[stsirohk]

Hello everyone,
i am working on my bachelor thesis. It is about the connection between the tube and tubesheet by using high internal pressure. I have the problem that there is no convergence when increasing the pressure. It´s a weird that the model is working at a pressure of 1600 and 1700 bar but not at a pressure of 1601 ( highly distorted elements ...). If you adjust a high tangent modulus it will work for a high pressure input. But i like to do it with a tangent modulus of zero. Has anyone a solution ?


fini
/clear
/FILNAME,HYDAUFWEITEN
/PREP7

!Geometrie Eingabeparameter[mm]

dia=10 !outer radius tube
ti=1 !wall thickness tube
gap=0.1 !gap between tube and tubesheet

!Aufweitdruck
pi=2600 !pressure in bar

!Geometrie berechnete Radien

RAA=40 !outer radius tubesheet
RAI=dia/2+gap !inner radius tubesheet
RIA=dia/2 !outer radius tube
RII=dia/2-ti !inner radius tube

!Meshing
nU=50
nRP=30
nRR=3

!Model POINTS tubesheet

K,1,RAI,0,0,
K,2,RAA,0,0,
K,3,0,RAA,0,
K,4,0,RAI,0,

!Model POINTS tube

K,5,RII,0,0,
K,6,RIA,0,0,
K,7,0,RIA,0,
K,8,0,RII,0,

K,9,0,0,0,

!LINES

L,1,2
LARC,2,3,9,RAA
L,3,4
LARC,4,1,9,RAI

L,5,6
LARC,6,7,9,RIA
L,7,8
LARC,8,5,9,RII

!AREAS

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

!Element Data

et,1,plane183
et,2,CONTA175
et,3,TARGE169

!KEYOPT,2,5,1
!KEYOPT,2,9,1

! Material 1

mp,ex,1,212000
mp,nuxy,1,0.3
!tb,biso,1
!tbdata,,300,0

!Material 2

mp,ex,2,200000
mp,nuxy,2,0.3
tb,biso,2
tbdata,,268,0

!Real Konst. Target Element
r,10,RAI

!Meshing Sizing
lsel,s,,,2
lsel,a,,,4
lsel,a,,,6
lsel,a,,,8
lesiz,all,,,nU
alls

!tubesheet, radial
lesiz,1,,,nRP,10
lesiz,3,,,nRP,1/10

!tube, radial
lesiz,5,,,nRR
lesiz,7,,,nRR

!Meshing Area 1 und Materialübergabe

asel,s,area,,1
aatt,1,,1,

CM,_Y,AREA
ASEL, , , ,1
CM,_Y1,AREA
CHKMSH,'AREA'
CMSEL,S,_Y

MSHKEY,1
AMESH,_Y1
MSHKEY,0

CMDELE,_Y
CMDELE,_Y1
CMDELE,_Y2


alls


!Meshing Area 2 und Materialübergabe

asel,s,area,,2
aatt,2,,1,

CM,_Y,AREA
ASEL, , , ,2
CM,_Y1,AREA
CHKMSH,'AREA'
CMSEL,S,_Y

MSHKEY,1
AMESH,_Y1
MSHKEY,0

CMDELE,_Y
CMDELE,_Y1
CMDELE,_Y2

alls

!contact

real,10

lsel,s,,,6
nsll,,1
type,2
esurf
alls

lsel,s,,,4
nsll,,1
type,3
esurf
alls


!Boundarys and Forces

DL,1,,UY,0
DL,3,,UX,0
DL,5,,UY,0
DL,7,,UX,0



/solu

!ANTYPE,4
NLGEOM,on
NSUBST,500
kbc,0


TIME,1
SFL,8,PRES,pi*0.1
LSWRITE,1,

Time,2
SFLDELE,8,PRES
LSWRITE,2,
lssolve,1,2,1,