Tire Bead Transition Element for Crack Propagation
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Solution Overview
Problem
Radial tires for heavy vehicles experience crack propagation due to bending cycles, primarily at the contact surface between polymeric filler materials with differing moduli of elasticity, leading to premature degradation.
Innovation Solution
Incorporating a transition element made of polymeric material with a constant thickness, positioned between the first and second polymeric filler materials, with a modulus of elasticity intermediate between the two, to create a gradual stiffness gradient that slows down crack propagation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a stack of at least two polymeric filling materials with different moduli of elasticity is used in the filler element, then the tire can accommodate varying stress conditions, but crack propagation occurs at the contact surface between materials with different rigidities, leading to premature degradation
Solution Approach 1:
A transition element made of transition polymeric material is introduced between the first and second polymeric filling materials. This intermediary material has a modulus of elasticity that is intermediate between the two adjacent filling materials, creating a gradual stiffness gradient that reduces stress concentration at material interfaces and prevents crack propagation while maintaining the ability to accommodate varying stress conditions
2Strength
If polymeric filling materials with different moduli of elasticity are stacked radially, then the filler element can handle different stress levels, but the gradient of rigidities initiates cracks at the contact surface during bending cycles
Solution Approach 1:
The transition element is positioned specifically at the contact surface between polymeric filling materials with different moduli of elasticity, where crack initiation is most likely to occur. This localized intervention creates a gradual stiffness gradient only where needed, maintaining the stress handling capability of the different materials while eliminating the harmful effect of abrupt rigidity changes at the interface
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 transition element reduces stress and deformation locally, significantly decreasing the speed of crack propagation without altering the overall bending stiffness of the bead, thereby enhancing the endurance of the tire.
Implementation Method 1
a transition element, consisting of a transition polymeric material of constant thickness being in contact, via its radially inner face, with the first polymeric filler material and in contact, via its radially outer face, with the second polymeric filler material and the module of elasticity at 10% elongation of the transition polymeric material being intermediate between the moduli of elasticity cited at 10% respective elongation of the first and second polymeric filler materials
Data Source
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AI summary
The invention relates to improving the endurance of the beads of a radial tire for a heavy civil engineering vehicle, by reducing the propagation rate of cracks initiated at the radially innermost contact surface between a first polymer fill material (23a) in contact with the bead wire core (22) and a second polymer fill material (23b) radially outside the first polymer fill material. According to the invention, a transition element (24), consisting of a polymer transition material and having a constant thickness (e), is in contact, on the radially inner surface (24a) thereof, with the first polymer fill material (23a) and in contact, on the radially outer surface (24b) thereof, with the second polymer fill material (23b), and the modulus of elasticity of the polymer transition material at 10% extension is between the respective elastic moduli of the first and second polymer fill materials at 10% extension.