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16 Computer Programs in Vibration Analysis
Table 16.3 (continued)
read(*,*)nrqd
call r8usiv(nrqd,freq,alpha)
*
write(2,167)(irqd,freq(irqd),irqd=1,nrqd)
*
print 167,(irqd,freq(irqd),irqd=1,nrqd)
endif
stop
end
*
Subroutine to calculate the stiffness matrix of the element
subroutine elst(iel,emod,len,estif)
parameter (ielt=50,inod=50,ntdf=inod*6,inb=50)
common /c/ area(ielt),ixx(ielt),iyy(ielt),izz(ielt)
dimension estif(12,12)
real len,l,ix,iy,iz,ixx,iyy,izz
e = emod
l = len
a = area(iel)
g = emod/(2.*(1+0.3))
ix = ixx(iel)
iy = iyy(iel)
iz = izz(iel)
*
g = 80.0E6
*
Geneartion of upper triangle of the stiffness matrix
estif(1,1)
= e*a/l
estif(1,7)
=-e*a/l
estif(2,2)
= 12.0*e*iz/l**3
estif(2,6)
= 6.0*e*iz/l**2
estif(2,8)
=-12.0*e*iz/l**3
estif(2,12) = 6.0*e*iz/l**2
estif(3,3)
= 12.0*e*iy/l**3
estif(3,5)
=-6.0*e*iy/l**2
estif(3,9)
=-12.0*e*iy/l**3
estif(3,11) =-6.0*e*iy/l**2
estif(4,4)
= g*ix/l
estif(4,10) =-g*ix/l
estif(5,5)
= 4.0*e*iy/l
estif(5,9)
= 6.0*e*iy/l**2
estif(5,11) = 2.0*e*iy/l
estif(6,6)
= 4.0*e*iz/l
estif(6,8)
=-6.0*e*iz/l**2
estif(6,12) = 2.0*e*iz/l
estif(7,7)
= e*a/l
estif(8,8)
= 12.0*e*iz/l**3
estif(8,12) =-6.0*e*iz/l**2
(continued)