Variable Teardrop Tire Sipe for Crack-Resistant Rib Rigidity
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Solution Overview
Problem
Existing tire sipes with teardrop shapes can cause irregular wear, increased rolling resistance, and cracking due to stress concentration, particularly in shoulder ribs, while attempts to mitigate cracking through larger teardrop sizes or shallower depths compromise rigidity and traction performance.
Innovation Solution
A sipe design with a teardrop that has a larger size at its lateral midpoint and smaller ends, maintaining rigidity and reducing crack initiation and propagation without affecting end-of-life traction or rolling resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the teardrop size is increased to prevent cracking at the bottom of the teardrop, then end of service traction is improved, but rigidity in the tread block decreases and wear performance is reduced
Solution Approach 1:
The teardrop sipe design implements local quality by varying the teardrop dimensions along its length. The lateral midpoint has a larger cross-sectional size (greater width and/or height) compared to the ends, creating zones of different structural properties. This allows the central region to provide crack resistance while the end regions maintain tread block rigidity, resolving the contradiction between preventing cracking and maintaining overall structural strength.
2Reliability
If the teardrop radius is increased to minimize cracking, then end of service traction increases, but rolling resistance performance is reduced
Solution Approach 1:
By concentrating the larger teardrop size at the lateral midpoint rather than uniformly increasing the teardrop radius throughout, the design provides crack prevention where most needed (at the vulnerable central region) while minimizing the overall material removal from the tread block. This localized approach reduces the negative impact on rolling resistance compared to a uniform teardrop enlargement.
3Reliability
If sipes are added to improve traction in snow, mud, and ice, then stopping distance and breakaway traction are improved, but irregular wear and sipe aggression increase
Solution Approach 1:
The variable teardrop design with larger lateral midpoint creates a more gradual stress distribution pattern compared to uniform teardrop shapes. The enlarged central region better accommodates stress concentrations that occur during tire operation, reducing the likelihood of stress-induced cracking and sipe aggression while maintaining the traction benefits of the sipe structure.
Solution Approach 2:
The teardrop shape with its curved, rounded morphology (larger at the midpoint, tapering toward ends) provides smoother stress transitions compared to sharp or angular sipe configurations. This curved geometry helps distribute mechanical stresses more evenly, reducing stress concentration points that lead to irregular wear and sipe failure.
Data Source
AI summary
A tread for a heavy truck tire that has a rib is provided. A sipe is located in the rib and extends from a first lateral surface to a second lateral surface. A first end of a teardrop of the sipe is located at the first lateral surface, and a second end is at the second lateral surface. A middle section is located between the first and second ends, and a lateral midpoint of the teardrop is located at the middle section. A cross-section of the middle section at the lateral midpoint is greater in size than a cross-section of the first end. The cross-section of the middle section at the lateral midpoint is greater in size than a cross-section of the second end.