Flexure Element Vibration Isolation for Reaction Wheel Bearings
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Solution Overview
Problem
Current methods for isolating vibrations in reaction wheel bearings of spacecraft are inefficient, leading to high power consumption, increased mass, and potential failure due to high stresses and complexity, especially during launch vibrations, as they either require large bearings, additional mass, or are not compatible with the vacuum environment.
Innovation Solution
A flexure element-based assembly that couples a rotatable mass to a body, incorporating a flexure layer with serpentine slots and damping elements to alter the natural frequency and provide damping, reducing vibration loads on the bearings and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If large bearings are used to support the reaction wheel assembly, then the load capacity increases and the bearing can withstand high vibration loads, but the viscous drag increases significantly and power consumption increases
Solution Approach 1:
The bearing support structure is segmented into multiple independent flexure elements arranged in parallel. Each flexure element carries a portion of the load, allowing the use of smaller individual elements with lower drag while collectively supporting the full reaction wheel load, thus reducing overall power consumption while maintaining load capacity
Solution Approach 2:
The flexure elements are constructed using composite material structures that provide high stiffness-to-weight ratios. This allows the bearing support to maintain adequate load capacity with reduced mass and smaller dimensions, thereby reducing viscous drag and power consumption while still withstanding vibration loads
2Use of energy by moving object
If small bearings are used to support the reaction wheel assembly, then power consumption is minimized and system mass is reduced, but the load capacity decreases and the bearing experiences high stresses leading to premature failure
Solution Approach 1:
The bearing support structure is divided into multiple flexure elements that distribute the reaction wheel load across several parallel load paths. This segmentation allows small individual bearings to share the total load, reducing stress on each bearing while maintaining adequate load capacity, thereby improving reliability without increasing power consumption
Solution Approach 2:
The flexure elements incorporate damping features and compliant structures that cushion the bearings against vibration loads before the loads reach the bearing contact points. This pre-cushioning effect reduces peak stresses on the bearings during launch vibrations, preventing premature failure while allowing the use of small, low-power bearings
3Strength
If snubbers with very small gaps are used to offload the rotor mass, then the bearing load is reduced, but the device complexity increases and failure modes are introduced due to potential jamming and friction
Solution Approach 1:
The mechanical snubber system with small gaps and potential contact interfaces is replaced with flexure elements that provide load support through elastic deformation and distributed compliance. This substitution eliminates the jamming and friction problems associated with small gaps while maintaining bearing load reduction, thereby reducing device complexity and eliminating failure modes
Solution Approach 2:
The flexure elements function as flexible structural components that provide the necessary compliance and load distribution without requiring small gaps or rigid contact surfaces. These flexible elements offload the rotor mass through distributed elastic support, achieving bearing load reduction without the complexity and failure risks of traditional snubber mechanisms
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 solution effectively isolates vibrations, reducing the load on reaction wheel bearings, minimizing power consumption, and preventing premature failure by adjusting the natural frequency and adding damping, thus enhancing the reliability and efficiency of the spacecraft system.
Implementation Method 1
alter the natural frequency and provide damping, reducing vibration loads on the bearings
Implementation Method 2
alter the natural frequency and provide damping, reducing vibration loads on the bearings
Data Source
AI summary
An assembly for coupling a rotatable mass to a body including a flexure layer, and a method for assembling and manufacturing the same. The flexure layer includes an inner region operable to be coupled to the rotatable mass via a bearing assembly, an outer region operable to be coupled to the body, and a flexure element including a first end coupled to the inner region and a second end coupled to the outer region.