Aircraft Axle Insert With Elliptical Void for Vibration Decoupling
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Solution Overview
Problem
Conventional aircraft wheel and brake assemblies experience vibrations due to axle bending modes, which can lead to component damage if not properly managed.
Innovation Solution
A damper with a cylindrical outside diameter and an elliptical inner surface is press-fit into the axle, featuring varying thickness to decouple bending modes along different axes, thereby mitigating harmonic vibrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional cylindrical axle assembly is used, then the structure is simple and easy to manufacture, but vibration occurs due to coupled bending modes along different axes
Solution Approach 1:
The patent applies asymmetry by introducing an elliptical void within the cylindrical axle body. This elliptical geometry creates different thicknesses along the major and minor axes, which decouples the bending modes along these two directions. The asymmetric distribution of material (thicker in one direction, thinner in another) allows independent control of vibrational characteristics along perpendicular axes, preventing the coupled vibration modes that occur in symmetric cylindrical structures.
Solution Approach 2:
The patent applies local quality by varying the thickness of the axle body locally through the elliptical void geometry. Rather than uniformly distributing material throughout the cylindrical structure, the design concentrates material in specific regions (thicker sections along the minor axis, thinner sections along the major axis). This localized variation in material distribution allows targeted control of bending stiffness and vibrational properties in different directions, addressing the vibration problem without requiring complete structural redesign.
2Reliability
If the axle body thickness is increased to reduce vibration, then vibration mitigation improves, but the weight of the axle increases
Solution Approach 1:
The elliptical void creates asymmetric thickness distribution that provides enhanced vibration control in critical directions without requiring uniform thickening of the entire axle. The thicker sections are strategically positioned along the minor axis where bending stiffness is needed, while thinner sections along the major axis reduce unnecessary weight. This asymmetric material distribution achieves vibration mitigation with minimized weight penalty compared to uniform thickening.
Solution Approach 2:
The patent applies parameter changes by modifying the geometric parameters of the axle - specifically introducing an elliptical void with defined major and minor axes. This geometric parameter change creates varying local thickness (a structural parameter) that controls bending stiffness and vibrational characteristics. By adjusting the ellipse dimensions relative to the cylindrical outer diameter, the design optimizes the balance between vibration control and weight, achieving sufficient stiffness in critical directions without excessive overall mass.
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 damper effectively reduces or prevents rotor-dynamic vibrations such as whirl modes, ensuring smooth operation and reducing the risk of damage to aircraft components.
Implementation Method 1
The varying thickness is configured to decouple a bending mode along the minor axis from the bending mode along the major axis
Data Source
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AI summary
Systems and methods are disclosed for aircraft wheels and brakes systems for use in, for example, an aircraft. In this regard, a damper (202) for an axle may comprise a solid body (208) defined by a cylindrical outside diameter (OD) surface (204) and an elliptical inner surface (222) configured to be inserted into a bore of the axle, the elliptical inner surface (222) defining a void. The damper (202) may comprise a varying thickness between the OD surface (204) and the elliptical inner surface (222), the varying thickness including a minimum thickness along a major axis of the inner surface (222) and a maximum thickness along a minor axis of the inner surface (222). The varying thickness may help to decouple a bending mode along the minor axis from the bending mode along the major axis.