Layered Sound-Absorbing Material for Low-Frequency Shock Durability
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Solution Overview
Problem
Existing sound absorbing materials formed from non-woven fabrics lack durability against mechanical shocks, particularly in the low-frequency region.
Innovation Solution
A sound absorbing material comprising a protective layer with a flexibility-toughness value of 1 to 75 MPa/µm, a first substrate layer with communication holes, and a second substrate layer, optionally including a resin layer and metal deposition, to enhance both sound absorption and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a sound absorbing material is formed from non-woven fabric to achieve excellent sound absorbing properties in low-frequency region, then sound absorption performance is improved, but durability against mechanical shock deteriorates
Solution Approach 1:
The invention uses a composite structure consisting of a protective layer and a sound absorbing layer. The protective layer (made from materials with high elongation at break ≥50% and tensile strength ≥5 MPa) provides mechanical durability and shock resistance, while the sound absorbing layer (non-woven fabric with specific fiber diameter and basis weight) provides excellent low-frequency sound absorption. This composite structure resolves the contradiction by combining materials with complementary properties.
Solution Approach 2:
The invention applies different material properties to different layers of the sound absorbing material. The protective layer is designed with high elasticity and strength to withstand mechanical shocks, while the sound absorbing layer is optimized with specific fiber characteristics (average fiber diameter 1-10 μm, basis weight 50-200 g/m²) for acoustic performance. Each layer performs its specialized function, resolving the contradiction between durability and sound absorption.
2Strength
If the protective layer is made with high flexibility-toughness value to improve durability, then resistance to mechanical shock is improved, but sound absorption performance may deteriorate
Solution Approach 1:
The invention specifies that the protective layer should have elongation at break ≥50% and tensile strength ≥5 MPa, with flexibility-toughness value in the range of 1-75 MPa/μm. These controlled parameters ensure the protective layer provides sufficient mechanical durability without compromising the sound absorption performance of the underlying sound absorbing layer. The localized optimization of material properties in each layer resolves this contradiction.
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 material achieves excellent sound absorption in the low-frequency region while providing improved durability, making it suitable for vehicle applications.
Implementation Method 1
a sound absorbing material, including: a protective layer; a first substrate layer having a communication hole; and a second substrate layer having a communication hole
Implementation Method 2
a first substrate layer having a communication hole; and a second substrate layer having a communication hole
Data Source
Figure 1
Figure 2
AI summary
Provided is a sound absorbing material, including: a protective layer; a first substrate layer having a communication hole; and a second substrate layer having a communication hole, in this order, in which a flexibility-toughness value of the protective layer, which is represented by Formula (I) described below, is 1 to 75 [MPa/µm]. Flexibility−ToughnessValue=TensileModulusMPaofProtectiveLayerat25°C×ShoreAHardnessofProtectiveLayer/ProtectiveLayerThicknessμm