Metals exposed to an explosion may undergo either geometrical macro-deformations or even only crystal microstructure deformations, as slip bands or mechanical twins, depending on the metal, on the explosive mass and on the mass to target distance. The parameter used as the one controlling the phenomena is the so-called reduced distance, r, defined as below.
r = d·m-1/3 [m·kg-1/3]
m, explosive mass [kg]
d, distance from explosive mass center to target [m]
The same value of the reduced distance and the same effects on the metal target can be obtained with large masses and distances as well as small charges and limited distances. Attention will be devoted to the latter case, when actions causing geometric macro deformations may intervene after an explosion, thus hiding its effects. Typical is the case of an aircraft that, after the explosion of a small charge on board, plunges either on the sea or on ground, distributing several wrecks around. The fall of Enrico Mattei airplane at Bascapè (PV) in 1962 is an example of the above- escribed scenario. It was studied several years after the fall of the aircraft.