How are total principal and equivalent strains calculated? Are these calculated based on total strain components or by summing elastic, plastic, creep (and thermal) principal and equivalent strains directly?
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Total equivalent strain is calculated by summing equivalent elastic, plastic, creep (and thermal) equivalent strains, per Section 19.12.5 of the ANSYS 9.0 Theory Reference. Note that the effective Poisson's ratio will differ for each equivalent strain calculation (elastic uses MP,PRXY or NUXY while plastic, creep use 0.5 since those strains are assumed to be incompressible). On the other hand, Total principal strains are evaluated using the total strain components since there is direction associated with principal strains. An example input file below demonstrates this calculation method for total principal strain (sample below calculates EPTT rather than EPTO): finish /clear /nopr /prep7 et,1,185 r,1 mp,ex ,1,10e6 mp,nuxy,1,.3 mp,alpx,1,10e-6 mp,alpy,1,12e-6 mp,alpz,1,15e-6 tb,biso,1 tbdata,,33e3,10e5 tb,creep,1,1,,10 tbdata,,1e-4,0.2,0 block,,10,,10,,10 esize,,1 vmesh,all asel,s,loc,x,0 nsla,s,1 d,all,all asel,s,loc,x,10 nsla,s,1 d,all,ux,-0.5 d,all,uy,0.5 tref,20 tunif,300 allsel,all finish /solu nlgeom,on rescon,define,none nsubst,10,100,1 rate,on time,10 allsel,all solve finish /post1 set,last *get,EPELX ,node,node(10,10,10),epel,x *get,EPELY ,node,node(10,10,10),epel,y *get,EPELZ ,node,node(10,10,10),epel,z *get,EPELXY ,node,node(10,10,10),epel,xy *get,EPELYZ ,node,node(10,10,10),epel,yz *get,EPELXZ ,node,node(10,10,10),epel,xz *get,EPPLX ,node,node(10,10,10),EPPL,x *get,EPPLY ,node,node(10,10,10),EPPL,y *get,EPPLZ ,node,node(10,10,10),EPPL,z *get,EPPLXY ,node,node(10,10,10),EPPL,xy *get,EPPLYZ ,node,node(10,10,10),EPPL,yz *get,EPPLXZ ,node,node(10,10,10),EPPL,xz *get,EPCRX ,node,node(10,10,10),EPCR,x *get,EPCRY ,node,node(10,10,10),EPCR,y *get,EPCRZ ,node,node(10,10,10),EPCR,z *get,EPCRXY ,node,node(10,10,10),EPCR,xy *get,EPCRYZ ,node,node(10,10,10),EPCR,yz *get,EPCRXZ ,node,node(10,10,10),EPCR,xz *get,EPTHX ,node,node(10,10,10),EPTH,x *get,EPTHY ,node,node(10,10,10),EPTH,y *get,EPTHZ ,node,node(10,10,10),EPTH,z *get,EPTHXY ,node,node(10,10,10),EPTH,xy *get,EPTHYZ ,node,node(10,10,10),EPTH,yz *get,EPTHXZ ,node,node(10,10,10),EPTH,xz EPTTX = EPELX + EPPLX + EPCRX + EPTHX EPTTY = EPELY + EPPLY + EPCRY + EPTHY EPTTZ = EPELZ + EPPLZ + EPCRZ + EPTHZ EPTTXY = (EPELXY + EPPLXY + EPCRXY + EPTHXY)/2 EPTTYZ = (EPELYZ + EPPLYZ + EPCRYZ + EPTHYZ)/2 EPTTXZ = (EPELXZ + EPPLXZ + EPCRXZ + EPTHXZ)/2 !*get,EPTTX ,node,node(10,10,10),EPTT,x !*get,EPTTY ,node,node(10,10,10),EPTT,y !*get,EPTTZ ,node,node(10,10,10),EPTT,z !*get,EPTTXY ,node,node(10,10,10),EPTT,xy !*get,EPTTYZ ,node,node(10,10,10),EPTT,yz !*get,EPTTXZ ,node,node(10,10,10),EPTT,xz *get,EPEL1 ,node,node(10,10,10),epel,1 *get,EPEL2 ,node,node(10,10,10),epel,2 *get,EPEL3 ,node,node(10,10,10),epel,3 *get,EPELEQV,node,node(10,10,10),epel,eqv *get,EPPL1 ,node,node(10,10,10),EPPL,1 *get,EPPL2 ,node,node(10,10,10),EPPL,2 *get,EPPL3 ,node,node(10,10,10),EPPL,3 *get,EPPLEQV,node,node(10,10,10),EPPL,eqv *get,EPCR1 ,node,node(10,10,10),EPCR,1 *get,EPCR2 ,node,node(10,10,10),EPCR,2 *get,EPCR3 ,node,node(10,10,10),EPCR,3 *get,EPCREQV,node,node(10,10,10),EPCR,eqv *get,EPTH1 ,node,node(10,10,10),EPTH,1 *get,EPTH2 ,node,node(10,10,10),EPTH,2 *get,EPTH3 ,node,node(10,10,10),EPTH,3 *get,EPTHEQV,node,node(10,10,10),EPTH,eqv AR11 = -(EPTTX + EPTTY + EPTTZ) AR12 = EPTTX*EPTTY + EPTTY*EPTTZ + EPTTX*EPTTZ AR12 = AR12 - EPTTXY**2 - EPTTYZ**2 - EPTTXZ**2 AR13 = EPTTX*EPTTY*EPTTZ + 2*EPTTXY*EPTTYZ*EPTTXZ AR13 = -(AR13 - EPTTX*(EPTTYZ**2) - EPTTY*(EPTTXZ**2) - EPTTZ*(EPTTXY**2)) *afun,rad AR20 = (3*AR12 - AR11**2)/3 AR21 = (2*AR11**3 - 9*AR11*AR12 + 27*AR13)/27 AR22 = AR21**2/4 + AR20**3/27 AR23 = sqrt(AR21**2/4 - AR22) AR24 = AR23**(1/3) AR25 = acos(-(AR21/(2*AR23))) AR26 = -AR24 AR27 = cos(AR25/3) AR28 = sqrt(3)*sin(AR25/3) AR29 = -(AR11/3) *dim,STI_TEMP_,array,3 STI_TEMP_(1) = 2*AR24*cos(AR25/3) - (AR11/3) STI_TEMP_(2) = AR26*(AR27 + AR28) + AR29 STI_TEMP_(3) = AR26*(AR27 - AR28) + AR29 *vfun,STI_TEMP_(1),dsort,STI_TEMP_(1) EPTTEQVc = (STI_TEMP_(1) - STI_TEMP_(2))**2 + (STI_TEMP_(2) - STI_TEMP_(3))**2 + (STI_TEMP_(3) - STI_TEMP_(1))**2 /gopr /com, ************************************************************************** /com, Calculated values /com, a = sum values directly /com, b = ANSYS values /com, c = based on summed components /com, -------------------------------------------------------------------------- /com, Max Principal Strain EPTT1a = EPEL1 + EPPL1 + EPCR1 + EPTH1 *get,EPTT1b ,node,node(10,10,10),EPTT,1 EPTT1c = STI_TEMP_(1) /com, -------------------------------------------------------------------------- /com, Mid Principal Strain EPTT2a = EPEL2 + EPPL2 + EPCR2 + EPTH2 *get,EPTT2b ,node,node(10,10,10),EPTT,2 EPTT2c = STI_TEMP_(2) /com, -------------------------------------------------------------------------- /com, Min Principal Strain EPTT3a = EPEL3 + EPPL3 + EPCR3 + EPTH3 *get,EPTT3b ,node,node(10,10,10),EPTT,3 EPTT3c = STI_TEMP_(3) /com, -------------------------------------------------------------------------- /com, Eqv Principal Strain /com, c=rough, approx v' EPTTEQVa = EPELEQV + EPPLEQV + EPCREQV + EPTHEQV *get,EPTTEQVb,node,node(10,10,10),EPTT,eqv EPTTEQVc = sqrt(EPTTEQVc/2)/1.5 /com, ************************************************************************** |
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