Monolithic Composite Fuselage Structure Manufacturing
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Solution Overview
Problem
The existing method for manufacturing box-shaped monolithic structures in composite materials for aircraft fuselages is inefficient, costly, and requires improvements in surface finishing quality, particularly inside the structure.
Innovation Solution
The method involves using support tools with shape memory polymers and elastic fibers, which allow direct lamination of prepreg profiled bars and eliminate the need for preforming tools, enabling uniform pressure application and extraction after curing, resulting in improved surface smoothness and reduced manufacturing complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional preforming tools and support tools are used, then the structure can be manufactured with defined geometry, but the manufacturing process becomes complex and costly with multiple dressing operations
Solution Approach 1:
The patent merges the preforming tool and support tool into a single integrated tool that performs both functions simultaneously. The tool includes a body with external surfaces that directly define the geometry of spars while also serving as the support structure during manufacturing, eliminating the need for separate preforming and support operations.
Solution Approach 2:
The manufacturing tool is designed with multi-functionality, serving as both the preforming device that shapes the prepreg material and the support tool that maintains structural integrity during curing. The tool's body simultaneously provides geometric definition and structural support functions.
2Manufacturing precision
If multiple dressing operations are performed on support tools, then extraction quality is improved, but manufacturing time and costs increase
Solution Approach 1:
The patent extracts the complex multi-step dressing operations from the manufacturing process by using a tool design that requires no dressing operations. The tool's geometry is inherently designed to enable direct extraction of spars without requiring separating agents, films, or fabric layers.
Solution Approach 2:
The tool design eliminates the need for expensive and time-consuming dressing materials such as separating agents, tubular bags, ventilation fabrics, and separator films. The tool surface is designed to allow direct extraction without these auxiliary materials.
3Strength
If rigid solid support tools are used, then structural support is provided during curing, but surface finishing quality inside the structure is insufficient
Solution Approach 1:
The tool body is designed with different surface qualities in different regions. The external surfaces that contact the prepreg material have finished surfaces with controlled roughness to ensure high-quality surface finishing inside the manufactured structure, while maintaining overall rigid structural support capability.
4Reliability
If traditional manufacturing methods are used, then structural integrity is achieved, but the process is costly and time-consuming
Solution Approach 1:
The tool is designed in advance with built-in separation features and extraction-friendly geometry, eliminating the need for time-consuming post-manufacturing extraction operations. The tool configuration is preliminarily optimized to enable direct extraction of cured spars without damage.
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 simplifies the manufacturing process, reduces costs, and achieves high finishing quality with average surface roughness of less than 2 microns, ensuring precise and stable connections within the aircraft fuselage.
Implementation Method 1
support tools with shape memory polymers and elastic fibers, which allow direct lamination of prepreg profiled bars and eliminate the need for preforming tools
Implementation Method 2
support tools with shape memory polymers and elastic fibers, which allow direct lamination of prepreg profiled bars
Data Source
AI summary
The invention relates to a method for manufacturing a box-shaped monolithic structure with a cavity by curing a fiber-reinforced prepreg material. The method comprises using two or more elongated and internally hollow support tools which have a complementary form to that of the cavities to be manufactured, and a composition based on reinforcement material and polymer suitable to allow the passage from a rigid state to a flexible elastomeric state and vice versa in response to heating/cooling down. In the rigid state, the support tools allow the direct lamination of the prepreg material on their external walls and are configured to set the flexible elastomeric state at a temperature lower than the curing temperature and higher than 50° C. During the curing operation, the curing pressure is applied both outside the structure being formed and inside the support tools, whose walls have become flexible, to push on the prepreg material to be cured.