Non-Pneumatic Tire Spoke Thickness Optimization
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Solution Overview
Problem
Non-pneumatic tire spokes are prone to fatigue failure due to crack initiation and propagation caused by cyclic stress, limiting the load capacity and durability of the tire.
Innovation Solution
The spoke geometry is optimized with a varying thickness profile along its length, featuring inflection points and zones that reduce peak strain energy density, allowing for elastic deformation and improved fatigue life without compromising mass or stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the spoke has a uniform thickness, then the manufacturing is simple, but the spoke is prone to fatigue failure due to high peak strain energy density
Solution Approach 1:
The spoke is designed with variable thickness along its length, creating different local properties: thicker sections at the ends for strength and connection, and a thinner middle section to reduce peak strain energy density. This local quality variation allows the spoke to withstand cyclic loading while reducing fatigue failure risk, resolving the contradiction between manufacturing simplicity and fatigue life.
Solution Approach 2:
The thickness parameter of the spoke is changed along its length rather than remaining uniform. The thickness varies from a first value at one end, through a minimum value in the middle section, to a second value at the other end. This parameter change optimizes the strain energy distribution, reducing peak values that cause fatigue failure while maintaining structural integrity.
2Strength
If the spoke thickness is increased to improve strength, then the fatigue life improves, but the mass of the spoke increases
Solution Approach 1:
Instead of uniformly increasing the spoke thickness throughout, the design applies thicker sections only where structurally necessary (at the ends for connection and load bearing), while maintaining a thinner profile in the middle section where peak strain energy density occurs. This local quality approach improves fatigue resistance without proportionally increasing overall mass.
Solution Approach 2:
The thickness parameter is optimized along the spoke length to balance strength and mass. By varying the thickness rather than using a uniform increase, the design achieves improved fatigue life through strategic thickening at critical locations while minimizing overall mass increase.
3Reliability
If the spoke geometry is optimized to reduce peak strain energy density, then the fatigue life improves, but the manufacturing complexity increases
Solution Approach 1:
The spoke geometry incorporates local quality variations with defined thick and thin sections at specific locations. While this creates geometric complexity, the pattern is systematic and repeatable, allowing for optimized fatigue performance through controlled variations in thickness distribution.
Solution Approach 2:
The thickness parameter varies along the spoke length following a specific profile: starting at a first value, reducing to a minimum, and increasing to a second value. This parameter change creates the optimized geometry that reduces peak strain energy density, accepting increased manufacturing complexity as a trade-off for significantly improved fatigue life.
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
This design reduces peak strain energy density by approximately 40%, resulting in a 200% improvement in fatigue life and maintaining tire performance, with the potential for reduced mass and improved rolling resistance.
Implementation Method 1
The spoke geometry is provided with an optimized thickness profile over the length of the spoke. This optimization results in a reduction in the peak strain energy density levels in the spoke, thereby reducing the likelihood of crack initiation and propagation
Data Source
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AI summary
The present invention provides spoke geometry for a non-pneumatic tire that is less prone to fatigue when used. In particular, the spoke geometry is provided with an optimized thickness profile over the length of the spoke. This optimization results in a reduction in the peak strain energy density levels in the spoke, thereby reducing the likelihood of crack initiation and propagation which in turn enhances the durability of the spoke and tire.