Tire Bead Transition Element for Crack Resistance
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Solution Overview
Problem
Radial tires for heavy construction vehicles face premature failure due to compressive deformations and cracking in the bead area, primarily caused by bending cycles and imperfect cohesion between polymer filling materials with differing stiffnesses, leading to reduced endurance and life expectancy.
Innovation Solution
Incorporating a transition element made of a polymer material with an elastic modulus between the inner and outer polymer filling materials, which reduces the stiffness gradient and slows crack propagation by interposing between the first and second polymer filling materials, thereby minimizing stress and deformation in the transition zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polymer filling materials with different stiffnesses are used in the bead, then the bead can be optimized for different functional zones, but cracking occurs at the interface between materials due to stiffness gradient
Solution Approach 1:
The patent applies local quality by using different polymer filling materials with different stiffnesses in different zones of the bead. The first polymer filling material has higher stiffness for structural support, while the second polymer filling material has lower stiffness for flexibility. This zonal differentiation optimizes each region for its specific function while managing the stiffness gradient to reduce cracking.
Solution Approach 2:
The patent introduces a transition element as an intermediary between the first and second polymer filling materials. This transition element has intermediate stiffness properties that bridge the stiffness gradient, reducing stress concentration at the interface and preventing crack propagation between the two dissimilar materials.
2Reliability
If a transition element with intermediate elastic modulus is introduced between polymer filling materials, then crack propagation is slowed, but the device complexity increases
Solution Approach 1:
The transition element serves as a mediator between the two polymer filling materials with different stiffnesses. By introducing this intermediate layer with elastic modulus values between those of the first and second materials, the patent creates a gradual stiffness transition that reduces stress concentration and slows crack propagation, accepting the trade-off of increased structural complexity for improved reliability.
3Strength
If the elastic modulus of polymer filling materials is increased to improve bead stiffness, then bending resistance improves, but compressive deformations and cracking increase under bending cycles
Solution Approach 1:
The patent applies local quality by differentiating the stiffness properties of polymer filling materials in different bead zones. The first polymer filling material has higher elastic modulus for bending resistance, while the second has lower elastic modulus to accommodate compressive deformations during bending cycles, thereby improving endurance.
Solution Approach 2:
The patent changes the elastic modulus parameter of polymer filling materials across different zones of the bead. By creating a gradient in this mechanical property, the structure can simultaneously achieve high bending resistance in critical areas while maintaining flexibility and crack resistance in areas subject to compressive deformations.
Data Source
AI summary
The invention relates to improving the endurance of the beads of a radial tire for a heavy vehicle of construction plant type, by reducing the cracking that starts at the surface of contact between a first polymer filling material that is radially furthest towards the inside and in contact with the bead wire and a second polymer filling material that is radially on the outside of the first polymer filling material. According to the invention, a transition element, made of a polymer transition material, is in contact, via its radially inner face, with the first polymer filling material and is in contact, via its radially outer face, with the second polymer filling material, and the elastic modulus at 10% elongation of the polymer transition material is somewhere between the respective elastic moduluses at 10% elongation of the first and second polymer filling materials.