Curable Composite Bush with Corrugations for Aircraft Joints
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Solution Overview
Problem
The assembly of aircraft structures is hindered by the need for precise machining of solid bushings, which is time-consuming and costly, and can result in incorrect fastener seating due to irregular hole dimensions, leading to increased redundancy, weight, and maintenance costs, as well as potential damage to composite materials.
Innovation Solution
A curable composite bushing made from a matrix material impregnated with reinforcement fibers, featuring corrugations that allow for compressibility and adaptability to fit multiple hole dimensions without machining, and a tooling system for easy installation, using either thermoplastic or thermoset materials with continuous fibers for enhanced mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solid bushings are machined to order to fit irregular hole dimensions, then manufacturing precision is improved, but assembly time increases and production costs rise
Solution Approach 1:
The bushing is designed with a compressible structure featuring corrugations that allow it to deform elastically under compression. This parameter change from rigid to compressible enables the bushing to adapt to varying hole dimensions without requiring precise machining for each specific application, thereby reducing assembly time while maintaining fit accuracy.
Solution Approach 2:
The bushing transitions from a static, rigid component to a dynamic, compressible one. The corrugated structure allows the bushing to dynamically adjust its shape and size during installation, accommodating irregular hole dimensions through elastic deformation rather than requiring custom machining for each case.
2Reliability
If solid bushings are used to correct hole irregularities, then fastener seating is improved, but the risk of damage to composite materials during installation increases
Solution Approach 1:
The bushing employs a flexible corrugated shell structure that can deform elastically during installation. This flexibility allows the bushing to be compressed and inserted into holes with irregular dimensions without requiring forceful hammering or excessive installation forces that could damage composite materials, while still achieving proper fastener seating.
Solution Approach 2:
The bushing is constructed from composite materials that combine the benefits of structural integrity with controlled flexibility. This composite construction allows the bushing to maintain sufficient strength for fastener support while exhibiting enough compliance to be installed without damaging the surrounding composite structure.
3Adaptability or versatility
If various sizes of solid bushings are kept in inventory, then adaptability to different hole dimensions is improved, but storage space and asset management complexity increase
Solution Approach 1:
The compressible bushing design serves as a universal component that can accommodate multiple hole dimensions through its elastic deformation capability. Instead of requiring separate bushings for different size requirements, a single bushing design can be compressed to fit various hole sizes, eliminating the need for maintaining multiple sizes in inventory and simplifying asset management.
4Strength
If traditional solid bushings are installed with interference fit, then structural strength is improved, but the assembly process becomes more costly and time-consuming
Solution Approach 1:
The bushing design changes the installation parameter from requiring high interference fit forces to utilizing controlled elastic compression. The corrugated structure allows the bushing to be compressed into place with lower forces, maintaining sufficient structural strength for joint integrity while significantly improving assembly efficiency by eliminating time-consuming machining and complex installation procedures.
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 solution reduces assembly time and costs, ensures full load transfer by the fasteners, allows for a lighter structural design with fewer parts, and is easier to store and handle, while being more tolerant of irregularities in hole dimensions, thus reducing the need for rework and scrap.
Implementation Method 1
the corrugations improve the compressibility of the bush in a direction substantially collinear to a longitudinal axis of the bush
Implementation Method 2
a generally hollow cylindrical body formed from a matrix material impregnated with a reinforcement material substantially composed of fibers
Data Source
AI summary
A curable composite bush for an aircraft joint comprising a generally hollow cylindrical body formed from a matrix material impregnated with a reinforcement material substantially composed of fibers, the fibers being oriented in a generally circumferential direction about a longitudinal axis of the bush. The body may define a plurality of corrugations extending between an inner and an outer diameter of the bush to improve the compressibility of the bush in a direction substantially collinear to a longitudinal axis of the bush.