Thermoplastic Aircraft Tip Structure with Integrated Lightning Protection
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Solution Overview
Problem
Conventional aircraft tip structures are complex, time-consuming, and costly to manufacture due to their multi-component assembly and use of metallic materials, which also result in a weight penalty.
Innovation Solution
A tip structure manufactured in a single-stage injection molding process using a thermoplastic composite material with integrated reinforcing structures and metallic conductivity for lightning strike resistance, eliminating the need for separate assembly and reducing weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional multi-component metallic tip structures are used, then structural strength and rigidity are achieved, but manufacturing complexity and production time increase significantly
Solution Approach 1:
The patent combines multiple separate components (tip fairing, ribs, spars, and metallic reinforcement) into a single integrated thermoplastic molded structure. The tip structure is manufactured as one piece with internal reinforcing elements already positioned and integrated, eliminating the need for separate assembly operations and reducing manufacturing complexity while maintaining structural integrity.
Solution Approach 2:
The patent uses composite thermoplastic materials with embedded metallic reinforcement (such as steel wires or meshes) to achieve the required structural strength. The composite material provides both the aerodynamic fairing function and the structural reinforcement in a single integrated component, resolving the contradiction between strength requirements and manufacturing complexity.
2Reliability
If conventional multi-component tip structures are assembled from separate parts, then structural integrity is maintained, but production time and manufacturing costs increase
Solution Approach 1:
The patent integrates the tip fairing and internal reinforcing structure into a single molded component manufactured in one operation. The thermoplastic material is injected or molded around pre-positioned metallic reinforcement elements, creating a unified structure that maintains structural integrity while eliminating multiple assembly steps, thereby significantly reducing production time.
Solution Approach 2:
The metallic reinforcement elements are pre-positioned within the mold cavity before the thermoplastic material is injected. This preliminary action ensures proper positioning and integration of the reinforcement structure, allowing the final molded part to achieve structural integrity without requiring subsequent assembly operations, thus improving productivity.
3Strength
If metallic materials are used for tip structures, then structural strength and lightning strike resistance are achieved, but weight increases
Solution Approach 1:
The patent employs composite construction by embedding metallic reinforcement elements (such as steel wires or meshes) within a thermoplastic matrix. This composite structure provides the necessary lightning strike resistance and structural strength while the thermoplastic material contributes to weight reduction compared to fully metallic constructions. The metallic reinforcement is used only where necessary for electrical conductivity and structural support.
Solution Approach 2:
The patent applies metallic reinforcement selectively in specific locations within the tip structure where lightning strike resistance and structural strength are most critical. The thermoplastic material is used in areas where full metallic construction is not necessary, optimizing the weight-strength balance by providing metallic properties only where required rather than throughout the entire structure.
4Strength
If complex multi-rib structures are manufactured using RTM process with composite materials, then structural requirements are met, but manufacturing time and cost increase
Solution Approach 1:
The patent changes the manufacturing process parameters by using thermoplastic materials instead of traditional thermosetting composites. Thermoplastic materials can be processed using injection molding or similar high-speed processes that are faster and more cost-effective than RTM for complex geometries. The material properties of thermoplastics (meltable and re-flowable) enable more efficient manufacturing while maintaining the ability to produce complex multi-rib structures with integrated reinforcement.
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 enhances productivity, reduces costs, and meets structural and aerodynamic requirements while minimizing weight and assembly complexity.
Implementation Method 1
The tip structure comprises a tip shell or fairing that is obtained by injection molding process using a thermoplastic composite material
Implementation Method 2
a metallic material suitable to withstand lighting strike events, that is to provide electrical conductivity without compromising the integrity of the structure, is applied on the outer surface of the tip shell
Implementation Method 3
injecting into a mold a thermoplastic composite material having fibers, particles or nano-reinforcements dispersed therein, to obtain a molded tip shell
Data Source
AI summary
A tip structure for an aircraft airfoil, such as a control surface (ailerons, flaps, elevators, rudders, etc) and/or a lifting surface (wings, HTP's, VTP's) is a unitary body and includes a tip shell and a metallic material on the outer surface of the tip shell suitable to withstand a lighting strike. The tip shell has been obtained by a single-stage injection molding process using a thermoplastic composite material having fibers dispersed therein, and the metallic material has been integrally formed with the tip shell.