Microperforated Acoustic Panel with Cellular Core for Low-Frequency Absorption
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Solution Overview
Problem
Conventional acoustic panels with honeycomb core structures and sound absorptive materials face challenges in effectively absorbing low-frequency sound while maintaining low weight and safety, as they often require thick, heavy, and costly materials, and are ineffective for frequencies below 1000 Hz.
Innovation Solution
A microperforated acoustic panel design featuring a first sheet with closely spaced microperforations and a second sheet with more widely spaced microperforations, sandwiched between two cellular cores, which tailors the open area to absorb specific acoustic frequencies by varying the diameter and spacing of microperforations, and optionally includes an airgap to enhance low-frequency absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional sound absorptive materials (polymer foams, rock-wool) are used to improve sound absorption, then sound absorption characteristics are improved, but weight increases and fire safety deteriorates
Solution Approach 1:
The invention extracts and removes the heavy fibrous sound absorptive materials (rock-wool, polymer foams) from the panel structure, replacing them with a lightweight cellular core structure that provides sound absorption through its geometric configuration rather than material density
Solution Approach 2:
The invention employs a cellular core structure with controlled porosity and cell geometry to provide sound absorption functionality, utilizing the air-filled cellular spaces rather than solid fibrous materials to achieve the desired acoustic performance with reduced weight
2Reliability
If conventional sound absorptive materials are used to absorb low-frequency sound, then low-frequency absorption is improved, but panel thickness and weight increase
Solution Approach 1:
The invention changes the geometric parameters of the cellular core structure, specifically the cell depth and cell size, to tune the sound absorption characteristics for low-frequency performance. By optimizing these parameters, the panel achieves effective low-frequency absorption without requiring excessive thickness
Solution Approach 2:
The invention transitions from relying on material thickness for absorption to utilizing the three-dimensional cellular geometry and microperforation patterns to achieve absorption across different frequency ranges, effectively adding dimensional complexity to the structure rather than simply increasing linear thickness
3Weight of stationary object
If microperforated panel absorbers are used to provide low-frequency absorption without fibrous materials, then weight is reduced and fire safety is improved, but absorption is limited to a narrow waveband
Solution Approach 1:
The invention segments the sound absorption function across multiple components: the microperforated facing sheet handles high-frequency absorption, while the cellular core structure with optimized cell depths handles low-frequency absorption. This segmentation allows the panel to achieve broadband absorption without relying on a single mechanism
Solution Approach 2:
The invention creates a composite structure combining the microperforated sheet (providing high-frequency absorption through resonance) with the cellular core structure (providing low-frequency absorption through its geometric configuration). This composite approach integrates multiple absorption mechanisms to achieve broadband performance while maintaining lightweight construction
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 panel achieves improved broadband sound absorption, effectively absorbing both high and low frequencies without the need for fibrous materials, offering a lightweight, cost-effective, and potentially non-combustible solution for various applications.
Implementation Method 1
an acoustic panel for absorbing sound, the acoustic panel including at least a first sheet having spaced microperforations, a second sheet having microperforations more widely spaced than the microperforations of the first sheet
Implementation Method 2
a first cellular core sandwiched between the first sheet and the second sheet
Data Source
AI summary
An acoustic panel (for absorbing sound) includes a first sheet with spaced microperforations, a second sheet with microperforations more widely spaced than the microperforations of the first sheet, and a first cellular core sandwiched between the first sheet and the second sheet. The panel can be spaced from a surface, such as a wall. A second cellular core can be provided between the second sheet and a third sheet. The third sheet is preferably solid without microperforations but can have microperforations. Noise Reduction Coefficient (NRC) can be 0.8.