/com  quartz tube external pressure buckling (from STAR/al_150_long.1.txt) 
t=.003	!tube thickness
r=.021		!tube radius, nom
l=1.2		!tube length
ndiv_long=100	!number of longitudinal elements
f=.7854*r**2*100000	!end force, unit load


/prep7
/view,1,.5,.5,1
/pbc,all,1
/title, [NEXT] quartz  tube ext. press. e_v_buckle, uz=0 100 kPA unit press.
/com    buckling analysis for NEXT WLS tube, from external pressure loading
/com 	code written for ansys 5.7

/com ELEMENT TYPES (nl layer shell elements)
/com ET, ITYPE, Ename, KOP1, KOP2, KOP3, KOP4, KOP5, KOP6, INOPR
et,1,63		!general shell 3d
/com          Real Set 1  al/pitch carbon composite
/com             layer thicknesses

mp,ex,1,72.4e9	!quartz
mp,prxy,1,0.17

r,1,t

/com               COORDINATE SYSTEM DEFINITIONS

csys,1	!1=cyl, z=axis
/com               CYLINDER BODY DEFINITION
mat,1
type,1
real,1
k,1
k,2,r
k,3,r,,l
k,4,,,l
l,2,3,ndiv_long,-3
arotate,1,,,,,,1,4,360,8
/com	lsel,s,line,,5,12
/com	lesize,all,,3
amesh,1,8
nrotate,all
nsel,s,loc,z,l,l+.000001
d,all,ux,,,,,uy
cp,1,uz,all
f,all,fz,-f
nsel,s,loc,z
d,all,ux,,,,,uy,uz
nall
save
sfa,all,2,pres,100000	!unit pressure of 100 kPa
fini
/eof
/solu
anty,0
/com	eqslv,sparse
pstress,on
solve
save
fini
/solu
antype,buckle
bucopt,lanb,20	!block lanczos option extract to mode x
mxpand,20,,,,yes
outpr/nsol,all
save
solve
fini
/solu
expass,on
mxpand,20
outres,all
solve
save
fini
/eof
/prep7
upgeom,.0001,,,al_150_long1,rst
fini
/solu
ANTYPE,0
nlgeom,on
pstress,on
sstif,on
solcontrol,on
nropt,unsym,,off
AUTOTS,on
LNSRCH,0
NEQIT,5   
PRED,0  
TIME,10
DELTIME,0.5,0.05,0.5,on 
/GO
kbc,0
SFA,all,2,PRES,1000000 
OUTPR,all,none   
OUTRES,ALL,ALL 
OUTPR,STAT  
OUTRES,STAT 
/STATUS,SOLU
SOLVE   
fini
/eof
/post26
STORE,NEW,all,
FILE,star_ripple_pipe,rst
TIMERANGE,1,50
NSTORE,1   
NSOL,2,5548,U,X,rad_disp  
VARNAM,uradial,rad_disp 
PLTIME,1,50 
XVAR,0  
SPREAD,0
PLCPLX,0
PLVAR,rad_disp