Heavy Vehicle Tire Crown Reinforcement Cracking Prevention
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Solution Overview
Problem
Tires intended for heavy-load vehicles face durability issues due to shear stresses and cracking at the ends of crown plies, despite previous solutions that have not provided a completely satisfactory improvement under harsh running conditions.
Innovation Solution
A tire design with a radial carcass reinforcement featuring at least three plies of reinforcing elements, where the axially outer ends of each ply are separated by profiled rubber compound elements creating gradients of moduli of elasticity that decrease from the liners to the plies, providing uncoupling and enhanced resistance to separation and cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single protective ply is used in the crown reinforcement, then the structure is simple and manufacturing is easier, but the durability is insufficient under harsh running conditions
Solution Approach 1:
The protective crown reinforcement is divided into multiple plies (at least two plies) instead of using a single ply. Each ply contains reinforcing elements oriented in different directions, creating a segmented structure that provides comprehensive protection against cracking while maintaining manufacturing feasibility through standardized ply construction processes.
Solution Approach 2:
The different plies are oriented at different angles (first ply at angle α, second ply at angle β where |α|≠|β|) to provide direction-specific reinforcement. This local variation in orientation creates tailored protection zones that address the complex stress patterns at ply ends, improving durability without significantly complicating the overall manufacturing process.
2Force
If reinforcing elements are oriented at small angles with the circumferential direction, then the tire can bear heavy loads, but shear stresses increase and cause cracking at ply ends
Solution Approach 1:
Different plies are oriented at different angles to the circumferential direction. The first ply is oriented at angle α and the second ply at angle β, where the absolute values of these angles are different. This creates localized reinforcement patterns that distribute shear stresses more effectively, preventing crack initiation and propagation while maintaining overall load-bearing capacity.
Solution Approach 2:
The crown reinforcement uses a composite structure with multiple plies having different orientations. This composite arrangement of reinforcing elements at varying angles creates a more robust structure that resists both the heavy radial loads and the tangential shear stresses that cause cracking at ply ends.
3Reliability
If the axially outer end of a profiled rubber compound element is situated at a distance greater than from the equatorial plane to the end of the widest ply, then the protective coverage is improved, but the structure becomes more complex
Solution Approach 1:
The profiled rubber compound elements are positioned with their axially outer ends at a specific distance from the equatorial plane that is less than the distance to the end of the widest ply. This dimensional positioning creates an overlapping arrangement where rubber compound elements from adjacent plies intersect, providing enhanced protective coverage without requiring additional structural components or complex assembly procedures.
Data Source
AI summary
A tire with a crown reinforcement that comprises at least three plies of reinforcing elements. At least a first profiled element P1 has an axially outer end that is situated at a distance from the equatorial plane of the tire which is less than the distance separating the plane from the end of a second ply. The profiled element P1 is radially separated from the radially outer liner C1 of a first ply by a second profiled rubber compound element G1. At least a third profiled element P2 has an axially outer end that is situated at a distance from the equatorial plane of the tire which is less than the distance separating the plane from the end of a third ply. The profiled element P2 is radially separated from the radially inner liner C2 of the first ply by a fourth profiled rubber compound element G2. The profiled rubber compound elements P1, P2 and G1, G2 and the liners C1, C2 have respective tensile secant moduli of elasticity at 10% elongation MP1, MP2, MG1, MG2, MC1, MC2 such that MC1≧MG1>MP1 and MC2≧MG2>MP2.