Silicone Intermediate Layer for Explosive Projectile Stress Management
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Solution Overview
Problem
High-launch acceleration in tubular weapons poses a risk of 'set back' for explosive projectiles, particularly with plastic-bound insensitive explosive charges, leading to stress cracking and premature detonation due to mismatched coefficients of expansion between the explosive charge and the steel projectile body, and existing solutions like lacquers are ineffective.
Innovation Solution
A partial silicone coating is applied between the explosive charge and the inner surface of the projectile body to minimize adhesion and absorb stress, ensuring adequate fixation and stress absorption, thereby preventing 'set back' and cracking during high-acceleration launches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the explosive charge is directly connected to the inner surface of the projectile body, then fixation is strong, but stress cracks occur during temperature shock tests due to mismatched expansion coefficients
Solution Approach 1:
A silicone intermediate layer is introduced between the explosive charge and the steel projectile body. This intermediate layer acts as a mediator that decouples the direct thermal contact, allowing differential thermal expansion without transmitting stress to the explosive charge, thereby preventing stress cracks while maintaining fixation.
Solution Approach 2:
The patent uses a composite structure consisting of the steel projectile body, the silicone intermediate layer, and the explosive charge. This composite material approach combines materials with different thermal expansion coefficients in a layered configuration, enabling each material to expand freely while maintaining overall structural integrity.
2Strength
If a lacquer coating is applied to prevent set back, then adhesion is improved for TNT-bound charges, but the solution is ineffective for plastic-bound insensitive explosive charges with high expansion coefficients
Solution Approach 1:
The patent changes the material parameter of the intermediate layer from lacquer (ineffective for plastic-bound charges) to silicone, which provides both adhesion and flexibility. This parameter change enables the solution to work effectively with plastic-bound insensitive explosive charges that have high expansion coefficients, resolving the compatibility issue.
3Reliability
If the explosive charge is completely separated from the shell by liners, then safety is improved, but fixation is weakened and set back effect increases
Solution Approach 1:
The silicone intermediate layer serves as a mediator that provides both separation (for safety) and adhesion (for fixation). Unlike complete separation by thick liners, the silicone layer maintains sufficient bonding strength to prevent set back while providing thermal decoupling to ensure safety during temperature shocks.
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 silicone intermediate layer effectively prevents stress cracking and premature detonation by controlling expansion differences and ensuring secure positioning of the explosive charge, even at extreme accelerations and temperature shocks.
Implementation Method 1
the coefficient of expansion of these explosive charges is significantly greater than that of charges bound by TNT and about 10 times as high as the coefficient of expansion of steel
Implementation Method 2
absorbs a large part of the stresses between the body of the projectile and the explosive charge during a temperature shock test
Implementation Method 3
A silicone layer is therefore proposed, since this represents a release agent. Due to the now only partial adhesion / non-adhesion of the explosive charge, the 'set back' effect is even avoided
Data Source
AI summary
The invention relates to an explosive projectile (1) having a projectile body (2) in which a cavity (4) is located, which extends in the direction of the longitudinal axis (3) of the projectile and is filled with an explosive charge (5). In order to ensure that the explosive projectile (1) can be fired with a high firing acceleration without any need to be concerned, even when using plastic-bonded insensitive explosive charges, that the high acceleration will lead to an explosion in the weapon barrel, and in order to avoid stress crack formation in the explosive charge, the invention proposes that a silicone intermediate layer (9) be provided at least in subareas between the explosive charge (5) and the inner surface (6) of the projectile body (2), which silicone intermediate layer (9) on the one hand ensures that the explosive charge (5) is adequately fixed in position with respect to the adjacent inner surface (6) of the projectile body (2), and on the other hand absorbs the majority of the stresses between the projectile body (2) and the explosive charge (5) in a temperature shock test, thus preventing crack formation in the explosive charge (5) during tests such as these.