SUBROUTINE UMIXMODEFATIGUE(DADN,SKI_MAX,SKII_MAX,SKIII_MAX,
     $  SKI_MIN,SKII_MIN,SKIII_MIN,TEMP,DTEMP,PREDEF,DPRED,NFIELD,NPROPS,
     $  PROPS,NSTATV,STATEV,NIARRAY,I_ARRAY,NRARRAY,R_ARRAY,NCARRAY,
     $  C_ARRAY, DA)
c     
      INCLUDE 'ABA_PARAM.INC'
c     
      dimension props(nprops),statev(nstatv), predef(nfield),
     $     dpred(nfield),i_array(niarray), r_array(nrarray)
      character*80 c_array(ncarray)
      parameter (tol=1.0d-6)

       skeff=sqrt((SKI_MAX-SKI_MIN)**2+(SKII_MAX-SKII_MIN)**2
     $     +(SKIII_MAX-SKIII-MIN)**2)
       skTT = sqrt(SKI_MAX**2+SKII_MAX**2+SKIII_MAX**2)
       skshear=sqrt(SKII_MAX**2+SKIII_MAX**2)
       test=1.0
       if (abs(skTT).gt.abs(skshear)*tol) test=0.0
       skModeR= abs(skshear)*(1.0-test)/(abs(skTT)+test)
       an1=props(1)
       an2=props(2)
       c1=props(3)
       c2=props(4)
       if(skModeR.gt.0.5)Then
          dadN=c1*skeff**an1
       else
          dadN=c2*skeff**an2
       endif
c       write(*,*) 'an1,c1',an1,an2,c1,c2
c       write(*,*) 'gtt','gmodeR','dadn',gtt,gmodeR,dadn
      return
      end