Composite Stiffener Core Segmentation for Precision Extraction
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Solution Overview
Problem
Existing methods for assembling composite material stiffeners in the aeronautical field face challenges in achieving dimensional precision and efficient core removal, particularly when using reusable cores with high elongation materials, which compromise on precision or are difficult to extract due to varying cavity sections and non-flat panel profiles.
Innovation Solution
A method utilizing a core with a first part having a low coefficient of expansion for geometric precision and a second part with a high coefficient of elongation (>600%) to facilitate extraction, comprising a foam core with a polytetrafluoroethylene coating and an elastomeric strip, allowing for controlled contraction and removal without deforming the stiffener or panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a reusable core made of material with high coefficient of elongation is used to facilitate removal, then the core can be extracted easily, but the dimensional precision is compromised
Solution Approach 1:
The core is divided into two distinct parts: a first part made of material with low coefficient of expansion for dimensional precision, and a second part made of material with high coefficient of elongation for easy extraction. This segmentation allows each part to fulfill its specific function without compromising the other.
Solution Approach 2:
Different parts of the core are made from materials with different physical properties tailored to their specific functions. The first part uses material with low expansion coefficient for precision, while the second part uses material with high elongation coefficient for extraction, creating local quality differentiation within the core structure.
2Adaptability or versatility
If a core made of deformable material is used to adapt to non-flat panel profiles, then the core can be deformed to fit complex geometries, but dimensional precision is not guaranteed
Solution Approach 1:
The core is segmented into two parts with different material properties: the first part provides dimensional precision while the second part provides deformability and adaptation to complex geometries. This segmentation resolves the contradiction between precision and adaptability.
Solution Approach 2:
The core is constructed as a composite structure combining two different materials: one with low coefficient of expansion for precision and another with high coefficient of elongation for deformability. This composite approach allows the core to simultaneously achieve both dimensional precision and geometric adaptation.
3Device complexity
If a single-material core is used to simplify the structure, then the manufacturing process is simpler, but both dimensional precision and easy extraction cannot be achieved simultaneously
Solution Approach 1:
The core is divided into two functional segments: a first part for maintaining dimensional precision during polymerization and a second part for facilitating extraction. This segmentation allows a relatively simple overall structure while achieving both precision and ease of extraction through material differentiation.
4Ease of operation
If the core section is reduced to facilitate extraction, then the core can be removed more easily, but the geometric precision during polymerization is compromised
Solution Approach 1:
The core is segmented into a first part that maintains its section during polymerization to ensure geometric precision, and a second part that is extracted after polymerization to facilitate removal. This temporal and functional segmentation resolves the contradiction between maintaining section for precision and reducing section for extraction.
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
Ensures geometric precision during polymerization and enables efficient extraction of the core without compromising the aerodynamic surface, suitable for non-planar panels and long stiffeners, with a simple implementation process.
Implementation Method 1
a first part (26) having a coefficient of expansion lower than that of the material of the stiffener to ensure the required geometric precision
Implementation Method 2
at least a second part (28) having a coefficient of elongation greater than or equal to 600% to allow the extraction of said part (28) by traction at one of the ends of said second part (28) so as to cause a contraction of its section
Data Source
Figure 1A~1D
Figure 2~3B
AI summary
The aim of the invention is to provide a method for producing a stiffener (12) on one surface (14) of a stiffened element (10), at least one of the two being made of a composite material not completely polymerized, said stiffener (12) including, along a transverse direction, two contact areas (16.1, 16.2) with the surface (14), between which the stiffener (12) and the stiffened element (10) form a cavity (18) emerging into at least one of the ends of the stiffener (12), comprising the use of a core (24) placed in the cavity (18) and removed from said cavity after polymerization; and characterized in that it involves the use of a core (24) with a first portion (26) having a weak expansion coefficient to ensure the required geometric precision and at least one second portion (28) having an elongation coefficient necessary for enabling the extraction of said portion by traction on one of the ends of said second portion such that a contraction of the section thereof is caused.