Low Impact EOD Projectile Water Column Shock Reduction
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Solution Overview
Problem
Current EOD disruptor technologies face challenges in safely penetrating thick steel-cased IEDs without detonating the explosives inside, as high-velocity steel projectiles can compress and ignite the contents due to matched shock impedances, leading to violent explosions.
Innovation Solution
A muzzle-loaded projectile with a variable shaft portion and bushings, designed to be fired at a velocity of less than 1000 feet per second, featuring a long shaft with a sub-caliber diameter and a front portion with a cutting edge, coated with non-sparking materials, and a water column to enhance propulsion and reduce shock waves, is used in conjunction with a restraint system to limit the projectile's travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high velocity steel projectiles are used to penetrate thick steel-cased IEDs, then penetration capability is improved, but shock pressure increases causing explosive ignition
Solution Approach 1:
The patent changes the velocity parameter from high (>2000 fps) to low (<1000 fps) to reduce shock pressure while maintaining penetration capability through increased projectile mass and optimized geometry. This parameter change directly addresses the contradiction by decoupling penetration from shock pressure generation.
Solution Approach 2:
The patent employs composite projectile construction with non-sparking materials such as fiberglass-reinforced plastic or carbon fiber composites. These materials provide sufficient structural strength for penetration while avoiding spark generation that could ignite explosives, thus resolving the contradiction between penetration capability and ignition risk.
2Length of stationary object
If conventional steel projectiles are used, then penetration of thick steel casings is achieved, but explosive detonation occurs due to adiabatic compression
Solution Approach 1:
The patent reduces projectile velocity from >2000 fps to <1000 fps, which fundamentally changes the impact dynamics. This velocity reduction prevents adiabatic compression heating that would otherwise raise explosive temperature to ignition levels, while still achieving penetration of thick casings through increased mass and optimized projectile design.
Solution Approach 2:
The patent employs frangible or disposable projectile designs that are optimized for single-use penetration tasks. These projectiles are designed to penetrate the casing and then disintegrate or be contained by the restraint system, preventing multiple impacts that could generate dangerous shock pressures or temperatures.
3Speed
If high velocity projectiles are fired, then penetration speed is improved, but shock wave propagation increases causing violent explosions
Solution Approach 1:
The patent fundamentally changes the velocity parameter from high (>2000 fps) to low (<1000 fps), which reduces the kinetic energy and consequently the shock wave generation. The penetration function is maintained through increased projectile mass and optimized geometry rather than relying on high velocity.
Solution Approach 2:
The patent introduces a water column as an intermediary medium between the projectile and the explosive charge. This water column absorbs and dissipates impact energy, reducing shock wave propagation while still allowing the projectile to penetrate the casing. The water acts as a buffer that mediates the interaction between the projectile and explosive.
4Strength
If steel projectiles are used for penetration, then structural strength is improved, but matched shock impedance causes efficient shock wave propagation
Solution Approach 1:
The patent employs composite materials such as fiberglass-reinforced plastic or carbon fiber composites that provide sufficient structural strength for penetration without the matched shock impedance characteristics of steel. These materials have different acoustic impedance properties that reduce efficient shock wave propagation into the explosive while maintaining the structural integrity needed for penetration.
Solution Approach 2:
The patent applies different material properties to different parts of the projectile. The forward portion may use harder materials for penetration while the rear portion uses materials with different acoustic properties to reduce shock wave generation. This local differentiation of material quality allows the projectile to penetrate effectively while minimizing harmful shock wave propagation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces the likelihood of ignition and detonation of IEDs by minimizing shock pressures and increasing the duration of impact, allowing for the safe penetration of thick steel casings without initiating the explosives, as demonstrated by successful tests on steel pipe bombs and other IED types.
Implementation Method 1
The unexpected consequences of this approach are the tremendous pressures and shock waves that are produced. Steel projectiles that hit steel targets have matched shock impedances and thus efficiently propagate shock waves.
Implementation Method 2
The explosives' compression occurs quickly and adiabatic conditions are created. For example, after projectile impact, black powder inside an IED can be compressed and heated to ignition
Data Source
AI summary
An EOD disruptor system for penetrating steel encased explosive devices has a barrel and a blank cartridge loaded in the EOD disruptor. A water column is disposed in the barrel in front of the blank cartridge. A water plug is disposed in front of the water column. A muzzle-loaded projectile is disposed in front of the water plug. The projectile includes a shaft portion at least partially disposed in the barrel and a front portion disposed outside of the barrel. The shaft portion may have a length from about four inches to about eighteen inches. The projectile may have a weight from about four ounces to about two pounds. The ratio of the length of the shaft portion of the projectile to the inner barrel diameter may be in a range of about two to about 50.