Linkage Assembly With Virtual Pivot for Constant-Length Material Layer
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Solution Overview
Problem
Existing mechanical systems with linkage assemblies fail to maintain a constant length of the material layer across a range of motion, leading to in-plane strain and limitations in configuration flexibility, particularly in applications like fuel tanks and airfoils.
Innovation Solution
A linkage assembly design featuring a hinge formed by a first and second pin-in-slot joint, allowing linkages to rotate relative to each other with a virtual pivot on the material layer, maintaining a constant length and reducing in-plane strain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional linkage assemblies are used to enable rotation and translation between linkages, then configuration flexibility is improved, but the material layer experiences in-plane strain and length variation
Solution Approach 1:
The linkage assembly is divided into multiple individual linkages (first linkage, second linkage, third linkage, fourth linkage) that are coupled through joints. Each linkage can move independently while maintaining the overall structural integrity, allowing the material layer to be segmented and attached to multiple linkages rather than requiring the entire assembly to move as a single unit.
Solution Approach 2:
Joints serve as intermediary elements between neighboring linkages, enabling rotation and translation while maintaining constant distance relationships. The joints act as mediators that allow relative motion between linkages without transmitting strain to the material layer, as the virtual pivot points remain stationary relative to the material layer attachment points.
2Adaptability or versatility
If linkage rotation is enabled to achieve different configurations, then adaptability is improved, but in-plane strain increases within the material layer
Solution Approach 1:
The mechanism employs virtual pivot points that create arc-shaped motion paths for the linkage endpoints. The curved slot geometry and pin-in-slot joints enable rotational movement along circular arcs, allowing the linkages to rotate while maintaining constant distance from the virtual pivot. This curved motion geometry ensures that the material layer attachment points move without stretching or compressing the material between them.
Solution Approach 2:
The system changes the motion parameters by using virtual pivot points located at specific positions relative to the material layer. By carefully selecting the virtual pivot locations and the geometry of the curved slots, the system ensures that the distance between material layer attachment points remains constant during rotation, thereby maintaining zero in-plane strain while enabling full configurational flexibility.
3Manufacturing precision
If pin-in-slot joints are used to form virtual pivots, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The pin-in-slot joint combines two functional elements into a single integrated component: the pin provides rotational freedom while the curved slot guides the motion path and defines the virtual pivot location. This merged joint design achieves precise virtual pivot positioning without requiring separate positioning mechanisms, reducing the overall number of parts while maintaining manufacturing precision.
Solution Approach 2:
The curved slot geometry is designed to automatically guide the pin along the correct arc-shaped path during linkage rotation. The slot's curvature is predetermined to match the required motion arc, allowing the joint to self-regulate the motion path without additional control mechanisms. This self-service approach ensures precise virtual pivot positioning while simplifying the control system.
Data Source
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AI summary
A reconfigurable structure includes one or more linkage assemblies that are each formed by one or more linkage chains of a plurality of linkages. Neighboring pairs of linkages of each linkage chain are rotatably coupled to each other via a first pin-in-slot joint and a second pin-in-slot joint. The reconfigurable structure includes a material layer mounted to the plurality of linkages of each linkage assembly. The material layer maintains a constant length across a range of motion of each linkage assembly, thereby reducing or eliminating in-plane strain of the material layer across the range of motion. In an example, the reconfigurable structure can provide a first configuration corresponding to an annular tube shape for a fluid vessel, conduit, or other suitable structure, and a second configuration corresponding to a flattened shape. The flattened shape of the second configuration can be used for storage and transport of the reconfigurable structure.