Tire Bead Turn-Up Geometry Reduces Compression Fatigue
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Solution Overview
Problem
Radial tires for heavy construction vehicles experience reduced endurance due to compressive deformations in the turn-up of the bead, leading to fatigue failure and reduced tire life, especially under bending cycles during vehicle operation.
Innovation Solution
The tire design features a carcass reinforcement with a turn-up geometry where the distance between the turn-up and the main part decreases continuously radially from the bead wire to a minimum, then remains constant, and finally increases to a maximum, reducing compressive deformations and shear forces, and utilizing a polymer coating material for the bead wire to soften its torsional stiffness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the turn-up is made long to allow carcass reinforcement to anchor to the bead wire, then the anchoring strength is improved, but the compressive deformations increase leading to fatigue failure
Solution Approach 1:
The patent applies the dynamics principle by making the turn-up geometry adaptable through a specific three-segment configuration (first segment with decreasing distance, second segment with constant minimum distance, third segment with increasing distance). This dynamic geometric design allows the turn-up to optimize its structural performance under bending cycles, reducing compressive deformations in critical areas while maintaining anchoring strength where needed.
Solution Approach 2:
The patent employs parameter changes by precisely controlling the distance variations between the turn-up and main part across different segments. The distance parameter is systematically varied: decreasing in the first segment, constant at minimum in the second segment, and increasing in the third segment. This parameter optimization reduces compressive stresses while preserving the anchoring function.
2Force
If the bead wire has high torsional stiffness to react tension forces, then the tension reaction capability is improved, but the compressive deformations in the turn-up increase during bending
Solution Approach 1:
The patent applies local quality by differentiating the functional requirements of different turn-up segments. The first segment maintains closer spacing for anchoring, the second segment uses constant minimum distance to reduce compression, and the third segment increases distance to accommodate bending. This localized optimization allows the bead wire to maintain high torsional stiffness for tension while minimizing compressive deformations in specific critical zones.
3Strength
If the turn-up extends radially outward to increase anchoring, then the anchoring effectiveness is improved, but the sensitivity to compression increases due to positioning in high-bending regions
Solution Approach 1:
The patent applies segmentation by dividing the turn-up into three distinct segments with different geometric characteristics and functions. The first segment handles anchoring with decreasing distance, the second segment reduces compression sensitivity with constant minimum distance, and the third segment accommodates radial extension with increasing distance. This segmentation isolates the anchoring function from high-compression zones while maintaining overall effectiveness.
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 significantly reduces the extent of turn-up compression, enhances tire endurance, and minimizes the risk of cracking by preloading the turn-up with tension and reducing shear forces, thereby extending the tire's lifespan.
Implementation Method 1
utilizing a polymer coating material for the bead wire to soften its torsional stiffness
Data Source
AI summary
The invention relates to improving the endurance of a bead of a radial tire for a heavy vehicle of construction plant type by reducing the compression to which the turn-up is subjected when the tire is driven on. According to the invention, for a tire for a heavy vehicle of construction plant type comprising two beads intended to come into contact with a rim having two rim flanges, a carcass reinforcement comprising at least one carcass reinforcement layer having a main part wrapped, within each bead, from the inside towards the outside of the tire, around a bead wire of substantially circular meridian section, to form a turn-up, a filling element extending the bead wire radially towards the outside and axially separating the main part and the turn-up, the distance (d) between a first segment of turn-up and the main part decreasing continuously, radially towards the outside, from the bead wire as far as a minimum distance (d1), the distance (d2) between a second segment of turn-up, extending the first segment of turn-up radially towards the outside, and the main part is substantially constant and equal to the minimum distance (d1) between the first segment of turn-up and the main part.