Tire Tread Surface Rubber Layer Elastic Modulus
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Solution Overview
Problem
Tires with foamed rubber applied to the tread surface experience a loss of foaming ingredients during the vulcanization process, resulting in a high elastic modulus near the tread surface, which compromises the initial on-ice performance due to insufficient water film removal capability and ground contact area.
Innovation Solution
A tire design with a surface rubber layer having a lower elastic modulus than the inner foamed rubber layer ensures a sufficient ground contact area and early exposure of the foamed rubber layer, stabilizing on-ice performance by maintaining a favorable elastic modulus ratio and thickness of the surface rubber layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If foamed rubber is applied to the tread surface to improve water film removal capability, then on-ice performance is improved, but the foaming ingredients evaporate during vulcanization causing the tread surface to become non-foaming or low-foaming, resulting in loss of initial performance
Solution Approach 1:
The tread is divided into two distinct layers: a surface rubber layer and an inner rubber layer. The inner layer contains the foamed rubber structure for water film removal, while the surface layer protects this structure during vulcanization. This segmentation allows each layer to perform its specific function without interfering with the other's integrity.
Solution Approach 2:
The surface rubber layer acts as an intermediary protective barrier between the mold heat and the foamed rubber structure. It shields the foaming ingredients in the inner layer from direct thermal exposure during vulcanization, preventing premature evaporation and maintaining the foamed structure's integrity until the tire is in service.
2Strength
If the tread surface has high elastic modulus due to loss of foaming ingredients, then structural strength is improved, but ground contact area is reduced, compromising initial on-ice performance
Solution Approach 1:
Different regions of the tread are assigned different elastic modulus characteristics. The inner rubber layer maintains high elastic modulus for structural strength, while the surface rubber layer is formulated with lower elastic modulus to ensure adequate ground contact area and flexibility on ice surfaces, optimizing both strength and contact performance.
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 tire achieves excellent on-ice performance from the beginning of its use by ensuring a larger ground contact area and early exposure of the foamed rubber layer, balancing braking and driving performance.
Implementation Method 1
the elastic modulus of rubber of the surface rubber layer Ms is lower than that of the inner rubber layer Mi
Data Source
Figure 1
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AI summary
A tire with a tread to which foamed rubber is applied that stably exhibits excellent on-ice performance, which is a combination of braking performance and driving performance of a tire, on the ice road surface from the beginning of its use is provided. The tire includes, in a tread thereof, a surface rubber layer forming at least a ground contact surface of the tread and an inner rubber layer that is adjacent to the inward of the surface rubber layer in the tire radial direction and is formed of foamed rubber, and the elastic modulus of rubber of the surface rubber layer Ms is lower than the elastic modulus of rubber of the inner rubber layer Mi.