Aircraft Spring Assembly Vibration Damping
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Solution Overview
Problem
Aircraft spring assemblies, such as those in landing gear, face premature failure due to operational vibrations from airflow and other sources, which can be exacerbated by down lock spring failures, affecting the reliability and lifespan of these components.
Innovation Solution
Incorporating a helical spring with a hollow core and a polymer damping member, where the damping member is narrower than the spring diameter, allowing it to move freely and absorb vibrations, thereby increasing the lifespan without interfering with the spring's operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If a polymer damping member is confined within the spring core, then vibration damping increases and lifespan extends, but the spring operation may be affected if the damping member interferes with coil movement
Solution Approach 1:
The polymer damping member is nested within the hollow core of the helical spring, placing the damping component inside the spring structure without interfering with the spring's external operation. This nested arrangement allows the damping member to absorb vibrations while the spring maintains its extension and retraction functionality.
Solution Approach 2:
The damping member is positioned locally within the hollow core of the spring, providing vibration damping specifically in the high-frequency vibration regime without affecting the low-frequency operational movement of the spring. This localized damping approach resolves the contradiction by targeting only the harmful vibrations while preserving operational reliability.
2Object-affected harmful factors
If the damping member has a free fit within the spring, then it can damp vibrations effectively, but it may not provide sufficient damping if too loose
Solution Approach 1:
The damping member's diameter is specifically parameterized to be less than the internal spring diameter, creating a controlled clearance. This parameter change allows the damping member to move freely and damp vibrations through gravitational contact with the spring's internal surface, while the specific dimensional relationship ensures sufficient damping effectiveness without interference with spring operation.
3Stability of the object's composition
If an interference fit is used to secure the damping member, then it remains fixed, but it causes abrasion and reduces spring lifespan
Solution Approach 1:
The damping member is extracted from the traditional fixed interference fit approach and allowed to move freely within the hollow core. By removing the constraint that causes abrasion, the damping member can damp vibrations through gravitational contact without causing wear to the spring, thereby extending spring lifespan while maintaining vibration damping effectiveness.
4Object-affected harmful factors
If the damping member is too long, then it provides better damping coverage, but it may interfere with spring contraction
Solution Approach 1:
The damping member's length is parameterized to be greater than the distance between adjacent coils in the extended condition, ensuring it spans multiple coils for effective damping. However, the length is controlled to be less than the axial distance between anchor elements in the contracted state, preventing interference with full spring contraction. This parameter optimization resolves the contradiction between damping coverage and operational ease.
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 polymer damping member effectively reduces high-frequency vibrations, potentially doubling the lifespan of the spring assemblies by absorbing operational vibrations without affecting low-frequency extension and retraction functionality.
Implementation Method 1
the damping member can freely move along the hollow core, the length of the damping member being greater than the distance between adjacent coils of the spring when the spring is in a fully extended condition such that the damping member is confined to the hollow core as the spring moves between extended and contracted conditions
Implementation Method 2
the damping member falls under the influence of gravity into contact with an internal surface of the spring; the vibration damping can therefore increase the potential lifespan of the spring
Data Source
Figure 1~3
Figure 4a~4b
Figure 5
AI summary
An aircraft spring assembly (10) includes a helical spring (12) having a hollow core (12c). A polymer damping member (16) is confined within the core (12c) and is narrower than the internal spring diameter so as to be free to move along the core (12c).