),DIRECT(3,3)
    1 T(3,3),TIME(2)
     dIMENSION ARRAY(15),JARRAY(15),JMAC(*),JMATYP(*),
    1 cOORD(*)
c
c   USER CODE START 

c   DO IT ONLY FOR SPECIFIC MATERIAL
    IF (cmname  .EQ. 'THERMOPLASTIC HDPE') THEN
C
C   DEFINE CONSTANTS
C
    K = 46.1
    E0 = 802

C   GET CURRENT STRAIN (VALUE EE) AND SAVE IT INTO 'ARRAY'
    CALL GETVRM('E',ARRAY,JARRAY,FLGRAY,JRCD,JMAC,JMATYP,
    MATLAYO,LACCFLA)

C   E1 OUTPUT = ARRAY(1) AND GET ABSOLUTE VALUE
    EPS = ABS(ARRAY(1))

C   CALCULATE THE Em
    Em = E0*(1-EXP(-K*EPS))/(K*EPS)

C   USE Em AS A FIELD VARIABLE
    FIELD(1) = Em

c   STORE Em AS A SOLUTION DEPENDENT STATE VARIABLE
    STATEV(1) = FIELD(1)
C
    RETURN 
    END

If you can do some corrections to my coding, it will be really appreciable. Thanks.

Best Regards,
Kuang Yu