frictional properties
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Friction ◽  
2022 ◽  
Author(s):  
Gianluca Costagliola ◽  
Federico Bosia ◽  
Nicola M. Pugno

AbstractThe contact of two surfaces in relative rotating motion occurs in many practical applications, from mechanical devices to human joints, displaying an intriguing interplay of effects at the onset of sliding due to the axisymmetric stress distribution. Theoretical and numerical models have been developed for some typical configurations, but work remains to be done to understand how to modify the emergent friction properties in this configuration. In this paper, we extend the two-dimensional (2D) spring-block model to investigate friction between surfaces in torsional contact. We investigate how the model describes the behavior of an elastic surface slowly rotating over a rigid substrate, comparing results with analytical calculations based on energy conservation. We show that an appropriate grading of the tribological properties of the surface can be used to avoid a non-uniform transition to sliding due to the axisymmetric configuration.


Solid Earth ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 117-136
Author(s):  
Andrei Maksymowicz ◽  
Daniela Montecinos-Cuadros ◽  
Daniel Díaz ◽  
María José Segovia ◽  
Tomás Reyes

Abstract. The objective of this work is to analyse the density structure of the continental forearc in the northern segment of the 1960 Mw 9.6 Valdivia earthquake. Regional 2D and local 3D density models have been obtained from available gravity data in the area, complemented by new gravimetric stations. Models are constrained by independent geophysical and geological information and new TEM and MT soundings. The results show a segmentation of the continental wedge along and perpendicular to the margin, highlighting a high-density anomaly, below the onshore forearc basin, that limits the late Paleozoic–early Mesozoic metamorphic basement in the region where Chaitenia terrane has been proposed. A progressive landward shift of this anomaly correlates with the high slip patch of the giant 1960 Mw 9.6 Valdivia earthquake. Based on these results, we propose that the horizontal extension of the less rigid basement units conforming the marine wedge and Coastal Cordillera domain could modify the process of stress loading during the interseismic periods, and also that changes in position and extension of the late Paleozoic–early Mesozoic accretionary complex could be linked with the frictional properties of the interplate boundary. This analysis provides new evidence of the role of the overriding plate structure in the seismotectonic process in subduction zones.


2022 ◽  
Author(s):  
D. Boldyrev

Abstract. Wear and crack resistance are important operational characteristics of brake discs. The paper presents the most optimal concentration of sulfur in cast iron, which ensures its least wear, and discusses the implementation of the front brake discs manufacture from Gh190 cast iron having 0.11 ... 0.13% sulfur content at contrast to the 0.01 ... 0.03% sulfur content, and proves the change leads to a significant increase in wear and frictional properties of the discs. In the course of research, it is found that the increase in the crack resistance of brake discs is possible due to the improvement of the thermophysical properties of cast iron with the increase in the carbon content (up to 3.55 ... 3.60%) and the decrease in the silicon content (up to 1.45 ... 1.50%), while the carbon equivalent is constant.


Author(s):  
Pawan Kumar Soni ◽  
Arun K. Singh ◽  
N. Sivakumar ◽  
Trilok N. Singh

2021 ◽  
Author(s):  
Huiqin Li ◽  
Jiaxin Tang ◽  
Ying Zhang ◽  
Yao Han

Background: Osteoarthritis is a severe disease for menopausal women, especially for those who exposed in the smoking and second hand-smoking. This study investigated the effect of the nicotine and estrogen on the articular cartilage. Methods: The articular cartilages were treated by nicotine and estrogen in vitro. Then the frictional properties and morphology on the surface were investigated using atomic force microscope. Proteoglycan 4(PRG4), as the key boundary lubricant of articular cartilage was characterized. Results: Nicotine down-regulates the friction coefficient and secretion of PRG4 significantly and then the estrogen increase them again. The adhesion forces also showed the same trend due to the content of anti-adhesive PRG4. Discussion: This study demonstrated that the present concentration nicotine has a negative effect on the articular cartilage and the estrogen has a better protecting effect. This may provide a potential guide for OA prevention and treatment.


Author(s):  
О.В. Башков ◽  
А.А. Афанасьева

В статье приведены результаты исследования фрикционных свойств и структуры нового композиционного фрикционного материала (КФМ). В ходе исследования были разработаны восемь перспективных составов КФМ, полученных методом порошковой металлургии. Фрикционные испытания новых материалов проводились на испытательной машине на трение и износ ИИ5018, оснащённой программным комплексом Tester 3.0, позволяющим точно фиксировать изменение момента трения в течение испытания с построением графика и автоматическим расчётом параметров трения. Методика испытаний позволила имитировать условия фрикционного взаимодействия, возникающие в муфтах электроприводов, применяемых в наземном и морском транспорте. По результатам испытаний оценивались величина коэффициента трения и его стабильность на протяжении цикла испытания и в диапазоне рабочих регулировок электропривода, а также износостойкость КФМ. На основании исследований структуры поверхности трения и качественной оценки стабильности коэффициента трения был определён оптимальный состав КФМ, способный обеспечить стабильную и безопасную работу электропривода в диапазоне рабочих регулировок. The article presents the results of a study of the frictional properties and structure of a new composite frictional material (CFM). In the course of the study, eight promising CFM compositions were developed, obtained by the method of powder metallurgy. Friction tests were carried out on a friction and wear testing machine II5018, equipped with the software package Tester 3.0, which allows registering the change in friction moment during the test with plotting and automatic calculation of friction parameters. The test technique made it possible to simulate the conditions of frictional interaction arising in the couplings of electric drives used in land and sea transport. After the tests, the value of the friction coefficient, its stability during the test cycle and in the range of operating adjustments of the electric drive and the wear resistance of the CFM were evaluated. Based on the analysis of the structure of the friction surface and a qualitative assessment of the stability of the coefficient of friction, the optimal composition of the CFM capable of ensuring stable and safe operation of the electric drive in the range of operating adjustments was determined.


2021 ◽  
Vol 118 (49) ◽  
pp. e2109109118
Author(s):  
Laurence Willemet ◽  
Khoubeib Kanzari ◽  
Jocelyn Monnoyer ◽  
Ingvars Birznieks ◽  
Michaël Wiertlewski

Humans efficiently estimate the grip force necessary to lift a variety of objects, including slippery ones. The regulation of grip force starts with the initial contact and takes into account the surface properties, such as friction. This estimation of the frictional strength has been shown to depend critically on cutaneous information. However, the physical and perceptual mechanism that provides such early tactile information remains elusive. In this study, we developed a friction-modulation apparatus to elucidate the effects of the frictional properties of objects during initial contact. We found a correlation between participants’ conscious perception of friction and radial strain patterns of skin deformation. The results provide insights into the tactile cues made available by contact mechanics to the sensorimotor regulation of grip, as well as to the conscious perception of the frictional properties of an object.


Author(s):  
L.I.U. Ben ◽  
Z.H.A.O. Hong-chao ◽  
L.I. Xiang-fen ◽  
Y.A.N.G. Zong-he ◽  
Z.H.A.N.G. Dong-qing ◽  
...  

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