Pneumatic Tire Side Surface Serrations for Crack Suppression
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Solution Overview
Problem
Pneumatic tires with longitudinal protrusion portions are prone to cracking due to stress concentration at the end portions, which can lead to crack growth and tire degradation, especially under heavy loads or cyclic loading conditions.
Innovation Solution
Incorporating serrations with inclined small grooves on the tire side surfaces near the end portions of the longitudinal protrusion portions, which are designed with varying angles and shapes to dissipate stress and prevent crack propagation, along with recessed portions to reduce stress concentration and air resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a longitudinal protrusion portion is provided on the tire side surface to improve visibility and reduce rolling resistance, then visibility and fuel efficiency are improved, but stress concentrates at the end portions of the protrusion, causing cracking and reducing tire durability
Solution Approach 1:
The end portions of the longitudinal protrusion are segmented by forming serrations with multiple small grooves. This segmentation divides the continuous protrusion structure into smaller segments, preventing stress concentration at the ends and suppressing crack initiation and propagation, thereby resolving the contradiction between maintaining the protrusion for fuel efficiency and preventing cracks for durability
Solution Approach 2:
The serration structure is applied locally only at the end portions of the longitudinal protrusion where stress concentration occurs, rather than along the entire length. This local modification maintains the overall protrusion structure for aerodynamic benefits while specifically addressing the crack susceptibility at the critical end regions
2Loss of energy
If the longitudinal protrusion portion extends along the tire side surface to reduce air resistance, then fuel efficiency is improved, but the protrusion creates stress concentration points that lead to crack growth in the direction along the protrusion
Solution Approach 1:
By segmenting the protrusion end portions with serrations, the continuous stress path along the protrusion is interrupted. The multiple small grooves create discontinuities that prevent crack propagation in the longitudinal direction, maintaining the aerodynamic benefits while improving crack resistance
Solution Approach 2:
The serration structure converts the harmful stress concentration effect into a beneficial crack-arresting feature. The same geometric discontinuities that might be expected to create stress concentrations instead serve to stop crack propagation by creating multiple reflection and termination points for stress waves
Data Source
AI summary
A pneumatic tire includes a longitudinal protrusion portion provided on at least one of tire side surfaces located on either side in a tire lateral direction, the longitudinal protrusion portion projecting from the tire side surface and extending along the tire side surface; and serration provided on the tire side surface in a region including an end portion of the longitudinal protrusion portion, the serration being formed of a plurality of small grooves arranged in parallel, and the plurality of small grooves being inclined with respect to a lateral centerline that passes through a center of the longitudinal protrusion portion in a width direction.