Munition Fuze Shock Mitigation via Damping and Venting
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Solution Overview
Problem
Current insensitive munitions (IM) release methods have limited secondary vent areas, rely on additional energetic materials for ignition control, and face issues with chemical compatibility and parasitic mass/volume, which can lead to shock transmission and inefficient cook-off mitigation.
Innovation Solution
The implementation of a direct impingement cook-off mechanism with unique geometrical configurations for secondary vent paths and a booster separation from the main energetic material, reducing shock transmission and chemical compatibility issues, while allowing for variable venting and improved fuze survivability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional energetic materials are used for ignition control, then ignition timing control is improved, but chemical compatibility issues and parasitic mass/volume increase
Solution Approach 1:
The patent extracts the ignition control function from separate energetic materials and integrates it into the main propellant grain geometry. The ignition system uses the propellant's own combustion characteristics and geometrically-controlled vent paths to achieve precise ignition timing without adding separate energetic materials, thereby eliminating parasitic mass and volume while maintaining chemical compatibility.
Solution Approach 2:
The propellant grain geometry serves multiple functions: it provides the main propellant mass, controls the combustion rate, and defines the ignition timing through its geometric configuration. The integrated design makes the propellant grain universal, eliminating the need for separate ignition control materials and reducing overall system mass and volume.
2Ease of operation
If conventional release methods are used, then fuze release is achieved, but shock transmission to the fuze increases
Solution Approach 1:
The patent incorporates a shock mitigation apparatus with damping elements positioned between the propellant charge and the fuze. This cushioning structure is pre-installed to absorb and attenuate shock waves before they reach the fuze during cook-off events, thereby protecting the fuze from excessive shock transmission while still allowing reliable release when needed.
3Device complexity
If secondary vent areas are limited, then structure simplicity is maintained, but cook-off mitigation efficiency decreases
Solution Approach 1:
The patent transitions from limited two-dimensional vent areas to three-dimensional venting pathways by creating geometrically-configured vent paths that extend through the propellant grain volume. These vent paths provide multiple escape routes for combustion gases in three dimensions, significantly enhancing cook-off mitigation efficiency while maintaining structural simplicity through integrated grain geometry rather than additional components.
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
This solution enhances munition response to Slow Cook-Off and Fast Cook-Off tests, reduces shock and vibrational pressures on fuzes, and eliminates parasitic mass and volume issues, enabling more efficient and reliable ignition control.
Implementation Method 1
Component material and orientation provides damping and impedance mismatches across interfaces. This additional damping, as well as impedance mismatches, results in reduced shock and vibrational pressures and stresses transmitted to munition fuzes.
Implementation Method 2
Component material and orientation provides damping and impedance mismatches across interfaces.
Implementation Method 3
direct impingement cook-off mechanism with unique geometrical configurations
Implementation Method 4
direct impingement cook-off mechanism
Data Source
AI summary
Embodiments employ venting features and damping components both inside and concentric to a fuzewell to improve munition fuze survivability. Damping components are selected based on their densities and stiffness properties. A shock damping liner with longitudinal grooves is affixed to an inner surface of the fuzewell and envelops the fuze. At least one shock damping collar constrains and attenuates shack experienced by the fuze. A shock damping ring is concentric about the outer surface of the fuzewell and attenuates shock, between the outermost munition system layer (the casing) and the fuzewell. Longitudinal vents in the fuzewell wall and radial apertures oriented transverse to the longitudinal vents are used for off-gassing. The venting and component orientation combination provides increased damping, resulting in impedance mismatches across multiple interface surfaces in the munition, which reduces shock vibrational pressures and stresses transferred to the fuze.