University of Twente tire wear test is up-to-scratch

Belval, Luxembourg – Researchers at the University of Twente in The Netherlands have developed a “simple but credible and potentially useful” contribution to the study of tire wear, focusing on the interaction between rubber and a ‘single asperity’.

The start-point was to find out what could be learned about wear initiation by studying the earliest local contact event in a controlled scratch-based test, according to prof dr. Anke Blume and dr Pilar Bernal Ortega.

Rather than full-scale wear testing, the aim was to find a simple way to understand deformation, crack-initiation and cutting under controlled conditions, they explained at the recent Endurica community conference* in Luxembourg.

Though straightforward, the resulting lab setup – an indenter, sample holder, controlled motion and force measurement units – is “still capable of producing meaningful outputs,” said the co-presenters.

Despite a lack of ‘scientific elegance,’ the system can measure parameters include frictional force, normal force, penetration behaviour, coefficient of friction, and visual evidence of damage progression, added Blume.

Furthermore, the scratch testing method was found to be usable, repeatable, and “worth adopting as a screening tool” with potentially significant value in comparative formulation studies.

Continued Blume, it can effectively identify four deformation stages: elastic deformation, ploughing, tearing and cutting – offering a useful aid to specialists working on tread compounds, abrasion resistance or frictional behaviour.

Tire wear is governed by multiple overlapping variables - compound design, filler system, hysteresis, contact mechanics, and environmental conditions, noted the research leaders.

To explore how polymer type and filler system influence scratch response, for instance, the team compared natural rubber and SBR systems with both carbon black and silica reinforcement.

The results indicated that silica-filled natural rubber performs unexpectedly well in this test, even relative to silica-filled SBR – as used for example in truck tires, earthmover compound applications

This surprising result, suggested Blume, invites closer attention to mechanisms such as strain crystallisation, elasticity, crosslink structure, filler networking, and crack propagation resistance.

In conclusion, the presenters underlined the potential value of a lab scratch test that can generate particles in a relevant size range, particularly amid the current focus on tire and road wear particles.

The method, they believe, could eventually attract significant industrial: serving not only as a screening tool but also as a platform for controlled particle generation studies.

*Themed ‘Dimensions of durability’, the Endurica community conference took place 5-6 May in Belval, Luxembourg: spotlighting how fracture mechanical analysis and simulation modelling are gaining traction across rubber materials and product R&D.  Read more