Tyre Crown Elastomer Modulus Layout for Crack Resistance
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Solution Overview
Problem
Current tires face challenges in maintaining endurance and preventing cracks, especially in the crown zone, when subjected to severe loads, pressures, or temperatures, leading to decohesion between layers.
Innovation Solution
The tire design incorporates a radial carcass reinforcement with layers of elastomeric mixtures, where axially continuous layers with specific secant modulus of elasticity values are used to reduce cracking and decohesion, particularly by ensuring equal or lower secant modulus values at interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the tread is provided with a sculpture formed of raised elements delimited by cutouts to improve wet road performance, then water drainage capability is improved, but the shear rigidities of the tread are excessively lowered
Solution Approach 1:
The patent applies local quality by providing different tread compositions in different zones: the central portion has higher shear rigidity for load-bearing, while the axially outer portions have lower shear rigidity to maintain flexibility near the cutouts. This localized differentiation allows the tread to simultaneously achieve good water drainage through cutouts and maintain necessary structural strength.
2Reliability
If layers of elastomeric mixtures with different secant modulus values are used to reduce crack propagation, then endurance is improved, but the complexity of manufacturing increases
Solution Approach 1:
The patent applies parameter changes by varying the secant modulus of elasticity at 10% elongation across different layers and portions of the tread. Specifically, the axially outer portions have lower secant modulus values than the central portion, creating a gradient that reduces stress concentration and crack propagation. This parameter differentiation is achieved through controlled variation in elastomeric compound formulation and curing conditions, balancing improved endurance with manageable manufacturing complexity.
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 enhances the tire's rolling performance and endurance by reducing crack propagation and decohesion, allowing for greater mileage without separation between layers, even under severe conditions.
Implementation Method 1
The value of the secant modulus of elasticity at 10% elongation of said two axially outer parts of said at least one second layer of elastomeric mixture being less than or equal to the value of the secant modulus of elasticity at 10% elongation of said at least one calendering layer of at least one layer of reinforcing elements of the crown reinforcement
Implementation Method 2
said at least one third layer of elastomeric mixture consisting of at least one central portion and two axially outer portions, each of the axially outer portions of said at least one second layer of elastomeric mixture having a contact surface with an axially outer portion of said at least one third layer of elastomeric mixture
Data Source
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AI summary
The invention relates to a tyre (1) with a radial carcass reinforcement, comprising a crown reinforcement (5) in turn capped radially by a tread (4) joined to two beads by means of two sidewalls. According to the invention, the tyre crown region comprises axially outer portions (622) of a second elastomer blend layer (62) and axially outer portions (632) of a third elastomer blend layer (63) having equal secant modulus values of elasticity at 10% elongation, and said secant modulus values of elasticity at 10% elongation are lower than the secant modulus values of elasticity at 10% elongation of at least some of the other elastomer blends in the layers with which they are in contact.