Pneumatic Tire Sidewall Decorative Layer Strain Management
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Solution Overview
Problem
Pneumatic tire decorative portions are prone to cracking and peeling due to deformation and external damage, necessitating improved durability and resistance.
Innovation Solution
A pneumatic tire design featuring a decorative portion with a print layer, an intermediate layer, and a protective layer, where the storage moduli of the intermediate and protective layers are higher than the print layer, and the intermediate layer mitigates the rigidity difference between the print and protective layers, enhancing durability and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a decorative portion is provided on the sidewall outer surface, then the tire appearance is improved, but cracks occur in the decorative portion due to strain caused by deformation during running
Solution Approach 1:
The decorative portion is divided into multiple layers (print layer, intermediate layer, protective layer) with different storage moduli. This segmentation allows each layer to have optimized properties: the print layer provides appearance, the intermediate layer with intermediate modulus bridges the rigidity difference, and the protective layer provides durability, resolving the contradiction between appearance and reliability.
Solution Approach 2:
The patent introduces an intermediate layer with storage modulus between that of the print layer and protective layer. This parameter change in rigidity across layers reduces stress concentration and strain-induced cracking, allowing the decorative portion to maintain both appearance quality and durability under deformation conditions.
2Shape
If a decorative portion with print layer is provided on the sidewall, then the tire appearance is improved, but the print layer peels off when the tire contacts external objects like curbstones
Solution Approach 1:
The decorative portion uses a composite structure with three layers having different material properties (storage moduli). The print layer provides appearance, the intermediate layer with intermediate modulus provides transition and adhesion, and the protective layer with high modulus provides resistance to external damage, preventing peeling while maintaining appearance.
Solution Approach 2:
The intermediate layer acts as a mediator between the soft print layer and the hard protective layer. Its intermediate storage modulus allows it to bridge the rigidity gap, distributing stresses and preventing direct stress transfer that would cause peeling, thus protecting the print layer while maintaining appearance.
3Strength
If a protective layer with high storage modulus is added to improve resistance, then resistance to external damage is improved, but strain-induced cracks occur more easily due to rigidity mismatch
Solution Approach 1:
Each layer in the decorative portion has locally optimized quality (storage modulus) suited to its function. The print layer has low modulus for flexibility, the intermediate layer has intermediate modulus for stress distribution, and the protective layer has high modulus for external damage resistance. This local quality differentiation allows both cracking resistance and external damage resistance coexist.
Solution Approach 2:
The patent changes the rigidity parameter (storage modulus) progressively across the layers from low to high. This gradual parameter change eliminates abrupt rigidity transitions that would cause stress concentration and cracking, allowing the protective layer to provide resistance without compromising cracking resistance.
Data Source
AI summary
Provided is a pneumatic tire including, on an outer surface of its sidewall portion, a decorative portion including a print layer and a protective layer located on a tire outer side of the print layer. The decorative portion further includes an intermediate layer located between the print layer and the protective layer. When a storage modulus of the print layer, a storage modulus of the protective layer, and a storage modulus of the intermediate layer are respectively defined as E1′, E2′, and E3′, the following relational expression is satisfied: E2′>E3′>E1′.