Auxetic Foam Tyre Cavity Sound Absorption
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional foam materials used in tyres for sound absorption experience a decrease in sound absorption capacity as the tyre's speed of rotation increases due to compression, leading to increased resonance noise.
Innovation Solution
A tyre with an auxetic foam material housed in its inner cavity, characterized by a Poisson's ratio of less than zero, is used to maintain sound absorption effectiveness even at higher speeds, where the foam material is preferably housed on the impermeable layer and occupies a specific volume and thickness within the cavity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional foam material is used for sound absorption in the tyre inner cavity, then sound absorption is achieved at low speeds, but sound absorption capacity decreases as tyre speed increases due to compression
Solution Approach 1:
The patent changes the fundamental material parameter from conventional foam to auxetic foam, which has a negative Poisson's ratio. This parameter change causes the material to expand in the direction of applied compression rather than contract, thereby maintaining sound absorption capacity across varying tyre speeds and compression conditions
Solution Approach 2:
The invention uses auxetic foam as a composite material solution that combines the sound absorption properties of foam with the unique mechanical properties of auxetic materials. This composite approach creates a material that simultaneously provides acoustic damping and resistance to compression-induced performance degradation
2Force
If foam material is compressed during tyre operation, then the material undergoes compression action, but porosity decreases resulting in dropped sound absorption capability
Solution Approach 1:
The patent fundamentally changes the material's mechanical response parameter by using auxetic foam with negative Poisson's ratio. When compressed, this material expands in lateral directions and maintains or increases its porosity, unlike conventional foam which contracts and loses porosity. This parameter change ensures sound absorption capability is maintained under compression forces during tyre operation
Solution Approach 2:
The invention converts the harmful effect of compression (which normally reduces porosity and sound absorption) into a beneficial effect. The auxetic foam's unique property causes it to expand when compressed, thereby maintaining open pore structures that continue to absorb sound effectively even under the compression forces experienced during high-speed tyre operation
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 auxetic foam material's sound absorption capabilities increase with compression, effectively reducing resonance noise across varying tyre speeds, unlike traditional materials which see a drop in performance.
Implementation Method 1
a foam material housed inside said cavity and suitable to provide sound absorption
Implementation Method 2
the use of a porous material applied to the air-impermeable layer of the tyre's inner cavity in a manner such that the resonance cavity sound is absorbed by the porous material
Implementation Method 3
said foam material is an auxetic material... said foam material has a Poisson's ratio of less than zero
Implementation Method 4
said foam material has a Poisson's ratio of less than zero
Data Source
AI summary
A tyre comprising an impermeable layer suitable to ensure the sealing under pressure of the air contained in the inner cavity of the carcass and a foam material with auxetic characteristics, which is housed inside the cavity and suitable to provide sound absorption.