By Sunish Vadakkeveetil, Mehran Shams Kondori, and Saied Taheri

Center for Tire Research (CenTiRe), Virginia Tech

 

 

 

 

 

 

 

 

Rubber, mainly because of its viscous nature, is a widely used material for most contact applications such as, seals, tyres, footwear, wiper blades, bushings etc. The material possesses the property of both a liquid (viscous) and a solid (elastic). Hence, rubber frictional losses at the contact interface is classified into three mechanisms as shown in Figure 1. Hysteresis  (μ_hys ) – Energy dissipated due to internal damping of rubber caused by undulation in the surface. Adhesion (μ_adh ) – Due to intermolecular or Vander Waals attraction at the contact interface. It vanishes in the presence of contaminants or lubricants on the surface. Viscous (μ_visc ) – Due to hydrodynamic resistance caused by the fluid in the contact interface. It mainly occurs under the presence of lubricant or fluid in between the contact interface.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Friction as a concept has evolved, as shown in Figure 2 from a simple empirical relation, developed by Amonton’s (1699) and Columb (1785) to more complex representations by considering these different mechanisms of friction. Initial experimental observations by Bowden and Tabor [1] observed the microscopic behaviour of the contact and obtained that the real area of contact is only a part of the nominal contact area. Grosch & Schallamach [2] performed experimental observation to determine the influential factors and obtain a relation between temperature and velocity-dependent friction to frequency-dependent viscoelastic behaviour. Savkoor[3] considers the frictional losses due to adhesive mechanism at the contact interface using a rudimentary theory where the interaction is considered as a series of processes from the growth of contact area in the initial stage to initiation and propagation of crack in the final stage.

Heinrich [4] developed an analytical representation to estimate the hysteretic component of friction by considering the energy losses at the contact interface to the internal damping of rubber from the undulations of the surface. The energy loss thus obtained is related to the frictional shear stress by the energy relation given by Eq. (2).

            ΔE=∫d^3 x dt u ̇ . σ (1)

           σ_f=ΔE/(A_0 v t)     (2)

Persson and Klüppel [5] extended the theory to consider the effect of the surface roughness by assuming the surface to behave as a fractal nature and obtaining the total energy loss being the sum over the different length scales. Klüppel considers the GW theory to consider the contact mechanics where Persson developed a stochastic based contact mechanics theory assuming the rubber deformations to follow the surface asperities, the results are as shown in Figure 3. To consider the actual deformation profile of rubber, an affine transformation approach [6] is considered to obtain the actual deformation of rubber contact. The results are as shown in Figure 4.

 

 

 

 

 

 

 

In addition to analytical methods, computational approaches are also considered to estimate deformation behaviour of a rubber block on a rough substrate (Figure 5). The numerical model [7] is validated using indentation experiment and compared against a single asperity model as shown in Figure 6. This is later being extended to obtain friction and wear characteristics of rubber at the contact interface by considering the deformations at the contact interface and obtaining the frictional force [5], [8].

 

 

 

 

 

 

 

 

 

 

Figure 6: FE Model Of Single Asperity Model & Comparison Of Results With Experimental & Analytical Approach

Wear is mainly due to the frictional shear stress generated at the contact interface leads to energy dissipation at the rubber – substrate contact interface that is either transformed into heat or responsible for crack initiation and propagation eventually leading to material removal. The major contribution of the wear occurs either due to the interaction of smooth asperity and rubber surface (adhesive wear), Figure 7 (a) instantaneous tearing of rubber by sharp asperities (abrasive wear), Figure 7 (b) or due to repeated cyclic contact stress (fatigue wear, Figure 7 (c)).

Due to the importance and complexity of the wear problem, it has been a vital topic of interest studied by many researchers [2]. Numerical techniques and empirical approaches have seen their light in the midst of the expensive and cumbersome experimental observations [9], [10]. Archard’s law states that “the volume rate of wear (W) is proportional to the work done by the frictional forces” as given by Eq. (3), where τ_f is the frictional shear stress and v is sliding velocity.

            W∝τ_f  v       (3)

 

 

 

 

 

 

 

 

 

 

 

In the case of road surfaces, the removal of rubber particles can be considered as a process of nucleation and propagation of crack like defects until it is detached to form a wear particle, as shown in Figure 8. Based on this mechanism of crack propagation, a physics-based theory assuming the crack propagates (Figure 9 & Figure 10) from already present defects or voids on the rubber surface was considered and then later compared with experimental methods performed using Dynamic Friction Tester (Figure 11) [6], [11], [12]. Future studies are being performed using analytical and computational approached to estimate the wear characteristics of a rubber material considering damage mechanics [8] and crack propagation theory considering the effect of surface roughness. An experimental technique is also being developed based on the Leonardo Da Vinci concept to experimental test the friction and wear characteristics of a rubber block under pure sliding.

 

References:

[1]       D. Bowden, F. P., & Tabor, The friction and lubrication of solids. Oxford university press., 2001.

[2]       A. Gent and J. Walter, The Pneumatic Tire, no. February. 2006.

[3]       A. R. Savkoor, “Dry adhesive friction of elastomers: a study of the fundamental mechanical aspects,” 1987.

[4]       H. Gert, “Hysteresis friction of sliding rubber on rough and fractal surfaces,” Pochvozn. i Agrokhimiya, vol. 25, no. 5, pp. 62–68, 1990.

[5]       S. Vadakkeveetil, “Analytical Modeling for Sliding Friction of Rubber-Road Contact,” Virginia Tech, 2017.

[6]       A. Emami and S. Taheri, “Investigation on Physics-based Multi-scale Modeling of Contact, Friction, and Wear in Viscoelastic Materials with Application in Rubber Compounds,” Virginia Tech, 2018.

[7]       S. Vadakkeveetil, A. Nouri, and S. Taheri, “Comparison of Analytical Model for Contact Mechanics Parameters with Numerical Analysis and Experimental Results,” Tire Sci. Technol., p. tire.19.180198, May 2019.

[8]       S. Vadakkeveetil and S. Taheri, “MULTI – LENGTH SCALE MODELING OF RUBBER TRIBOLOGY FOR TIRE APPLICATIONS,” Virginia Tech, 2019.

[9]       K. R. Smith, R. H. Kennedy, and S. B. Knisley, “Prediction of Tire Profile Wear by Steady-state FEM,” Tire Sci. Technol., vol. 36, no. 4, pp. 290–303, 2008.

[10]    B. W. and R. N. D. Stalnaker, J. Turner, D.Parekh, “Indoor Simulation of Tire Wear: Some Case Studies,” Tire Sci. Technol., vol. 24, no. 2, pp. 94–118, 1996.

[11]    A. Emami, S. Khaleghian, C. Su, and S. Taheri, “Comparison of multiscale analytical model of friction and wear of viscoelastic materials with experiments,” in ASME International Mechanical Engineering Congress and Exposition, Proceedings (IMECE), 2017, vol. 9.

[12]    M. Motamedi, C. Su, M. Craft, S. Taheri, and C. Sandu, “Development of a Laboratory Based Dynamic Friction Tester,” in ISTVS 7th Americas Regional Conference, 2013.

 

Yokohama Rubber completed enforcement action to halt the production and distribution of counterfeit versions of its “ADVAN Racing” aluminium wheels in China following a coordinated investigation with local authorities.

The Japanese tyre and wheel manufacturer filed an administrative complaint with the Municipal Administration for Market Regulation in Anlu City, Hubei Province, after uncovering a local manufacturer producing unauthorised copies of its high-performance wheels for sports cars.

Authorities in Anlu conducted a raid at the site in November 2024, seizing all counterfeit wheels. A subsequent investigation led to the identification of another company that had commissioned the counterfeit production. Administrative penalties were imposed on the ordering party, including a fine and an order to cease all illegal activity and surrender any remaining fake products.

This marks Yokohama Rubber’s latest successful enforcement action in China. The company had previously filed complaints targeting distributors of counterfeit wheels, resulting in the removal of fake products from the market.

“Yokohama Rubber remains resolute in its stance against the infringement of intellectual property rights, including the production and sale of counterfeit goods, and will strengthen its efforts against such illegal activities in Japan and overseas to ensure that its customers around the world are confident and secure in the knowledge that they are using genuine YOKOHAMA products,” the company said in a statement.

Japanese chemical manufacturer Tosoh Corporation announced plans on Wednesday to construct a second chloroprene rubber production facility at its Nanyo Complex, representing an investment of approximately ¥75 billion (£460 million) to meet rising global demand for the speciality polymer.

The new facility, scheduled to begin construction in spring 2027, will add 22,000 metric tonnes of annual production capacity for Tosoh’s SKYPRENE chloroprene rubber brand. Commercial operations are expected to commence in spring 2030 at the Shunan City site in Yamaguchi Prefecture.

Chloroprene rubber serves as a critical component across multiple industries, from automotive manufacturing to medical applications. The synthetic rubber’s popularity stems from its exceptional resistance to oil, weather conditions, and flame exposure, making it suitable for demanding applications, including automotive hoses, industrial belts, adhesives, and medical gloves.

The expansion comes as global demand for high-performance polymers continues to grow, driven by increasing automotive production and stricter safety requirements across industrial sectors. Medical applications have also seen increased demand following heightened awareness of the requirements for protective equipment.

Tosoh’s decision to double down on chloroprene rubber production reflects the material’s position within what the company terms its “Chemical Chain Business” - a strategy focused on value-added speciality chemicals rather than commodity products.

The investment represents one of the larger capacity expansion projects announced by Japanese chemical companies this year, signalling confidence in long-term demand fundamentals despite current global economic uncertainties.

The Nanyo Complex already houses Tosoh’s existing chloroprene rubber operations alongside other chemical production facilities. The site’s established infrastructure and logistics capabilities influenced the decision to expand at the existing location rather than develop a greenfield facility.

Industry analysts note that the three-year construction timeline reflects the technical complexity of chloroprene rubber production, which requires specialised equipment and stringent safety protocols due to the chemical processes involved.

The expansion aligns with broader trends in the Japanese chemical industry, where companies are increasingly focusing on high-margin speciality products to offset competitive pressures in traditional commodity chemicals from lower-cost Asian producers.

Epsilon Carbon, a leading global manufacturer of carbon black, has launched N134, which it claims is a specialised ‘Hard Grade’ carbon black known for its superior abrasion resistance and durability.

At present, the high-quality N134 grade is being imported due to the lack of consistent quality and supply chain issues in the Indian market. As a result, the tyre makers have to modify their formulations using other grades of carbon black, which it shared often leads to reduced performance.

But now, Epsilon Carbon has become the first company in India to install a dedicated manufacturing unit designed for N134 grade hard carbon. The company is expanding its existing Vijayanagar Carbon complex facility to produce 215,000 tonnes of carbon black.

This will not only ensure consistent supply of N134 carbon black for tyre makers in the country, reduce import dependency, but also open up export potential to markets such as Europe and USA. Epsilon Carbon will also focus on integrate advanced processing techniques to ensure batch consistency for durability and performance.

Vikram Handa, Managing Director, Epsilon Carbon, said, “This is a proud moment for us and for India’s carbon black manufacturing sector as the high quality N134 black will significantly reduce import dependency and provide tire manufacturers in India and abroad with a reliable, high-quality product. Our goal is to match global standards while building India’s capability to serve premium markets.”

Lummus Technology, a leading provider of process technologies and energy solutions, has signed a memorandum of understanding (MoU) with InnoVent Renewables to collaborate on the global licensing and deployment of InnoVent’s continuous tyre pyrolysis technology.

Under the proposed agreement, Lummus will become the exclusive licensor for InnoVent’s proprietary pyrolysis process, which transforms end-of-life tyres into valuable outputs, including pyrolysis oil, gas, recycled carbon black and steel. Additionally, Lummus will offer integrated technology packages that combine InnoVent’s pyrolysis system with its own downstream processing solutions, enhancing the value of fuel and chemical products derived from waste tyres.

InnoVent’s technology provides a fully scalable, end-to-end solution for converting discarded tyres into renewable fuels and high-value petrochemicals, covering everything from pre-processing to purification. The company currently operates a commercial-scale facility in Monterrey, Mexico, with an annual processing capacity of up to one million passenger tyres, and has the capability to expand further.

Leon de Bruyn, President and Chief Executive Officer, Lummus Technology, said, “This is another significant step in expanding and strengthening our portfolio for the circular economy. By combining InnoVent’s tyre recycling technology with Lummus’ global licensing and engineering expertise, we will be addressing the global challenge of waste tyres and creating new pathways for sustainable product development.”

Vibhu Sharma, Chief Executive Officer, InnoVent Renewables, said, “Partnering with Lummus has the potential to accelerate the global deployment of our technology and help us address the environmental and public health challenges of one billion end-of-life tyres that are disposed of annually. Together, we can transform waste into valuable resources, reduce carbon emissions and support the transition to a more sustainable future.”