Shock factor is a commonly used figure of merit for estimating the amount of shock experienced by a naval target from an

underwater explosion An underwater explosion (also known as an UNDEX) is a chemical or nuclear explosion that occurs under the surface of a body of water. While useful in anti-ship and submarine warfare, underwater bombs are not as effective against coastal facilities. ...

as a function of explosive charge weight,

slant range In radio electronics, especially radar terminology, slant range or slant distance is the distance along the relative direction between two points. If the two points are at the same level (relative to a specific datum), the slant distance equals t ...

, and depression angle (between vessel and charge).

SF =

* ''R'' is the slant range in feet * ''W'' is the equivalent

TNT Trinitrotoluene (), more commonly known as TNT, more specifically 2,4,6-trinitrotoluene, and by its preferred IUPAC name 2-methyl-1,3,5-trinitrobenzene, is a chemical compound with the formula C6H2(NO2)3CH3. TNT is occasionally used as a reagen ...

charge weight in pounds = charge weight (lbs) ·

Relative effectiveness factor TNT equivalent is a convention for expressing energy, typically used to describe the energy released in an explosion. The is a unit of energy defined by that convention to be , which is the approximate energy released in the detonation of a ...

\phi

is the depression angle between the hull and

warhead A warhead is the forward section of a device that contains the explosive agent or toxic (biological, chemical, or nuclear) material that is delivered by a missile, rocket, torpedo, or bomb. Classification Types of warheads include: * Expl ...

. The application scenario for Equation 1 is illustrated by Figure 1. The numeric result from computing the shock factor has no physical meaning, but it does provide a value that can be used to estimate the effect of an underwater blast on a vessel. Table 1 describes the effect of an explosion on a vessel for a range of shock factors. ::

Background

The idea behind the shock factor is that an explosion close to a ship generates a shock wave that can impart sudden vertical motions to a ship's hull and internal systems. Many of the internal mechanical systems (e.g. engine coupling to prop) require precise alignment in order to operate. These vibrations upset these critical alignments and render these systems inoperative. The vibrations can also destroy lighting and electrical components, such as relays. The explosion also generates a gas bubble that undergoes expansion and contraction cycles. These cycles can introduce violent vibrations into a hull, generating structural damage, even to the point of breaking the ship's

keel The keel is the bottom-most longitudinal structural element on a vessel. On some sailboats, it may have a hydrodynamic and counterbalancing purpose, as well. As the laying down of the keel is the initial step in the construction of a ship, in Br ...

. In fact, this is a goal of many undersea weapon systems. The magnitude of an explosion's effects have been shown through empirical and theoretical analyses to be related to the size of the explosive charge, the distance of the charge from the target, and the angular relationship of the hull to the shock wave.

References

{{DEFAULTSORT:Shock Factor Explosives