Studies on wear mechanics of tire are classified to three categories; analytical study, study on indoor and outdoor evaluation, application of computational mechanics. The performance of tire wear is related to resource saving and is incompatible with other environmental performances such as rolling resistance. Hence the study on tire wear becomes important. In this article, the analytical wear model studied by Schallamach and Turner, methods of indoor and outdoor evaluation for tire wear, and the application of computational mechanics will be reviewed.
Rolling resistance of tires is a highly important property for tire development as well as tire traction. The rolling resistance is mainly generated by energy loss of tire components during tire deformation, because tires transform their shape from round to flat at their contact patch. It is known that to reduce the rolling resistance, tanδ of rubber around 10 Hz should be decreased. In general, silica filled rubber shows lower tanδ around 10 Hz compared to carbon black filled rubber. On the other hand, frictional force of rubber consists of two main terms. One is hysteresis term and the other is adhesion term. It is reported that silica filled rubber shows higher frictional force in comparison with carbon black filled rubber, because of higher adhesion component of friction. Therefore, silica filled rubber can improve not only rolling resistance but also traction of tires. X-ray and Neutron scattering results show that dispersed structure of silica agglomerates in rubber is different from that of carbon black agglomerates. It is considered that the good performance of silica filled rubber in rolling resistance and traction correlates to the silica dispersed structure in rubber.
In recent years, tribological studies using polymeric materials as sliding surfaces have drawn attention of researchers. Using transparent polymeric materials makes it possible to observe the contact interface directly, where their elasticity increases the magnitude of deformation and decreases the time rate of change occurring in the contact interface, which makes it easier for us to visualize what really happens in the contact interface. In this article, the trends of studies on the dynamics of contact interface are introduced, including the abrasion patterns, the Schallamach waves, and some transient phenomena from the stick phase to the slip phase.
It is well known that elastomer surfaces vary friction behavior with the sliding conditions. These frictional characteristics depend on interfacial dissipation of viscoelastic asymmetric deformation and adhesion. As adhesion plays a dominant role in such friction behavior at very low sliding velocities, adhesive friction of elastomer is focused and discussed. The one mechanism of adhesive friction force generation is macroscopic dissipation of fracture and healing of contact junction. The other one is microscopic dissipation of attachment and deformation of molecular chain of elastomer. It is shown that the combination of these two mechanisms can explain the friction characteristics at very low speed conditions.
Recently, there has been strong attention to science and engineering inspired by biological systems. In this paper, we discuss a topic on bio-inspired tribology: switchable frictional adhesion of a gecko-inspired adhesive pad. Through this topic, we will point out the importance of design and mechanics of soft matter.