Ballistic-resistant article with thin separating film
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Solution Overview
Problem
Existing ballistic-resistant articles require a high weight to achieve a certain protection level, and vice versa, making them unsuitable for applications where low weight and high protection are simultaneously needed, such as in personal protection and vehicle armor.
Innovation Solution
A preformed sheet comprising at least two mono-layers with unidirectionally oriented fibers of high tensile strength and modulus, rotated at specific angles, and a separating film with an areal density between 1 and 5 g/m², which allows for improved energy absorption and flexibility, enabling lighter yet more protective ballistic-resistant articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If traditional separating films with higher areal density are used, then the structural stability and handling ease of the preformed sheet is improved, but the weight of the ballistic-resistant article increases and the specific energy absorption decreases
Solution Approach 1:
The patent applies a thin separating film with areal density of 1-5 g/m² (preferably 2-4 g/m²) instead of traditional heavier films. This thin film is made from biaxially stretched polyolefin with high tensile strength (≥200 MPa) and modulus (≥1000 MPa), enabling it to provide sufficient structural stability and handling ease while minimizing weight addition to the ballistic-resistant article
Solution Approach 2:
The patent changes the areal density parameter of the separating film from traditional higher values to a specific range of 1-5 g/m². This parameter change is compensated by optimizing the film's material properties (biaxial stretching, high tensile strength, high modulus) to maintain the necessary structural stability without the weight penalty of traditional films
2Reliability
If more layers are added to increase protection level, then the ballistic protection performance is improved, but the weight of the article increases proportionally
Solution Approach 1:
The ultralight separating film enables the use of multiple thin layers to achieve the desired protection level without proportionally increasing weight. The film's high strength-to-weight ratio allows it to contribute to ballistic performance while maintaining low areal density, improving the specific energy absorption of the multi-layer structure
Solution Approach 2:
The patent creates a composite structure combining high-strength fibers (aramid, UHMWPE, or PBO with tensile strength ≥1.2 GPa) with the thin separating film. This composite approach allows the layers to work synergistically, where the fiber layers provide primary ballistic resistance and the thin film layers provide structural stability with minimal weight, achieving higher protection at lower overall weight
3Stability of the object's composition
If opaque or translucent separating films are used, then the structural integrity is maintained, but the quality control and visual inspection capability deteriorates
Solution Approach 1:
The patent specifies that the separating film should be transparent with high light transmission, enabling visual inspection and quality control while maintaining structural integrity. The thin film structure (1-5 g/m²) combined with transparency allows operators to visually detect defects, misalignments, or quality issues during production without compromising the film's mechanical stability
Solution Approach 2:
The patent emphasizes transparency as a key property of the separating film, which can be considered an optical property similar to color changes. The transparent nature of the film (as opposed to opaque or translucent) directly improves detectability and visual inspection capability during quality control while the film's material properties maintain structural integrity
Data Source
AI summary
The invention relates to a preformed sheet comprising at least two mono-layers, each mono-layer containing a fibrous network with fibers having a tensile strength of at least about 1.2 GPa and a tensile modulus of at least 40 GPa and a binder, and a separating film on at least one of its outer surfaces, characterized in that the separating film has an areal density of between 1 and 5 g/m2. With this preformed sheet assemblies and articles offering a substantially higher ballistic protection level at a certain weight can be obtained. The invention further relates to an assembly of at least two such sheets and to a flexible ballistic-resistant article comprising said assembly.