Preformed Sheet Separating Film for Ballistic Retention
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Solution Overview
Problem
Existing ballistic-resistant preformed sheets experience significant degradation in ballistic protection against 9 mm bullets when immersed in JP8 fuel or seawater, necessitating a solution for improved retention of ballistic properties in such environments.
Innovation Solution
A preformed sheet comprising unidirectionally oriented high-strength fibers with a tensile strength of at least 1.2 GPa, a binder, and a separating film with a surface tension of less than 35 mN/m and crystallinity between 50 and 90%, which enhances the retention of ballistic properties when soaked in JP8 fuel or seawater.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional preformed sheets with standard separating films are used, then the structure provides basic ballistic protection, but the ballistic protection significantly degrades after immersion in JP8 fuel or seawater
Solution Approach 1:
The patent applies parameter changes by modifying the surface tension of the separating film to be less than 35 mN/m and adjusting the crystallinity to between 50-90%. These parameter changes make the separating film hydrophobic and resistant to JP8 fuel, preventing liquid absorption and maintaining ballistic protection properties after immersion in harsh environments.
Solution Approach 2:
The patent uses composite materials by combining high-strength fibers (such as aramid or UHMWPE) with a specially designed separating film that has specific surface tension and crystallinity characteristics. This composite structure provides both the mechanical strength needed for ballistic protection and the chemical resistance required to maintain performance in liquid environments.
2Strength
If a separating film with higher areal density is used to improve ballistic protection, then protection level increases, but flexibility and weight distribution of the article deteriorates
Solution Approach 1:
The patent employs thin film technology by using a separating film with very low areal density (1-10 g/m²) that provides sufficient ballistic protection through optimized surface tension and crystallinity properties rather than through mass. This thin film approach maintains flexibility and weight efficiency while delivering the required protection level.
Solution Approach 2:
The patent changes the critical parameters of the separating film (surface tension < 35 mN/m and crystallinity 50-90%) to achieve high ballistic protection with minimal areal density. This allows the film to provide enhanced protection without increasing weight or reducing flexibility.
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 provides a higher retention of ballistic resistance after immersion in JP8 fuel and seawater, maintaining a high level of protection against ballistic impacts, with improved flexibility and weight distribution in the resulting articles.
Implementation Method 1
the separating film has surface tension of less than 35 mN/m at the surface faced to the fibrous network
Implementation Method 2
a crystallinity of between 50 and 90%
Data Source
AI summary
The invention relates to a preformed sheet comprising mono-layers from a fibrous network with fibers having a tensile strength of at least about 1.2 GPa and preferably a binder, and a separating film on at least one of its outer surfaces, the separating film having an areal density of between 1 and 10 g/m2 and a surface tension of less than 35 mN/m at the surface faced to the fibrous network and the separating film has a crystallinity of between 50 and 90%.