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Surface Failure
Published in Ansel C. Ugural, Youngjin Chung, Errol A. Ugural, Mechanical Engineering Design, 2020
Ansel C. Ugural, Youngjin Chung, Errol A. Ugural
Abrasive wear occurs when a hard surface slides across a softer surface. The ASTM defines abrasive wear as the loss of material due to hard particles that are forced against and move along solid surface. Abrasion takes place in two modes, known as two-body and three-body abrasive wear, when two interacting surfaces are in direct physical contact and one is significantly harder than the other. Two-body wear occurs when the hard particles remove material from the opposite surface. Examples include soft Babbitt bearings used with hard automotive crankshafts and wearing down of wood or soft metal with sandpaper.
Possible wear mechanisms at the wear-flat of rock cutting tools
Published in H.J.R. Deketh, Wear of Rock Cutting Tools, 2020
Abrasion can be divided into four types of material failure: microploughing, microcutting, microfatigue and microcracking (Figure 7). Microploughing, microcutting and microfatigue are the dominant types of material failure in more ductile materials such as steel. In the ideal case, microploughing due to a single pass of one abrasive particle does not result in any detachment of material from a wearing surface. A prow is formed ahead of the abrading particle and material is continually displaced sideways to form ridges adjacent to the groove produced. During microploughing, material loss can however occur due to many abrasive particles which are acting simultaneously or successively. Material may be ploughed aside repeatedly by passing particles and may break of by fatigue. Microcracking is related to brittle materials like tungsten carbide.
Design Perspective of Wear Behavior
Published in Raymond G. Bayer, Engineering Design for Wear, 2019
While abrasion is wear caused by hard particles or protuberances, it is generally only significant in situations that involve hard particles, either loose or attached to a surface. The size, shape, hardness, and number of particles are significant parameters in this type of wear, as well as their friability. When the wearing surfaces are softer than the particles, the dominant mechanisms for wear are single-cycle deformation processes, e.g., cutting and plowing. When the surface is harder, repeated-cycle deformation processes become dominant. In either case, oxidative wear processes can be involved and be significant, particularly in situations where there are liquids or hostile gaseous environments involved.
Electromagnetic interference shielding effectiveness of sol-gel coating on Cu-plated fabrics
Published in The Journal of The Textile Institute, 2021
P. V. Kandasaamy, M. Rameshkumar
Generally, the coated materials strongly influence the surface of the fabric and their porosity. In this case, it is important to measure the air permeability to know how the coated fabric is permeable. The rate of flow of air passing perpendicularly through a known area with pressure of air as prescribed is known as the air permeability. SDL air permeability tester is used to perform the test for fabric coated with copper as per ISO9237. 100 Pa is the air pressure differential among the two exteriors of the material. For abrasion durability, the EMI SET value was measured at 1.5 GHz and thereafter the sol-gel treated Cu-plated samples were abraded for different cycles (i.e. 100, 500, 1000, 2000, 3000, 5000, 10000 cycles). Abrasion resistance was measured by using Martindale Abrasion tester with respect to the ISO 12947-1:1998 standard. After specified abrasion resistance measurement, again the sample was re-measured for the EMI SET values which are plotted and discussed in the subsequent sections.
Assessment of induction heating in the performance of porous asphalt mixtures
Published in Road Materials and Pavement Design, 2020
Pedro Lastra-González, Irune Indacoechea-Vega, Miguel A. Calzada-Pérez, Ángel Vega-Zamanillo, Daniel Castro-Fresno
Concerning the steel wool, fibres with less than 0.5 mm diameter and a maximum of 6 mm length have been used (Figure 1(B)). This product is normally used in industrial applications such as the reinforcement of materials exposed to high levels of abrasion (for example, car breaks components). A special care should be taken with the addition of fibres in the asphalt mixture because of the high risk in clusters formation. The percentage of clusters has been observed to increase with the amount and length of fibres and with the use of fibres with low diameters (García, Norambuena-Contreras, & Partl, 2014). In case of Asphalt concrete mixtures, to guarantee a good dispersion, the length of the fibres must be below 2 mm and the diameter above 0.15 mm (García, Norambuena-Contreras, Partl, & Schuetz, 2013).
Hydrodynamic modelling approaches to assess mechanisms affecting the structural performance and maintenance of vortex drops shaft structures
Published in Journal of Structural Integrity and Maintenance, 2019
Alan Carty, Colin O’ Neill, Stephen Nash, Eoghan Clifford, Sean Mulligan
With knowledge of the streamline angles and hence the tangential and axial velocities in the vicinity of the liner surface, it is also possible to draw conclusions on the wearing effects of erosion and abrasion on the liner given that such flows generally contain large solids concentrations. Abrasion is a wear phenomenon involving progressive material loss due to hard particles forced against and moving along a solid surface (Auel, Albayrak, Sumi, & Boes, 2015). Particles are transported in sliding, rolling or saltation motion depending on the flow conditions causing grinding, rolling or saltating impact stress on a liner material. According to Sklar and Dietrich (2001), the governing process causing abrasion is saltation, whereas sliding and rolling do not cause significant wear. Regarding the vortex chamber flow dynamics, saltation would be expected to be largely present again at the entrance to the vortex generator due to the change of direction of flow. Sliding and rolling would dominate the remainder of the drop shaft where the radial velocity is negligible. A number of models exist to predict the abrasion rate of materials due to the abovementioned mechanisms (Ishibashi, 1983; Sklar & Dietrich, 2004; Auel, Albayrak, Sumi, & Boes, 2015) wherein the parameters required can be derived from the hydrodynamic variables explored in this study (impact angle, stream velocity components, suspended solids concentration, centrifugal forces, wall pressures etc.) together with material properties. Although not explored further in this study, this topic wold nonetheless be a fruitful future investigation.