Machinable Composite Layer for Precision Assembly
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Solution Overview
Problem
Molded composite materials face challenges in achieving precise dimensions and tolerances similar to machined metal parts, and they are difficult to machine without compromising structural integrity, especially when used in structural applications like aircraft components.
Innovation Solution
A composite material with a machinable layer made of random discontinuous fiber composite is used, allowing for machining without penetrating the fibrous structure, enabling precise dimensions and adaptability during assembly, while maintaining structural integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If molded composite parts are used to connect aircraft structures, then high strength-to-weight ratio is achieved, but manufacturing precision and dimensional tolerances are insufficient compared to machined metal parts
Solution Approach 1:
The invention uses a composite material consisting of a fibrous structure (unidirectional fibers) combined with a machinable layer (random discontinuous fiber composite). This composite structure allows the part to achieve the high strength-to-weight ratio of traditional composite materials while the machinable layer enables precise dimensional control and tight tolerances, resolving the contradiction between strength and manufacturing precision.
2Manufacturing precision
If composite parts are machined to achieve precise dimensions, then manufacturing precision improves, but structural integrity is compromised due to fiber disruption and delamination
Solution Approach 1:
The invention divides the composite part into two distinct segments: a fibrous structure that provides structural integrity and strength, and a machinable layer that provides precise dimensional control. By segmenting the material functions, the fibrous structure remains intact and undamaged during machining, while the machinable layer absorbs the machining operations, preventing fiber disruption and delamination that would compromise structural integrity.
Solution Approach 2:
The machinable layer acts as an intermediary between the external machining process and the internal fibrous structure. This intermediate layer allows machining operations to be performed without directly affecting the load-bearing fibrous structure, thereby maintaining structural integrity while achieving precise dimensions through the removal or adjustment of the machinable layer.
3Device complexity
If a single mold is used to produce multiple parts with varying geometries, then device complexity is reduced, but manufacturing precision decreases due to the inability to accommodate geometric variations
Solution Approach 1:
The invention introduces dynamic adjustability through the machinable layer, which allows the geometry of the part to be modified after molding. This dynamic capability enables a single mold to produce multiple parts with varying geometries by machining the machinable layer to the required final dimensions, thereby reducing the number of molds needed while maintaining manufacturing precision through controlled machining operations.
Data Source
AI summary
An assembly that includes a first part composed of a fibrous structure that includes fibers and a cured resin matrix. The fibrous structure has at least one surface and a layer that is located on the surface. The layer includes a discontinuous fiber composite that is composed of randomly oriented short fibers and a cured resin matrix wherein the layer has been machined to provide a machined surface. The assembly also includes a second part that is attached to the first part. The second part includes at least one surface that fits against the machined surface on the first part.