Fragmentation of shell cases

A theory is given of the break-up of the metal case of a cylindrical ring-bomb, in which the lines of fracture perpendicular to the axis of the bomb are predetermined. From the theory an expression is given for the length of the average fragment; this is shown to depend, if certain hypotheses are made, on the radius and velocity of the case at the moment of break-up, and on the mechanical properties of the metal.