# Are there any implicit creep examples showing how ANSYS interpolates temperature-dependent material properties?

 Yes, please see the ANSYS 8.1 implicit creep example below. It shows how the creep constants themselves are linearly interpolated before the Norton algorithm (implicit creep material model #10) is evaluated. The input is also attached to this record as "creep_temp_int.inp".fini/clearunif_t = 100.0 ! uniform temperature (illustrates temp-dependent mat props)/title, Implicit Creep #10 (Norton) with Constant Uniaxial Stress in ANSYS 8.1/plopts,info,1/view,,1,2,3/prep7et,1,SOLID185,,1 ! uniform reduced integration with hourglass controlr,1mp,ex,1,10.0e6 ! Young's modulus, psimp,nuxy,1,0.30 ! Poisson's ratio, unitlessT1 = 25.0 ! temperature 1 = 25 degrees FT2 = 150.0 ! temperature 2 = 150 degrees FT3 = 200.0 ! temperature 3 = 200 degrees FC1_T1 = 0.11e-9 ! C1 at temperature T1C2_T1 = 1.1 ! C2 at temperature T1C3_T1 = 0.0 ! C3 at temperature T1C1_T2 = 0.12e-9 ! C1 at temperature T2C2_T2 = 1.2 ! C2 at temperature T2C3_T2 = 0.0 ! C3 at temperature T2C1_T3 =0.13e-9 ! C1 at temperature T3C2_T3 = 1.3 ! C2 at temperature T3C3_T3 = 0.0 ! C3 at temperature T3tb,creep,1,3,3,10 ! implicit creep model #10 (Norton)tbtemp,T1tbdata,1,C1_T1,C2_T1,C3_T1 ! C1, C2, and C3 at temperature T1tbtemp,T2tbdata,1,C1_T2,C2_T2,C3_T2 ! C1, C2, and C3 at temperature T2tbtemp,T3tbdata,1,C1_T3,C2_T3,C3_T3 ! C1, C2, and C3 at temperature T3! Note: Creep strain rate = C1 * (Sigma^C2) * (e^(-C3/T))!! Therefore, the creep strain rate dependence on temperature! is removed (other than interpolation of constants), since! C3 = 0 for each temperature specified ...n,1,0.0,0.0,0.0n,2,1.0,0.0,0.0n,3,1.0,1.0,0.0n,4,0.0,1.0,0.0n,5,0.0,0.0,1.0n,6,1.0,0.0,1.0n,7,1.0,1.0,1.0n,8,0.0,1.0,1.0e,1,2,3,4,5,6,7,8 ! single element (1/4 symmetry)fini/soluantype,static ! no inertia effects, so transient not needed ...nlgeom,onnsel,s,loc,x,0.0d,all,ux,0.0 ! YZ symmetry planensel,s,loc,y,0.0d,all,uy,0.0 ! XZ symmetry planensel,s,loc,z,0.0d,all,uz,0.0 ! XY plane is held (pull nodes at Z=1) ...nsel,s,loc,z,1.0sf,all,pres,-20.0e3 ! constant stress as area of pressure decreases ...nsel,alltunif,unif_t! uniformtemperaturetoffst,460 ! Fahrenheit to Rankine conversion ...outres,all,alloutpr,all,lasttime,1.0e-8deltim,1.0e-8,1.0e-9,1.0e-8rate,offsolvesavetime,1.0e4deltim,1.0e-1,1.0e-2,1.0e2 ! largest time step = 100 seconds ...rate,on,onnlgeom,on ! load drop matches cross section area decreasesolvesavefini/post1/graph,full/dscale,,1 ! true scale displacement magnificationset,firstprnsol,epel,prin ! elastic strain (RATE,OFF result)plnsol,u,sum,2/wait,1set,lastprnsol,epel,prin ! elastic strain (RATE,ON result)prnsol,epcr,prin ! correctly uses EFFNU=0.5plnsol,u,sum,2prnsol,u,comp/wait,1fini/post26numvar,200file,,rstesol,2,1,,s,eqv,seqv ! average equivalent stress (constant)esol,3,1,,epcr,eqv,epcreqv ! average equivalent creep strainesol,4,1,,nl,creq,nlcreq ! average accumulated equivalent creep strainesol,5,1,,epel,eqv,epeleqv ! average equivalent elastic strainstore,mergeprvar,2,3,4,5plvar,3,5 ! creep strain and elastic strain/wait,3! Note: Creep strain rate = C1 * (Sigma^C2) * (e^(-C3/T))const_T1 = C1_T1*exp(-C3_T1/T1) ! constant part of equation ...const_T2 = C1_T2*exp(-C3_T2/T2)const_T3 = C1_T3*exp(-C3_T3/T3)nlog,11,2,,,C2_T1_ln_Sigma,,,,C2_T1 ! C2_T1 * ln(Sigma)nlog,12,2,,,C2_T2_ln_Sigma,,,,C2_T2 ! C2_T2 * ln(Sigma)nlog,13,2,,,C2_T3_ln_Sigma,,,,C2_T3 ! C2_T3 * ln(Sigma)exp,21,11,,,cr_rate_T1,,,,const_T1 ! const_T1*Sigma^C2_T1exp,22,12,,,cr_rate_T2,,,,const_T2 ! const_T2*Sigma^C2_T2exp,23,13,,,cr_rate_T3,,,,const_T3 ! const_T3*Sigma^C2_T3solu,30,dtime,,delta_t ! time step sizeprod,31,21,30,,crinc_T1 ! creep strain increment for T1prod,32,22,30,,crinc_T2 ! creep strain increment for T2prod,33,23,30,,crinc_T3 ! creep strain increment for T3plvar,21,22,23 ! creep strain rates at T1, T2, and T3prvar,30,21,22,23 ! creep strain ratesprvar,30,31,32,33 ! creep strain increments/eof= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =Note: SLIGHT differences in the creep strain rates and creep strain increments from the POST26 calculations are due to slightly different convergence history for the different temperatures. Incidentally, by setting C3 to zero, the strain rate was not effected by the current temperature, so the temperature was only used to interpolate the creep constants, not determine the creep strain rate when the equation was evaluated.= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =For 0 degrees: (Matches 25 degree data, as expected ...)============== THE FOLLOWING DEGREE OF FREEDOM RESULTS ARE IN GLOBAL COORDINATES NODE UX UY UZ USUM 1 0.0000 0.0000 0.0000 0.0000 2 -0.29762E-01 0.0000 0.0000 0.29762E-01 3 -0.29762E-01-0.29762E-01 0.0000 0.42090E-01 4 0.0000 -0.29762E-01 0.0000 0.29762E-01 5 0.0000 0.0000 0.63141E-01 0.63141E-01 6 -0.29762E-01 0.0000 0.63141E-01 0.69804E-01 7 -0.29762E-01-0.29762E-01 0.63141E-01 0.75884E-01 8 0.0000 -0.29762E-01 0.63141E-01 0.69804E-01 ***** ANSYS POST26 VARIABLE LISTING ***** TIME 1 S EQV 71E-01 0.12204 0.14516 8 0.0000 -0.55571E-01 0.12204 0.13410 ***** ANSYS POST26 VARIABLE LISTING ***** TIME 1 S EQV 1 EPCREQV 1 NL CREQ 1 EPELEQV seqv epcreqv nlcreq epeleqv 9695.5 20000.0 0.109704 0.109704 0.200000E-02 9795.5 20000.0 0.110836 0.110836 0.200000E-02 From the actual creep strain data above, we compute the creep strain increment to be: 0.110836 - 0.109704 = 0.001132 in/in The creep strain increment for the majority of the run is based on the maximum delta time step size of 100.0 seconds (see below). Since the stress remains constant at 20,000 psi, the following confirms that the creep strain increment for T = 100 degrees is 1.1315e-3 in/in. This value is arrived at by linear interpolation of the creep constants: T1 = 25.0 C1_T1 = 0.110e-9 C2_T1 = 1.10 T = 100.0 C1_T = 0.116e-9 C2_T = 1.16 (60% from T1 to T2) T2 = 150.0 C1_T2 = 0.120e-9 C2_T2 = 1.20 Creep strain rate = C1 * (Sigma^C2) * (e^(-C3/T)) e_rate = 0.116e-9 * 20,000.0^1.16 * e^(0/T) = 1.1315e-5 in/in/sec e_inc = (1.1315e-5 in/in/sec) * (100 seconds) = 1.1315e-3in/in Note: The linear interpolation is done on the creep constants and not on the evaluated creep strain rates at the two bounding temperatures (T1 and T2 in this case) ... TIME 0 DTIM 21 EXP 22 EXP 23 EXP delta_t cr_rate_T1 cr_rate_T2 cr_rate_T3 9695.5 100.000 0.592279E-05 0.173947E-04 0.507322E-04 9795.5 100.000 0.592279E-05 0.173947E-04 0.507322E-04 TIME 0 DTIM 31 PROD 32 PROD 33 PROD delta_t crinc_T1 crinc_T2 crinc_T3 9695.5 100.000 0.592279E-03 0.173947E-02 0.507322E-02 9795.5 100.000 0.592279E-03 0.173947E-02 0.507322E-02= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =For 150 degrees:================ THE FOLLOWING DEGREE OF FREEDOM RESULTS ARE IN GLOBAL COORDINATES NODE UX UY UZ USUM 1 0.0000 0.0000 0.0000 0.0000 2 -0.83849E-01 0.0000 0.0000 0.83849E-01 3 -0.83849E-01-0.83849E-01 0.0000 0.11858 4 0.0000 -0.83849E-01 0.0000 0.83849E-01 5 0.00000.0000 0.19238 0.19238 6 -0.83849E-01 0.0000 0.19238 0.20985 7 -0.83849E-01-0.83849E-01 0.19238 0.22599 8 0.0000 -0.83849E-01 0.19238 0.20985 ***** ANSYS POST26 VARIABLE LISTING ***** TIME 1 S EQV 1 EPCREQV 1 NL CREQ 1 EPELEQV seqv epcreqv nlcreq epeleqv 9695.5 20000.1 0.168651 0.168651 0.200001E-02 9795.5 20000.1 0.170390 0.170390 0.200001E-02From the actual creep strain data above, we compute the creep strainincrement to be: 0.170390 - 0.168651 = 0.001739 in/inThe creep strain increment for the majority of the run is based on themaximum delta time step size of 100.0 seconds (see below). Since thestress remains constant at 20,000 psi, the following confirms that thecreep strain increment for T2 (150 degrees) is 0.173948E-02 in/in. TIME 0 DTIM 21 EXP 22 EXP 23 EXP delta_t cr_rate_T1 cr_rate_T2 cr_rate_T3 9695.5 100.000 0.592281E-05 0.173948E-04 0.507323E-04 9795.5 100.000 0.592281E-05 0.173948E-04 0.507323E-04 TIME0 DTIM 31PROD 32 PROD 33 PROD delta_t crinc_T1 crinc_T2 crinc_T3 9695.5 100.000 0.592281E-03 0.173948E-02 0.507323E-02 9795.5 100.000 0.592281E-03 0.173948E-02 0.507323E-02= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =For 200 degrees:================ THE FOLLOWING DEGREE OF FREEDOM RESULTS ARE IN GLOBAL COORDINATES NODE UX UY UZ USUM 1 0.0000 0.0000 0.0000 0.0000 2 -0.22452 0.0000 0.0000 0.22452 3 -0.22452 -0.22452 0.0000 0.31752 4 0.0000 -0.22452 0.0000 0.22452 5 0.0000 0.0000 0.66420 0.66420 6 -0.22452 0.0000 0.66420 0.70112 7 -0.22452 -0.22452 0.66420 0.73619 8 0.0000 -0.22452 0.66420 0.70112 ***** ANSYS POST26 VARIABLE LISTING ***** TIME 1 S EQV 1 EPCREQV 1 NL CREQ 1 EPELEQV seqv epcreqv nlcreq epeleqv 9695.5 20000.8 0.491894 0.491894 0.200008E-02 9795.5 20000.8 0.496967 0.496967 0.200008E-02From the actual creep strain data above, we compute the creep strainincrement to be: 0.496967 - 0.491894 = 0.005073 in/inThe creep strain increment for the majority of the run is based on themaximum delta time step size of 100.0 seconds (see below). Since thestress remains constant at 20,000 psi, the following confirms that thecreep strain increment for T3 (200 degrees) is 0.507345E-02 in/in. TIME 0 DTIM 21 EXP 22 EXP 23 EXP delta_t cr_rate_T1 cr_rate_T2 cr_rate_T3 9695.5 100.000 0.592303E-05 0.173955E-04 0.507345E-04 9795.5 100.000 0.592303E-05 0.173955E-04 0.507345E-04 TIME 0 DTIM 31 PROD 32 PROD 33 PROD delta_t crinc_T1 crinc_T2 crinc_T3 9695.5 100.000 0.592303E-03 0.173955E-02 0.507345E-02 9795.5 100.000 0.592303E-03 0.173955E-02 0.507345E-02= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =For 250 degrees: (Matches 200 degree data, as expected ...)================ THE FOLLOWING DEGREE OF FREEDOM RESULTS ARE IN GLOBAL COORDINATES NODE UXUY UZ USUM 1 0.0000 0.0000 0.0000 0.0000 2 -0.22452 0.0000 0.0000 0.22452 3 -0.22452 -0.22452 0.0000 0.31752 4 0.0000 -0.22452 0.0000 0.22452 5 0.0000 0.0000 0.66420 0.66420 6 -0.22452 0.0000 0.66420 0.70112 7 -0.22452 -0.22452 0.66420 0.73619 8 0.0000 -0.22452 0.66420 0.70112 ***** ANSYS POST26 VARIABLE LISTING ***** TIME 1 S EQV 1 EPCREQV 1 NL CREQ 1 EPELEQV seqv epcreqv nlcreq epeleqv 9695.5 20000.8 0.491894 0.491894 0.200008E-02 9795.5 20000.8 0.496967 0.496967 0.200008E-02= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = =