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Surface Failure
Published in Ansel C. Ugural, Mechanical Engineering Design, 2022
Friction is the force resisting relative movement between surfaces in contact. When a force is applied to a body, the resistive force of friction acts in the opposite direction, parallel to mating surfaces. The fundamental kinds of friction are sliding and rolling. The fundamental equation for determining the resistive force of friction when trying to slide two solid bodies together states that the force of friction equals the coefficient of friction times the normal compressive force pushing the two bodies together. Therefore, F=fP
Motor Brake
Published in Wei Tong, Mechanical Design and Manufacturing of Electric Motors, 2022
There are two main types of friction: static friction and dynamic (kinetic) friction. Static friction refers to the resistance between contacted stationary objects to prevent relative movement between them. As shown in Figure 7.1, when a stationary object placed on the ground is subjected to a small horizontal force p, a static friction force Fs is generated tangentially at the contact interface in the direction opposite to the tendency of motion. Static friction is typically considered as a self-adjusting force because the relationship Fs= p is held until its maximum value Fs,max is reached.
Surface Failure
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
Friction is the force resisting relative movement between surfaces in contact. When a force is applied to a body, the resistive force of friction acts in the opposite direction, parallel to mating surfaces. The fundamental kinds of friction are sliding and rolling. The fundamental equation for determining the resistive force of friction when trying to slide two solid bodies together states that the force of friction equals the coefficient of friction times the normal compressive force pushing the two bodies together Therefore, F=fP
Tribological Behaviors of OA-ZIF-8/GO as Additives of the Lubricating Oil
Published in Tribology Transactions, 2022
Friction and wear can lead to production failures and energy losses in machinery. According to statistics, nearly 80% of machine failures are caused by friction and wear, and the frictional contact consumes about 23% of the world's overall energy (1). The friction and wear have a serious impact on the low-carbon environmental protection and efficient use of resources in human society (2). Hence, there is a great necessity to develop methods that can effectively reduce friction and wear on equipment. Numerous surveys have shown that the most effective way to reduce frictional wear is through the use of lubricants in solid, liquid, or gaseous form. Lubricating oils are the most commonly employed liquid lubricants, and form an oil film between two moving solid surfaces and thus effectively reduce friction and wear. To boost the lubrication efficiency of lubricants, lubrication additives were often added to the lubricant. The conventional additives, such as ZDDP, generally contain heavy metals, sulfur, phosphorus, and other elements that can be harmful to the environment (3). In recent years, with the growing demand for lubrication and environmental protection, traditional friction-reducing and antiwear agents are under great challenges, and research on the excellent performance of green friction-reducing and antiwear agents has become one of the hotspots in the field of tribology.
Slip safety risk analysis of surface properties using the coefficients of friction of rocks
Published in International Journal of Occupational Safety and Ergonomics, 2019
Gültekin Çoşkun, Gencay Sarıışık, Ali Sarıışık
Studies aiming to reduce accidents due to slipperiness have increased as a result of increasing numbers of pedestrian slipping accidents [23]. The importance of surface roughness (SR) in slip resistance (SLR) measurements and its role as one of the factors determining optimal material and floor covering have been emphasized in many studies since 1988 [24–30]. The SLR depends on friction, and SR has an effect on friction. Friction is the resistance to relative motion between two bodies in contact with each other. These bodies are the slider and test specimens, or the base of the shoe and the surface upon which it is moved. Friction force is the force acting tangentially in the contact area [31–34]. Determining the role of SR on friction can benefit floor producers and designers. Increase of SR increases the SLR of floor covering, thereby reducing slipperiness [35–37]. Note that every surface has some degree of roughness, although the scale of the roughness might be microscopic [38].
Fiber-on-fiber friction measurement using hanging fiber method
Published in The Journal of The Textile Institute, 2018
Azam Alirezazadeh, Mohammad Zarrebini, Mohammad Ghane, Parham Soltani
Friction is an important property of textile materials that affects their desirable processing and performance. Friction is important in cases such as needle punching process, carding and spinning of yarns, wool felting, abrasion, and wear of cloth (P. Soltani & M. S. Johari, 2012). Despite conduction of vast amount of researches on various aspects of frictional behavior of textiles, the subject still is one of the most complicated, partly understood, and difficult to control phenomenon associated with textiles. Friction phenomenon arises from interaction between two in-contact surfaces. Factors affecting this interaction system either individually or collectively are bound to influence the frictional behavior of the two surfaces. Numerous investigations with the aim of measuring or understanding this phenomenon have been conducted. These investigations have led to classification of the relevant factors into material-related and process-related categorizes. While the former includes fiber morphology factors such as surface features, cross-sectional shape, dimensions, surface lubricant, and molecular orientation, the latter includes normal force between the two surfaces, contact area, sliding speed, and the environmental conditions (Marcicano, Tu, & Rylander, 2004; Rajanala, 2007; Wang et al., 2016).