📄 p66.f90
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program p66
!-----------------------------------------------------------------------
! program 6.6 axisymmetric 'undrained' strain of an elastic-plastic
! (Mohr-Coulomb) solid
! using 8-node quadrilateral elements; viscoplastic strain method
!------------------------------------------------------------------------
use new_library ; use geometry_lib ; implicit none
integer::nels,nxe,nye,neq,nband,nn,nr,nip,nodof=2,nod=8,nst=4,ndof, &
i,j,k,iel,iters,limit,incs,iy,ndim=2,loaded_nodes
logical::converged ; character (len=15) :: element='quadrilateral'
real::e,v,det,phi,c,psi,dt,f,dsbar,dq1,dq2,dq3,lode_theta, &
sigm,pi,snph,bulk,cons,presc,ptot,radius,tol
!----------------------------- dynamic arrays----------------------------------
real ,allocatable :: kv(:),loads(:),points(:,:),bdylds(:),totd(:), &
evpt(:,:,:),oldis(:),width(:),depth(:),stress(:), &
dee(:,:),coord(:,:),jac(:,:),weights(:),storkv(:), &
der(:,:),deriv(:,:),bee(:,:),km(:,:),eld(:),eps(:), &
sigma(:),bload(:),eload(:),erate(:),g_coord(:,:), &
evp(:),devp(:),m1(:,:),m2(:,:),m3(:,:),flow(:,:), &
tensor(:,:,:),etensor(:,:,:),pore(:,:),fun(:)
integer, allocatable :: nf(:,:) , g(:), no(:) ,num(:), g_num(:,:) ,g_g(:,:)
!--------------------------input and initialisation----------------------------
open (10,file='p66.dat',status= 'old',action='read')
open (11,file='p66.res',status='replace',action='write')
read (10,*) phi,c,psi,e,v,bulk,cons, nels,nxe,nye,nn,nip
ndof=nod*nodof
allocate (nf(nodof,nn), points(nip,ndim),weights(nip),g_coord(ndim,nn), &
width(nxe+1),depth(nye+1),num(nod),evpt(nst,nip,nels), &
coord(nod,ndim),g_g(ndof,nels),tensor(nst,nip,nels),fun(nod), &
etensor(nst,nip,nels),dee(nst,nst),pore(nip,nels),stress(nst), &
jac(ndim,ndim),der(ndim,nod),deriv(ndim,nod),g_num(nod,nels), &
bee(nst,ndof),km(ndof,ndof),eld(ndof),eps(nst),sigma(nst), &
bload(ndof),eload(ndof),erate(nst),evp(nst),devp(nst),g(ndof), &
m1(nst,nst),m2(nst,nst),m3(nst,nst),flow(nst,nst))
nf=1; read (10,*) nr ; if(nr>0) read(10,*)(k,nf(:,k),i=1,nr)
call formnf(nf); neq=maxval(nf);read(10,*) width , depth
!------------ loop the elements to find nband and set up global arrays --------
nband = 0
elements_1: do iel = 1 , nels
call geometry_8qyv(iel,nye,width,depth,coord,num)
call num_to_g(num,nf,g) ; g_num(:,iel)=num
g_coord(: , num )=transpose(coord); g_g( : , iel ) = g
if (nband<bandwidth(g)) nband = bandwidth(g)
end do elements_1
write(11,'(a)') "Global coordinates "
do k=1,nn;write(11,'(a,i5,a,2e12.4)')"Node",k," ",g_coord(:,k);end do
write(11,'(a)') "Global node numbers "
do k = 1 , nels; write(11,'(a,i5,a,8i5)') &
"Element ",k," ",g_num(:,k); end do
write(11,'(a,i5,a,i5)') &
"The system has ",neq," equations and the half-bandwidth is",nband
allocate(kv(neq*(nband+1)),loads(0:neq),bdylds(0:neq),oldis(0:neq),totd(0:neq))
kv=0.0; oldis=0.0; totd=0.0 ; tensor = 0.0; etensor = 0.0
call deemat(dee,e,v); call sample(element,points,weights)
!------------------ fluid bulk modulus is "bulk" --------------------------
do i=1,nst; do j=1,nst;if(i/=3.and.j/=3)dee(i,j)=dee(i,j)+bulk; end do; end do
pi = acos( -1. ); snph = sin(phi*pi/180.)
dt = 4.*(1.+ v)*(1.-2.*v)/(e*(1.-2.*v+snph*snph))
!---------- element stiffness integration and assembly & initial conditions----
elements_2: do iel = 1 , nels
num = g_num(: ,iel ) ; coord = transpose (g_coord(: ,num ))
g = g_g( : ,iel ) ; km=0.0
gauss_pts_1: do i =1 , nip ; call shape_fun(fun,points,i)
call shape_der (der,points,i); jac = matmul(der,coord)
det = determinant(jac) ; call invert(jac)
deriv=matmul(jac,der);call bmataxi(bee,radius,coord,deriv,fun)
km=km+matmul(matmul(transpose(bee),dee),bee)*det*weights(i)*radius
tensor(1:2,i,iel)=cons; tensor(4,i,iel)=cons
end do gauss_pts_1
call formkv (kv,km,g,neq)
end do elements_2
!--------------- prescribe displacements and factorise l.h.s. ---------------
read(10,*) loaded_nodes ; allocate(no(loaded_nodes),storkv(loaded_nodes))
read(10,*)no , presc , incs , tol , limit
do i=1,loaded_nodes
kv(nf(2,no(i)))=kv(nf(2,no(i)))+1.e20 ; storkv(i)=kv(nf(2,no(i)))
end do ; call banred(kv,neq)
!-------------------displacement increment loop--------------------------------
call deemat(dee,e,v)
load_increments: do iy=1,incs
ptot = presc * iy
write(11,'(/,a,i5)') 'Load increment',iy ; iters=0; bdylds=.0; evpt=.0
!--------------------------- iteration loop --------------------------------
iterations: do
iters=iters+1; loads = .0
do i=1,loaded_nodes;loads(nf(2,no(i)))=storkv(i)*presc; end do
loads = loads + bdylds ; call bacsub(kv,loads)
!------------------------ check convergence ---------------------------------
call checon(loads,oldis,tol,converged)
if(iters==1)converged=.false.
!----------------------- go round the Gauss Points ----------------------------
elements_3: do iel = 1 , nels
bload=.0
num = g_num( : , iel ) ; coord = transpose( g_coord( : , num ))
g = g_g( : , iel ) ; eld = loads ( g )
gauss_points_2 : do i = 1 , nip
call shape_fun(fun,points,i)
call shape_der ( der,points,i); jac=matmul(der,coord)
det = determinant(jac) ; call invert(jac)
deriv = matmul(jac,der) ; call bmataxi (bee,radius,coord,deriv,fun)
eps=matmul(bee,eld); det = det * radius; eps=eps-evpt(:,i,iel)
sigma=matmul(dee,eps) ; stress=sigma+tensor(: , i , iel)
call invar(stress,sigm,dsbar,lode_theta)
!-------------------- check whether yield is violated ------------------------
call mocouf (phi, c , sigm, dsbar , lode_theta , f )
if(f>=.0) then
call mocouq(psi,dsbar,lode_theta,dq1,dq2,dq3)
call formm(stress,m1,m2,m3)
flow=f*(m1*dq1+m2*dq2+m3*dq3) ; erate=matmul(flow,stress)
evp=erate*dt; evpt(:,i,iel)=evpt(:,i,iel)+evp;devp=matmul(dee,evp)
eload=matmul(devp,bee) ; bload=bload+eload*det*weights(i)
end if
if(converged.or.iters==limit) then
!---------------- update stresses and calculate porepressures --------------
tensor(:,i,iel)=stress
etensor(:,i,iel)=etensor(:,i,iel)+eps+evpt(:,i,iel)
pore(i,iel)=(etensor(1,i,iel)+etensor(2,i,iel)+etensor(4,i,iel))*bulk
end if
end do gauss_points_2
! compute the total bodyloads vector
bdylds( g ) = bdylds( g ) + bload ; bdylds(0) = .0
end do elements_3
if(converged.or.iters==limit)exit
end do iterations
totd = totd + loads
write(11,'(a,e12.4)') " Displacement" , ptot
write(11,'(a,3e12.4)') &
" Effective stresses",tensor(1,1,1),tensor(2,1,1),tensor(4,1,1)
write(11,'(a,2e12.4)') " Deviator stress and porepressure",dsbar,pore(1,1)
write(11,'(a,i5,a)') "It took",iters," iterations to converge"
if(iters==limit)stop
end do load_increments
end program p66
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