Bonded Composite Empennage Assembly for Weight Reduction
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Solution Overview
Problem
Current aircraft empennage designs rely heavily on metal components, which add weight, are labor-intensive to assemble, and limit the optimization of flight characteristics, making it challenging to reduce weight, increase fuel efficiency, and meet certification requirements for damage tolerance and aerodynamic stability.
Innovation Solution
A bonded and tailorable composite assembly with a Z-stiffened grid-like understructure and multi-functional composite laminate skins, eliminating the need for metal fasteners and flutter control devices, while optimizing interlaminar fracture toughness and stiffness to enhance structural durability and aerodynamic performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal components and fasteners are used in composite assemblies, then structural strength and certification compliance are improved, but aircraft weight increases and fuel efficiency decreases
Solution Approach 1:
The patent replaces mechanical fastening systems (screws, bolts, rivets) with chemical bonding systems (adhesives). The bonded composite assembly uses adhesive bonds to join composite structures, eliminating the need for metal fasteners and their associated hardware, thereby reducing weight while maintaining structural integrity.
Solution Approach 2:
The patent employs composite materials throughout the assembly, including adhesive bonds themselves as composite joining elements. The assembly consists of multiple composite components (composite structures, composite fasteners, composite adhesives) that work together to provide both strength and weight efficiency, replacing traditional metal-composite hybrid constructions.
2Strength
If metal components are used in stabilizers, then structural integrity is maintained, but manufacturing time and labor intensity increase
Solution Approach 1:
The bonding process replaces complex mechanical assembly operations (drilling, countersinking, inserting, tightening fasteners) with a simpler adhesive application and curing process. This substitution significantly reduces the number of manufacturing steps, labor requirements, and assembly time while maintaining structural integrity through chemical bonds.
Solution Approach 2:
The patent integrates multiple functions into the adhesive bonding process itself, combining joining, sealing, and structural load transfer functions into a single bonding operation. This merging of functions eliminates the need for separate operations that would be required with mechanical fasteners, thereby improving manufacturing efficiency.
3Weight of moving object
If traditional composite designs are used, then weight reduction is achieved, but tailoring flight characteristics and optimizing damage tolerance become difficult
Solution Approach 1:
The patent applies local quality by using composite fasteners and adhesives with specifically tailored properties for different locations and loading conditions within the assembly. The composite materials can be customized with varying fiber orientations, material compositions, and structural configurations to optimize performance for specific flight characteristics and damage tolerance requirements at different assembly locations.
Solution Approach 2:
The patent utilizes parameter changes by modifying the physical and mechanical properties of composite materials (fiber type, resin composition, layer orientation, thickness) to achieve desired flight characteristics. The composite fasteners and bonded joints can be designed with specific stiffness, strength, and fracture toughness parameters to optimize aerodynamic performance and damage tolerance while maintaining weight efficiency.
4Weight of moving object
If composite materials are used throughout the assembly, then weight and fuel consumption are reduced, but manufacturing complexity and certification challenges increase
Solution Approach 1:
The patent employs universal composite bonding techniques and adhesive systems that can be applied across different composite components and assembly configurations. The composite fastener designs and bonding processes are developed to handle multiple loading conditions and joint types, reducing the need for specialized manufacturing procedures for each application and thereby simplifying overall manufacturing complexity.
Solution Approach 2:
The patent addresses manufacturing complexity by optimizing adhesive curing parameters, bonding surface preparations, and composite material selections to achieve reliable bonds under varied manufacturing conditions. The composite fastener and joint designs incorporate parameter optimizations that facilitate manufacturing while ensuring certification compliance for damage tolerance and structural integrity.
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 significantly reduces aircraft weight, improves fuel efficiency, enhances damage tolerance, and optimizes flight characteristics, achieving improved structural fail-safety, aerodynamic stability, and reduced complexity by using all-composite vertical and horizontal stabilizers with tailored interlaminar fracture toughness and stiffness.
Implementation Method 1
a first composite skin and a second composite skin respectively bonded to the composite understructure
Data Source
Figure 1
Figure 2
Figure 2A
AI summary
An all-composite assembly such as a composite laminate aircraft empennage has vertical and horizontal stabilizers with differing sets of interlaminar fracture toughnesses and differing stiffnesses to improve flight characteristics. Composite laminate skins are bonded to unitized and stiffened understructure to reduce weight and improve damage containment.