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Bruker UMT test rig consisting of: (1) load cell, (2) fixtures, (3) alumina sphere indenter, (4) aluminum surface, (5) three-jaw chuck.
Source publication
In this study, an experimental method is proposed to measure the real area of contact between an alumina sphere and an Al surface based on the adhesive transfer of the Au film and the scanning electron microscope in the back-scattered mode. A thin film of Au is sputtered on the alumina sphere before the indentation with the Al surface. After indent...
Contexts in source publication
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... indentation test setup is shown in Figure 1. As the alumina sphere is forced into the flat aluminum surface, the force is recorded by the load cell. ...
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... that the yield strength used in the models is taken just a third of the measured hardness in Table 1. The real contact area model predictions are then plotted alongside the measured real area of contact in Figure 10(a) and (b), which are normalized by the nominal area of contact, A n , which in the experiment is the field of view considered. In Figure 10(a) the bulk yield strength is employed, while in Figure 10(b) the nanoindentation hardness is used in the models. ...
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... real contact area model predictions are then plotted alongside the measured real area of contact in Figure 10(a) and (b), which are normalized by the nominal area of contact, A n , which in the experiment is the field of view considered. In Figure 10(a) the bulk yield strength is employed, while in Figure 10(b) the nanoindentation hardness is used in the models. A few observations can be made from the comparisons shown in Figure 10(a) and (b). ...
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... real contact area model predictions are then plotted alongside the measured real area of contact in Figure 10(a) and (b), which are normalized by the nominal area of contact, A n , which in the experiment is the field of view considered. In Figure 10(a) the bulk yield strength is employed, while in Figure 10(b) the nanoindentation hardness is used in the models. A few observations can be made from the comparisons shown in Figure 10(a) and (b). ...
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... Figure 10(a) the bulk yield strength is employed, while in Figure 10(b) the nanoindentation hardness is used in the models. A few observations can be made from the comparisons shown in Figure 10(a) and (b). First, the elastic multiscale and statistical models both grossly underpredict the real area of contact. ...
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A novel static friction model for the unlubricated contact of random rough surfaces at micro/nano scale is presented. This model is based on the energy dissipation mechanism that states that changes in the potential of the surfaces in contact lead to friction. Furthermore, it employs the statistical theory of two nominally flat rough surfaces in co...
Citations
... Nonetheless, they did show that the pressure in the fully plastic asperity contacts of a rough surface can vary significantly from the conventional hardness of approximately three times the yield strength. Recent experimental measurements of the elastic-plastic rough surfaces also suggested the real contact pressures can be much higher than the hardness [4,45] as was predicted by theoretical works discussed in the review paper. In addition, in a subsequent work [46], deterministic models confirmed the decreasing static friction coefficient with load trend and junction growth observed by many previous researchers for single asperities [47,48] and statistically considered rough surface contacts [49]. ...
... Experimental measurements of the nanoscale real area contact between metal surfaces were achieved by Xu using an adhesive stamp methodology [51]. These measurements also agreed well with spherical contact models on a larger macroscale and rough surface contact models on the nanoscale [45]. ...
It has been five years since this review of elastic-plastic contact mechanics was published. The area still remains very active and many advancements have been made since then. This discussion summarizes these advances and points out what might be considered the most significant ones. In some cases experimental measurements have confirmed previous theoretical predictions. In most cases the models of contact mechanics have increased in complexity in order to improve predictions for real applications. As a fundamental area, contact mechanics will undoubtedly remain active as its implementation is often required for new applications of technology to succeed.
... As the contact is closed to the outside environment, the real contact surface does not easily lend itself to direct observation. It can be investigated by means of the experimental method which uses a specimen and a transparent loading element [2] or the adhesion-based method described in study [3]. The latter method consists in transferring a gold film from the loading element's surface to the surface of the specimen and quantitatively evaluating this film by means of SEM. ...
The reliability of contact coupling simulation results was evaluated. Deformations were simulated using FEM and non-contact rough surface scanning. Milled aluminium specimens were loaded normally to their base with a flat steel stamp deforming only a few single microasperities. In such cases there is no guarantee that the microasperity shapes used in 3D modelling will correspond to those in the place of stamp action. The density of points describing the shapes is important. A scatter of the values of the parameters describing the contact characteristics can occur depending on the specimen’s area selected for loading with the stamp. Using the experimental-computational method it was determined how much the contact characteristic simulation results can differ from the experimental results.
... The FEM simulations were conducted on novel CAD generated geometries, modelling the surface roughness by adding hemispheres with various radius to a flat surface. The obtained results confirm the theoretical evidence recently found by Yang Zu et al. [19], and will be validated experimentally in future researches on the basis of the used specimens. ...
The purpose of this research was the analysis and the evaluation of the real contact area (RCA) of 15 rough samples with different mechanical properties. The investigation was carried out by the realization of a FEM model which simulates the contact between a rough deformable surface and rigid smooth sapphire plane. The roughness of the rough plane was modelled as a series of hemispheres of different radius which represent the asperities. Adhesion and asperities interaction were not considered and the peaks were distributed according to a Gaussian function. All the results, in terms of total area, load, pressure, deformation, were compared with the values calculated by two classical contact statistical models.
The interface physics is very important to the electrical contact reliability of current switching devices. In this article, the arcing electrode material surface topographies are measured consecutively in the electrical endurance experiments. A novel data processing algorithm is proposed for reconstructing the real contact interface between electrodes. The characterization parameters of contact interface including
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-spots number, area, centroid distance, and contact resistance are extracted. The comparison between the experimental recorded resistance and the analytical calculation results shows the validity of the proposed method. In the electrical endurance testing, three typical evolution stages of electrical contact interface are presented and analyzed. The contact spots are limited to the surface peaks in the initial operations, and then distributed evenly across the whole electrode surface. At the end of the testing, the contact area decreases slowly with the shrinkage of central convex face. It is determined that the electrical material redistribution caused by the arc erosion is the root reason for the contact interface evolution.
The purpose of this research was the analysis and the evaluation of the real contact area (RCA) of 15 rough samples with different mechanical properties. The investigation was carried out by the realization of a FEM model which simulates the contact between a rough deformable surface and rigid smooth sapphire plane. The roughness of the rough plane was modelled as a series of hemispheres of different radius which represent the asperities. Adhesion and asperities interaction were not considered and the peaks were distributed according to a Gaussian function. All the results, in terms of total area, load, pressure, deformation, were compared with the values calculated by two classical contact statistical models.
