Dynamic response of finite sized elastic runways subjected to ...

3162
G. PAN AND S. N. ATLURI
4'00e-71 Deflection (in)
'. -.
'. -.
. .
1 ......
0.14,.
0.12.
0.1;
0.08.
0.06.
0. 04-
0.02.
Figure 14. Maximum deflection at the plate centre in the whole history of a load moving through a plate versus
load-moving-velocity in the problem of an finite-sized elastic plate resting on an infinite elastic half-space, subjected to
a moving point-load
The deflection distributions of the plate due to the load, moving in the positive X direction, are
shown in Figure 15 for c = 1000,2000,6000 in/s, respectively. This result shows that in the low
velocity case, symmetry is exhibited in the deflection distribution. But as the moving-velocity
increases, the unsymmetry takes over and it becomes more and more pronounced.
The time history of deflection of another plate whose size is 1 x b = 120 x 60 in2 for
c = 500, 5000 in/s at the transmit time t/T = 0,0.2,0.4,06,0.8 and t/T = 0,02,0~4,0-6,0-8, 1.0
(where T is the time needed for the moving load to travel across the plate) is shown in Figure
16(a), (b) from left to right, respectively. Figure 16(a) shows the result of the low velocity case
c = 500 in/s. There is almost no upward deflection. The static deflection due to the load plays
a dominant role.
The case of relatively high velocity c = 5000 in/s is illustrated in Figure 16(b). It is observed
that the point of maximum transverse displacements is always behind the load and it proceeds in
a wave-like manner. Unlike that in the low velocity case, the plate exhibits an upward deflection.