Civil Engineering Reference
In-Depth Information
k2
working variable
omega
frequency of forcing term
10
20
set to 1
×
penalty
holds elapsed time
t
time
set to 2.0
two
Scalar character:
element
element type
New Dynamic integer arrays:
g num
global element node numbers matrix
New Dynamic real arrays:
bigk
eigenvector matrix
element nodal coordinates
coord
global lumped mass vector
diag
nodal coordinates for all elements
g coord
global stiffness vector
kh
element stiffness matrix
km
global stiffness matrix stored as upper triangle
ku
vector holding reciprocal of square root of lumped mass
rrmass
transformed and untransformed eigenvectors
udiag
solutions to modal SDOF equations
xmod
x
-coordinates of mesh layout
x coords
y
-coordinates of mesh layout
y coords
Since the basis of this method is the synthesis of the undamped natural modes of the
vibrating system, it follows very naturally from the programs of the previous chapter. Indeed
this program can be built up, with minor extensions, from Program 10.2. The method is
described in Section 3.13.1.
The illustrative problem chosen for this program and the two that follow is shown in
Figure 11.4 and is similar to the cantilever beam considered in Figure 10.6. The beam in
4.0
16
1
4
1.0
17
2
5
18
3
E = 1 kN/m
2
n
= 0.3
r
= 1 t/m
3
F= cos
w
t
Figure 11.4
Mesh and data for Program 11.2 example (
Continued on page 476
)
