bcho
Subscriber

Hi,


Thanks again for your reply.


For the soil I model the quarter of a sphere with solid186 and add infin257 at the outer surface of the sphere. Additionally I apply a spring-mass-system with combin39 and mass21.


For the static analysis I add a load in z-direction. The transient analysis is done by a loop in time with a sinusodial load or an impulse.


So the model does not change between static and transient except for the analysis type and the load.


I tried the following:
linear + transient --> converges
non-linear + static --> converges
non-linear + transient --> does not converge


I added a picture of step 6 when the calculation does not converge and my APDL commands although I'm not sure if it'll be helpful for you since the comments are in german.


Thanks a lot in advance.


Kind regards,


Bettina Chocholaty


APDL commands:


finish
/clear


/PREP7
RM=0.5                ! Lastradius
RB=10              ! Bodenradius
Gx=80000000        ! Schubmodul
NUxy=0.33        ! Poisson Zahl
freq=100        ! Frequenz in Hz          
rho=2000        ! Dichte
cs=sqrt(Gx/rho)        ! Scherwellengeschwindigkeit
Exx=2*Gx*(1+NUxy)    ! E-Modul
lambda=cs/freq        ! Wellenlänge
le=lambda/8        ! maximale Elementlänge
lnele=(RM+RB)/le        ! Elementanzahl
lneleh=lnele/2
lnelemh=NINT(lneleh)
lnelem=lnelemh*2
!lnelem=48
dt=le/cs        ! Zeitschritt
t=(RM+RB)/cs        ! Ankunftszeitpunkt Welle an Rand von Modell
RGES=RM+RB


ET,1,SOLID186           ! 3D 20 NODE STRUCTURAL SOLID


MP,EX,1,Exx             ! Materialzuweisung
MP,PRXY,1,NUxy
MP,DENS,1,rho

!---Geometrie der Platte                                                         !*!
*SET,H,0.4                       ! Plattenhoehe [m]                                  !*!
*set,r,5/2            ! Halbe Breite/Länge Fundament
*set,ri,3.75/2            ! Halbe innere Breite/Länge Fundament

! MATERIAL
!---Materialdaten der Platte                                                     !*!
rho=0                          ! Dichte der Platte [kg/m^3]                        !*!
nue=0                         ! Querkontraktionszahl der Platte                   !*!
EModul=9710000000              ! E-Modul der Platte [N/m^2]         
MP,EX,2,EModul                   ! E-Modul
MP,NUXY,2,nue                    ! Querkontraktionszahl
MP,DENS,2,rho,,,                 ! Dichte

! Angaben für Masseschwinger
m=10000                ! Masse
knl=597000000            ! Fließgrenze-Steifigkeit
Fnl=149000000            ! Fließgrenze-Kraft


K,1
K,2,,RM+T
PCIRC,0,RGES,0,90               ! Kreisfläche
!! für Plattengenerierung
!Pcirc,RM,RM+T/2,0,90
!PCIRC,0,RM,0,90         
!Pcirc,RM/2,RM,0,90
VROTAT,all,,,,,,1,2,-90,,       ! Kugelvolumen

allsel
vplot

! Unterteilung der radialen Linien
lsel,inve
lsel,s,length,,RGES
lesize,all,,,lnelem,,1         ! Linienunterteilung nach elementzahl
!lesize,all,le,,,,1        ! Linienunterteilung nach Elementgröße

! Unterteilung der Bogenlinien
Csys,2
lsel,s,loc,x,RGES
lesize,all,,,lnelem,,1        ! Linienunterteilung nach elementzahl
!lesize,all,le,,,,1        ! Linienunterteilung nach Elementgröße

allsel
csys,0

!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!! MASSE-SCHWINGER !!!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!! Masse-Fdeder-System
ET,10,COMBIN39,,,,1,,1                ! ELEMENT WITH DISPLACEMENT ALONG NODAL z-AXIS
KEYOPT,10,4,1
ET,11,MASS21,,,0                      ! MASS WITHOUT ROTARY INERTIA
KEYOPT,11,3,2
R,10,-5,-Fnl,-0.5,-Fnl,0.0,0.0  ! SPRING DATA
RMORE,0.5,Fnl,5,Fnl 
!R,11,0,0,m,0,0,0                  ! MASS DATA
R,11,m
csys,0 
NSEL,All
!NSEL,S,LOC,X,-r+(r-ri)/2
!NSEL,R,LOC,Y,-r+(r-ri)/2
!NSEL,R,LOC,Z,-H
!*GET,n_center1,NODE,,NUM,MIN
!*GET,n_center1,NODE,1,NSEL,,
!NSEL,S,LOC,X,+r-(r-ri)/2
!NSEL,R,LOC,Y,-r+(r-ri)/2
!NSEL,R,LOC,Z,-H
!*GET,n_center2,NODE,,NUM,MIN
!*GET,n_center2,NODE,1,NSEL,,
*GET,knotenanzahl,NODE,,NUM,MAX
N,knotenanzahl+1,+r-(r-ri)/2,+r-(r-ri)/2,-H
NSEL,S,LOC,X,+r-(r-ri)/2
NSEL,R,LOC,Y,+r-(r-ri)/2
NSEL,R,LOC,Z,-H
!*GET,n_center3,NODE,,NUM,MIN
*GET,n_center3,NODE,,NUM,MIN
!*GET,n_center3,NODE,1,NSEL,,
!NSEL,S,LOC,X,-r+(r-ri)/2
!NSEL,R,LOC,Y,+r-(r-ri)/2
!NSEL,R,LOC,Z,-H
!*GET,n_center4,NODE,,NUM,MIN
!*GET,n_center4,NODE,1,NSEL,,
 
NSEL,all
*GET,n_max,NODE,,NUM,MAX
!N,n_max+1,-r+(r-ri)/2, -r+(r-ri)/2,-5*H
!N,n_max+2,+r-(r-ri)/2, -r+(r-ri)/2,-5*H
N,n_max+3,+r-(r-ri)/2 , +r-(r-ri)/2,-5*H
!N,n_max+4,-r+(r-ri)/2, +r-(r-ri)/2,-5*H
!TYPE,10
!REAL,10
!E,n_center1,n_max+1   !Non-linear spring
!TYPE,11
!REAL,11
!E,n_max+1 !Mass
!nummrg,all
 
!TYPE,10
!REAL,10
!E,n_center2,n_max+2   !Non-linear spring
!TYPE,11
!REAL,11
!E,n_max+2 !Mass
!nummrg,all

TYPE,10
REAL,10
E,n_center3,n_max+3   !Non-linear spring
TYPE,11
REAL,11
E,n_max+3 !Mass
nummrg,all

!TYPE,10
!REAL,10
!E,n_center4,n_max+4   !Non-linear spring
!TYPE,11
!REAL,11
!E,n_max+4 !Mass
!nummrg,all
NSEL,All
nummrg,nodes
nummrg,all



! Meshing
Mat,1
mshape,0,3D            ! Elementform
vmesh,1


! Infinite Elements oder Feste Auflager
*GET,NMAX,NODE,0,NUM,MAXD
NPOLE=NMAX+1
N,NPOLE

CSYS,2                     
ASEL,S,loc,x,RGES
NSLA,S,1
EINFIN,,NPOLE                   ! Infinite Elements
!d,all,all            ! Feste Auflager
ALLSEL


! Symmetriebedingungen
CSYS,0
!NSEL,S,LOC,Z,0
!DSYM,SYMM,Z                 ! SYMMETRIC CONSTRAINTS,UZ
ALLSEL,ALL,ALL
NSEL,S,LOC,Y,0
DSYM,SYMM,Y                    ! SYMMETRIC CONSTRAINTS,UY
ALLSEL,ALL,ALL
NSEL,S,LOC,X,0
DSYM,SYMM,X                    ! SYMMETRIC CONSTRAINTS,UX
ALLSEL,ALL,ALL

!shpp,on

!shpp,summ

! Knoten für Last auswählen
NSEL,All
nummrg,nodes

csys,2
!asel,s,loc,x,0,RM
nsel,s,loc,x,0,RM
csys,0
!asel,r,loc,z,0
nsel,r,loc,z,0
CM,CM_load,node

allsel

!*DIM,displ,Table,17                                ! Kraftvektor
!*TREAD,displ,'last','sis',' ',,
!*VPLOt,displ(1,0),displ(1,1)


!!! LAST
NSEL,All
nummrg,nodes

*DIM,displ,Table,17                               ! Kraftvektor
*TREAD,displ,'last','sis',' ',,
*VPLOt,displ(1,0),displ(1,1)


/SOLU
ANTYPE,trans

tend=dt*300
!dt=0.9108e-5
ntime=NINT(tend/dt)+1

!timint,on
!nlgeom,on
EMATWRITE,YES

*afun,rad

 *do,itime,1,70 !* Beginn der Zeitschleife
    zeit=itime*dt            ! Variable 'zeit' definieren
    !F,CM_load,fz,1000*sin(freq*2*3.14*zeit)
    !D,CM_load,uz,0.5*sin(2*3.14*zeit)
    !SF,CM_load,Pres,100*sin(10*2*3.14*zeit)
    !F,CM_load,fz,-sin(2*3.14*5)
    D,CM_load,uz,displ(zeit)*0.5
    *MSG,WARN, itime, ntime, zeit,
    *** Step %I von %I  Zeit %G
    TIME,%zeit%            ! Zeit des nächsten Berechnungs-Schrittes
    NSUB,10,30,1
    SOLCONTROL,On
     !NROPT,FULL
     !LNSRCH,ON
     !CNVTOL,F,,0.05 ! 5% Tolerance
     !PRED,on,,on
     !NEQIT,500
   SOLVE                  ! selbstredend
   save
 *enddo

!*** ENDE DER ZEITSCHLEIFEN ***

 FINISH                   ! Ende des Solution-Prozesses



/EOF