Tire Tread Segmentation for Shear Force Reduction
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Solution Overview
Problem
Heavy load tires experience significant shearing forces due to differential deformations and angles between belt plies and the tire circumferential direction, leading to uneven wear and reduced performance, especially when subjected to rotational and braking forces.
Innovation Solution
The tire design incorporates segmented land portions with angled grooves that extend in both the circumferential and width directions, featuring a central groove system with specific ratios of length to height for the land portions and grooves, which reduces shearing forces by optimizing belt tension and wear distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the tire uses a heavy load design with multiple belt plies and large land portions, then the load bearing capacity is improved, but the shearing force generated during rotation increases
Solution Approach 1:
The tread portion is segmented into multiple land portions by circumferential direction grooves and width direction grooves. This segmentation divides the continuous tread structure into discrete units, allowing each land portion to independently manage stress and deformation, thereby reducing overall shearing forces while maintaining load bearing capacity through the distributed structure
Solution Approach 2:
The patent applies different groove configurations to different regions of the tread. Width direction grooves with angled portions are positioned at specific locations to address local stress concentrations, while the central land portions have optimized dimensions. This localized optimization reduces shearing forces in critical areas without compromising the overall structural strength needed for heavy load capacity
2Stability of the object's composition
If the cord angles in the belt plies are optimized for load bearing, then the structural stability is improved, but differential deformation between tread areas increases
Solution Approach 1:
By segmenting the tread into multiple land portions separated by grooves, the patent prevents differential deformation from propagating across the entire tread width. Each segmented land portion deforms independently, reducing the cumulative shape distortion that would occur in a continuous tread structure under the same cord angle configuration
Solution Approach 2:
The patent optimizes cord angles locally in different belt ply regions to balance structural stability with deformation control. The width direction grooves with angled portions are strategically placed to counteract local deformation tendencies created by the cord angle configuration, ensuring that each region maintains its shape characteristics while contributing to overall structural stability
3Strength
If the land portion length in width direction is increased to 30% or more, then the heavy load performance is improved, but the wear energy increases due to shearing forces
Solution Approach 1:
The tread is divided into multiple land portions by circumferential direction grooves and width direction grooves, which segment the large land area into smaller units. This segmentation reduces the cumulative shearing forces that would act on a single large land portion, thereby reducing wear energy while preserving the overall heavy load performance through the distributed land structure
Solution Approach 2:
The patent optimizes the dimensions and positioning of individual land portions and their separating grooves to minimize shearing forces in high-wear regions. Width direction grooves with angled portions are placed to reduce stress concentrations at land portion boundaries, reducing local wear energy while maintaining the sufficient land portion length needed for heavy load capacity
Data Source
AI summary
A tire 1 includes plural land portions 40 formed on a tread portion 10. The plural land portions 40 are segmented by a circumferential direction groove 30 extending in a tire circumferential direction L and a width direction groove 20, or segmented by an end portion 10E of the tread portion 10 in the tire width direction W and the width direction groove 20. A length of the width direction groove 20 in the tire width direction W is not less than 30% of a length of the tread portion 10 in the tire width direction W. The width direction groove 20 has at least one angled portion 50A/50B configured to be bent toward an opposite direction to a tire rotational direction R on at least one side of a tire equator line CL.