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Contact area

About: Contact area is a research topic. Over the lifetime, 12358 publications have been published within this topic receiving 256401 citations. The topic is also known as: contact patch & contact region.


Papers
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Journal ArticleDOI
TL;DR: The results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction.
Abstract: The dynamics of fingertip contact manifest themselves in the complex skin movements observed during the transition from a stuck state to a fully developed slip. While investigating this transition, we found that it depended on skin hydration. To quantify this dependency, we asked subjects to slide their index fingertip on a glass surface while keeping the normal component of the interaction force constant with the help of visual feedback. Skin deformation inside the contact region was imaged with an optical apparatus that allowed us to quantify the relative sizes of the slipping and sticking regions. The ratio of the stuck skin area to the total contact area decreased linearly from 1 to 0 when the tangential force component increased from 0 to a maximum. The slope of this relationship was inversely correlated to the normal force component. The skin hydration level dramatically affected the dynamics of the contact encapsulated in the course of evolution from sticking to slipping. The specific effect was to reduce the tendency of a contact to slip, regardless of the variations of the coefficient of friction. Since grips were more unstable under dry skin conditions, our results suggest that the nervous system responds to dry skin by exaggerated grip forces that cannot be simply explained by a change in the coefficient of friction.

115 citations

Book ChapterDOI
TL;DR: In this article, the main formulae of the JKR theory of adhesion are extended to any material with rotational symmetry of the elastic properties and the BG method introduced for extracting adhesive and elastic properties of isotropic elastic materials from depth-sensing diagrams of spherical indenters is described.
Abstract: Connections between the Hertz-type contact problems and depth-sensing indentation of materials are studied. Formulations of Hertz-type contact problems with various boundary conditions within the contact area are discussed in detail. The problems under investigations can be subdivided into two large groups: self-similar problems for anisotropic materials with various rheological properties and adhesive contact problems for arbitrary bodies of revolution or for power-law shaped blunt indenters. Specific features of indentation problems are described and the common methods for extracting elastic and adhesive properties of materials are briefly reviewed. The basic formulae are extended to the case of nonslipping boundary conditions between a probe and the material. The main formulae of the JKR theory of adhesion are extended to any material with rotational symmetry of the elastic properties. These materials include not only isotropic or transversely isotropic elastic solids but also homogeneously prestressed isotropic or transversely isotropic nonlinear elastic materials. The BG method introduced for extracting adhesive and elastic properties of isotropic elastic materials from depth-sensing diagrams of spherical indenters, is described and extended to linear or linearized materials with rotational symmetry of the elastic properties.

114 citations

Journal ArticleDOI
TL;DR: In this article, it was shown that it is not possible to measure uniquely these mechanical properties of a sample in that way, and that even hardness is not a readily measurable magnitude since the real contact area depends on both the elastic and plastic properties of the sample.
Abstract: The connection between parameters that can be measured by means of instrumented indentation with the real mechanical properties has been a matter of discussion for several years. In fact, even hardness is not a readily measurable magnitude since the real contact area depends on both the elastic and plastic properties of the sample. Recently, Dao et al. [ Acta Mater49, 3899 (2001)] proposed a method based on numerical fittings to calculate by a forward-reverse algorithm the elastoplastic properties of a sample from the load-penetration curve obtained with a sharp indenter. This work will show, in contrast, that it is not possible to measure uniquely these mechanical properties of a sample in that way.

114 citations

Journal ArticleDOI
K. Uno, K. Hayashi1, T. Hayashi1, Kensaku Ito1, Hiromi Kitano1 
TL;DR: In this article, a microscopic observation of particles in the droplets of polymer latex dispersion on hydrophilic and hydrophobic surfaces was examined in light of the mechanism of particle adsorption in evaporating droplets.
Abstract: Stain patterns formed by drying up of droplets of polymer latex dispersion on hydrophilic and hydrophobic surfaces were examined in light of the mechanism of particle adsorption in evaporating droplets. On hydrophilic surfaces, the volume of droplets decreased with time, keeping the initial outline of contact area, and circular stain patterns were formed after the dry-up of droplets. By the microscopic observation of particles in the droplets, it was found that a large portion of the particles were forced to adsorb on the outline of the contact area where a microscopic thin water layer was formed because of hydrophilicity of the surface. On hydrophobic surfaces, on the other hand, the contact area of droplets decreased as evaporation proceeded, while no particle was adsorbed on the surface at the early stages. The particles in the droplets started to aggregate when the concentration of particles reached a critical value, and the aggregates adsorbed on the surface forming tiny spots after the dry-up. Time evolutions of contact angle, contact area and volume of the droplets were analyzed in light of differences in the adsorption mechanisms between hydrophilic and hydrophobic surfaces.

114 citations

Journal ArticleDOI
TL;DR: In this paper, the Cattaneo theory of frictional contact is extended to elastic half-spaces in contact through rough disordered interfaces, and a multiscale numerical contact algorithm is provided.

114 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023102
2022253
2021375
2020467
2019554
2018528