Aircraft Acoustic Panel Repair with Aligned Patch Perforations

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Solution Overview

Problem

Existing repair methods for acoustic panels in aircraft nacelles diminish the acoustic properties due to misalignment of perforations between replacement patches and the existing top skin, often resulting from voids or delamination during manufacturing or service.

Innovation Solution

A method involving coupling a fiberglass ply to the acoustic panel, creating dimples within perforations, and aligning these dimples with perforations in a replacement patch to ensure accurate alignment and bonding, thereby maintaining the acoustic properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If existing repair techniques use overlapping patches without aligned perforations, then the repair process is simple and quick, but the acoustic properties are diminished

Engineering Contradiction:
Improveease of repairVSAvoidacoustic properties
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by creating dimples in the fiberglass ply before bonding the patch. These dimples are formed at the locations where perforations will eventually be drilled, serving as precise guides for perforation alignment. This preliminary positioning ensures that when perforations are created in both the existing top skin and the replacement patch, they align perfectly across the overlap area, thereby maintaining acoustic properties while using a straightforward repair process

Inventive Principle:
Principle #10Preliminary action

2Productivity

If perforations are drilled in replacement patch without alignment guidance, then the repair process is fast, but perforation alignment with existing top skin is poor

Engineering Contradiction:
Improverepair speedVSAvoidperforation alignment
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent introduces an intermediary element - the fiberglass ply with pre-formed dimples - that mediates between the repair process and the final perforation alignment. The dimples act as physical guides or templates that indicate exactly where perforations should be drilled in the replacement patch. This intermediary structure ensures precise alignment with the existing top skin perforations without requiring complex measurement or alignment procedures, thus maintaining both speed and precision

Inventive Principle:
Principle #24Intermediary (Mediator)

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 method effectively repairs acoustic panels by ensuring aligned perforations, thus preserving and restoring the acoustic properties of the panels without compromising their performance.

Implementation Method 1

The acoustic panel and the fiberglass ply may be placed in a bag, and a vacuum may be created within the bag

Methodology Applied
Scientific EffectVacuum: Vacuum

Implementation Method 2

creating dimples in the fiberglass ply using a differential pressure

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 3

creating dimples in the fiberglass ply using a differential pressure, wherein the dimples are located within first perforations in the acoustic panel

Methodology Applied
Scientific EffectPressure differential: Pressure Gradient

Implementation Method 4

The replacement patch may be bonded to the acoustic panel

Methodology Applied
Scientific EffectBonding: Adhesive

Data Source

PatentEP4230390B1Acoustic panel repair with retention of acoustic properties
Publication Date: 2025.01.01 ROHR INC
  • EP4230390B1 patent drawingFigure 1
  • EP4230390B1 patent drawingFigure 2
  • EP4230390B1 patent drawingFigure 3

AI summary

An acoustic panel (300) for an aircraft nacelle may comprise a perforated first skin, a second skin, and a core sandwiched between them. A damaged portion of the perforated first skin may be removed. A fiberglass ply (510) may be coupled to the acoustic panel. A pressure differential may cause the fiberglass ply to form dimples (515) within the perforations of the first skin. The fiberglass ply may be used as a template to drill holes in a replacement patch (400).