Dynamic friction test
Introduction
Tribology (from the Greek τρίβω tríbō, "rub or rub") is the science that studies surfaces that interact in relative motion, and any aspect that is related to the design of a machine such as friction, wear and lubrication. The term has been used universally since the end of the century.
“Tribology is key in the analysis of bearings, studying the interaction between friction, lubrication and wear.” [1].
To understand tribology, knowledge of other sciences is required, such as physics, chemistry, mathematics, engineering, computer science, materials technology and many others. The tasks of the tribology specialist (tribologist) are to reduce friction and wear by lubricating the surfaces in contact to conserve and reduce energy, achieve faster and more precise movements, increase productivity, reduce maintenance and extend the useful life of the machine.
History
Early history
Despite the relatively recent name of the field of tribology, quantitative studies of friction date back to 1493, when Leonardo da Vinci first noted the two fundamental 'laws' of friction. According to Leonardo, frictional resistance was the same for two different objects of the same weight but the contact was of different widths and lengths. He also observed that the force needed to overcome friction doubled when the weight was doubled. However, Leonardo's findings remained unpublished in his notebooks.[2].
The two fundamental 'laws' of friction were first published in 1699 by Guillaume Amontons, with whose name they are now generally associated. They claim that:[2].
• - the friction force acting between two sliding surfaces is proportional to the load pressing the surfaces together;.
• - the friction force is independent of the apparent area of contact between the two surfaces.
Although not universally applicable, these simple statements are valid for a surprisingly wide variety of systems.[3] These laws were developed in 1785 by Charles-Augustin de Coulomb, who noted that the force of static friction can depend on the contact time and that sliding (kinetic) friction can depend on the sliding speed, the normal force, and the contact area.[4][5].
In 1798, Charles Hatchett and Henry Cavendish carried out the first reliable friction wear test. In a study commissioned by the Privy Council of the United Kingdom, they used a simple reciprocating machine to evaluate the rate of gold coin wear. They found that coins with sand between them wore more quickly compared to self-rigged coins.[6] In 1860, Theodor Reye")[8] proposed the Reye hypothesis").[9] In 1953, John Frederick Archard") developed the Archard equation") which describes sliding wear and is based on the theory of contact with asperities").[10].