Ammunition Cartridge Base Plug with Fusible Venting
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Solution Overview
Problem
Existing ammunition cartridges are prone to violent reactions and collateral damage when exposed to external fires due to auto-ignition of propellants, which is not adequately addressed by current venting technologies, particularly in gun-fired ammunition.
Innovation Solution
A cartridge design with a fusible material support for the base plug that loses mechanical strength at elevated temperatures, allowing the plug to eject and create a vent channel, preventing auto-ignition by releasing propellant gases into an unconfined space, thereby reducing the severity of the energetic event.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a base plug is used to seal the cartridge case, then the cartridge maintains structural integrity and contains propellant gases during normal operation, but the cartridge becomes vulnerable to violent reactions and auto-ignition when exposed to external fires
Solution Approach 1:
The base plug incorporates a fusible material that changes its mechanical properties based on temperature parameters. At normal operating temperatures, the material maintains high strength to seal the cartridge. When exposed to external fire temperatures, the material undergoes a parameter change (loss of mechanical strength) that allows the plug to eject and vent gases, preventing violent reactions.
Solution Approach 2:
The base plug transitions from a static sealing component to a dynamic safety mechanism. The fusible material allows the plug to respond dynamically to temperature changes, automatically ejecting when thermal conditions indicate danger. This dynamic behavior enables the same component to serve both sealing and venting functions under different conditions.
2Object-affected harmful factors
If venting technology is implemented to prevent auto-ignition, then safety under external fire exposure is improved, but the structural integrity and sealing capability during normal operation deteriorates
Solution Approach 1:
The fusible material in the base plug exploits temperature-dependent parameter changes to differentiate between normal and dangerous conditions. The material's mechanical strength parameter is high at operational temperatures, ensuring proper sealing. When temperature exceeds a threshold indicating external fire exposure, the parameter changes and the plug ejects to vent gases, preventing auto-ignition.
3Reliability
If a fusible material support is used for the base plug, then the cartridge can automatically vent under thermal stress, but the manufacturing complexity and material selection requirements increase
Solution Approach 1:
The base plug is constructed as a composite structure incorporating fusible material support within the plug body. This composite design integrates the thermal response function directly into the sealing component, eliminating the need for separate sensing and actuation mechanisms. The composite structure maintains structural integrity during manufacturing while enabling automatic venting when thermal conditions are exceeded.
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 minimizes collateral damage and ensures safe operation by preventing propellant auto-ignition and reducing the violence of combustion when cartridges are exposed to external heating, while maintaining functionality in normal operational modes.
Implementation Method 1
a fusible material support for the base plug that loses mechanical strength at elevated temperatures
Implementation Method 2
creating a vent channel, preventing auto-ignition by releasing propellant gases into an unconfined space
Data Source
AI summary
An ammunition cartridge comprised of a projectile inserted in, and mechanically connected to, a metal cartridge case assembly having a propulsion chamber and a base, and an energetic propellant disposed in the propulsion chamber, includes a base plug in which is mounted an igniter with an energetic primer. During manufacture of the cartridge, a fusible support ring is incorporated into a metal cavity. The cartridge base includes a cavity allowing the fusible material to solidify at ambient temperatures. When exposed to heat from an external fire, the fusible support plug liquefies losing its strength and subsequently, when a propellant or primer off-gasses or auto-ignites the pressure from the reaction ejects a metal plug or lid from the cartridge case base, creating a void that allows the propellant and primer to combust in an unconfined space.