Learning Forum

[hasanilkerceliker]

Hello,
I need to perform paint removal on a composite material. The birth and death technique was used in the study, but I have never used it before. How can I do it ? 

[ErKo]

 

Search this forum and the internet and there are many posts on this topic. E.g.:

 

/forum/forums/topic/how-to-use-simulation-results-temperatur-to-control-birth-and-death-elements/

All the best

 

Erik

 

[hasanilkerceliker]

Hello,
The result of the analysis that I have been working on and trying to achieve is given above. I don't know how to enter my entries into the system. I would be very happy if you could help me with this subject.

[mrife]

Hi hasanilkerceliker

Please give more details - are you modeling in Workbench Mechanical or Mechanical APDL?  What is the criteria to kill the elements?

[hasanilkerceliker]

What I want to do is this:
I have 3 different materials together with CFRP, epoxy resin and paint. There is resin on CFRP and paint on them. It is desired to apply 7,14,21,28,35 and 42 W energy with laser cleaning. This will also be simulated with the element death method. Modeling needs to be done via APDL. With the given laser energy, the paint on the surface will be removed. I will use this work in my doctoral study. But how can it be done? I do not know this. I would be very happy if you could help with this. In addition, I have mechanical properties related to 3 different materials. But I don't know how I can use some data.

[mrife]

hasanilkerceliker The link that Erik provided above shows how to do this, generally speaking, in MAPDL.  There is one big thing to keep in mind: when running MAPDL in SMP parallel mode the results are kept in memory, while in DMP parallel they are not (until read in with the SET command during post processing).

So let's say your criteria for killing the elements is "A" (you've not yet defined that).  Then some psuedo APDL to solve this would be:

/solu

*do,...  loop over time in some time increments

apply load

solve

select nodes that meet "A", then elements attached to those selected nodes.  Maybe unselect from this set the nodes/elements that have loads or boundary conditions applied if needed.

ekill elements

select everything

*enddo....close do loop

The node selection can be by result if running SMP parallel.  Test out a simple model that uses same physics.

[hasanilkerceliker]

The value you denote as "A" here is the value I need to formulate here. Did I get it right?

[vangapandu goutham]

so I have this very small doubt 

my solution keeps on showing the error that the element is highly distorted (* I have tried reducing the mesh size and increasing the load steps to 10k)

should I need to use this element of birth and death technique

 

here is my model script

 

 

/clear

/prep7

 

!keypoints

k,1,0,0,0

k,2,0,1.72,0

k,3,0,4.72,0

k,4,0,16.5,0

k,5,0,19.5,0

k,6,0,20,0

k,7,0,22,0

k,8,8,22,0

k,9,8,20,0

k,10,8,19.5,0

k,11,8,16.5,0

k,12,8,4.72,0

k,13,8,1.72,0

k,14,8,0,0

k,15,8.5,22,0

k,16,8.5,20,0

k,17,8.5,19.5,0

k,18,8.5,16.5,0

k,19,8.5,4.72,0

k,20,8.5,1.72,0

k,21,18,22,0

k,22,18,20,0

k,23,18,19.5,0

k,24,18,16.5,0

k,25,18,4.72,0

k,26,18,1.72,0

k,27,25.4,19.5,0

k,28,25.4,16.5,0

k,29,25.4,4.72,0

k,30,25.4,1.72,0

k,31,100,19.5,0

k,32,100,16.5,0

k,33,100,4.72,0

k,34,100,1.72,0

 

 

!element type

allsel

et,1,183,,,1

 

a,1,2,13,14

a,2,3,12,13

a,3,4,11,12

a,4,5,10,11

a,5,6,9,10

a,6,7,8,9

a,9,8,15,16

a,10,9,16,17

a,11,10,17,18

a,12,11,18,19

a,13,12,19,20

a,20,19,25,26

a,19,18,24,25

a,18,17,23,24

a,17,16,22,23

a,16,15,21,22

a,24,23,27,28

a,25,24,28,29

a,26,25,29,30

a,30,29,33,34

a,29,28,32,33

a,28,27,31,32

 

 

!material properties 

!Stainless steel 303

mp,ex,1,193000

mp,prxy,1,0.25

 

!Hysol EA 9394 Adhesive

mp,ex,2,4068

mp,prxy,2,0.37

 

 

 

!need to add stress and strain values

 

!E-QXM 3608 glass laminate

mp,ex,3,18850

mp,ey,3,18850

mp,ez,3,18850

mp,prxy,3,0.3

mp,pryz,3,0.3     

mp,prxz,3,0.3

mp,gxy,3,7230

mp,gyz,3,7230

mp,gxz,3,7230

 

!Vinyl ester balsa core 

mp,ex,4,2800

mp,ey,4,83

mp,ez,4,32

mp,prxy,4,0.014

mp,pryz,4,0.011

mp,prxz,4,0.65

mp,gxy,4,140

mp,gyz,4,76

mp,gxz,4,45

 

!Vinyl-ester glass composite

mp,ex,5,3710

mp,prxy,5,0.28

 

 

/NERR,9999999999

 

 

AESIZE,ALL,2

allsel

amesh,all,all

 

SHPP,ON 

 

allsel

asel,s,,,1,6,1

asel,a,,,7,16,9

esla

emodif,all,mat,1

 

 

 

asel,s,,,8,11,1

asel,a,,,15

esla

emodif,all,mat,2

 

 

asel,s,,,12,14,2

asel,a,,,17,19,2

asel,a,,,20,22,2

esla

emodif,all,mat,3

 

 

asel,s,,,21

esla

emodif,all,mat,4

 

 

asel,s,,,13,18,5

esla

emodif,all,mat,5

 

 

!allsel

et,2,186

emodif,all

type,2

 

!To clear 2d plane elements and extrude 

allsel

extopt,aclear,1

eextrude,axis,0,,,90,,

 

 

allsel

eplot

 

!load conditioning

 

allsel

nsel,r,loc,y,21.9,22

d,all,uy,9

 

allsel

nsel,r,loc,y,1.62,1.72

csys,5

nsel,u,loc,x,0,50.8

d,all,all

csys

 

 

!Symmetry

allsel

nsel,r,ang,zx,0

d,all,uz,0

 

allsel

nsel,r,ang,zx,-90

d,all,ux,0

 

allsel

eplot

 

/solu

antype,static,new

CNVTOL,F,1000000,0.001,2,,

NROPT,AUTO

 

OUTRES,all,all

NLGEOM,ON

AUTOTS,AUTO

 

nsubst,100,100,100

neqit,100

 

allsel

solve

 

 

!!All the dimensions are in mm and Mpa

[hasanilkerceliker]

Normally I have to give the laser intensity with the adiabatic boundary conditions and the formula you see in the picture. So where am I doing wrong?

/solu

 

ALPHAP=89000

 

q=((2*(1-RP)*ALPHAP*EXP(-ALPHAP*Y)*EP*(-T^2/TAU^2))*(((-2*(X^2)+(Z^2))/RB^2))/(TAU*PI*RB^2)

 

*do, 

 

apply load

 

solve

 

ekill elements

 

select everything

 

*enddo....close do loop