Superplastic Formed Rib Assembly for Engine Fairing
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Solution Overview
Problem
The existing manufacturing techniques for internal transverse stiffening ribs in lower rear aerodynamic fairings for aircraft engine attachment devices struggle to produce thin ribs with precise tolerances, as machining methods are limited by stress constraints and superplastic forming results in imprecise tolerances.
Innovation Solution
A method involving superplastic forming to produce rib preforms, followed by precise assembly of half-parts using a common industry positioning tool, allowing for thin rib production with precise dimensions by adjusting their relative position before joining, and using a TAV6 titanium alloy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If machining is used to manufacture thin ribs, then precise tolerances can be achieved, but the rib thickness is limited by machining stress constraints and cannot be made sufficiently thin
Solution Approach 1:
The invention changes the manufacturing method from machining to superplastic forming, which allows the rib thickness parameter to be reduced below the machining stress limit while still achieving the required dimensional precision through a subsequent positioning and assembly process
Solution Approach 2:
The rib is divided into two half-parts that are formed separately by superplastic forming and then positioned and assembled together using positioning tools, enabling each half to be formed as a thin structure without machining stress constraints while maintaining overall precision
2Length of moving object
If superplastic forming is used to manufacture ribs, then thin rib structures can be produced, but the manufacturing precision and tolerances become imprecise
Solution Approach 1:
The rib is segmented into two half-parts formed by superplastic forming, which can be produced as thin structures. The segmentation allows for subsequent positioning and assembly using positioning tools that restore dimensional precision in the final assembled rib
Solution Approach 2:
Positioning tools are introduced as intermediaries during the assembly process to precisely position the two half-parts relative to each other, thereby compensating for the imprecise tolerances inherent in superplastic forming and achieving the required final dimensional accuracy
3Strength
If traditional manufacturing methods are used, then structural strength can be ensured, but the rib mass increases
Solution Approach 1:
The invention changes from machining to superplastic forming, enabling the rib thickness to be reduced to below 2mm while maintaining structural strength through the forming process and subsequent assembly, thereby reducing rib mass
Solution Approach 2:
The rib is constructed as a composite structure formed by assembling two half-parts, which allows for optimized material distribution and reduced mass while maintaining the required mechanical strength through proper positioning and joining
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
Enables the production of thin, precisely dimensioned internal transverse stiffening ribs that meet the mechanical requirements while maintaining low mass, addressing the limitations of both machining and superplastic forming methods.
Implementation Method 1
The existing manufacturing techniques for internal transverse stiffening ribs in lower rear aerodynamic fairings for aircraft engine attachment devices struggle to produce thin ribs with precise tolerances, as machining methods are limited by stress constraints and superplastic forming results in imprecise tolerances
Data Source
Figure 1
Figure 2~3
Figure 4a~4b
AI summary
The present invention relates to a method for manufacturing a transverse internal stiffening rib (46) for aerodynamic fairing of an engine mounting device, comprising: - the production of a rib preform by superplastic forming having an overall quadrilateral contour, as well as a central opening (52) through this preform; - the cutting of the preform along two parallel straight segments (56, 60), diagonally opposed, generating the separation into two half-parts (46a', 46a") of the rib preform; and - splicing the two half-parts of the rib preform (46a', 46a") by bolting.