Bypass Turbomachine Panel Fixing With Composite Bushing-Stud Assembly
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Solution Overview
Problem
The existing methods for assembling turbomachine components, such as the annular secondary air stream in bypass turbomachines, face challenges due to additional mass and complexity in manufacturing, particularly with the use of metal panels and bosses, which are heavy and require complex draping and heating processes.
Innovation Solution
The proposed solution involves using a bushing and stud assembly where the bushing is inserted into a hole in the panel, with a stud clamped radially between the panel and the annular wall, allowing for remote fixing of panels made of carbon fiber composite material without the need for bosses, simplifying the manufacturing process and distributing clamping force effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal panels with bosses are used for fixing, then mechanical strength is improved, but additional mass and manufacturing complexity increase
Solution Approach 1:
The invention extracts the boss structure from the panel design and replaces it with a bushing-insert system. The bushing is inserted into a simple hole in the panel, eliminating the need for complex boss structures while maintaining mechanical strength through the bushing's clamping mechanism.
Solution Approach 2:
The invention uses composite material panels (such as carbon fiber reinforced polymers) instead of solid metal panels. These composite panels achieve comparable or superior mechanical strength-to-weight ratio, reducing additional mass while maintaining structural integrity for the fixing application.
2Strength
If metal panels with bosses are used for fixing, then mechanical strength is improved, but manufacturing complexity and draping time increase
Solution Approach 1:
The complex boss structure is extracted and replaced with a simple hole in the panel that receives a bushing. This simplifies the panel manufacturing process, particularly for composite materials where adding boss structures would require complex draping and heating processes.
Solution Approach 2:
The bushing is pre-inserted into the panel hole before the panel is draped and cured. This preliminary action simplifies the manufacturing process by eliminating the need to form complex boss structures during the composite layup process, reducing both manufacturing complexity and draping time.
3Strength
If bosses are added to panels for fixing, then mechanical connection is improved, but clamping force distribution becomes concentrated
Solution Approach 1:
The bushing acts as an intermediary element between the panel and the fixing member (screw or bolt). It distributes the clamping force from the fixing member across the entire periphery of the hole in the panel, preventing stress concentration that would occur with direct screw insertion into the panel material.
Solution Approach 2:
Composite material panels with embedded bushings provide superior stress distribution compared to metal panels with bosses. The bushing interfaces with the composite material over its entire circumference, distributing clamping forces evenly and preventing localized stress concentrations that could lead to panel failure.
Data Source
AI summary
The invention relates to an assembly for a turbomachine with a longitudinal axis comprising a first annular wall (24), panels (38) being arranged around the longitudinal axis (A) and extending radially opposite said first annular wall (24) so as to form a flow surface for a flow of air, each panel (38) being secured to the first annular wall (24) by at least one fixing member (72) passing through an orifice in the panel (38) and secured to the first annular wall (24) by means of a sleeve and a stud forming a spacer.