Spacecraft Through-Pivot With Flexible Web Rings
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Solution Overview
Problem
Existing spacecraft pivot systems lack sufficient mechanical strength, transverse rigidity, and angular capacity for fine pointing applications, with limited lifespan and high wear due to irreversible stress and alternating movements, failing to meet the requirements for precise and long-lasting rotation in space applications.
Innovation Solution
A through-pivot design featuring two rings with a floating frame connected by sets of flexible elements, allowing for high mechanical resistance, low resistive torque, and increased angular capacity through the use of inclined flexible blades that operate in bending mode, doubling the angular capacity compared to previous designs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a pivot with crossed flexible blades is used, then the device can support rotation, but the mechanical strength and transverse rigidity are limited
Solution Approach 1:
The pivot is divided into two separate rings (first ring and second ring) connected by flexible elements, allowing each component to be optimized independently. The flexible elements are segmented into sets connecting different rings, distributing mechanical loads and improving overall structural strength while maintaining rigidity.
Solution Approach 2:
The invention transitions from a single-plane flexible blade structure to a three-dimensional configuration with two rings connected by flexible elements extending in transverse directions. This spatial arrangement increases transverse rigidity and mechanical strength by distributing stresses across multiple dimensions.
2Ease of operation
If ball bearings are used to support the shaft, then rotation is smooth, but wear increases and lifespan is limited
Solution Approach 1:
The invention replaces traditional ball bearing mechanical contact systems with a flexible element-based suspension system. The flexible elements accommodate rotation through elastic deformation rather than rolling contact, eliminating wear and significantly extending the operational lifespan while maintaining smooth rotation.
Solution Approach 2:
The flexible elements are designed with specific material properties and geometric parameters (thickness, length, cross-section) that allow them to provide the necessary compliance for smooth rotation while withstanding repeated cyclic loads for over 300,000 cycles without wear.
3Strength
If a bladed through pivot is used, then mechanical strength is improved, but angular capacity is limited to low angles
Solution Approach 1:
The flexible elements are designed to operate dynamically in bending mode, allowing the pivot to accommodate large angular corrections (at least 5-10 degrees) while maintaining mechanical strength. The flexibility of the elements enables the structure to adapt to varying rotation angles without compromising structural integrity.
Solution Approach 2:
The invention uses flexible elements (thin-walled structures) that can bend and deform elastically to accommodate large angular movements. These flexible elements provide both the mechanical strength needed for structural support and the angular capacity required for large corrections, resolving the contradiction between strength and adaptability.
4Device complexity
If the shaft is mounted cantilevered, then the pivot structure is simplified, but stresses in the blades increase significantly
Solution Approach 1:
The pivot structure is segmented into two rings connected by flexible elements, distributing the cantilever stresses across multiple components rather than concentrating them in single blades. This segmentation reduces the stress in each individual flexible element while maintaining structural simplicity.
Solution Approach 2:
By transitioning to a two-ring configuration with flexible elements extending in transverse directions, the invention distributes cantilever stresses across three-dimensional space, reducing the stress concentration in any single element compared to a planar cantilever structure.
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 provides a robust and precise guidance system capable of supporting over 300,000 rotational cycles with enhanced mechanical strength and transverse rigidity, enabling larger angular corrections while maintaining low torque and high precision, thus addressing the limitations of existing pivot systems.
Implementation Method 1
comprising at least one floating frame movable around the longitudinal axis, and the two rings being connected to the floating frame by at least a first set, respectively at least a second set, of several flexible elements extending in a direction transverse to the two rings
Data Source
Figure 1~2
Figure 3~4
Figure 5a~5b
AI summary
The through-pivot has a fixed ring (1) and a moving ring both including a symmetry of revolution around a single longitudinal axis (10), where one of the rings is mobile in rotation around the longitudinal axis with respect to the other ring. A floating frame is mobile about the longitudinal axis and connected to the rings by a set of flexible webs (7) and another set of flexible webs, respectively. The flexible webs are extended in a direction transversal with respect to the rings. The sets of flexible webs are arranged radially with respect to the rings in a rest state.