Learning Forum

[mohammed.ismail.ul.haq]

I have an issue with INISTATE command in Ansys Mechanical apdl, where i apply linear varying stress i tried checking through Inistate list command , but the stress dont seem to vary linearly , not sure how to go about, the task is LTB check in angled section non linear.
i am not sure about the entire code as well am i progressing in right direction , plus the code works in only this specific order other wise ansys crashes , I need any tips on how to progress , BMD for Solid  to get critical moment MCR. IF posssible please let me know how to improve the code as well.

!!=======Material parameters (steel)==========
/CLEAR,START
/FILNAME,L_section,1
/UNITS,SI
/COM, Structural
E_STEEL=2.1e11 !n/m^2
NU_STEEL=0.3
DENS_STEEL=7850
f_y =235000000 !n/m^2

!!========Modelling=========

!*clear
/prep7

!!======Element Type=======

ET,1,SOLID186
!DOF,UX,UY,UZ,ROTX,ROTY,ROTZ

!!=======Material Properties=======

mp,ex,1,E_STEEL
mp,prxy,1,NU_STEEL
mp,dens,1,DENS_STEEL

!!========Geometric properties=======

Total_Length=1 !!!LENGTH 1M
Length_leg= 0.25 !!!EQUAL ANGLED
Thickness_leg=0.02 !!!THICKNESS OF LSECTION
Radius_1=0.018
Radius_2=0.009


!!========Define keypoints========

k,1,0,0,0
k,2,Thickness_leg,0,0
k,3,Length_leg,0,0
k,4,Length_leg,Thickness_leg,0
k,5,Thickness_leg,Thickness_leg,0
k,6,Thickness_leg,Length_leg,0
k,7,0,Length_leg,0
k,8,0,Thickness_leg,0

!!========Lines=========

LSTR, 7, 6
LSTR, 7, 8
LSTR, 5, 6
LSTR, 8, 1
LSTR, 1, 2
LSTR, 5, 4
LSTR, 4, 3
LSTR, 3, 2

LFILLT,1,3,Radius_2,0,
LFILLT,6,7,Radius_2,0,
LFILLT,3,6,Radius_1,0,
GPLOT

!!=========Area=========
LSEL,S,LINE,,1,11 !!(AL COMMAND NOT WORKING SO USING LSEL TO SELECT ALL LINES AND PLOTING AREA)
AL,ALL
ALLS

!!========Extrude Volume========
VEXT,1, , ,0,0,Total_Length,,,
ESYS, 0


!!=======Meshing========
ASEL,S,AREA,,1,2,1
!AESIZE, ALL, LENGTH_LEG/50,
AESIZE, all, Length_leg/50,
ALLSEL,ALL

EXTOPT,VSWE,AUTO,0 !SPECIFY SOURCE AND TARGET SURFACE FOR SWEEP
EXTOPT,ESIZE,50

TYPE,1
MAT,1
MSHAPE,0,3D
MSHKEY,1
ALLSEL,ALL
Vsweep,ALL,1,2,1

/SOL
! ========Bolts ========
Bolt1_x = Thickness_leg*4
Bolt1_z = Thickness_leg*5
Bolt_dia = Thickness_leg

!BLOCK, Bolt1_x, Bolt1_x+ Bolt_dia,0,Thickness_leg, Bolt1_z, Bolt1_z+ Bolt_dia
Nsel,s,loc,x, Bolt1_x, Bolt1_x+Bolt_dia
Nsel,r,loc,z, Bolt1_z, Bolt1_z+ Bolt_dia
D,ALL,,,,,,UX,UY,UZ
ALLSEL,ALL

Nsel,s,loc,x,(Length_leg-Bolt1_x), (Length_leg-Bolt1_x)+Bolt_dia
Nsel,r,loc,z, Bolt1_z, Bolt1_z+ Bolt_dia
D,ALL,,,,,,UX,UY,UZ
ALLSEL,ALL

Nsel,s,loc,x, Bolt1_x, Bolt1_x+Bolt_dia
Nsel,r,loc,z, (Total_Length-Bolt1_z),(Total_Length-Bolt1_z)+ Bolt_dia
D,ALL,,,,,,UX,UY,UZ
ALLSEL,ALL

Nsel,s,loc,x,(Length_leg-Bolt1_x), (Length_leg-Bolt1_x)+Bolt_dia
Nsel,r,loc,z, (Total_Length-Bolt1_z),(Total_Length-Bolt1_z)+ Bolt_dia
D,ALL,,,,,,UX,UY,UZ
ALLSEL,ALL
!!====CONSTraints AT EDGE LINE

LSEL,S,LINE,,19,20
NSLL,S,1
D,ALL,,,,,,UX,UY ! should not be ux constrained instead of uz?
ALLSEL,ALL

!!====CONSTARINT AT EDGE LINE
LSEL,S,LINE,,5
LSEL,A,LINE,,8
CM,LINE_1,LINE
CMSEL,S,LINE_1,LINE
NSLL,S,1
D,ALL,,,,,,UX,UY,UZ
ALLSEL,ALL
GPLOT

NSEL,ALL
ACEL,0,-9.8,0


!!====imperfection============
/SOL
antype,static
!PSTRES,1
Outres,all,all
allsell,all
solve
finish

/post1
pldisp,1
finish

/sol
antype,buckle
bucopt,lanb,2
mxpand,2,,,yes
solve
finsh
/post1
set,first
pldisp,1
set,next
pldisp,1
finish

/prep7
upgeom,0.001,1,1,L_section,rst !0.01 is the scale factor which can be varied thus varing geometery

!!=======Material Properties=======

!elastic part

!plastic
TB,BISO,1,1,2
TBTEMP,0
TBDATA,,f_y,0,,,,

!===residual stress========

/SOL
!initial stress for the second part
NSEL,S,LOC,Y,0,Length_leg/2
NSEL,R,LOC,X,0,0.1*Thickness_leg
INISTATE,SET,DATA,FUNC
INISTATE,SET,DTYP,STRE
INISTATE,define,ALL,,,,LINY,(-0.22*f_y),((0.92*f_y)/Length_leg)

!initial stress for the first part
NSEL,S,LOC,Y,Length_leg/2,Length_leg
INISTATE,SET,DATA,FUNC
INISTATE,SET,DTYP,STRE
INISTATE,define,,,,,LINY,(0.73*f_y),((-0.98*f_y)/Length_leg)


!initial stress for the third part
NSEL,S,LOC,X,0,Length_leg/2
NSEL,R,LOC,Y,0,Thickness_leg
INISTATE,SET,DATA,FUNC
INISTATE,SET,DTYP,STRE
INISTATE,define,,,,,LINX,(-0.22*f_y),((0.92*f_y)/Length_leg)

!initial stress for the forth part
NSEL,S,LOC,X,Length_leg/2,Length_leg
NSEL,R,LOC,Y,0,Thickness_leg
INISTATE,SET,DATA,FUNC
INISTATE,SET,DTYP,STRE
INISTATE,define,,,,,LINX,(0.73*f_y),((-0.98*f_y)/Length_leg)


!!===LOADING CONDITIONS=====
force_12 = 5000 ! the value of the load
NSEL,S,LOC,Z,0,0
*GET, N_COUNTz, NODE,,COUNT
load_1=force_12/N_COUNTz
f,all,fz,load_1
allsel,all

NSEL,S,LOC,Z,Total_Length,total_length
*GET, N_COUNTd, NODE,,COUNT
load_2=force_12/N_COUNTd
f,all,fz,-load_2
allsel,all


!===nonlinear analysis============


/sol

ANTYPE,0,new
NLGEOM,1
NSUBST,100,1000,50
NEQIT,1000
OUTRES,ERASE
OUTRES,ALL,ALL
solve

[Ashish Khemka]

Hi,

When you apply an initial condition then can you try to see if the response is linear for a linear model. For example a bar stretched in elastic region initially will try to regain its shape. Does you see a similar behavior if you simplify the model. This may be a simple check for the model setup.

Regards,

Ashish Khemka

[mohammed.ismail.ul.haq]

Ashish Khemka sir , thank you for your reply will try this