Evolving Tire Tread Stiffness via Segmented Rubber Layers
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Solution Overview
Problem
Tire treads constructed of single materials become stiffer as they wear, compromising performance and durability, particularly in varying temperature conditions, and lack effective wear indicators.
Innovation Solution
A multi-layered tread structure with a base layer of softer, more pliable material and a cap layer of stiffer material, where the base layer is designed to maintain tread stiffness and serve as a wear indicator by changing color or reflectivity as it is exposed, ensuring consistent performance across different seasons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single-material tread is used, then the structure is simple and manufacturing is easier, but the tread becomes stiffer as it wears, compromising performance and durability
Solution Approach 1:
The tread is segmented into multiple layers with different material properties. The base layer uses softer rubber compound while the cap layer uses harder rubber compound. This segmentation allows each layer to perform its specific function: the base layer maintains flexibility and provides wear indication, while the cap layer provides abrasion resistance and structural integrity, resolving the contradiction between manufacturing simplicity and performance consistency.
Solution Approach 2:
The tread employs composite material construction by combining two different rubber compounds in a multi-layered structure. The first rubber compound (base layer) has lower hardness and higher elasticity, while the second rubber compound (cap layer) has higher hardness and better abrasion resistance. This composite approach maintains reliable performance throughout the tread's service life by preventing overall stiffening.
2Reliability
If a multi-layered tread structure is used, then tread stiffness and durability are maintained, but the device complexity increases
Solution Approach 1:
The tread is divided into functional segments (base layer and cap layer) with distinct material properties. The base layer uses softer rubber for flexibility and wear indication, while the cap layer uses harder rubber for durability. This segmentation maintains tread stiffness and performance reliability while keeping the structural complexity manageable through clear functional differentiation.
Solution Approach 2:
Different regions of the tread are assigned different material qualities based on their functional requirements. The base layer has softer, more pliable material properties for maintaining flexibility and providing wear indication, while the cap layer has harder material properties for abrasion resistance. This local quality differentiation achieves reliable stiffness maintenance without excessive overall complexity.
3Strength
If the tread rubber is made harder for durability, then abrasion resistance improves, but traction and performance in varying temperature conditions deteriorate
Solution Approach 1:
The tread is segmented into a base layer and cap layer with different hardness levels. The base layer uses softer rubber compound that maintains flexibility and provides good traction across varying temperature conditions. The cap layer uses harder rubber compound that provides superior abrasion resistance. This segmentation resolves the contradiction by assigning each material property to the appropriate functional layer.
Solution Approach 2:
The tread employs composite rubber materials with different compounds in each layer. The first rubber compound (base layer) has lower hardness for temperature adaptability and traction, while the second rubber compound (cap layer) has higher hardness for abrasion resistance. This composite material approach simultaneously achieves both abrasion resistance and temperature condition adaptability.
Data Source
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AI summary
A tire (100) includes a circumferential tread (115) having a base layer (160) and a cap layer (165) disposed above the base layer. The base layer is constructed of a first material having a first complex dynamic modulus and a first glass transition temperature, and the cap layer is constructed of a second material having a second complex dynamic modulus greater than the first complex dynamic modulus and a second glass transition temperature higher than the first glass transition temperature. The base layer has a shaped geometry with a bottom portion that is wider than a top portion, such that an exposed surface area of the first material increases as the circumferential tread wears.