Thin-Interlayer Composite Structures for Stiffness and Vibration Damping

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Solution Overview

Problem

Stiff structural materials often lack sufficient damping capacity, leading to vibrations that can compromise structural integrity, generate noise, and affect human health and wellbeing.

Innovation Solution

A composite structure comprising alternating layers of a stiff material and a viscoelastic material, where the viscoelastic material has a high loss factor and is confined between stiff layers, enhancing both stiffness and damping capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If stiff structural materials are used to maintain structural integrity, then stiffness is improved, but damping capacity deteriorates

Engineering Contradiction:
ImprovestiffnessVSAvoiddamping capacity
Core Design Contradiction:
StrengthVSLoss of energy

Solution Approach 1:

The patent applies composite materials by combining stiff structural layers with viscoelastic damping layers to create a multi-layer composite structure. This composite design allows the structure to simultaneously exhibit high stiffness from the rigid layers and high damping capacity from the viscoelastic layers, resolving the contradiction between stiffness and damping capacity.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent implements local quality by assigning different material properties to different layers of the composite structure. The stiff layers provide structural integrity and stiffness where needed, while the viscoelastic layers provide damping capacity in specific regions, allowing each layer to perform its specialized function optimally.

Inventive Principle:
Principle #3Local quality

2Reliability

If active treatments are employed to mitigate mechanical vibrations, then vibration control is improved, but energy consumption and additional mass increase

Engineering Contradiction:
Improvevibration controlVSAvoidenergy input
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies self-service by using passive damping materials that automatically dissipate vibration energy without requiring external power sources or active control systems. The viscoelastic layers inherently convert mechanical vibration energy into heat through internal friction, providing self-contained vibration mitigation without energy input or additional actuators.

Inventive Principle:
Principle #25Self-service

3Strength

If materials that are simultaneously stiff and lossy are sought, then both stiffness and damping are improved, but material availability deteriorates

Engineering Contradiction:
ImprovestiffnessVSAvoidmaterial availability
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent resolves material availability constraints by creating composite structures that combine separately available stiff materials (such as metals, ceramics, or rigid polymers) with separately available viscoelastic materials. This approach allows the use of common, readily available materials in combination rather than requiring rare monolithic materials that possess both high stiffness and high loss factors.

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 composite structure achieves a high loss flexural modulus and a high product of loss factor and stiffness-to-density ratio, effectively damping vibrations and reducing noise over a broad range of temperatures and frequencies.

Implementation Method 1

at least one second layer, in particular comprising at least one elastomer and/or at least one component having a glass-transition temperature below an operation temperature

Methodology Applied
Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 2

The composite structure has a loss flexural modulus E'' above 1 GPa when measured at a temperature in the range of -50 °C to 100 °C and at a frequency in the range of 0.007 Hz to 10 Hz

Methodology Applied
Scientific EffectInternal friction damping: Damping

Data Source

PatentEP4570490A1Stiff and damping composite structures with thin interlayers
Publication Date: 2025.06.18 ETH ZURICH
  • EP4570490A1 patent drawingFigure 1a~1b
  • EP4570490A1 patent drawingFigure 2a~2b
  • EP4570490A1 patent drawingFigure 3a~3b

AI summary

A composite structure (1) for a damping structure (100) comprises at least one first layer (2), and at least one second layer (3) preferably comprising at least a first component (4) and optionally at least a second component (5). The first layer (2) and the second layer (3) are arranged above one another with respect to a thickness direction (D) of the composite structure (1). A thickness ratio h1/h2 between a thickness (h1) of the first layer (2) and a thickness (h2) of the second layer (3) along the thickness direction (D) is above 50, preferably above 100. The composite structure (1) has a loss flexural modulus E" above 1 GPa when measured at a temperature in the range of -50 °C to 100 °C and at a frequency in the range of 0.007 Hz to 10 Hz. The composite structure (1) has a product tanδ · (E'/ρ)1/2 above 50 (Pa/kg/m3)1/2 at said temperature and at said frequency.