Perforated Sound Absorbing Boxes for Noise Barriers
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Solution Overview
Problem
Noise barriers made of materials like autoclaved aerated concrete and normal concrete have poor sound absorption characteristics, requiring a large number of sound absorbing boxes to achieve high sound absorption levels, leading to increased costs and complexity in production, assembly, and maintenance.
Innovation Solution
A noise structure comprising sound absorbing boxes with perforated front and rear walls, filled with sound absorbing materials, strategically spaced to create Helmholtz resonator effects and optimized with a fibrous structure and stepped configuration, enhancing acoustic absorption through porosity, cavity resonance, and reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a large number of sound absorbing boxes are applied to increase sound absorption properties to A4 level, then sound absorption performance is improved, but production costs, assembly complexity, and maintenance difficulty increase
Solution Approach 1:
The patent applies porous sound absorbing materials within the boxes to enhance sound absorption efficiency. The porous structure allows sound waves to penetrate and be absorbed effectively, achieving high sound absorption performance (A4 level) with fewer boxes compared to non-porous materials.
Solution Approach 2:
The patent optimizes parameters such as box spacing, perforation patterns on front and rear walls, and sound absorbing material properties to maximize sound absorption efficiency. By carefully adjusting these parameters, the system achieves high performance with a reduced number of boxes, resolving the contradiction between performance and complexity.
2Reliability
If sound absorbing boxes are applied to concrete barriers, then sound absorption characteristics are improved, but production and assembly costs increase
Solution Approach 1:
The noise barrier system is segmented into modular sound absorbing boxes that can be independently manufactured and then assembled on the concrete barrier. This segmentation allows for standardized production of boxes with optimized sound absorption features, reducing overall production costs while maintaining high sound absorption characteristics.
Solution Approach 2:
The use of porous sound absorbing materials enables effective sound absorption with simpler box designs, reducing manufacturing complexity and costs while achieving the required sound absorption characteristics when applied to concrete barriers.
3Reliability
If densely packed sound absorbing boxes are used to achieve high sound absorption, then acoustic performance is improved, but maintenance difficulty increases
Solution Approach 1:
The modular box design allows individual boxes to be accessed, removed, and replaced independently. This segmentation significantly eases maintenance operations compared to a densely packed continuous structure, as damaged boxes can be quickly swapped without affecting the entire barrier system.
Solution Approach 2:
Instead of requiring complete coverage with densely packed boxes, the patent uses optimally spaced boxes with specific perforation patterns and sound absorbing material configurations. This partial action approach achieves high acoustic performance while maintaining accessibility and ease of maintenance.
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 solution significantly improves sound absorption capabilities with a reduced number of boxes, lowering production, assembly, and maintenance costs, while achieving high-performance sound absorption across various acoustic classifications.
Implementation Method 1
a strong additional acoustic absorption can be obtained, due both to porosity (the porosity of the filling material) and cavity resonance
Implementation Method 2
filled with a proper sound absorbing material
Implementation Method 3
a strong additional acoustic absorption can be obtained, due both to porosity (the porosity of the filling material) and cavity resonance, caused by the very chamber resulting between the box and the surface of the barrier
Implementation Method 4
between two boxes placed and spaced apart one under the other, an Helmholtz resonator effect is also obtained because of the chambers behind the rear walls and the gap between the two boxes, the latter representing the neck of the resonator
Data Source
Figure 1~3
Figure 2
Figure 4~5
AI summary
A noise structure comprising a barrier made of a generally sound redirecting material defining a surface of the barrier, and a plurality of sound absorbing boxes connected to this surface, each box comprising a rear wall (4) and an extensively perforated front wall (2), said walls defining a longitudinal channel (5) at least partially occupied by a filling (6) made of a sound absorbing material, in which the rear wall (4) is a substantially flat plane wall assembled parallel to and spaced apart from the surface of the barrier and is in its turn extensively perforated.