Composite Leaf Spring Mounting for Delamination-Resistant Landing Gear
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Solution Overview
Problem
Aircraft landing gear assemblies using fibre composite leaf springs face challenges such as stress concentrations, delamination, and component failure due to post-processing methods like drilling, which can lead to performance loss and increased manufacturing complexity.
Innovation Solution
The design incorporates a fibre composite leaf spring with varying numbers of composite layers and a mounting assembly that engages the spring without post-processing, preventing stress concentrations and delamination, and simplifying the manufacturing process by avoiding bolted end fittings and ensuring the spring bends perpendicularly to the composite layers for enhanced strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If post-processing methods like drilling are used to couple the leaf spring to landing gear elements, then the leaf spring can be securely attached, but stress concentrations and delamination occur leading to component failure
Solution Approach 1:
The patent extracts the harmful post-processing steps (drilling, bolting) from the attachment process. Instead of using traditional drilling and bolting methods that cause stress concentrations and delamination, the invention uses a mounting assembly that couples to the leaf spring through its side surfaces, eliminating the need for holes or fasteners that would compromise the composite structure's integrity.
Solution Approach 2:
The mounting assembly serves as an intermediary component between the leaf spring and the landing gear elements. Rather than directly attaching to the composite material (which would require damaging post-processing), the mounting assembly provides an intermediate coupling mechanism that distributes loads without creating stress concentrations or delamination in the composite layers.
2Ease of manufacture
If the leaf spring is made with uniform composite layers throughout, then manufacturing is simpler, but stress concentrations occur at critical regions leading to delamination and failure
Solution Approach 1:
The patent applies local quality by varying the number of composite layers in different regions of the leaf spring. The first region (mounting region) has a first number of composite layers optimized for attachment, while the second region (span region) has a second number of composite layers optimized for structural performance. This regional differentiation allows each area to have the specific properties needed for its function, preventing stress concentrations at critical interfaces.
3Strength
If bolted end fittings are used to attach the leaf spring, then secure coupling is achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the mounting assembly with the landing gear elements, integrating the attachment function directly into the existing structure. Rather than adding separate bolted end fittings as additional components, the mounting assembly is formed as part of the landing gear element itself, eliminating the need for separate fasteners and reducing manufacturing steps while maintaining secure coupling.
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 configuration reduces the risk of component failure, improves the spring's properties, and simplifies the manufacturing process, resulting in a robust and cost-effective landing gear assembly with reduced stress concentrations and delamination risks.
Implementation Method 1
the leaf spring being arranged to bend when the first element moves from the first condition to the second condition
Data Source
AI summary
An aircraft landing gear assembly having a first landing gear element movably coupled relative to a second landing gear element to move between a first condition and a second condition. The aircraft landing gear assembly further comprises a fibre composite leaf spring formed from a plurality of composite layers and arranged between the first and second elements, the leaf spring being arranged to bend when the first element moves from the first condition to the second condition. The fibre composite leaf spring comprises a first region and a second region, wherein the number of composite layers in the first region is greater than the number of composite layers in the second region. The landing gear further comprises a mounting assembly arranged to engage the first region of the leaf spring to couple the leaf spring to the first landing gear element.