Frictional Properties of a Mesoscopic Contact with Engineered Surface Roughness

Sondhauss, Johannes; Fuchs, Harald; Schirmeisen, André

doi:10.1007/s11249-011-9776-8

Cited by 14 publications

(23 citation statements)

References 27 publications

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“…Several different parameters determine the performance of the patterned structures, including the surface chemistry and the pitch (distance between the pillars), diameter, and height of the micro-and nano-features. 6,[9][10][11] In addition, the shape of these features also contributes to their tribological and wetting behavior. Contrary to surface chemistry, the relationship between geometric parameters and friction and adhesion is quite complex.…”

Section: Introductionmentioning

confidence: 99%

Nanotribological and wetting performance of hierarchical patterns

et al. 2016

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Surface modification is a promising method to solve the tribological problems in microsystems. To modify the surface, we fabricated hierarchical patterns with different pitches of nano-scale features and different surface chemistries. Micro- and nano-patterns with similar geometrical configurations were also fabricated for comparison. The nano-tribological behavior of the patterns was investigated using an atomic force microscope at different relative humidity levels (5% to 80%) and applied normal loads (40 nN to 120 nN) under a constant sliding velocity. The results showed significant enhancement in the de-wetting and tribological performance of the hierarchical patterns compared with those of flat and micro- and nano-patterned surfaces. The PTFE-coated hierarchical patterns showed similar dynamic contact angles (advancing and receding) to those of the real lotus leaf. The influence of relative humidity on adhesion and friction behavior was found to be significant for all the tested surfaces. The tribological performance was improved as the pitch of the nano-scale geometry of the hierarchical pattern increased, even though the wetting property was not influenced significantly. A model was proposed based on the role of intermolecular force to explain the effect of the pitch of the hierarchical patterns on the adhesion and friction behavior. According to the model based on the molecular force, the contact between a ball and the patterned surface was a multi-asperity contact, contrary to the single-asperity contact predicted by the Johnson-Kendall-Roberts (JKR) and Maugis-Dugdale (MD) models. The strong intermolecular forces, which are activated in the confined spaces between the adjacent nano-pillars and the ball, contributed to the contact area and hence the adhesion and friction forces.

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Section: Introductionmentioning

confidence: 99%

Nanotribological and wetting performance of hierarchical patterns

et al. 2016

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“…In the present study, we used a similar experimental setup to characterise frictional properties of the SIMPS. Additionally, frictional properties of a broad variety of epoxy surfaces with different types and dimensions of the microstructure were characterised to understand the influence of two general tribological phenomena on friction: (1) molecular interaction depending on the real contact area between surfaces and (2) the interlocking of surface asperities of both contacting surfaces [36–38]. This approach of investigating the contribution of different geometries and dimensions of microstructures to the friction coefficient was chosen, because the complex phenomenon of friction cannot be reduced to a single mechanism: It is rather a result of various simultaneously acting mechanisms at different scales [39–41] and this approach opens up opportunities (i) to draw conclusions on the influence of the microstructure of the snake skin on frictional properties and thereby to extend the knowledge on specific surface modifications due to the legless locomotion of snakes and (ii) to evaluate which particular features (shape, dimension, orientation) of the snake skin are worth of mimicking for technological applications.…”

Section: Introductionmentioning

confidence: 99%

Dry friction of microstructured polymer surfaces inspired by snake skin

Baum¹,

Heepe²,

Fadeeva³

et al. 2014

Beilstein J. Nanotechnol.

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SummaryThe microstructure investigated in this study was inspired by the anisotropic microornamentation of scales from the ventral body side of the California King Snake (Lampropeltis getula californiae). Frictional properties of snake-inspired microstructured polymer surface (SIMPS) made of epoxy resin were characterised in contact with a smooth glass ball by a microtribometer in two perpendicular directions. The SIMPS exhibited a considerable frictional anisotropy: Frictional coefficients measured along the microstructure were about 33% lower than those measured in the opposite direction. Frictional coefficients were compared to those obtained on other types of surface microstructure: (i) smooth ones, (ii) rough ones, and (iii) ones with periodic groove-like microstructures of different dimensions. The results demonstrate the existence of a common pattern of interaction between two general effects that influence friction: (1) molecular interaction depending on real contact area and (2) the mechanical interlocking of both contacting surfaces. The strongest reduction of the frictional coefficient, compared to the smooth reference surface, was observed at a medium range of surface structure dimensions suggesting a trade-off between these two effects.

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“…However, this microscopic contact also entails the risk that unfavorable geometrical dimensions of the contact partners cause an interlocking of the smooth friction partner in the microstructure of the counterface and therefore significantly increase the frictional force [9]. This relationship has already been investigated in the friction of technical structured surfaces [16,32]. Two crucial mechanical interactions between the contacting surfaces can be identified with the effect on the sliding coefficient of friction μ k : (1) on a nanoscale, by the influence of the real contact area; and (2) on a microscale, by the geometrical and stress-induced interlocking of the samples with the grooves of the structured countersurface.…”

Section: Discussionmentioning

confidence: 99%

“…From this, it can be concluded that the dimension of the most friction-optimized biological microstructures must reduce the real contact area of the tribological pair as much as possible without causing mechanical interlocking, both geometrically and contact-mechanically. In technical systems, Sondhauss et al [32] report that the friction coefficient for a ball microstructure contact pair could be reduced by 50%, if the interlocking could be prevented. Sondhauss et al [32] and Baum et al [16,33] show that the friction response is dominated by the geometry of the tribological pair, which is characterized by the macroscopical shape [32,34], as well as the specific geometry of the microstructural elements [35,36,37].…”

Section: Discussionmentioning

confidence: 99%

The Topology of the Leg Joints of the Beetle Pachnoda marginata (Scarabaeidae, Cetoniinae) and Its Implication for the Tribological Properties

et al. 2018

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Locomotion of walking insects is exceptionally efficient. The function of their leg joints in different movement scenarios depends on their kinematics and contacting conditions between moving parts. The kinematics was previously studied in some insects, but contact mechanics within the joints remains largely unknown. In order to understand the complex topology of the contacting surfaces of the leg joints in the Congo rose beetle Pachnoda marginata peregrina (Scarabaeidae, Cetoniinae), we have investigated the shape, the waviness, and the roughness of the joint base and its counter body by applying confocal laser scanning microscopy and white light interferometry. Additionally, we performed nanoindentation tests on the contacting joint surfaces, in order to analyze material properties (elasticity modulus and hardness) of the joint cuticle. We found two topological design principles of the contact surfaces that might be considered as adaptations for reducing frictional drag during leg movements. First, the contact pairs of all leg joints studied consist of convex and concave counterparts. Second, there is a smooth and a rough surface in contact in which microprotuberances are present on the rough surface. These principles might be potentially interesting for technical implications, to design bioinspired joints with both reduced friction and wear rate.

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Frictional Properties of a Mesoscopic Contact with Engineered Surface Roughness

Cited by 14 publications

References 27 publications

Nanotribological and wetting performance of hierarchical patterns

Nanotribological and wetting performance of hierarchical patterns

Dry friction of microstructured polymer surfaces inspired by snake skin

The Topology of the Leg Joints of the Beetle Pachnoda marginata (Scarabaeidae, Cetoniinae) and Its Implication for the Tribological Properties

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