Civil Engineering Reference
In-Depth Information
Fig. 14.21
Impact with an offset cylindrical target
impact on a convoy reactor building. In such a simulation the aircraft has been
almost entirely compressed to the contour of the cylindrical target after approx.
350 ms. The load function only changes slightly in comparison to the straight target,
however. The wing sections hit the obstacle a little later in the case of a cylindrical
obstacle than in the case of a straight one. The mass density of the outer wing
sections is relatively small compared to the fuselage and the middle wing sections
with the integrated tanks, however such that the impact load-time function only
shows small differences in comparison to the rigid straight target and is covered by
this case.
In additional studies the rigid cylindrical target was offset to the flight direction.
Figure
14.21
shows the initial state. The load on the target is decreased compared to
the central impact. This raises the question of whether the aircraft could be diverted
and deflected by the impact surface that is tilted with respect to the fuselage axis.
14.4.2
Impact Areas Boeing 747
To calculate the structural behaviour it is necessary to analyze and define the
possible impact areas in addition to the temporal progression of the impact force.
Using the geometric data of the B747 and the knowledge gained through the
calculations of the load function the following areas can be used for example:
39 m
2
: Substitute area for the fuselage only: circle with a diameter of 7 m.
A
R
¼
64 m
2
: Substitute area for the entire aircraft including wing components:
ellipse with the semi-diameters 17.00 m and 5.00 m or alternatively a circle with
a diameter of 9 m.
A
G
¼
