Segmented Fishplate Assembly for Fuselage Stiffener Alignment
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Solution Overview
Problem
The assembly of aircraft fuselage sections is hindered by alignment issues and high costs due to manufacturing tolerances and the need for numerous tightening operations, especially when using composite materials with omega-shaped stiffeners, which complicates the alignment and fixing of fishplates.
Innovation Solution
An assembly device comprising fishplate pieces with longitudinal sole plates and transverse support heads, along with demountable connecting members that allow for alignment adjustment and mutual clamping, facilitating the transmission of both traction and compression forces, reducing the number of operations required during assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional fishplates are used to connect longitudinal stiffeners of fuselage sections, then structural forces can be transmitted between sections, but alignment difficulties and deformations are required due to manufacturing tolerances
Solution Approach 1:
The fishplate is divided into two separate pieces (first fishplate piece and second fishplate piece) that can be independently positioned and adjusted. Each piece connects to one fuselage section, allowing independent alignment adjustments without requiring the entire fishplate to be deformed to accommodate manufacturing tolerances.
Solution Approach 2:
The demountable connecting member allows the two fishplate pieces to be connected or disconnected. This dynamic connection enables adjustment during assembly - the pieces can be positioned independently to achieve proper alignment, then connected to form the complete fishplate structure for force transmission.
2Strength
If fishplates are fixed to longitudinal stiffeners using conventional bolting techniques, then structural connection is achieved, but a large number of tightening operations are required increasing cost and time
Solution Approach 1:
The demountable connecting member integrates multiple functions into a single component: it connects the two fishplate pieces together, provides alignment adjustment capability, and enables the structural force transmission path. This merging reduces the number of separate tightening operations required compared to conventional multi-bolt fishplate installations.
3Ease of operation
If fishplates are deformed to accommodate alignment issues, then assembly can proceed, but mechanical properties of the fishplates are degraded
Solution Approach 1:
By segmenting the fishplate into two independently adjustable pieces, each piece can be positioned to match the actual location of the longitudinal stiffeners without requiring deformation. This maintains the mechanical properties of the fishplate material while enabling assembly to accommodate manufacturing tolerances.
Data Source
AI summary
A device and method for assembling two aircraft fuselage sections each comprising a skin and longitudinal stiffeners, the device comprising fishplates fishing couples of mutually aligned longitudinal stiffeners belonging respectively to said sections, each fishplate comprising two fishplate pieces each comprising at least one longitudinal sole plate intended to be fixed to a longitudinal stiffener, and a transverse support head, and at least one demountable connecting member able to mutually clamp the respective support heads of said fishplate pieces to allow a transmission of longitudinal forces between these fishplate pieces.