Role of wave reverberations in exit vibrations of projectiles and shells

Carlucci et al. (2013) proposed a theoretical model describing exit vibrations of a shell
launched by a gun. The model treats the shell as a system of a spring, damper and a rigid
mass. In this paper, similar models describing vibrations of shells and monolithic projectiles
are compared with some 1D models taking into account wave reverberations. The comparison
proves that the models taking into account the wave motion, forecast similar amplitudes and
frequencies of vibrations as discrete models. However, details of acceleration time courses
differ considerably. The problem of the influence of the friction force between the shell wall
and the filling is also discussed. The results of modelling serve as well for assessing if some
projectile velocity oscillations detected by making use of the Doppler radar can be solely
attributed to the exit vibrations.