Multi-Layer Metallic Armour With Non-Bonded Regions for Crack Containment

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Solution Overview

Problem

Forming high-strength multi-layered metallic parts, such as armor steel plates, is challenging due to difficulties in shaping and controlling crack propagation, especially under impact, as conventional methods struggle to effectively dissipate or constrain cracks in layered structures.

Innovation Solution

A method involving the stacking of ductile and high-strength metallic layers with strategically placed diffusion-bond preventing elements, typically thermally insulating materials like boron nitride or yttrium oxide, to create non-bonded regions that help absorb and redirect crack propagation, thereby enhancing the part's ability to capture projectile fragments and dissipate impact energy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If high-strength steel plates are made thick and strong to withstand powerful impacts, then strength and impact resistance are improved, but the formation of such steel plates into desired shapes becomes difficult

Engineering Contradiction:
Improveimpact resistanceVSAvoidformability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The steel plate is divided into multiple layers of alternating high-strength and ductile steel, allowing each layer to contribute different properties to the overall structure

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses composite layered structure combining high-strength steel and ductile steel to achieve both high impact resistance and improved formability

Inventive Principle:
Principle #40Composite materials

2Strength

If conventional high-strength steel plates are used, then strength is maintained, but controlling crack propagation through the part becomes difficult

Engineering Contradiction:
ImprovestrengthVSAvoidcrack control
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The layered structure segments the potential crack propagation path, forcing cracks to navigate through multiple interfaces between layers

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Different layers have different mechanical properties (high-strength vs. ductile) to locally control crack behavior, with ductile layers providing crack deflection and energy absorption

Inventive Principle:
Principle #3Local quality

3Ease of manufacture

If ductile steel layers are used to improve formability, then ease of manufacture is improved, but the overall strength of the steel plate decreases

Engineering Contradiction:
ImproveformabilityVSAvoidstrength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The steel plate is segmented into alternating layers of high-strength and ductile steel, distributing the functional requirements across different layers

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The composite layered structure combines materials with different properties to achieve both formability (from ductile layers) and strength (from high-strength layers)

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 approach allows for the formation of complex-shaped high-strength metallic parts with improved crack containment and energy absorption, effectively managing crack propagation and enhancing the structural integrity under impact conditions.

Implementation Method 1

diffusion bonding the at least two metallic layers to each other at locations other than a location contiguous with the diffusion-bond preventing element

Methodology Applied
Scientific EffectDiffusion bonding: Diffusion Welding

Implementation Method 2

The diffusion-bond preventing element comprises a thermally insulating material

Methodology Applied
Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentEP3782813A1Multi-layered metallic armour with non-bonded regions and method for forming the same
Publication Date: 2021.02.24 THE BOEING CO
  • EP3782813A1 patent drawingFigure 1
  • EP3782813A1 patent drawingFigure 2
  • EP3782813A1 patent drawingFigure 3

AI summary

Disclosed herein is a method of forming a multi-layered metallic part. The method comprises stacking at least two metallic layers, each made of a metallic material having a ductility, to form a multi-layered metallic assembly. The method also comprises interposing a diffusion-bond preventing element directly between adjacent ones of the at least two metallic layers of the multi-layered metallic assembly. The method further comprises diffusion bonding the at least two metallic layers to each other at locations other than a location contiguous with the diffusion-bond preventing element to produce a multi-layered metallic part having a non-bonded region between the at least two metallic layers at the location of the diffusion-bond preventing element.