Determination of a Load Approaches for Aircraft Impacts - The Risks of Nuclear Energy Technology - page 273

Fig. 14.23 Example of a load function for a medium-range aircraft A320; mass 74.5 t, v ¼ 175 m/

s; comparison between calculation results and idealized functional

14.5 Compilation of the Load Approaches

In the following figures the impact load-time functions of the different types of
aircraft mentioned above are compiled for comparison. The load functions are
plotted once as absolute force values, once taken over the particular effective
impact area and once over the perimeter of the impact area. It shall be noted that
the values presented here for the Boeing 747 and the Airbus A320 are only to be
treated as examples. Using different boundary conditions and other mathematical
models deviating functions can be determined (Figs. 14.24 , 14.25 , and 14.26 ).
This compilation clearly shows that the loads are very different with respect to
the absolute force values. In comparison to the design standards of the newer
nuclear power plants that use the Phantom, the B747 has an impact force that is
four times higher and a momentum that is 15 times higher. These values can be
relevant with respect to the global structural stability and the induced vibrations.
For the local load concentration on the impact area the scaled quantities are more
meaningful. A comparison of the loads divided by the impact area shows that the
Phantom is the most unfavorable case. The quantities scaled to the perimeter
describe the sectional load of a hit structure in a first approximation. The integrated
load of the impact area has to be distributed to the perimeter and transferred to the
remaining structure. This results in values that are only 30 % higher for the B747
than for the Phantom.