73
Before the employing the Fourier transformation (4) we introduce the dimensionless coordinates
and dimensionless
transformation parameter
1
1
x
x h
,
2
2
x
x
h
,
s
sh
. (5)
Below we will omit the over-bar on the symbols in (5). Moreover, we will also
use the notation
'
V
V h
,
(1)
(1)
(1)
0
. (6)
For reducing the volume of the paper we do not give here the other details of the solution
procedure, which are similar to those given in the papers [1, 2]. Nevertheless, we recall that under
the mentioned solution procedure the
dimensionless parameters
1
0
'
V h
a
,
2
2
(1)
'
w
V h
N
,
(1)
V
M
h
(7)
are introduced. Note that the dimensionless number
w
N in (7) can be taken as a Womersley
number and characterizes the influence of the fluid viscosity on the mechanical behavior of the
system under consideration. However, the dimensionless frequency
1
in (7) can be taken as the
parameter through which the influence of the compressibility of the fluid on the mechanical
behavior of the system under consideration can be characterized. At the same time, the parameter
M characterizes the ratio of the characteristic stress caused by fluid viscosity to the shear modulus
of the plate material.
Thus, within the scope of the solution procedure discussed in the papers [1, 2], we obtain
analytical expression of the sought quantities, after which we determine the originals of those
through
the expression
1
2
11
12
22
1
2
11
12
22
1
2
11
1
;
;
;
;
; ;
;
;
;
Re
;
;
;
2
F
F
F
u u
v v T
T
T
u
u
1
12
22
1
2
11
12
22
;
;
;
;
;
;
isx
F
F
F
F
F
F
F
v
v
T
T
T
e
ds
. (8)
The integrals in (8) are calculated numerically for which the infinite interval
[
,
]
is replaced
with the finite one
*
*
1
1
[
,
]
S
S
. The values of the
*
1
S
are determined from the convergence criterion
of these integrals in (8). Under calculation of the integrals in (8), the interval
*
*
1
1
[
,
]
S
S
is divided
into a certain number of sorter intervals. Let us denote this number through
2
N
. Consequently, the
length of the mentioned shorter intervals is
*
1
S
N
and in each of these shorter intervals the
integration is made by the use of the Gauss integration algorithm with the sample points.
Consequently, convergence of the mentioned numerical integration can be estimated with respect to
the values of
*
1
S
and
N
. The various testing of the convergence of the numerical results show that
for the quite converge and validate results are obtained in the case where
2000
N
and
*
1
5.0
S
.
We do not here consider examples of the numerical results illustrated this convergence, however
note that such examples are given in the paper [1].
This completes the consideration of the solution method.
3.
Numerical results and discussions
It follows from the foregoing discussions that the problem under consideration is characterized
through the dimensionless parameters
1
,
w
N and
M which are determined by the expressions in
74
(7),
where
and
are the mechanical constants which enter the expression of the elastic
relations in Eq. (1). Note that the case where
1
0
corresponds to the case where the fluid is
incompressible, but the case where 1
0
w
N
corresponds to the case where the fluid is inviscid.
In the numerical investigation we assume that the material of the plate-layer is Steel with
mechanical constants:
9
79 10
Pa
,
9
94.4 10
Pa
and density
3
1160
kg m
[7], but the
material of the fluid is Glycerin with viscosity coefficient
(1)
1,393
(
)
kg m s
, density
(1)
3
0
1260
kg m
and sound speed
0
1459.5
a
m s
[6]. We also introduce the notation
2
c
which is the shear wave propagation velocity in the layer material.
Fig.1. Distribution of the
22
0
/
T h P
with respect to the
1
x h
Thus, after selection of these materials, the foregoing dimensionless parameters can be determined
through the two quantities:
h
(the thickness of the plate-layer) and
V
(the velocity of the external moving
load). Numerical results which will be discussed below relate to the normal stress acting on the interface
plane between the fluid and plate-layer and to the velocities of the fluid (or of the plate-layer) on the
mentioned interface plane in
the directions of the
1
Ox
and
2
Ox
axes.
Fig. 2. The distribution of the
2
0 2
/ (
)
v
h
P c
with
respect of the
1
x h