# Tomsk and Berlin scientists specified the 230-year law of friction

Scientists of Technical University of Berlin (TU Berlin) and Tomsk Polytechnic University (TPU) developed a method for exact description of friction, complementing the Amonton-Coulomb law formulated in 18th century; thanks to this it will be possible to produce less wear-prone goods, professor of TU Berlin and TPU Valentin Popov reported RIA Tomsk.

Usually, the friction is described by the law of Amonton-Coulomb, which states that the frictional force is proportional to the normal force. The law is named after the French physicists who formulated the concept of the coefficient of friction and the corresponding formula. The year of the creation of the law is 1781.

## Two universities, one problem

“Friction remains one of the most incomprehensible processes. Though this phenomenon occurs in each mechanism, the parts of which move relative to each other, – from motor proteins in living cells to tectonic plates”, – explains Popov, the head of the Department of System Dynamics and the Physics of Friction and an honorary professor of TPU.

According to him, modern scientists and manufacturers who are solving high-precision technological tasks are no longer satisfied with the Amont-Coulomb law, which is over 230 years old. A more effective method is needed. Therefore, the scientists of TPU and TU Berlin joined their efforts in trying to find a method for describing friction depending on the speed, temperature and pressure.

They developed the so-called “method of generalized characteristic curves“. Using it, it is possible to predict the friction values over a wide range of temperatures, slip velocities and normal loads. Previously, it was impossible to make it.

What will it change?

“We have assembled a puzzle of various parameters and characteristics. Now there is the universal method to accurately calculate the friction, for example, in treatment of metals by pressure, in designing of precision micromechanical devices, and prolongation of the life of medical implants”, – Popov says.

According to him, the new method will allow, for example, to adjust the shape of the dental implant so that it was more wear-resistant. The same concerns car tires and many other directions.

The joint work of the TU Berlin and TPU scientists became possible thanks to the cooperation agreement signed in 2007. It involves scientific projects, academic exchange, as well as a “double degree” programs for students.

“In this project, Tomsk residents have done a great job. I will give a comparison: in my house there is a puzzle on the wall composed of 30,000 parts. To collect it, my family passed every detail through the scanner, wrote a program which helped to unite the details into a single whole. So: Tomsk scientists just became such a program – they suggested how to assemble a puzzle from various characteristics and parameters of friction”, – the professor shared.

Material provided by RIA Tomsk.