Pneumatic Tire Carcass Cord Layout for Strain Distribution
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Solution Overview
Problem
Pneumatic tires experience durability deterioration due to strain concentration between the tread part and the side part during running, particularly when carcass cords' extending directions are not optimally controlled.
Innovation Solution
A pneumatic tire design with carcass cords having varying extending directions, controlled by specific angles (A1 and A2) and adjusted complex elastic modulus, along with a reinforcing layer composed of belts and bands, adhering to specific inequalities to distribute strain effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If carcass cords are configured with a fixed extending direction to simplify structure, then manufacturing precision is improved, but durability deteriorates due to strain concentration between the tread part and side part
Solution Approach 1:
The carcass cord extending direction is varied locally across different regions of the tire. Specifically, cords in the central region extend at a different angle than cords in the shoulder regions, allowing each local area to optimally handle the strain characteristics of that region. This local variation prevents strain concentration while maintaining overall structural integrity.
Solution Approach 2:
The carcass cord configuration transitions from a static, uniform extending direction to a dynamic, region-dependent orientation. The cords are arranged to follow the natural deformation pattern of the tire under load, with angles adjusted according to position. This dynamic adaptation allows the structure to respond optimally to varying stress conditions throughout the tire's operation.
2Strength
If carcass cords extend at a larger angle from the circumferential direction to improve rigidity, then strength is improved, but strain concentration increases at the transition zone between tread and side part
Solution Approach 1:
Different regions of the tire are assigned different carcass cord extending angles optimized for their specific functional requirements. The central region uses angles that maximize rigidity and load-bearing capacity, while the shoulder regions use angles that reduce strain concentration and improve flexibility. This local optimization allows the tire to achieve both strength and durability simultaneously.
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 design suppresses durability deterioration by optimizing strain distribution, enhancing tire durability and high-speed performance through controlled carcass cord directions and elastic modulus adjustments.
Implementation Method 1
30°C E*c represents a complex elastic modulus at 30°C of a rubber composition constituting the cap tread
Data Source
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AI summary
Provided is a pneumatic tire comprising a carcass, a reinforcing layer, and a cap tread, wherein A1, A2, Wa, Wb, 30°C E*c, and K satisfy the following inequalities: A2−A1>0 Wb−Wa>0 30°CE*c>K/A2−A1×Wb−Wa (provided that K is 145.). where A1 represents an angle of carcass cord inclined from a tire circumferential direction on a tire center line, A2 represents an angle of carcass cord inclined from the tire circumferential direction at a tire maximum width position, Wa represents a length of a belt in a tire width direction, Wb represents a length of a band in the tire width direction, 30°C E*c represents a complex elastic modulus of the cap tread, and K represents a constant.