Progressive Stiffness Sandwich Panel for Structural-Acoustic Trade-off

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Solution Overview

Problem

Traditional sheet structures face a dilemma in achieving both mechanical strength and high acoustic attenuation, often requiring a trade-off between mechanical stiffness and sound wave transmission loss.

Innovation Solution

A sandwich structure with an architected core secured between two facesheets, featuring a compliant layer with a low modulus for elastic shear waves at low static loads, which stiffens at high loads to provide structural strength and stiffness, while maintaining significant acoustic attenuation through a micro-truss material and compliant layers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If traditional sheet structures use high stiffness materials to achieve mechanical strength, then mechanical strength is improved, but acoustic attenuation deteriorates

Engineering Contradiction:
Improvemechanical strengthVSAvoidacoustic attenuation
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The sheet structure is segmented into multiple layers including rigid facesheets and compliant core layers with alternating stiffness properties. This segmentation allows different layers to specialize: rigid layers provide structural strength while compliant layers provide acoustic attenuation, resolving the contradiction between mechanical strength and acoustic performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention uses composite materials combining rigid and compliant properties in a single structure. The multilayer sandwich construction with varying stiffness characteristics creates a composite material system that simultaneously achieves high mechanical strength and high acoustic transmission loss, eliminating the need to choose between the two opposing requirements.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If traditional sandwich structures use compliant materials to achieve high acoustic transmission loss, then acoustic attenuation is improved, but mechanical stiffness deteriorates

Engineering Contradiction:
Improveacoustic transmission lossVSAvoidmechanical stiffness
Core Design Contradiction:
Object-affected harmful factorsVSStrength

Solution Approach 1:

The structure is divided into functional segments where compliant core layers handle acoustic attenuation while rigid facesheets handle mechanical loading. This segmentation allows the compliant materials to be used extensively for acoustic performance without compromising overall structural stiffness, as the rigid facesheets provide the necessary mechanical support.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The composite sandwich structure combines compliant core materials with rigid facesheet materials to create a hybrid system. The compliant core provides high acoustic transmission loss while the rigid facesheets maintain mechanical stiffness, allowing the structure to achieve both high acoustic attenuation and adequate mechanical strength simultaneously.

Inventive Principle:
Principle #40Composite materials

3Device complexity

If a single material is used for both structural and acoustic functions, then device complexity is reduced, but performance in both domains cannot be optimized

Engineering Contradiction:
Improvestructural simplicityVSAvoidacoustic transmission loss
Core Design Contradiction:
Device complexityVSObject-affected harmful factors

Solution Approach 1:

The multilayer sandwich structure serves multiple functions simultaneously: rigid layers provide structural support while compliant layers provide acoustic attenuation. This multi-functionality allows a single integrated structure to perform both structural and acoustic roles, optimizing performance in both domains without requiring separate components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The composite multilayer construction allows different materials to be assigned to different functional requirements within a single integrated structure. Rigid materials are used where structural strength is needed, while compliant materials are used where acoustic attenuation is needed, creating a unified structure that optimizes both functions simultaneously.

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 structure achieves both structural strength and high acoustic attenuation by segregating the stiffness requirements for noise reduction and structural deflections, maintaining performance in both domains without significant compromise.

Implementation Method 1

The compliant layer has a low modulus, resulting in a low speed for elastic shear waves in the sandwich structure, at low static loads

Methodology Applied
Scientific EffectElastic shear wave propagation: Elasticity

Implementation Method 2

At high static loads the compliant material stiffens and allows the sandwich structure to exhibit significant structural strength and stiffness

Methodology Applied
Scientific EffectProgressive stiffness: Viscoelasticity

Implementation Method 3

the sandwich structure exhibiting both mechanical strength and high attenuation of acoustic waves

Methodology Applied
Scientific EffectAcoustic attenuation: Acoustic Absorption

Data Source

PatentEP3180185B1Progressive stiffness structural-acoustic sandwich panel
Publication Date: 2020.10.14 HRL LAB
  • EP3180185B1 patent drawingFigure 1A~1B
  • EP3180185B1 patent drawingFigure 2A~2B
  • EP3180185B1 patent drawingFigure 3

AI summary

A sandwich material having both structural strength and significant acoustic attenuation. In one embodiment, a sandwich is composed of an architected core secured between two facesheets, with a compliant layer forming the connection between the core and the facesheets. The compliant core has a low modulus, resulting in a low speed for elastic shear waves in the sandwich, at low static loads. At high static loads the compliant material stiffens and allows the sandwich to exhibit significant structural strength.