Flexible Multi-Material Ring Structure for Asymmetric Stiffness
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Solution Overview
Problem
Existing flexible structures, such as non-load bearing joints and cylindrical structural columns, struggle to achieve asymmetric global stiffness properties, which are essential for applications in medical and aerospace industries where they need to withstand large global displacements, maintain a smooth outer surface, and provide sufficient mechanical rigidity.
Innovation Solution
The development of a flexible multi-material structure comprising a spring skeleton with repeating cells filled with an infill material, where the spring skeleton can be either a machined spring structure or a wave spring structure, and the infill material can be foamed and monolithic elastomers. This structure is designed to provide asymmetric global stiffness properties by optimizing material properties and substructure topology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a monolithic design is used for flexible structures, then manufacturing simplicity is improved, but the ability to achieve asymmetric global stiffness properties deteriorates
Solution Approach 1:
The patent employs composite materials combining a stiff skeleton (metallic or stiff polymeric blends) with compliant infill materials (foamed and monolithic elastomers). This composite structure enables asymmetric global stiffness properties where the structure is radially stiff yet compliant in bending, resolving the contradiction between manufacturing simplicity and achieving specific stiffness characteristics.
Solution Approach 2:
The structure is segmented into distinct functional components: a spring skeleton comprising repeating cells providing structural framework, and infill material filling the cells providing compliance. This segmentation allows each component to be optimized independently while working together to achieve the desired asymmetric stiffness properties.
2Ease of operation
If the structure is designed to be compliant in bending, then flexibility is improved, but radial rigidity deteriorates
Solution Approach 1:
The patent applies local quality by providing different mechanical properties in different directions and locations. The spring skeleton with repeating cells provides radial stiffness where needed, while the infill material provides compliance in bending directions. This local differentiation of material properties enables the structure to be simultaneously flexible and radially rigid.
Solution Approach 2:
The structure exhibits asymmetric stiffness properties through its geometric design and material distribution. The spring skeleton geometry and infill material placement create a structure that is radially stiff but compliant in bending, achieving the desired asymmetric mechanical behavior that satisfies both flexibility and radial rigidity requirements.
3Adaptability or versatility
If the structure undergoes large global displacements, then adaptability is improved, but maintaining a smooth outer surface deteriorates
Solution Approach 1:
The patent employs a nested structure where the infill material is contained within the spring skeleton cells. This nested arrangement allows the inner infill material to accommodate large global displacements and deformations while the outer spring skeleton maintains the smooth outer surface geometry, resolving the contradiction between adaptability and surface smoothness.
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 proposed structure effectively transfers loads under changing configurations while maintaining a smooth outer surface, achieving the necessary mechanical rigidity and flexibility required for advanced applications in the medical and aerospace industries.
Implementation Method 1
a flexible multi-material structure comprises a spring skeleton comprising a plurality of repeating cells, the cells filled with an infill material
Implementation Method 2
The infill material may consist of one or more of foamed and monolithic elastomers
Data Source
AI summary
A flexible multi-material structure comprises a plurality of overlapping rings that form a generally circular shape perpendicular to a longitudinal axis of the structure; an internal compliant hollow frame having a circumference corresponding to the generally circular shape of the plurality of rings, the internal frame comprising: a plurality of connection clips wherein each connection clip is attached one of the plurality of rings, the internal frame and connection clips defining a longitudinal spacing between the plurality of rings, each of the plurality of rings is shaped to minimize contact with adjacent rings when the structure is articulated, each ring including a spherical profile along an aft interior region which nests with a forward outer region of an adjacent ring, wherein connections between the rings and the frame allows independent motion of the rings and frame, allowing each ring to pivot about a geometric center of the spherical profile.