## General Mechanical

Topics relate to Mechanical Enterprise, Motion, Additive Print and more

#### how to select elements in elliptical shape in a cylinder using ansys apdl?

• Ikram DJABROUHOU
Subscriber

Dear all,

I am working on damage detection on a composite cylinder. the idea is to insert damage with an elliptical shape in a cylinder in a different location and use the buckling response as a damage indicator that later will be inserted into a CNN-based algorithm for damage detection. I have modeled the cylinder and now want to insert the elliptical shape damage (which is selecting elements in a defined elliptical shape and assigning them a low rigidity). unfortunately, I didn't succeed till now.

Any hints or ideas are welcome
Ps: the code I did is below

FINISH

FINISH

/CLEAR, NOSTART ! NOSTART avoids reading again START.ANS
/CWD,'D:\Damage_Detection_CNN\NewLastCode'
/RGB,INDEX,100,100,100,0
/RGB,INDEX,0,0,0,15
/PREP7
/VIEW,1,1,1,1
/ANGLE,1
/VUP,,Z
/UNITS,SI
/ESHAPE,0
*AFUN,DEG ! Use degrees for input and output of parameter ANGular functions
DmageON = 1 ! 1: Damage is activated
! 0: Damage is Desactivated
C*** Input data
C*** RUN

*SET, PI, 3.14159265359

! Ler variaveis externas
PARRES, change, variaveis.txt

Dc= 0.05 ! [m] Diameter of cylinder
Lc= 0.3 ! [m] Length of the cylinder
Th= 0.00012 ! [m] Wall thickness
ElSiz = 2e-3 ! [mm] Element Size

C*** Material proprties ************************************

*SET,ANG1,45.0000
*SET,ANG2,0.0000
*SET,ANG3,-45.0000
*SET,ANG4,0.0000
*SET,ANG5,45.0000
*SET,ANG6,45.0000
*SET,ANG7,0.0000
*SET,ANG8,-45.0000
*SET,ANG9,0.0000
*SET,ANG10,45.0000

*SET,E1,101860000000.0000
*SET,E2,3410000000.0000
*SET,E3,3410000000.0000
*SET,v12,0.2900
*SET,v23,0.2900
*SET,v13,0.2900
*SET,G12,7560000000.0000
*SET,G23,1321705426.3566
*SET,G13,7560000000.0000
*SET,rho,1510.0000
*SET,E_Layer,Th

C*** Force ************************************
*SET,Fcomp,-1

*SET,RedictioRatio,2000

C*** Failure Criteria ************************************
FC,1,S,XTEN,1363.49e6
FC,1,S,YTEN,5.86e6
FC,1,S,ZTEN,5.86e6
FC,1,S,XCMP,-572.27e6
FC,1,S,YCMP,-102e6
FC,1,S,ZCMP,-102e6
FC,1,S,XY,200.61e6
FC,1,S,YZ,200.61e6
FC,1,S,XZ,200.61e6
FC,1,S,XYCP,-1
FC,1,S,YZCP,-1
FC,1,S,XZCP,-1
FC,1,EPEL,XTEN,
FC,1,EPEL,YTEN,
FC,1,EPEL,ZTEN,
FC,1,EPEL,XCMP,
FC,1,EPEL,YCMP,
FC,1,EPEL,ZCMP,
FC,1,EPEL,XY,
FC,1,EPEL,YZ,
FC,1,EPEL,XZ,

FC,2,S,XTEN,1363.49e6
FC,2,S,YTEN,5.86e6
FC,2,S,ZTEN,5.86e6
FC,2,S,XCMP,-572.27e6
FC,2,S,YCMP,-102e6
FC,2,S,ZCMP,-102e6
FC,2,S,XY,200.61e6
FC,2,S,YZ,200.61e6
FC,2,S,XZ,200.61e6
FC,2,S,XYCP,-1
FC,2,S,YZCP,-1
FC,2,S,XZCP,-1
FC,2,EPEL,XTEN,
FC,2,EPEL,YTEN,
FC,2,EPEL,ZTEN,
FC,2,EPEL,XCMP,
FC,2,EPEL,YCMP,
FC,2,EPEL,ZCMP,
FC,2,EPEL,XY,
FC,2,EPEL,YZ,
FC,2,EPEL,XZ,

C*** Assigne Material Proprties ************************************

MP,EX,1,E1
MP,EY,1,E2
MP,EZ,1,E3
MP,PRXY,1,V12
MP,PRYZ,1,V23
MP,PRXZ,1,V13
MP,GXY,1,G12
MP,GYZ,1,G23
MP,GXZ,1,G13
MP,DENS,1,rho

E11=RedictionRatio*E1
E22=RedictionRatio*E2
E33=RedictionRatio*E3
G122=RedictionRatio*G12
G232=RedictionRatio*G23
G132=RedictionRatio*G13

MP,EX,2,E11
MP,EY,2,E22
MP,EZ,2,E33
MP,PRXY,2,V12
MP,PRYZ,2,V12
MP,PRXZ,2,V12
MP,GXY,2,G122
MP,GYZ,2,G232
MP,GXZ,2,G132
MP,DENS,2,RedictionRatio*2100

C*** Material Composite ************************************

ET,1,SHELL281
SECT,1,SHELL,,
SECDATA, E_Layer,1,ANG1,3
SECDATA, E_Layer,1,ANG2,3
SECDATA, E_Layer,1,ANG3,3
SECDATA, E_Layer,1,ANG4,3
SECDATA, E_Layer,1,ANG5,3
SECDATA, E_Layer,1,ANG6,3
SECDATA, E_Layer,1,ANG7,3
SECDATA, E_Layer,1,ANG8,3
SECDATA, E_Layer,1,ANG9,3
SECDATA, E_Layer,1,ANG10,3
secoffset,MID
seccontrol,,,, , , ,
SECPLOT, 1,,,

ET,2,SHELL281
SECT,2,SHELL,,
SECDATA, E_Layer,2,ANG1,3
SECDATA, E_Layer,2,ANG2,3
SECDATA, E_Layer,2,ANG3,3
SECDATA, E_Layer,2,ANG4,3
SECDATA, E_Layer,2,ANG5,3
SECDATA, E_Layer,2,ANG6,3
SECDATA, E_Layer,2,ANG7,3
SECDATA, E_Layer,2,ANG8,3
SECDATA, E_Layer,2,ANG9,3
SECDATA, E_Layer,2,ANG10,3
secoffset,MID
seccontrol,,,, , , ,

C*** Cylinder Geomtry ************************************

K,1,0.,0.,0. ! CENT Point
K,2,0.,0.,Lc ! AXIS Point
K,3,0.,Dc/2,0. ! ZERO Point
CIRCLE,1,Dc/2,2,3,360 ! CIRCLE, PCENT, RAD, PAXIS, PZERO, ARC, NSEG
L,1,2 ! Line for Path in following ADRAG --> Line N.5 (4 Lines used for the CIRCLE)

C*** Meshing (Shells) ************************************

ASEL,ALL
ESIZE,ElSiz
AMESH,ALL

C*** Damage ************************************

!pos_z = Lc/3
!a = 0.02
!b = 0.01
!theta = 10
!r = 1

*IF,DmageON,EQ,1,then
LOCAL,11,1,0,Dc/2,pos_z,,,theta,r
CSYS, 11
ESEL, S, CENT, 0.01, 0.00001, b, , , , 0
!ESEL, S, CENT, Y, 0, (b/(10*r)),,,,0
EMODIF,ALL,MAT,2,,,,,,
EMODIF,ALL,Type,2,,,,,
EMODIF,ALL,SECT,2,,,,,
ESEL,ALL
!CSYS,0
*EndIF
Allsel,all
Finish

C*** Analysis ************************************

/SOL
Lsel,s,line,,1,4
DL,ALL, ,ALL,
Allsel,all
!! Analysis
ANTYPE,0
Lsel,s,line,,6
Lsel,a,line,,9
Lsel,a,line,,11
Lsel,a,line,,13
NSLL, S, 1
F,all,FZ,Fcomp

Allsel,All

PSTRES,1
SOLVE
FINISH
/SOLUTION
ANTYPE,1
BUCOPT,LANB,20,0,0,CENTER
SOLVE
FINISH

/POST1
/output,

SET,LIST
/out

• Dave Looman
Ansys Employee

To create an ellipsoidal volume you can first create a sphere and then scale it with vlscale.Â  The scale factors are in the active coordinate system so you could create a coordinate system aligned with the tilted axis you show in the sketch.Â  Then if you want to create an ellipsoidal cavity you could use VSBV to subtract the ellipsoidal volume from the cylindrical volume.

• Ikram DJABROUHOU
Subscriber

Dear Dave,

Thanks for the valuable feedback, I would also bother with other questions. What if I want to select a set of elements with an elliptic shape is there any method you recommend ??Â

Â

• Dave Looman
Ansys Employee

You can create an elliptical coordinate system with PAR1 and PAR2 of the LOCAL command.Â  I've never used an elliptical coordinate system to select entities, but you could try with a simple test model:

csys,12Â  Â ! elliptical coordinate system

nsel,s,loc,x,valueÂ  ! hard to say what this will do.

esln,s,1Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â  Â ! select elements with all nodes selected

allsel

• Ikram DJABROUHOU
Subscriber

Thanks Dave,

The idea you proposed works great. so basically I did place a local coordinate and rotate then I used Esel to select the required elements as Bellow:Â  Â

LOCAL,12,1,0,Dc/2,pos_z,,,theta,rÂ
Â  Â CSYS, 12
Â  ESEL, S, CENT, z, -b/r,b/r
Â  ESEL, r, CENT, x, -b,b

Many thanks again for your valuable feedback

Â

Â

• Dave Looman
Ansys Employee

You've done something maybe no one has ever done with Ansys!Â Â

• Ikram DJABROUHOU
Subscriber

This was performed thanks to your help