Acoustic Panel Patch Drilling for Perforation-Aligned Nacelle Repair

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Solution Overview

Problem

Existing repair techniques for acoustic panels in aircraft nacelles diminish the acoustic properties due to misaligned perforations between replacement patches and the existing top skin, leading to suboptimal noise attenuation.

Innovation Solution

A method involving scanning the perforation pattern of a damaged acoustic panel, using a computer numeric control machine to drill matching perforations in a replacement patch, and bonding it to the panel with precise alignment, ensuring the perforations are perpendicular and aligned with the original panel.

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:
Improverepair process simplicityVSAvoidacoustic properties
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent applies preliminary action by scanning and storing the perforation pattern of the damaged top skin before removing it. This stored pattern is then used to guide the drilling of replacement perforations, ensuring they match the original acoustic design. The preliminary capture of the pattern information enables precise replication during the repair process.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements copying by creating a digital replica of the original perforation pattern through scanning. This copied pattern is stored in a computer and used to guide the CNC drilling process, effectively replicating the original acoustic panel's perforation configuration in the replacement patch, thereby preserving acoustic properties.

Inventive Principle:
Principle #26Copying

2Device complexity

If perforations are manually drilled in replacement patches, then the equipment required is simple, but the alignment precision with existing top skin is poor

Engineering Contradiction:
Improveequipment simplicityVSAvoidperforation alignment
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent replaces manual mechanical drilling with a computer numeric control (CNC) drilling system. The CNC machine is controlled by digital data representing the stored perforation pattern, substituting human-operated mechanical drilling with an automated, computer-controlled system that achieves superior alignment precision while maintaining reasonable equipment complexity.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of repair

If the top skin is removed and replaced with a patch, then damaged sections can be repaired, but the acoustic properties are compromised due to misaligned perforations

Engineering Contradiction:
Improvedamage repairabilityVSAvoidnoise attenuation capability
Core Design Contradiction:
Ease of repairVSReliability

Solution Approach 1:

The patent implements feedback by scanning the damaged top skin to capture its perforation pattern, storing this information digitally, and then using it to control the drilling of replacement perforations. This feedback loop ensures that the repair process replicates the original acoustic design, maintaining noise attenuation capability while enabling damage repair.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4056355B1Machine vision acoustic panel repair with retention of acoustic properties
Publication Date: 2024.05.08 ROHR INC
  • EP4056355B1 patent drawingFigure 1
  • EP4056355B1 patent drawingFigure 2
  • EP4056355B1 patent drawingFigure 3

AI summary

An acoustic panel (300) for an aircraft nacelle may comprise a perforated first skin (220), a second skin (230), and a core (210) sandwiched between them. A camera system (330) may scan a perforation pattern of a damaged portion (311) of the perforated first skin. The damaged portion of the perforated first skin may be removed. A replacement patch (400) may be formed. A CNC machine (450) may drill the replacement patch according to the perforation pattern. The perforations in the replacement patch may be aligned with perforations in the perforated first skin.