Original Article Design and development of a new portable test setup to study friction and wear Anahita Emami 1 , Seyedmeysam Khaleghian 2 , Tyler Bezek 3 and Saied Taheri 3 Abstract In this paper, a novel portable sliding friction and wear test rig is introduced. Unlike other laboratory-based test setups, this setup can be used for both indoor and outdoor experiments. There is also no limitation on the size and type of the substrate surface that can be used for the friction and wear test in contrast to typical test rigs, which have some limitations for the size and type of substrate surface. A small six-wheel ground robot is developed to drag the sample on an arbitrary surface for a desired distance and velocity. A ground robot is an unmanned ground vehicle, capable of driving on the ground without humans on board. The speed of this robot can be measured and controlled precisely. The nominal normal load is adjusted using dead weights placed on the sample holder and the friction force is measured using a load cell. An adjustable sample holder was also designed and built to hold different-size specimens. The results of styrene– butadiene rubber block sliding on an asphalt track are presented to validate the test setup and illustrate the potential of the system for friction and wear testing. In addition, the effect of sliding velocity on the friction and wear is studied, and the correlation between the wear rate and the friction coefficient is investigated. These experimental results can be used to estimate the friction and life span of a tire tread compound on the real asphalt road. Finally, the formation of abrasion pattern observed on the rubber surface sliding on an asphalt track is discussed, which provides an insight into the understanding of dominant wear mechanism of tire tread compound on typical asphalt surfaces. Keywords Portable sliding friction and wear tester, rubber friction, wear rate, abrasion pattern, friction and wear, asphalt surface Date received: 30 August 2018; accepted: 15 July 2019 Introduction Friction and wear are subjects of importance in many applications that involve components in contact with one another. In some applications, such as generators and motors, it is desired to reduce the friction between the components to increase energy conservation, while in others, such as tires and shoes, the objective is to increase the friction as much as possible to pre- vent slip. On the other hand, in all these applications, the mass loss due to wear must be minimized to increase the lifespan of the components. Typically, the wear loss is closely associated with frictional work, 1,2 particularly in rubbers. 3–7 The correlation between friction and wear creates challenges for material designers when high friction is desired. The well-known Archard equation of wear, 8 presents a linear relation between volume loss and frictional work, assuming the friction and abrasion coefficients remain constant. However, in general, the relationship between wear rate and friction does not obey a simple rule, and it depends on different parameters such as environmental conditions, e.g. temperature and humidity, 9 and operating condition such as normal load, 10 velocity, 11 and the topography of contact sur- faces. Moreover, in some conditions, there is no direct relationship between friction and wear, and they behave oppositely. For example, it has been found that at a fixed velocity, the rubber wear is very high at very low temperature, e.g. T ¼50  C, and it 1 Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA 2 Department of Engineering Technology, Texas State University, San Marcos, TX, USA 3 Department of Mechanical Engineering, Virginia Polytechnic Institute and State University, Blacksburg, VA, USA Corresponding author: Anahita Emami, Department of Biomedical Engineering and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA. Email: anahita@vt.edu Proc IMechE Part J: J Engineering Tribology 0(0) 1–13 ! IMechE 2019 Article reuse guidelines: sagepub.com/journals-permissions DOI: 10.1177/1350650119867795 journals.sagepub.com/home/pij