Isostatic Pressurization for Ballistic-Resistant Moulded Articles
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Solution Overview
Problem
Existing methods for manufacturing ballistic-resistant moulded articles, such as helmets, result in significant variations in ballistic resistance across the surface, leading to inconsistent performance against projectiles.
Innovation Solution
The process involves using isostatic pressurization with a container filled with a pressurizing liquid, such as water, to uniformly apply pressure to a stack of monolayers of unidirectional high-strength polyolefin fibers and a thermoplastic matrix, ensuring consistent areal density and reduced variation in ballistic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If compression moulding in a hydraulic press is used to manufacture ballistic-resistant moulded articles, then the manufacturing process can be completed, but the ballistic resistance shows large variation over the surface of the article
Solution Approach 1:
The patent applies isostatic pressurization using a liquid medium (water or oil) to uniformly consolidate the stack of monolayers. The liquid pressure is transmitted isotropically to all surfaces of the stack, ensuring uniform consolidation and areal density across the entire article surface, which directly resolves the ballistic resistance variation problem caused by conventional hydraulic press compression moulding
Solution Approach 2:
The patent changes the consolidation method from uniaxial compression (hydraulic press) to isostatic pressurization (liquid medium). This parameter change in the consolidation process ensures uniform pressure distribution, resulting in consistent areal density and uniform ballistic resistance across the article surface
2Manufacturing precision
If isostatic pressurization with liquid medium is used to consolidate the stack, then uniform areal density and reduced ballistic performance variation are achieved, but the device complexity increases
Solution Approach 1:
The patent uses a liquid medium (water or oil) in a closed container to apply isostatic pressure. The liquid is pressurized using a pump or compressor and transmitted through hoses to the container holding the stack. This hydraulic system provides uniform pressure distribution while maintaining relatively simple equipment compared to other isostatic pressurization methods
Solution Approach 2:
The liquid medium automatically transmits pressure isotropically to all surfaces of the stack without requiring complex mechanical pressure distribution mechanisms. The fluid naturally equalizes pressure across the entire contact surface, eliminating the need for sophisticated pressure control systems
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 approach yields moulded articles with higher reliability and better anti-ballistic performance, reducing material costs and achieving more uniform protection across the surface, especially for curved shapes like helmets, with improved V0 values against AK47 bullets.
Implementation Method 1
isostatic pressurizing means are intended to mean pressurizing means which are able to subject a body to equal pressure from every side
Implementation Method 2
the isostatic pressurizing means comprise a container filled with a pressurizing liquid, and means to pressurize the liquid to the desired consolidating pressure level
Implementation Method 3
consolidating is carried out at high to very high pressures, at which level the boiling temperature of water is significantly above 100°C
Implementation Method 4
The matrix material is a thermoplastic material
Data Source
AI summary
The invention relates to a process for the manufacture of a moulded article comprising the steps of forming a stack by stacking (2) or more sheets comprising monolayers of unidirectional fibers and optionally a binder; providing isostatic pressurizing means; placing the stack in the isostatic pressurizing means; and consolidating the stack under temperature and isostatic pressure into a moulded article. The invention furthermore relates to products obtainable with said process, which are very suitable for use in anti-ballistic applications and include e.g. helmets, curved panels, cones and domes.