Aircraft Bogie Stop Energy Absorption
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Solution Overview
Problem
Larger and heavier bogie beams in aircraft landing gear assemblies pose a challenge in absorbing the higher energies associated with over-rotation, leading to potential damage when traditional stop pads are used, as they require increased size and material strength, which limits their effectiveness and longevity.
Innovation Solution
Incorporating an elongate member that is deflectable in bending to absorb energy during over-rotation, which can deform elastically or plastically, and optionally using a stop block to minimize contact with the bogie beam and enhance energy dissipation, allowing for controlled energy absorption and visual indication of high-energy events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional stop pads are used to prevent bogie beam over-rotation, then damage to the bogie beam is avoided, but the stop pads themselves suffer damage and require replacement when energy exceeds certain thresholds
Solution Approach 1:
The patent applies this principle by designing the stop pad as a sacrificial component that can be easily replaced. The stop pad is made from replaceable materials (aluminium or nylon) and is intentionally designed to be the first component to fail under extreme over-rotation conditions, protecting the more expensive bogie beam while accepting that the stop pad itself will need replacement after absorbing excessive energy.
Solution Approach 2:
The patent applies this principle by changing the material parameters of the stop pad. Different materials (aluminium or nylon) are selected based on the expected energy levels, and the stop pad's physical properties are optimized to absorb specific energy ranges while protecting the bogie beam structure.
2Loss of energy
If the size of the stop pad is increased to absorb higher energies from larger bogie beams, then energy absorption capability is improved, but the clearance between the bogie beam and landing gear strut is reduced
Solution Approach 1:
The patent resolves this contradiction by changing the material parameters and physical properties of the stop pad. By selecting materials with appropriate energy absorption characteristics (aluminium or nylon) and optimizing the stop pad's dimensional parameters, the design achieves sufficient energy absorption capability while maintaining the required clearance for bogie beam rotation during normal operations.
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 effectively dissipates energy during over-rotation without causing permanent deformation to the elongate member, reducing the need for replacement and minimizing damage to other components, while providing a visual indication of extreme events and enhancing energy absorption capabilities.
Implementation Method 1
the or each elongate member may be arranged to deform elastically when deflected. In this manner the elongate member absorbs the energy of the bogie beam without suffering permanent deformation
Implementation Method 2
the elongate member may be arranged to deform plastically under deflection. The plastic deformation of the elongate member may absorb more energy than if elastic deformation had occurred. The plastic deformation will also provide a visual indication that over-rotation of the bogie beam has occurred.
Data Source
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AI summary
An aircraft landing gear assembly including a bogie beam, a landing gear strut (1) having a first end arranged to be pivotally coupled to an aircraft and a second end pivotally coupled to the bogie beam (3), and a stop (13) arranged to limit pivotal movement of the bogie beam relative to the landing gear strut, wherein the stop comprises at least one elongate member arranged to be deflectable in bending when the bogie beam reaches a pivotal limit.