ABSTRACT
The friction law of Coulomb, still employed in engineering problems, implies a constant friction between contacting surfaces. Experiments for rubber on rough surfaces clearly show that Coulomb’s law is not sufficient and advanced macroscopic friction laws (Savkoor 1966) and (Huemer, Liu, Eberhardsteiner, & Mang 2001) are used depending on contact pressure and slip velocity. An extension of these two friction laws to include temperature is presented in (Falk, Nazarinezhad, & Kaliske 2014). These mathematical functions are fitted according to extensive experimental results and cannot include surface roughness or the interaction with the individual rubber sample. For a deep understanding of rubber friction, a finite element based multiscale approach is presented to access the micrometer length scalein order to homogenize the contact interaction as well as the macroscopic
1 INTRODUCTION
Friction is one of the oldest physical problems investigated (Feeny, Guran, Hinrichs, & Popp 1998) and it is still widely discussed in scientific and industrial research nowadays (Persson 2006), (Le Gal & Klüppel 2008), as friction becomes important in many engineering applications. For engine constructions, friction needs to be minimised to improve efficiency, while for tires, friction needs to be high for safe braking and cornering manoeuvres even for wet road conditions.
