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sliding-friction
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Elastic Properties of Wet Granular Material
, M.Sc. Thesis Sharif University of Technology ; Rouhani, Shahin (Supervisor)
Abstract
To explain the dependence of sliding friction on or between the layers of wet sand, one first needs to have a rather good understanding of the elastic properties of wet granular material. Experimental work that has been done on the subject so far, has shown that these elastic properties have a peculiar dependence on the water volume fraction of the sand system. But till nowno theoretical model has been presented that could illustrate the physical causes of such findings. More specifically, these handful of theoretical models have not been able to explain the complex relationship between the shear modulus of sand and the water volume percentage. In this thesis at first the nature and...
Empirical comparison of sliding friction and wear behaviors of gray and white cast iron
, Article ASME 2010 10th Biennial Conference on Engineering Systems Design and Analysis, ESDA2010, 12 July 2010 through 14 July 2010, Istanbul ; Volume 1 , 2010 , Pages 489-493 ; 9780791849156 (ISBN) ; Ghajar, R ; Sharif University of Technology
2010
Abstract
In this paper, sliding friction and wear behaviors of gray cast iron A35 and white cast iron manufactured by quenching from the same cast iron in water were studied and compared by employing pin-on-disk wear tests. Microstructure of the worn surfaces before and after the wear tests were investigated by optical microscope observations. These images show that flakes separated from the surface in gray cast iron due to delamination process, while in white cast iron, the separation of materials from its surface is in the form of powder. In addition, the gray cast iron had higher graphite volume fraction with Type-A graphite flake morphology. The results show that white cast iron has less rate of...
Sliding on wet sand
, Article Granular Matter ; Volume 22, Issue 3 , May , 2020 ; Aliasgari, M ; Maleki Jirsaraei, N ; Rouhani, S ; Bonn, D ; Sharif University of Technology
Springer
2020
Abstract
We present sliding experiments of a sledge on wetted sand and describe that the frictional response is controlled by the penetration hardness of the granular medium. Adding a small amount of water to sand increases the hardness which results in a decrease of the sliding friction. Pouring even more water to sand results in a decrease of the hardness and a subsequent increase of the friction. This inverse correlation between hardness of a wetted granular material and its frictional response to sliding is found to be due to ploughing of the sledge. When the load of the sledge exceeds the penetration hardness of the water-sand mixture the granular material is irreversibly deformed, which is...
Evaluation of the Cyclic Performance of Buckling Restrained Braces with Sliding Friction Connection
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masood (Supervisor)
Abstract
In today’s world, the use of lateral load-bearing systems, such as bracings, has become a pretty common practice. Often showing axial deformation behavior, these members exhibit proper performance under tensile loads but tend to become unstable under compressive loads. In contrast to common bracing systems, the buckling-restrained bracing (BRB) systems perform well under not only tensile loads but also compressive loads. Recent studies have paid greater deals of attention to the application of short-core BRB systems in different structures. The bracing core has been shortened to increase the core deformation and hence the energy dissipation capacity of the bracing system. In this condition,...
The sliding frictional contact problem in two dimensional graded materials loaded by a flat stamp
, Article Advanced Materials Research, 7 January 2012 through 8 January 2012 ; Volume 463-464 , January , 2012 , Pages 336-342 ; 10226680 (ISSN) ; 9783037853634 (ISBN) ; Adibnazari, S ; Tashi, S ; Sharif University of Technology
2012
Abstract
In this article, the sliding frictional contact problem for a half-plane which is graded in two dimensions is studied. The effect of medium properties gradient and coefficient of friction in contact mechanics of two dimensional (2D) graded materials which is loaded by a flat stamp have been investigated by developing two Finite Element (FE) models, in macro and micro scales. Discretizing the graded half-plane by quadrants for whose material properties are specified at the centroids by Mori-Tanaka method in both directions has been used to model the 2D FGM in macro scale. In micro scale, the ideal solid quadrant particles which are spatially distributed in a homogeneous matrix used to model...
Interface between tire and pavement
, Article Journal of Materials in Civil Engineering ; Volume 29, Issue 9 , 2017 ; 08991561 (ISSN) ; Toufigh, V ; Sharif University of Technology
Abstract
Sliding friction between a pavement and tire is an important concern in traffic safety. The British pendulum test has been used worldwide to evaluate friction characteristics of pavement surfaces. However, because of considerable differences in apparatus, procedures, and operation, significant variability can occur for evaluations of British pendulum number (BPN). In this investigation, a direct shear test (DST) device is modified and proposed to determine the sliding friction coefficient between tire and pavement surface under dry and wet conditions. Dissipated energy values obtained from DST were compared with evaluations of BPN, and a high correlation was obtained. Tests were done using...
Effect of casting process on microstructure and tribological behavior of LM13 alloy
, Article Journal of Alloys and Compounds ; Volume 475, Issue 1-2 , 2009 , Pages 321-327 ; 09258388 (ISSN) ; Niroumand, B ; Karimzadeh, F ; Hamani, M ; Pouranvari, M ; Sharif University of Technology
2009
Abstract
LM13 alloy is widely used in piston industry, due to its low coefficient of thermal expansion, excellent castability and hot tear resistance. In this research effect of casting process on wear behavior of LM13 alloy was investigated. First, samples were produced using two casting processes and heat treated. Then wear behavior of these samples under dry sliding condition was examined. Results of hardness and strength tests indicated that squeeze cast specimens exhibited higher mechanical properties. Wear experiment results showed that in both squeeze and gravity cast specimens, amount of weight loss increases with increase in sliding distance which is accompanied by reduction in wear rate and...