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Common Problems Involving Friction
Published in G. Boothroyd, C. Poli, Applied Engineering Mechanics, 2018
When a rope or belt is coiled around a shaft or pulley (Fig. 10.1) the tendency for the rope or belt to slip depends substantially on the angle subtended by the arc of contact. For example, a rope coiled around a ship’s capstan (Fig. 10.2) is able to provide so much resistance to sliding that the ship can be pulled toward the dock by rotating the capstan. This frictional resistance is known as belt friction, a phenomenon which also allows the transmission of large quantities of power through belt and rope drives.
Evaluating the surface hairiness of woven fabric belts with a yarn hairiness tester
Published in The Journal of The Textile Institute, 2022
Zhigang Xia, Mian Zhou, Hongshan Wang, Kezuo Wang, Youshun Wan
Figure 6 showed the 2mm wide belt fabric could withstand frictions for hundreds of times. This again validated that the 2mm wide belt of fabric had both excellent anti-friction and qualified accurate detectable hairs in this study. Furthermore, Figure 6 also revealed that the wider the fabric belt width was, the better the fabric belt friction was. In specific, 4mm and 5mm wide belts had much better frictional resistance performances than 2mm and 3mm wide belts. This was because under the same belt tension, the wider belt got a lower pressure contacting the belt guides, resulting in less damage of the belts. Once the 2mm wide belt of some light and weak fabrics cannot meet anti-friction requirement during testing, 4mm wide fabric belt can be transformed as a composite belt with 2mm measurable width via symmetrically consolidating belt edges using flexible adhesives (illustrated in Figure 6).
Effectiveness of center-mounted airbag in far-side impacts based on THOR sled tests
Published in Traffic Injury Prevention, 2019
Sagar Umale, Hans Hauschild, John Humm, Klaus Driesslein, Narayan Yoganandan
Limited studies have examined alternative restraint designs for protecting far-side occupants. Modifications to existing restraint systems such as combinations of belt routing methods (reversed geometry, or 4-point belt configurations), updated pretensioner force and seat belt friction, and the use of inflatable belts, etc., have been explored as potential countermeasures (Bostrom et al. 2008; Edwards and Nash 2017; Umale et al. 2018). A novel method of restraining occupants in far-side impacts is a center-mounted airbag that can be activated during the crash event (Thomas et al. 2013). The center-mounted airbag may reduce occupant motion along the PDOF, thus limiting injuries to the head and thorax (Bostrom and Johansson 2009; Choi and Choi 2013; Fujiwara 2016).
Metabolic and kinematic responses while walking and running on a motorised and a curved non-motorised treadmill
Published in Journal of Sports Sciences, 2019
Paolo Bruseghini, Enrico Tam, Andrea Monte, Carlo Capelli, Paola Zamparo
A subject was asked to run on CNMT up to a speed of about 5 m · s−1 and then to jump off the belt by pushing himself upwards on the handlebars. The decrease in belt speed as a function of time (data were sampled every 1 s) as determined in 14 trials is reported in Figure 2: s = 5.203 – 0.304 · t, r2 = 0.969. The slope of this relationship is the belt deceleration: −0.304 m · s−2. By knowing the mass of the treadmill belt (29 kg, according to manufacturer data), belt friction (Fb) was calculated (Fb = m · a) and found to be equal to 8.81 N.