Rotatable Friction Damper Assembly for Aircraft Drive Shaft Vibration
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Solution Overview
Problem
Current friction dampers in rotary aircraft drive shafts, when placed at anti-nodes of natural frequencies, nutate and reduce their effectiveness as they rotate, leading to inadequate vibration reduction due to impeded motion by mounting studs.
Innovation Solution
A damper assembly comprising a rotatable damper element within a recess of a first plate, secured by a second plate, allowing the damper element to rotate freely and constrain radial motion, ensuring continuous damping effectiveness by interacting with the rotating shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If friction dampers are placed at anti-nodes of natural frequencies to reduce vibration, then damping effectiveness is improved, but the dampers nutate and rotate in the direction of shaft rotation until impeded by mounting studs, reducing their effectiveness
Solution Approach 1:
The damper assembly allows the friction damper to rotate dynamically with the shaft rotation while maintaining damping effectiveness. The mounting structure provides rotational freedom through the natural clearance between the damper outer diameter and mounting bore, eliminating the need for rotational constraint while preserving vibration reduction capability across the operational speed range.
2Stability of the object's composition
If mounting studs are used to secure the damper, then the damper is fixed in position, but the studs impede the rotation of the damper, reducing damping effectiveness
Solution Approach 1:
The mounting structure is segmented into separate functional zones: axial positioning features (shoulders and flats) that maintain radial alignment, and rotational clearance that permits free rotation. This segmentation allows the damper to be securely mounted axially while remaining free to rotate, resolving the conflict between positional stability and rotational freedom.
3Device complexity
If the damper is constrained rotationally by mounting studs, then the mounting structure is simple, but the damping effectiveness is reduced due to impeded motion
Solution Approach 1:
The mounting structure performs multiple functions simultaneously: it provides axial positioning through shoulders, prevents radial displacement through flats, and permits free rotation through intentional clearance. This multi-functional design achieves both secure mounting and rotational freedom without increasing complexity, as the same mounting features serve both positioning and rotational freedom purposes.
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 assembly effectively reduces vibrations across natural frequencies by allowing the damper element to rotate freely and constrain radial motion, maintaining damping effectiveness throughout the shaft's operational speed range.
Implementation Method 1
friction dampers are placed at anti-nodes of natural frequencies in order to reduce vibration by controlling shaft deflection
Data Source
AI summary
An aircraft, damper assembly for an aircraft and method for reducing a vibration in a rotating shaft. The damper assembly includes a damper element, a first plate and a second plate. The damper element has a damper opening shaped to surround the shaft. The first plate has a first opening shaped to surround the shaft and a recess receptive to the damper element, the damper element being rotatable within the recess. The second plate has a second opening shaped to surround the shaft and secured to the first plate to close the recess and secure the damper element between the first plate and second plate. The damper element rotates within the closed recess.