RAT Strut Inner Damper Rod Frictional Damping
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Solution Overview
Problem
Existing strut systems for connecting ram-air turbines (RAT) to aircraft fail to effectively dampen resonance-induced loads, leading to vibrations that can compromise the stability and efficiency of the turbine deployment and stowing processes.
Innovation Solution
A strut system incorporating a damper rod with a bushing and guide shaft configuration, where the damper rod is secured under tension within a strut conduit, allowing for sliding contact between the bushing and guide shaft to generate frictional damping, thereby mitigating resonance-induced forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional strut system is used to connect the RAT to the aircraft, then the structural connection is simple, but resonance-induced vibrations occur and cannot be effectively damped
Solution Approach 1:
The damper rod is nested within the strut conduit, forming an inner damper rod configuration. This nested structure allows the damping mechanism to be integrated within the existing strut without requiring a completely separate external damping system, thereby improving reliability while controlling complexity
Solution Approach 2:
A bushing is introduced as an intermediary element between the damper rod and the guide shaft. The bushing enables frictional damping by allowing controlled sliding contact between the damper rod and guide shaft while maintaining the structural connection. This intermediary component transforms the simple mechanical connection into a damping-capable system
2Stability of the object's composition
If the damper rod is secured firmly within the strut conduit, then structural stability is improved, but the ability to move along the second axis for damping motion is restricted
Solution Approach 1:
The damper rod is designed with dynamic characteristics that allow it to move along the second axis while remaining secured in the first direction. The rod can slide within the conduit along the damping direction (second axis) to provide motion damping, while maintaining secure attachment at the first end to prevent dislocation. This dynamic design resolves the contradiction between securing and mobility
Solution Approach 2:
The damper rod is segmented into distinct functional portions: a first end that is fixed within the strut conduit to provide secure attachment, and a second end that is free to move along the second axis for damping purposes. This segmentation allows different parts of the same component to perform different functions - stabilization at one end and motion damping at the other
3Reliability
If the rod body is made larger to increase damping capacity, then frictional damping is improved, but the space available within the strut conduit is reduced
Solution Approach 1:
The damper rod is designed with non-uniform cross-sectional properties - the rod body has a specific size optimized for frictional damping capacity, while the first end includes a reduced-diameter portion that fits within the strut conduit. This local quality variation allows the rod to provide adequate damping through its body while maintaining clearance for movement through the conduit, resolving the volume contradiction
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 system effectively reduces resonance-induced vibrations by applying frictional damping, ensuring stable rotational motion and efficient energy dissipation during RAT deployment and stowing, enhancing the structural integrity and operational reliability of the aircraft.
Implementation Method 1
allowing for sliding contact between the bushing and guide shaft to generate frictional damping
Implementation Method 2
generate frictional damping, thereby mitigating resonance-induced forces
Data Source
Figure 1A
Figure 1B
Figure 2
AI summary
A strut system for a RAT includes a strut body, a strut first end is connected to the aircraft and rotate about a first axis, a strut second end is spaced apart from the strut first end by the strut body and is connected to the RAT turbine generator unit, the strut has a strut conduit extending from the strut first end toward the strut second end; and a damper rod that includes a rod body and disposed within the strut conduit, the damper rod having a rod first end that is fixed within the strut conduit at the strut first end, and a rod second end that is spaced apart from the rod first end by the rod body and is located intermediate the strut first end and the strut second end, wherein the rod second end moves along a second axis that is parallel to the first axis.