Transparent Armor Using Refractive Index Matching

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Solution Overview

Problem

Laminated transparent armor is prone to lateral tearing or bursting upon impact, offering limited multi-hit protection, is heavy due to thickness requirements, and has limited design flexibility and transparency issues, making it unsuitable for applications like military vehicles.

Innovation Solution

A composite armor comprising transparent pellets embedded in a visco-elastic polymer matrix with matching refractive indices, forming a monolithic structure for enhanced transparency and mechanical properties, including a backing layer of the same polymer class for improved integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If laminated transparent armour is made thicker to provide adequate antiballistic protection, then protection level is improved, but weight increases

Engineering Contradiction:
Improveantiballistic protection levelVSAvoidarmour weight
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

The invention uses a composite structure consisting of a hard transparent material layer (providing scratch resistance and initial impact protection) bonded to a transparent resilient material layer (absorbing impact energy). This composite approach achieves adequate antiballistic protection with reduced thickness compared to conventional single-layer laminated armour, thereby reducing weight while maintaining protection level.

Inventive Principle:
Principle #40Composite materials

2Reliability

If laminated transparent armour is made thicker to provide adequate antiballistic protection, then protection level is improved, but thickness increases

Engineering Contradiction:
Improveantiballistic protection levelVSAvoidarmour thickness
Core Design Contradiction:
ReliabilityVSLength of stationary object

Solution Approach 1:

The composite structure of hard transparent material and resilient transparent material layers provides adequate antiballistic protection with optimized thickness. The hard layer handles surface impacts and scratching while the resilient layer absorbs penetration energy, achieving protection requirements with thinner overall construction than conventional laminated armour.

Inventive Principle:
Principle #40Composite materials

3Ease of manufacture

If conventional laminated armour is used, then manufacturing is simpler, but transparency is reduced

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidarmour transparency
Core Design Contradiction:
Ease of manufactureVSIllumination intensity

Solution Approach 1:

The invention optimizes the refractive index of the transparent materials used in both the hard and resilient layers to match each other and to glass, minimizing optical distortion and maximizing transparency. This parameter optimization allows the armour to maintain high transparency (luminous transmission 85% or more) while using the simpler composite layer structure.

Inventive Principle:
Principle #35Parameter changes

4Device complexity

If conventional laminated armour is used, then structural simplicity is maintained, but multi-hit protection is limited

Engineering Contradiction:
Improvearmour structure complexityVSAvoidmulti-hit protection
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The composite structure with hard transparent material layer and resilient transparent material layer provides superior multi-hit protection. The resilient layer absorbs and dissipates impact energy from multiple projectiles, preventing lateral tearing and bursting that plagues conventional laminated armour. This maintains structural simplicity while dramatically improving reliability against multiple impacts.

Inventive Principle:
Principle #40Composite materials

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 lightweight, thin, and transparent armor with improved multi-hit protection, maintaining high transparency and allowing for complex shapes, as demonstrated by successful ballistic tests and manufacturing examples.

Implementation Method 1

the ratio of the refractive index of the pellets to the refractive index of the polymeric material is in the range of 0.9:1 to 1.1:1

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP1916495B1Transparent armour
Publication Date: 2013.12.04 NEDERLANDSE ORG VOOR TOEGEPAST NATUURWETENSCHAPPELIJK ONDERZOEK TNO
  • EP1916495B1 patent drawingFigure 1A~1C
  • EP1916495B1 patent drawingFigure 1D~1F
  • EP1916495B1 patent drawingFigure 2~3

AI summary

The invention relates to a transparent armour suitable for providing ballistic protection from an impacting projectile, the armour comprising a plurality of transparent pellets (1) arranged in a layer and embedded in a transparent matrix (2), wherein the ratio of the refractive index of the pellets (1) to the refractive index of the matrix (2) is in the range of 0.9:1 to 1.1:1.