*heading
 Input file for the postbuckling analysis.
*parameter
#
#	filenames
#
 buckle_file = 'file1.dat'
 imperf_file = 'file2.dat'
#
#  	workaround to allow parametrization of a 
#  	filename read with *INCLUDE
#
 line1 = '*imperfection,file=' + buckle_file + ',step=2'
 line2 = '*include, input=' + imperf_file	
#
#	geometric/load parameters
#
 radius = 5.0
 length = 2.0
 thickness = 0.01
#
#	this is the pcritical for the 1st value from 
#	the linear eigenvalue analysis
#
 eig1_load = 1.18305e+4 
#
#	elastic material properties
#
 young = 30e+06
 poisson=0.3
#
#	internal pressure
#
 int_press = 0.0
#
#	mesh parameters
#
 node_circum = 240
 node_length = 21
##
##	dependent parameters (do not modify)
##
 chn = node_circum*node_length-node_circum
 node_ang = -360.0/float(node_circum)
 node_tot = node_circum*node_length
 node_tmp = node_tot-node_circum+1
 node_int = node_length-1
 node_circum1 = node_circum+1
 node_circum2 = node_circum+2
 node_circum0 = node_circum-1
 e1 = node_circum*2
 p = -eig1_load/float(node_circum)
 pn = eig1_load/float(node_circum)
#
#  end of parameter list
#
*node,system=c
 1,<radius>,0.0,0.0
 <node_circum>,<radius>,<node_ang>,0.0
 <node_tmp>,<radius>,0.0,<length>
 <node_tot>,<radius>,<node_ang>,<length>
*ngen,line=c,nset=bottom
 1,<node_circum>,1,,0.0,0.0,0.0,0.0,0.0,1.0
*ncopy,new set=top,old set=bottom,shift,change number=<chn>
 0.0,0.0,<length>
 0.0,0.0,0.0,0.0,0.0,1.0,0.0
*nfill
 bottom,top,<node_int>,<node_circum>
**specify the imperfection as a function of modeshape amplitude
 <line1>
 <line2>
*element,type=s4
 1,1,2,<node_circum2>,<node_circum1>
 <node_circum>,<node_circum>,1,<node_circum1>,<e1>
*elgen,elset=cylinder
 1,<node_circum0>,1,1,<node_int>,<node_circum>,<node_circum>
 <node_circum>,1,,,<node_int>,<node_circum>,<node_circum>
*shell section, elset=cylinder, material=mat_1
 <thickness>,
*material,name=mat_1
*elastic
 <young>,<poisson>
*nset,nset=ends
 bottom,top
*nset,nset=node_out
 <node_tot>,
*transform,type=c,nset=ends
 0.0,0.0,0.0,0.0,0.0,1.0
*boundary
 ends,1,2
 ends,4,4
 ends,6,6
 1,3
**
*step,nlgeom
 static preload for internal pressure
*static
 1.0,1.0
*monitor,node=<node_tot>, dof=3
*dload
 cylinder,p,<int_press>
*end step
**
*step,nlgeom,inc=50
 postbuckling (riks) analysis
*static,riks
 0.05,1.0,,0.05,,<node_tot>,3,-0.1
*monitor,node=<node_tot>,dof=3
*controls,parameter=field,field=global
 1.e-5,
*cload
 top,3,<p>
 bottom,3,<pn>
*node file,freq=20,nset=top
 u,
*output,field,freq=20
*node output
 u,
*output,history,freq=1
*node output,nset=node_out
 u,
*end step