Multi-layer transparent armor laminate for multi-hit ballistic protection

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Solution Overview

Problem

Current glass-based transparent armor systems provide single-hit protection against armor-piercing projectiles but are limited in multi-hit scenarios and are costly compared to ceramic-based systems, which are not available in larger sizes and volumes.

Innovation Solution

A multi-layer transparent laminate comprising an outer soda-lime or borosilicate glass strike face layer, multiple glass-ceramic layers, an internal soda-lime or borosilicate glass layer, and a polymer spall layer, all bound together by polymer interlayers, achieving multi-hit protection at reduced thickness and areal density.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional glass-based transparent armor systems are used, then single-hit protection against armor-piercing projectiles is achieved, but multi-hit protection capability is limited and cost is high

Engineering Contradiction:
Improvemulti-hit protection capabilityVSAvoidcost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The armor system is divided into multiple discrete layers including glass-ceramic layers, glass layers, and polymer interlayers. Each layer serves specific functions: glass-ceramic layers provide hardness and projectile defeat, glass layers provide toughness and spall resistance, and polymer layers provide bonding and energy absorption. This segmented multi-layer structure enables multi-hit protection by distributing impact forces across multiple layers, allowing the system to withstand multiple projectile impacts while maintaining cost-effectiveness through optimized material selection and thickness distribution.

Inventive Principle:
Principle #1Segmentation

2Strength

If transparent ceramic materials are used, then superior ballistic performance is achieved, but cost per square inch increases more than 5 times and availability in larger sizes is limited

Engineering Contradiction:
Improveballistic performanceVSAvoidcost and availability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The invention employs a composite material system combining glass-ceramic layers, glass layers, and polymer interlayers. The glass-ceramic layers (such as lithium-alumino-silicate or lithium-disilicate) provide high hardness and projectile defeat capability comparable to monolithic transparent ceramics. The glass layers add toughness and spall resistance. The polymer interlayers provide bonding and energy absorption. This composite approach achieves superior ballistic performance similar to transparent ceramic systems while maintaining cost-effectiveness and availability in larger sizes, as each component material can be manufactured separately and laminated together.

Inventive Principle:
Principle #40Composite materials

3Reliability

If thicker composite armor is used to stop projectiles, then protection capability is improved, but weight and residual vision are compromised

Engineering Contradiction:
Improveprotection capabilityVSAvoidareal density
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

Different layers in the composite armor structure have locally optimized properties tailored to specific functions. The glass-ceramic layers are positioned to provide localized hardness and projectile tip defeat. The glass layers are positioned to provide localized toughness and spall resistance. The polymer interlayers are positioned to provide localized bonding and energy absorption. This local quality optimization allows each layer to be as thin as possible while performing its specific function, reducing overall areal density and weight while maintaining protection capability. The optimized thickness distribution also minimizes optical distortion, preserving residual vision.

Inventive Principle:
Principle #3Local quality

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 laminate provides effective protection against 0.30 cal. AP-M2 projectiles at speeds up to 2750 fps with an areal density of less than 30 psf, offering improved residual vision and cost-effectiveness compared to traditional glass-based systems.

Implementation Method 1

a plurality of layers bound together by polymer interlayers

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

impact resistant transparent laminates

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 3

engage various defeat mechanisms, including projectile fragmentation and mass removal by projectile erosion

Methodology Applied
Scientific EffectStress distribution:

Data Source

PatentEP2244988B1Lightweight transparent armor window
Publication Date: 2019.12.25 ORAN SAFETY GLASS INC
  • EP2244988B1 patent drawingFigure 1
  • EP2244988B1 patent drawingFigure 2
  • EP2244988B1 patent drawingFigure 3~4

AI summary

The invention relates to a lightweight transparent armor laminate comprising layers of borosilicate glass, layers of transparent glass-ceramics and a polymer spall layer of polycarbonate and/or polymethyl methacrylate. The layers are bound by polyurethane and/or polyvinylbutyral interlayer films.