Metal Foam Shell Structure for Acoustic Lightweight Components

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Solution Overview

Problem

Existing methods for manufacturing components often compromise on weight, cost, or time due to the monolithic nature of raw materials, making it challenging to produce lightweight components that meet performance criteria while being cost-effective.

Innovation Solution

A method involving a metallic foam core formed into a desired configuration using hot or cold forming and machining processes, followed by the application of an external metallic shell via spray processes, with optional resonant chambers and openings for acoustic attenuation, to create a lightweight, rigid structure with tailored structural and acoustic properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If subtractive manufacturing or machining oversized blocks is used to meet performance criteria, then the component meets the required performance, but the component weight increases and material waste increases

Engineering Contradiction:
Improveperformance criteriaVSAvoidcomponent weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The component is divided into two distinct parts: a metallic foam core providing the required structural performance and an external metallic shell providing the final surface finish and dimensional accuracy. This segmentation allows each part to be optimized independently - the foam core can be lightweight while the shell provides the necessary performance characteristics.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses a composite structure combining metallic foam and metallic shell materials. This composite approach allows the component to achieve the desired performance criteria through the synergistic combination of materials rather than relying on a single monolithic material, reducing overall weight while meeting performance requirements.

Inventive Principle:
Principle #40Composite materials

2Reliability

If subtractive manufacturing or machining oversized blocks is used to meet performance criteria, then the component meets the required performance, but the manufacturing time and cost increase

Engineering Contradiction:
Improveperformance criteriaVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The metallic foam core is pre-formed into a configuration that is slightly smaller than the final dimensions, and the external metallic shell is applied beforehand. This preliminary action reduces the amount of subsequent machining required, significantly decreasing manufacturing time while still achieving the required performance criteria.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

By segmenting the manufacturing process into separate steps for forming the foam core and applying the shell, the invention allows for more efficient production methods compared to machining a single monolithic block, thereby improving productivity and reducing manufacturing time.

Inventive Principle:
Principle #1Segmentation

3Strength

If a monolithic material structure is used, then the component achieves required strength, but the component weight and material usage increase

Engineering Contradiction:
Improvecomponent strengthVSAvoidcomponent weight
Core Design Contradiction:
StrengthVSWeight of moving object

Solution Approach 1:

The composite structure of metallic foam core and metallic shell provides the required strength through the combined properties of the two materials. The foam core offers structural integrity while the shell provides additional strength and surface durability, achieving the required strength with reduced weight compared to a monolithic structure.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The external metallic shell is applied to provide localized quality enhancement at the component's exterior surfaces, providing the necessary strength and surface properties where needed, while the interior foam core provides lightweight structural support. This local differentiation of material properties optimizes the strength-to-weight ratio.

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

This approach results in low-cost, lightweight components with improved structural rigidity and acoustic attenuation capabilities, reducing material waste and manufacturing time, and enabling complex shapes that were previously difficult to produce.

Implementation Method 1

the sheet of metallic foam is formed to the desired configuration by a hot or cold forming process wherein the sheet of metallic foam is placed in a die

Methodology Applied
Scientific EffectHot forming:

Implementation Method 2

the sheet of metallic foam is formed to the desired configuration by a hot or cold forming process

Methodology Applied
Scientific EffectCold forming: Cold-forming

Implementation Method 3

the external metallic shell is applied via a spray application process, wherein the spray application process is selected from the group comprising: flame spray application process; plasma spray application process; and cold-spray application process

Methodology Applied
Scientific EffectFlame spray application: Plasma Spray

Implementation Method 4

the external metallic shell is applied via a spray application process, wherein the spray application process is selected from the group comprising: flame spray application process; plasma spray application process; and cold-spray application process

Methodology Applied
Scientific EffectPlasma spray: Plasma Spray

Implementation Method 5

attenuating the component to a frequency by forming a plurality of openings in the external metallic shell

Methodology Applied
Scientific EffectAcoustic attenuation: Acoustic Absorption

Implementation Method 6

forming a plurality of resonant chambers in the metallic foam core prior to the application of the external metallic shell, wherein at least some of the plurality of openings are in fluid communication with a respective one of the plurality of resonant chambers

Methodology Applied
Scientific EffectResonance: Resonance

Data Source

PatentEP3231598B1Method of making light weight component with acoustic attenuation
Publication Date: 2021.08.18 RTX CORP
  • EP3231598B1 patent drawingFigure 1~2
  • EP3231598B1 patent drawingFigure 3~4
  • EP3231598B1 patent drawingFigure 5~7

AI summary

A method of making a light weight component (28) is provided. The method including the steps of: forming a metallic foam core (11) into a desired configuration; applying an external metallic shell (20) to an exterior surface of the metallic foam core after it has been formed into the desired configuration; and attenuating the component to a desired frequency by forming a plurality of openings (34) in the external metallic shell.