Aircraft Nose Composite Frames for Bird Strike Elastic Deflection
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Solution Overview
Problem
Current aircraft nose sections are made heavier and stiffer to withstand bird strikes, which increases weight and costs, and can shatter or delaminate upon impact, posing challenges for repair and compliance with stringent FAA regulations.
Innovation Solution
The use of hoop-shaped composite frames with a substructure that includes a cap with longitudinal and transverse fibers, designed to elastically deflect under impact loads, reducing the risk of damage and allowing the structure to return to its original shape without permanent deformation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If frames and stiffeners are made heavier and stiffer to withstand bird strike impact loads, then impact resistance is improved, but aircraft weight increases
Solution Approach 1:
The patent changes the material parameters by using composite materials with specific fiber orientations (longitudinal and transverse plies) and material properties (strain characteristics). The longitudinal fibers are made of material that strains substantially more than transverse fibers, creating an anisotropic composite structure that provides impact resistance while maintaining lower weight compared to traditional homogeneous heavy structures.
Solution Approach 2:
The patent employs composite materials consisting of multiple plies with different fiber orientations and material properties. The cap includes plies of longitudinal fibers and plies of transverse fibers, where longitudinal fibers have substantially higher strain capacity. This composite construction allows the structure to absorb impact energy through controlled deformation of the longitudinal fibers while the transverse fibers provide structural stability, achieving impact resistance without excessive weight.
2Strength
If frames are made heavier and stiffer to withstand bird strikes, then impact resistance is improved, but repair costs and downtime increase due to shattering and delamination
Solution Approach 1:
The patent modifies the material parameters by selecting longitudinal fiber materials with substantially higher strain capacity than transverse fibers. This parameter change allows the cap to undergo large elastic deformations during bird strike impact without exceeding the material's elastic limit, preventing permanent damage, delamination, and shattering that would otherwise require expensive repairs.
Solution Approach 2:
The patent converts the potentially harmful impact energy from bird strikes into beneficial elastic deformation of the cap. The longitudinal fibers, with their high strain capacity, allow the cap to deflect and absorb impact energy elastically, transforming the harmful shock load into a controlled deformation that dissipates energy without causing structural damage, thereby eliminating repair needs.
3Weight of moving object
If current composite structures are used, then weight is reduced compared to traditional structures, but they shatter and delaminate under high energy impact loads
Solution Approach 1:
The patent uses a specialized composite material structure with two distinct fiber types: longitudinal fibers with substantially higher strain capacity and transverse fibers with lower strain capacity. This composite configuration allows the structure to maintain low weight while achieving high impact durability. The longitudinal fibers absorb impact energy through large elastic deformations, preventing shattering and delamination that occur in conventional composite structures.
Solution Approach 2:
The patent applies local quality by creating different fiber compositions in different regions of the cap. The cap includes plies of longitudinal fibers oriented to resist impact loads with high strain capacity, and plies of transverse fibers providing structural stability. This localized differentiation of material properties allows the structure to be lightweight overall while having specific high-durability zones where impact loads are applied.
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 design reduces the reaction load during bird strikes by 1-3 times, minimizing weight and repair costs, while maintaining impact resistance, and can adapt to more stringent FAA regulations with further weight savings.
Implementation Method 1
The longitudinal fibers are made of a material that strains substantially more than the transverse fibers and fibers in the skin
Data Source
AI summary
An aircraft comprises a forward-facing aircraft section including composite aircraft skin and a substructure for the skin. The substructure includes a plurality of hoop-shaped composite frames. The frames are designed to deflect elastically under bird impact loads.