Acoustic Panel Perforation via Laser Ablation
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Solution Overview
Problem
Existing double degree of freedom (DDoF) acoustic panels face high manufacturing costs and weak bonding strength due to complex septum configurations and adhesive issues, limiting their effectiveness in attenuating noise across broader frequency bands.
Innovation Solution
A method involving the use of a laser to form perforations in the top skin and septum, with tailored focal lengths and powers to ensure strong bonding and efficient noise attenuation, while minimizing damage to the septum and other components, and fluid coupling of cavities to enhance noise absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If discrete septum pieces are individually bonded in each cavity, then the septum can be positioned to divide cavities, but the manufacturing costs become very high due to difficulty of shaping and positioning
Solution Approach 1:
The patent merges multiple discrete septum pieces into a single continuous septum layer that spans across multiple cavities. This continuous septum is formed by extruding material through a die that creates the desired shape, eliminating the need to individually shape and position separate septum pieces in each cavity, thereby significantly reducing manufacturing complexity and cost.
Solution Approach 2:
The continuous septum layer serves multiple functions simultaneously: it divides multiple cavities, provides structural support across the entire panel, and maintains acoustic performance. This universal component replaces multiple specialized discrete pieces, simplifying the manufacturing process while achieving the same acoustic objectives.
2Ease of manufacture
If a continuous septum layer is used, then manufacturing is simplified, but bonding strength between core structure walls and septum becomes weak because walls overlap pores or perforations
Solution Approach 1:
The patent applies local quality by creating non-perforated regions in the septum layer where core structure walls are positioned. These localized solid regions provide strong bonding areas, while the surrounding perforated regions maintain acoustic functionality. This spatial variation in septum density optimizes both bonding strength and acoustic performance.
Solution Approach 2:
The core structure walls are positioned in alignment with the non-perforated regions of the septum layer before the bonding process. This preliminary alignment ensures that the adhesive has full contact with solid septum material, maximizing bonding strength before any potential wicking issues can occur.
3Strength
If adhesive bonding is used to connect core structures to septum, then bonding can be achieved, but adhesive may wick onto the septum and close pores or perforations
Solution Approach 1:
The patent extracts the bonding function from the perforated regions of the septum and concentrates it in the non-perforated regions. By removing pores from the bonding areas, the adhesive cannot wick into the septum material, eliminating the harmful effect of pore closure while maintaining strong bonding in the solid regions.
Solution Approach 2:
The non-perforated regions act as an intermediary zone between the core structure walls and the perforated acoustic regions. This intermediary structure provides a dedicated bonding interface that prevents adhesive from reaching and clogging the acoustic pores, thus mediating between structural and acoustic requirements.
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
This approach reduces manufacturing costs and strengthens the bond between core structures and the septum, improving the acoustic panel's ability to attenuate noise across broader frequency bands with enhanced bonding and noise absorption efficiency.
Implementation Method 1
A method involving the use of a laser to form perforations in the top skin and septum
Data Source
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AI summary
In a method for manufacturing an acoustic panel (20), a core structure (25) is provided between and bonded to a top skin (22) and a septum (23). A plurality of perforations (32) are formed in the top skin (22) using an energy beam device (52). A plurality of perforations (34) are formed in the septum (23) through the top skin holes (32) using the energy beam device (56). A plurality of cavities (44) in the core structure (25) fluidly couple at least some of the perforations (32) in the top skin (22) with at least some of the perforations (34) in the septum (23).