Non-Pneumatic Tire Spoke Geometry for Lower Edge Stress Concentration
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Solution Overview
Problem
Existing non-pneumatic tires are susceptible to failure due to stress concentration at orthogonal axial edges of spokes, which can lead to cracks and reduced fatigue life from surface imperfections.
Innovation Solution
The design of non-pneumatic tires incorporates spokes with nonrectangular cross sections and continuously curved or chamfered edges to eliminate orthogonal axial edges, combined with surface roughness less than 25 microns to enhance fatigue life and reduce sensitivity to surface imperfections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If spokes have rectangular cross section with orthogonal axial edges, then manufacturing is simple, but stress concentration occurs at edges leading to cracks and reduced fatigue life
Solution Approach 1:
The patent applies curvature by replacing the orthogonal axial edges of rectangular spokes with continuously curved edges. This eliminates the sharp corners that cause stress concentration, thereby improving fatigue life and reliability while maintaining manufacturing feasibility through processes like curved extrusion or molding.
2Ease of manufacture
If surface roughness is high, then manufacturing is easier, but surface imperfections reduce fatigue life and increase sensitivity to cracks
Solution Approach 1:
The patent applies parameter changes by specifying a controlled surface roughness parameter (less than 25 microns) for the spoke surfaces. This quantitative parameter control reduces stress concentration at surface imperfections and enhances fatigue life, while remaining achievable through standard manufacturing processes.
3Reliability
If spokes have nonrectangular cross section with curved edges, then stress concentration is reduced and fatigue life is enhanced, but manufacturing complexity increases
Solution Approach 1:
The patent applies local quality by modifying only the axial edges of the spoke cross section to be continuously curved, while maintaining the overall rectangular shape and functional requirements. This localized geometric modification reduces stress concentration at critical areas without fundamentally changing the spoke structure or significantly complicating manufacturing.
Data Source
AI summary
A non-pneumatic and method of making a non-pneumatic tire. The non-pneumatic tire includes a lower ring having a first diameter and an upper ring having a second diameter greater than the first diameter. The upper ring is substantially coaxial with the lower ring. A support structure extends between the lower ring and the upper ring. The support structure includes a first face and a second face opposite the first face, a first axial edge and a second axial edge. The first and second axial edges space the first face from the second face. At least one of the first edge and the second edge may have a geometry that provides the support structure with a nonrectangular cross section. At least one of the first face and the second face may have a surface roughness of less than 25 microns. The support structure may be free from orthogonal axial edges.