Fire-Resistant Composite Plies for Aircraft Fuselage Weight Reduction
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Solution Overview
Problem
Current aircraft fuselage structures, particularly in smaller aircraft, face challenges in meeting fire resistance standards without adding weight or increasing manufacturing time, as they are not thermally thick and lack sufficient flammability safety without specialized materials or additional process steps.
Innovation Solution
A multi-ply composite structure with at least eleven plies, including fire-resistant plies made of epoxy-based resin with additives, positioned strategically within the structure to enhance flammability resistance while maintaining fracture toughness, thereby meeting safety standards without additional coatings or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fire-resistant coatings or additional process steps are applied to smaller aircraft fuselages, then fire resistance meets standards, but manufacturing time and complexity increase
Solution Approach 1:
The patent combines fire-resistant plies with structural plies into a single integrated multi-ply composite structure. The fire-resistant plies are positioned between the innermost and outermost plies, merging the fire protection function with the structural skin layers, thereby eliminating separate fire-resistant coatings or additional process steps while meeting fire resistance standards
Solution Approach 2:
The multi-ply composite structure serves multiple functions simultaneously: the innermost and outermost plies provide structural integrity and skin function, while the intermediate fire-resistant plies provide flame propagation protection. This multi-functional integration allows the structure to meet both mechanical loading requirements and fire resistance standards without additional specialized components
2Reliability
If fire-resistant coatings or additional process steps are applied to smaller aircraft fuselages, then fire resistance meets standards, but manufacturing time increases
Solution Approach 1:
The fire-resistant plies are incorporated into the multi-ply composite structure during the initial manufacturing process, before the fuselage is completed. The plies are positioned and cured as part of the standard composite manufacturing sequence, eliminating the need for subsequent fire-resistant coating applications or post-processing steps, thereby maintaining manufacturing speed
3Reliability
If minimum skin gages are increased to provide thermal thickness, then fire resistance improves, but weight increases
Solution Approach 1:
The patent applies fire-resistant plies locally at specific positions within the multi-ply composite structure, specifically between the innermost and outermost plies. This localized application of fire-resistant material provides the necessary flame propagation protection without requiring a uniform increase in skin gage thickness across the entire fuselage, thereby avoiding excessive weight gain
4Reliability
If fire-resistant plies are added to the multi-ply composite structure, then flammability resistance increases, but the number of plies and structural complexity increases
Solution Approach 1:
The fire-resistant plies are merged with the structural plies into a single integrated multi-ply composite structure. By positioning the fire-resistant plies between the innermost and outermost plies and curing them as part of the standard manufacturing process, the design achieves fire protection without creating a separate or additional structural system, thereby managing complexity
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
The solution provides enhanced fire protection and maintains fracture toughness, allowing for thinner structures that meet industry standards, reducing manufacturing time and weight, and enabling design based on mechanical rather than fire resistance limitations.
Implementation Method 1
the first additive increases a flammability resistance of the multi-ply composite structure
Data Source
AI summary
Methods and apparatus to increase fire resistance and fracture toughness of composite structures are described. An example multi-ply composite structure has at least eleven plies including an innermost ply forming a first external surface of the multi-ply composite structure, and an outermost ply forming a second external surface of the multi-ply composite structure, with the second external surface being located opposite the first external surface. The at least eleven plies further include at least one and no more than three fire-resistant plies positioned between the innermost ply and the outermost ply within either an innermost 33% of the at least eleven plies or an outermost 33% of the at least eleven plies. Respective ones of the fire-resistant plies include an epoxy-based resin and a first additive mixed into the epoxy-based resin. The first additive increases a flammability resistance of the multi-ply composite structure.