Thick Tread Locking Blocks to Reduce Shear Strain
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Solution Overview
Problem
Civil engineering vehicle tires with thick treads (at least 25 mm) face issues with rapid localized wear and cracking due to differences in shear strain between tread pattern elements, leading to reduced traction and wear performance, and existing solutions compromise groove volume and active edge length.
Innovation Solution
A tire tread design featuring circumferentially and transversely oriented grooves and recesses in edge ribs that lock central blocks, maintaining space between them to reduce shear strain and prevent contact with neighboring blocks, thereby preserving groove volume and active edge length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of wearable tread material is increased to at least 25 mm to improve durability and load-carrying capacity, then the tire can support heavier loads and provide better traction, but the differences in shear strain between tread pattern elements are amplified, leading to rapid localized wear and cracking of the rubber on the bottoms of grooves
Solution Approach 1:
The tread pattern is segmented into multiple circumferential rows with grooves that divide the tread into discrete blocks and ribs. This segmentation allows each element to move independently, reducing the amplification of shear strain differences across the thick tread material and preventing concentrated stress that leads to cracking and localized wear.
Solution Approach 2:
The tread pattern incorporates elements of different geometries and configurations at different locations - varying groove depths, block sizes, and rib arrangements - to locally adapt to the stress distribution in the thick tread. This allows optimal performance in different circumferential rows while managing the shear strain variations caused by the increased tread thickness.
2Reliability
If platforms are placed between the blocks to limit bending movement during running, then the cracking of rubber on the bottoms of grooves is reduced, but the available groove volume is reduced and the active edge length is reduced when the tread is worn down to the level of these platforms
Solution Approach 1:
Transverse grooves act as intermediary elements between adjacent blocks in the same circumferential row. These grooves provide space that allows blocks to move independently and reduces direct contact between neighboring blocks, thereby limiting bending movement and crack propagation without requiring solid platforms that would reduce active edge length.
Solution Approach 2:
The design accepts that blocks may come into contact during severe cornering, but the transverse grooves provide recovery space. When the tread wears down, the grooves maintain their volume and continue to provide separation space, allowing the tire to maintain crack resistance throughout its service life without sacrificing active edge length at any stage of wear.
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 design enhances wear resistance, traction, and reduces cracking in the bottoms of grooves, maintaining effective groove volume and active edge length, even under heavy load and cornering conditions.
Implementation Method 1
this load generating extension constraints by the Poisson effect
Data Source
AI summary
Tread for civil engineering tires, having blocks in the central part and edge ribs, each block having a width Ltb measured parallel to transverse edges and a width Lcb measured along the circumferential direction, wherein each edge rib has a plurality of recesses, forming housings, with a transverse width Lte and a circumferential length Lce, delimited over the whole of its height He by transversely orientated walls and a circumferentially orientated wall, having a suitable geometry to receive at least an end part of a block of the central region with a circumferential clearance Ac in the circumferential direction and a transverse clearance At in the transverse or axial direction, these clearances determined to ensure that, in the usual running conditions of the tire the end part of said block of the central region is at least partially in contact with at least one of the transversely orientated walls of each recess, thereby preventing each of the blocks, having its ends locked in said recesses, from coming into contact with the neighboring blocks of the central row.