| 1. |
- Duvefelt, Kenneth B. K., et al.
(författare)
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Towards simultaneous measurements of skin friction and contact area : Results and experiences
- 2015
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Ingår i: Proceedings of the Institution of mechanical engineers. Part J, journal of engineering tribology. - : Sage Publications. - 1350-6501 .- 2041-305X. ; 229:3, s. 230-242
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates one of the important parameters when designing for feel, namely the friction coefficient. An experiment was performed to evaluate how fringe projection could be used to investigate the topography of the fingertip, especially while in contact and sliding on a smooth surface. By allowing this smooth surface to be a small sheet of glass, a topographic camera could take pictures through it. The glass was also connected to a universal force gauge to measure normal and tangential forces from which the coefficient of friction could be calculated. The intention was to get dependable data on the forces, coefficient of friction, apparent contact area and actual contact area. This set-up was tested using 66 students who used one and three fingers in both dry and wet conditions and with a rubber glove. In order to measure natural everyday friction, they were not given any particular instructions on how to clean or slide their fingers. This method resulted in a much higher variation in friction coefficients than has been found in previous research. In particular, many higher values were noticed. This illustrates that the friction coefficient is a very hard parameter to rely on when it comes to designing surfaces for feel.
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| 2. |
- Duvefelt, Kenneth, et al.
(författare)
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Model for contact between finger and sinusoidal plane to evaluate adhesion and deformation component of friction
- 2016
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Ingår i: Tribology International. - : Elsevier. - 0301-679X .- 1879-2464. ; 96, s. 389-394
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Tidskriftsartikel (refereegranskat)abstract
- One of the main parameters affecting finger friction, friction-induced vibrations in the finger, and consequently tactility is surface topography. Recently Skedung et al. performed finger friction measurements on fine controlled surfaces. These surfaces were sinusoidal with wavelengths from 0.27 to 8.8 mu m and amplitudes from 0.007 to 6 mu m. Building on those tests an analytical model for the contact was developed to explain the differences in friction coefficient. The contact was modelled as trapezoids in a circular pattern pressed against a sinusoidal plane. Results showed that the calculated contact area and therefore friction coefficient corresponded well with the measurements. This model can be used to see how the different surface parameters influence friction.
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| 3. |
- Wang, Lixin, et al.
(författare)
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Effect of surface roughness on attachment ability of locust Locusta migratoria manilensis
- 2015
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Ingår i: Wear. - : Elsevier BV. - 0043-1648 .- 1873-2577. ; 332, s. 694-701
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Tidskriftsartikel (refereegranskat)abstract
- To explore how surface roughness affects locust's attachment ability, friction force of locust Locusta migratoria manilensis on substrates with variable roughness was measured with an insect micro-force measurement system. Extensive values of the friction force were acquired, respectively exhibiting the trends of inverted parabola variation, linear pattern growth and saturation period with the increased surface roughness. Obviously small values of the friction force were generated by locusts on substrates possessing a particular roughness range. The morphology and structure of locust attachment organ were examined and quantitively analyzed with a scanning electron microscope. Based on the acquired structure information, a schematic was proposed to explain the interaction between the attachment organ and the surface irregularity, also a mechanical analysis was conducted to present the effect of surface asperity on locust's claw tip. Results demonstrated that surface roughness with appropriate values can considerably reduce locust's attachment ability via simultaneously restricting the generation of mechanical interlock and adhesive attachment. The achieved conclusion gives a further interpretation to friction behavior of insect on variable substrates, also provides theory for biomimetic designing a slippery plate utilized for trapping plague locusts.
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