Composite Preform Connection to Tube via Split Plies
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Solution Overview
Problem
Existing methods for attaching structural elements to composite material tubes, such as those used in aircraft landing gear, face challenges in ensuring strong and continuous fiber continuity, leading to cumbersome and heavy assemblies with inadequate resistance.
Innovation Solution
A method involving preforms made from cut blanks of fiber plates, where the plies are separated at the connection area to allow for continuous fiber distribution and large surface contact, enabling efficient stress transmission and assembly with resin impregnation and polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If thick reinforcement pieces with large surface area are used to ensure good resistance to the connection, then the connection strength is improved, but the assembly becomes heavier and more cumbersome
Solution Approach 1:
The structural element is divided into two separate composite pieces that are joined together. The first piece includes fibers continuous between the structure and the tube, while the second piece is joined to the first. This segmentation allows for optimized fiber paths and eliminates the need for thick reinforcement pieces, reducing weight while maintaining connection strength.
Solution Approach 2:
The invention uses composite materials with continuous fibers throughout the connection zone. The fibers are arranged to provide strength exactly where needed, eliminating the need for additional thick reinforcement pieces. The composite structure achieves both light weight and high strength through proper fiber orientation and material distribution.
2Ease of manufacture
If fibers of the structural element end at the right of the tube, then the structural element can be formed, but no continuity is ensured in the connection
Solution Approach 1:
The first composite piece is manufactured with fibers that extend continuously from the structural element through the connection zone to the tube, establishing fiber continuity before the second piece is added. This preliminary action ensures that the critical fiber paths are established during the forming process, maintaining both manufacturability and reliability.
Solution Approach 2:
The fiber reinforcement is made continuous by having the first composite piece contain fibers that extend uninterrupted from the structural element through the connection zone to the tube. This continuity of fiber action ensures load transfer without interruption, maintaining reliability while allowing the structural element to be properly formed.
3Ease of manufacture
If glued reinforcing pieces are used to connect the structural element to the tube, then the connection can be achieved, but the connection is more cumbersome and difficult to achieve
Solution Approach 1:
The invention merges the structural element and the connection into a single integrated composite structure. The first composite piece forms both the structural element and the connection zone with continuous fibers, eliminating the need for separate reinforcing pieces and glue applications. This integration simplifies the manufacturing process and reduces connection complexity.
Solution Approach 2:
The connection is achieved through composite material construction where fibers provide the primary load transfer mechanism rather than relying on glued reinforcing pieces. The composite structure inherently provides both the connection and the structural function, reducing the number of components and simplifying the assembly process.
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 approach ensures excellent mechanical strength and continuity in the connection between structural elements and tubes, reducing weight and complexity while maintaining economic viability.
Implementation Method 1
a preform comprising two blanks (40, 60, 100) which are cut from a fabric (13) composed of several superposed plies (A, B, C, D), the two blanks (40, 60, 100) being superimposed and sewn at the level of the structure portions (51, 53, 81, 83, 101, 103), being left free at the level of the connecting portion (54, 64, 104)
Implementation Method 2
The assembly thus produced is then impregnated with resin, for example by a known transfer process such as resin injection under pressure or vacuum infiltration. The resin is then hardened by polymerization.
Data Source
Figure 1~2
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Figure 10~13
AI summary
The invention relates to a method for making a structural part comprising a tubular portion (30) from which a structural member made of a composite material protrudes, said method comprising the steps of: shaping a planar preform (59) including a stack of several fibre plies placed one on top of the other so that the plies are secured together on at least a portion of the preform intended to form a structure portion, and so that the plies are separable so as to form two opposite leaflets (54) on at least another portion of the preform intended to form a portion for connecting to the tube; inserting a tube (30) between the leaflets of the connection portion so that the leaflets at least partially surround said tube; connecting the tube to the preform so that the tube forms the tubular portion and so that the preform forms the structural member of the structural part.