Rotor Mast Vibration Attenuator With Tunable Moving Masses
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Solution Overview
Problem
Rotary-wing aircraft experience vibrations due to rotor blades, which are difficult to predict and can reduce component lifespan and passenger comfort, as conventional vibration attenuation systems are not effective in accurately mitigating these vibrations.
Innovation Solution
A hub- or mast-mounted vibration-reduction device with mass assemblies biased toward a rest position, where the center of mass moves in a circular path to counteract hub vibrations, and can be tuned by altering mass, spring rate, or translation distance, optimized for different rotor RPMs, using either passive or active components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional vibration attenuation systems are used, then some vibration reduction is achieved, but the systems are not effective in accurately mitigating the unpredictable vibration modes
Solution Approach 1:
The patent employs dynamic vibration absorbers with adjustable mass and stiffness parameters that can be tuned to match different vibration modes. The system includes movable masses that can change position along the rotor mast to adapt to varying vibration frequencies and amplitudes, allowing the attenuation system to effectively counteract unpredictable vibration patterns.
Solution Approach 2:
The invention utilizes adjustable parameters including mass value, spring stiffness, and damper coefficients that can be modified to optimize vibration attenuation for different operating conditions. The system allows parameter tuning based on measured vibration characteristics, enabling accurate mitigation across multiple vibration modes and rotor speeds.
2Reliability
If mass assemblies are added to counteract vibrations, then vibration reduction is achieved, but the device complexity increases
Solution Approach 1:
The patent integrates multiple vibration attenuation mechanisms into a single unified assembly mounted on the rotor mast. The mass-spring-damper systems are combined with the rotor hub structure, and multiple functions (vibration absorption, damping, and tuning) are merged into compact integrated components rather than separate distributed systems.
Solution Approach 2:
The vibration attenuation masses are nested within or alongside the rotor mast structure, with adjustable mass elements that can be positioned within confined spaces. The spring and damper components are arranged in nested configurations within the rotor hub assembly, minimizing overall system footprint while maintaining attenuation effectiveness.
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
Effectively reduces vibrations in rotary-wing aircraft by counteracting hub vibrations, extending component lifespan and improving passenger comfort, while allowing for adaptability across varying rotor RPMs.
Implementation Method 1
A vibration attenuator for a rotor system includes a mass assembly translatably coupled to a central member. The mass assembly includes a first mass and a second mass. A first spring is coupled between the first mass and the central member. A second spring is coupled between the second mass and the central member. The first spring and the second spring are coaxial and define a first axis of motion. The first mass and the second mass are configured to move in a circular path about a second axis that is orthogonal to the first axis of motion.
Implementation Method 2
A first spring is coupled between the first mass and the central member. A second spring is coupled between the second mass and the central member.
Implementation Method 3
A first spring is coupled between the first mass and the central member. A second spring is coupled between the second mass and the central member. The first mass and the second mass are configured to move in a circular path about a second axis that is orthogonal to the first axis of motion.
Data Source
AI summary
A vibration attenuator for a rotor is rotatable about a mast axis and has a frame configured for rotation about the mast axis relative to the rotor. A first mass is axially translatable in a first direction relative to the frame parallel to a first axis, and a first biasing force urges the first mass toward a first-mass rest position in which the first mass is symmetric about the mast axis. A second mass is axially translatable in a second direction relative to the frame parallel to a second axis, and a second biasing force urges the second mass toward a second-mass rest position in which the second mass is symmetric about the mast axis. A selected first or second mass moves radially outward from the rest position to oppose vibrations in the rotor.