## Materials

#### time varying thermal conductivity for transient thermal analysis

• vkr535
Subscriber
Hello,nIs there a way to define time varying quantities of thermal conductivity for a transient thermal? nI'm trying to solve a transient thermal problem, where in I knew the time variation of conductivities a priori. Basically, i was doing a multiple solve, and a each step i was using the MPDELE, and then try to redefine the material at a given time using MPDATA.nnThe solver triggered a warning that ' changing the material property during solution is a 'non-standard way'. Is it a correct way to define time varying quantities of a thermal- material property? nMay i know if there any other standard way to define it.nBelow is the script i tried to come up withnnFINISH n/CLEAR,NOSTART n/PREP7nLENGTH=2e-03 ! 2*LENGTH, mmnHEIGHT=LENGTH/100 ! HEIGHT, mm nTHICK=HEIGHTnesize=HEIGHTnarea=HEIGHT*THICKnkxx_1 = 5.000000000E-03 ! VALUE AT initial time, t=0ncx_1 = 4.039360000E-02 ! VALUE AT initial time, t=0nnt1=t358.000 ! inital temperaturenmptemp,1,t1nmpdata,KXX,1,1,kxx_1nmpdata,C,1,1,cx_1nnET,1,LINK33nR,1,area ! AREAnk,1,-0.5*LENGTHnk,2, 0.0nk,3, 0.5*LENGTHnl,1,2nl,2,3nlglue,1,2nlesize,all,esizentype,1nreal,1nmat,1nlmesh,allnesel,s,type,,1nnsle,rnIC,all,temp,1 nallsel,all,allnd,node(-0.5*LENGTH,0,0),temp,0nd,node(0.5*LENGTH,0,0),temp,0nFINISHn/SOLU,nANTYPE,TRANSnKBC,0nnleng=40ndeltime=2n*dim,dxx_1,array,nleng,1n*dim,ccstinter_1,array,nleng,1n*do,tt,1,40ncurrtime=deltime*ttncurr_temp=(273+85)+2*deltime*(tt)ndxx_1(tt,1)=D0_1*exp((-ED_1)/(R*curr_temp))nccstinter_1(tt,1)=RH*S0_1*P0_1*exp((ES_1-EVP_1)/(R*curr_temp))nmptemp,1,0nmpdele,kxx,1nmpdata,kxx,1,,dxx_1(tt,1)nmpdele,c,1nmpdata,c,1,,ccstinter_1(tt,1)nallsel,all,allnOUTRES,ALL,ALLnTIME,currtimenNSUBS,1,1,1nsolven*enddonFINISH
• Rahul Kumbhar
Ansys Employee
you are getting warning because it is not ideal way but if the results are okay, you should go with this option. There is one more way you can try using MPCHG command in solution processor for each load step.n
• ramgopisetti
Subscriber
why have you complicated the procedure, are you familiar that thermal conductivity can be defined as function of temperature in the engineerign data module and use it in your analysis, or are your trying to include any special mechanism in it. n