When Particles Meet Nanoindentation: A Novel Strategy for Studying Particle Motion and Particle/Surface Interaction

2014 ◽  
Vol 1652 ◽  
Author(s):  
Regina Fuchs ◽  
Thomas Weinhart ◽  
Jan Meyer ◽  
Hao Zhuang ◽  
Thorsten Staedler ◽  
...  
Keyword(s):  
Adhesion Force ◽  
Particle Surface ◽  
Rolling Friction ◽  
Rolling Contact ◽  
Research Fields ◽  
Typical Particle ◽  
Load Regime ◽  
Particle Ensemble ◽  
Novel Strategy ◽  
Key Aspects

ABSTRACTA plethora of applications in pharmacy, cosmetics, food industry and other areas are directly linked to the research fields of particle technology and contact mechanics. Here, a typical particle ensemble features particle sizes ranging from the nanometer up to the micrometer regime. In this context we introduce a nanoindentation based approach capable of probing mechanical interaction of micron-sized particles. Basically, the concept of the colloid probe technique, which is well established in the AFM community, is transferred to a nanoindenter. In particular, this setup allows addressing limitations, which are typically associated with AFM based techniques, such as particle weight and accessible load regime. Additionally, we will show the versatility of this approach by presenting simple experimental paths capable of probing sliding, rolling and torsional friction. The potential of such setting is shown by studying rolling friction of silica microspheres featuring radii of about 2.5µm, 10µm, 25 and 50µm in contact with various substrates, respectively. Substrates utilized within the framework of this study are Si surfaces featuring various roughness as well as flat gold films (300nm film thickness). Key aspects of this work include the influence of surface roughness, adhesion force, humidity and the elastic/plastic transition on the rolling contact of the corresponding particles.

Threshold Stress Criterion in New Wheel/Rail Interaction for Limiting Rail Damage Under Heavy Axle Loads

1992 ◽  
Vol 114 (3) ◽  
pp. 284-288 ◽  
Author(s):  
S. Kumar ◽  
S. P. Singh
Keyword(s):  
Threshold Stress ◽  
Rolling Friction ◽  
Contact Stresses ◽  
Rolling Contact ◽  
Internal Damage ◽  
Stress Criterion ◽  
Plasticity Region ◽  
Proper Design ◽  
Axle Loads ◽  
Qualitative Discussion

This paper presents a qualitative discussion of the effects of increasing new (initial) wheel-rail contact stresses on the degree of damage to the rail due to heavy axle loads. The importance and need of heavy axle loads and its relationship to rail damage as a result of the increasing wheel-rail contact stresses is discussed. Various mechanisms of energy absorption/losses due to free rolling and modes of rail damage are presented. These modes include surface and internal damage due to wear, contact shear, plasticity, fatigue, shelling, crack formation, etc. The concept of threshold stress observed in free rolling friction much earlier by Drutowski is discussed and analyzed. It is believed by the authors that the threshold stress is s material property. This concept of threshold stress, based on sharply increased rates of wear in free rolling contact, is then presented and analyzed. Considerations of increased plasticity-region development, due to increasing contact stresses and their relationship to increased rates of wear seen in experiments, is utilized to determine an upper bound of contact stresses for new wheel and rail under heavy axle load conditions. It is indicated that new wheel-rail profiles, which will achieve contact stresses below the threshold stress, will enable the U.S. railroads to carry heavy axle loads without serious future damage to the rails. It is concluded that a satisfactory solution for maintaining rail integrity under heavy axle loads is possible with proper design accompanied with laboratory experimentation for the new steels as they may be used in the rails.

scholarly journals Fuzzy Sliding Mode Wheel Slip Ratio Control for Smart Vehicle Anti-Lock Braking System

Energies ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2501 ◽  
Author(s):  
Jinhong Sun ◽  
Xiangdang Xue ◽  
Ka Wai Eric Cheng
Keyword(s):  
Controller Design ◽  
Adhesion Force ◽  
Sliding Mode ◽  
Rolling Friction ◽  
Resistance Force ◽  
Wheel Slip ◽  
Slip Ratio ◽  
Braking System ◽  
Wheel Rolling ◽  
Braking Torque

With the development of in-wheel technology (IWT), the design of the electric vehicles (EV) is getting much improved. The anti-lock braking system (ABS), which is a safety benchmark for automotive braking, is particularly important. Installing the braking motor at each fixed position of the wheel improves the intelligent control of each wheel. The nonlinear ABS with robustness performance is highly needed during the vehicle’s braking. The anti-lock braking controller (CAB) designed in this paper considered the well-known adhesion force, the resistance force from air and the wheel rolling friction force, which bring the vehicle model closer to the real situation. A sliding mode wheel slip ratio controller (SMWSC) is proposed to yield anti-lock control of wheels with an adaptive sliding surface. The vehicle dynamics model is established and simulated with consideration of different initial braking velocities, different vehicle masses and different road conditions. By comparing the braking effects with various CAB parameters, including stop distance, braking torque and wheel slip ratio, the SMWSC proposed in this paper has superior fast convergence and stability characteristics. Moreover, this SMWSC also has an added road-detection module, which makes the proposed braking controller more intelligent. In addition, the important brain of this proposed ABS controller is the control algorithm, which can be used in all vehicles’ ABS controller design.

scholarly journals A DECADE OF ARCHITECTURAL AND URBAN RESEARCH PUBLISHED IN ‘ARCHNET-IJAR: INTERNATIONAL JOURNAL OF ARCHITECTURAL RESEARCH’

2017 ◽  
Vol 11 (1) ◽  
pp. 6 ◽  
Author(s):  
Ashraf M. Salama ◽  
Adel M. Remali ◽  
Farzad Pour Rahimian
Keyword(s):  
Urban Studies ◽  
Current Position ◽  
Future Aspirations ◽  
The Past ◽  
Research Fields ◽  
Acceptance Rates ◽  
Key Aspects ◽  
Architectural Research ◽  
Published Research

This article commemorates a decade of discourse and published research on architecture and urbanism in ArchNet-IJAR (March 2007-March 2017). While the journal does not publish regular editorials associating each issue, it is believed that offering key highlights of growth since the inception of the journal is now due. The article presents the current position of ArchNet-IJAR within the international provision of journals in architecture and urban studies in key databases and index-bases. This is substantiated by key statistics of submissions, published contributions, and acceptance rates during the past 10 years. Coupled with analytical discussion on the global reach of the ArchNet-IJAR, the article identifies 11 research fields, which were covered in 10 volumes since the journal’s inception. Analytical discussions of recent two theme issues as well as latest developments and contributions during the past few years are presented to reflect on the rigor and quality of the journal while depicting its thrust and interest. The article concludes by key aspects relevant to the future aspirations of ArchNet-IJAR while highlighting initiatives and prospective endeavours.

scholarly journals Sulfated Polysaccharide-Directed Recruitment of Mammalian Host Proteins: a Novel Strategy in Microbial Pathogenesis

1999 ◽  
Vol 67 (9) ◽  
pp. 4463-4468 ◽  
Author(s):  
Thomas D. Duensing ◽  
Jenny S. Wing ◽  
Jos P. M. van Putten
Keyword(s):  
Bacterial Species ◽  
Sulfated Polysaccharide ◽  
Microbial Pathogens ◽  
Sulfated Polysaccharides ◽  
Bacterial Invasion ◽  
Mammalian Host ◽  
Heparin Binding ◽  
Pathogenic Potential ◽  
Novel Strategy ◽  
Key Aspects

ABSTRACT Fundamental to the virulence of microbial pathogens is their capacity for adaptation and survival within variable, and often hostile, environments encountered in the host. We describe a novel, extragenomic mechanism of surface modulation which may amplify the adaptive and pathogenic potential of numerous bacterial species, including Staphylococcus, Yersinia, and pathogenic Neisseria species, as well as Helicobacter pylori and Streptococcus pyogenes. The mechanism involves specific bacterial recruitment of heparin, glycosaminoglycans, or related sulfated polysaccharides, which in turn serve as universal binding sites for a diverse array of mammalian heparin binding proteins, including adhesive glycoproteins (vitronectin and fibronectin), inflammatory (MCP-3, PF-4, and MIP-1α) and immunomodulatory (gamma interferon) intermediates, and fibroblast growth factor. This strategy impacts key aspects of microbial pathogenicity as exemplified by increased bacterial invasion of epithelial cells and inhibition of chemokine-induced chemotaxis. Our findings illustrate a previously unrecognized form of parasitism that complements classical virulence strategies encoded within the microbial genome.

Early Stages of the Wear Behavior of AISI 440C Stainless Steel under Rolling Contact in Water

2012 ◽  
Vol 566 ◽  
pp. 654-659
Author(s):  
Takashi Honda ◽  
Katsuyuki Kida ◽  
Edson Costa Santos ◽  
Takuya Shibukawa
Keyword(s):  
Surface Roughness ◽  
Wear Track ◽  
Adhesion Force ◽  
Wear Behavior ◽  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Contact ◽  
Wear Loss ◽  
Adhesion Wear ◽  
Laser Confocal Microscope

In the present work, rolling contact fatigue (RCF) tests in water were performed on AISI 440C stainless steels under different loading. Each test was interrupted at 3.6×104, 7.2×104, 1.44×105, 2.16×105, 2.88×105 and 2.88×105 rotating cycles and the wear track at different stages was observed by using a 3D laser confocal microscope. The wear loss at 2100 N was a significantly higher compared to 500 N or 1000 N. The contact surface roughness in samples tested at 2100 N increased during the rolling contact and severe adhesion wear was present at the entire surface. In case of 500 and 1000 N tests, the surface roughness remained low with mild adhesion wear occurring. It is concluded that adhesion force levels are higher under high load rolling contact. They greatly influence the surface conditions and cause high wear loss.

Wear Mechanism of Ceramic Materials in Dry Rolling Friction

1986 ◽  
Vol 108 (4) ◽  
pp. 522-526 ◽  
Author(s):  
S. S. Kim ◽  
K. Kato ◽  
K. Hokkirigawa ◽  
H. Abe´
Keyword(s):  
Silicon Nitride ◽  
Wear Rate ◽  
Contact Area ◽  
Ceramic Materials ◽  
Rolling Friction ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Hertzian Contact ◽  
Real Contact Area ◽  
Wear Process

Wear tests in dry rolling contact were carried out at room temperature on five ceramic materials, such as silicon nitride, silicon carbide, cermet, titania, and alumina. The results showed that wear rate of silicon nitride was smaller than any of the other ceramic materials and bearing steel. Observations of worn surface and wear debris revealed that ceramic materials have two types of wear, one related to real contact area and another related to Hertzian contact area. It was also found that brittle fracture dominates the wear process of ceramic materials in dry rolling contact. Based on the experimental results, wear rate of ceramic materials was expressed with a new nondimensional parameter.

Influence of Particle Size, Applied Compression, and Substratum Material on Particle−Surface Adhesion Force Using the Centrifuge Technique

2009 ◽  
Vol 48 (2) ◽  
pp. 877-887 ◽  
Author(s):  
Marcos A. Felicetti ◽  
Giancarlo R. Salazar-Banda ◽  
José R. Coury ◽  
Mônica L. Aguiar
Keyword(s):  
Particle Size ◽  
Adhesion Force ◽  
Particle Surface ◽  
Surface Adhesion

scholarly journals History of Mitigating Rolling Contact Fatigue and Corrugation of Railway Rails in Japan - Review

2018 ◽  
Vol 1 (2) ◽  
pp. 13-24
Author(s):  
Makoto Ishida
Keyword(s):  
Rolling Contact Fatigue ◽  
Contact Fatigue ◽  
Rolling Friction ◽  
Theory And Practice ◽  
Rolling Contact ◽  
Stick Slip ◽  
Rail Corrugation ◽  
Long Wavelength ◽  
Vertical Loading ◽  
History Of

Rail is the one of the most important materials to support and guide railway vehicles safely and smoothly. Since rail suffers from variousinteracting forces and environmental atmosphere, wear and fatigue pose large problems with wheel and rail. Hence, wear and fatigue ofwheel and rail have been studied so far to keep running safety and some level of riding comfort of vehicle taking into account trackmaintenance cost in the world. In this review, the history of theory and practice of rail maintenance in Japanese railways is describedfocusing on rolling contact fatigue (RCF) corrugation of rails caused by dynamic rolling friction at wheel/rail interface. In particular, “squat”mainly callled in UK or “rail surface shelling” called in Japan which is one of typical fatigue phenomenon for steel wheel-on-rail system andrail corrugations caused by dynamic lateral friction and vertical loading at sharp curves and/or long wavelength of rail corrugation causedby longitudinal roll-slip or stick-slip excited by the resonance of unsprung mass of bogie vertical vibration supported by track stiffness. Inaddition, the practice of countermeasure for RCF defect of squat, preventive grinding, and countermeasure for top of low rail corrugation,top of low rail lubrication “Friction Moderating System” are described. Also, the possibility of preventing long wavelength of rail corrugationformed in tangential track in undersea tunnel (salty water) enviornment is described.

The Model of Nano-Scale Cu-Particle Removal in CO2-Based Micelle Solutions with Different Surfactants

2014 ◽  
Vol 936 ◽  
pp. 624-627 ◽  
Author(s):  
Yun Run Wang
Keyword(s):  
High Pressure ◽  
Adhesion Force ◽  
Pressure Effect ◽  
Particle Surface ◽  
Separation Distance ◽  
Particle Removal ◽  
Surfactant Micelle ◽  
Fluorinated Surfactants ◽  
Surface Separation ◽  
Micelle Solution

This work focused on the analysis of static forces of a Cu particle in CO2-based micelle solutions with different surfactant, including fluorinated surfactants PFPE COO-NH4+, 8FS(EO)2and hydrocarbon surfactants L31, DiF8-PO4-Na+. Calculations demonstrated that high pressure could impose enough capillary pressure effect beneath a particle to compete with the net adhesion force and increase the particle surface separation distance. The ESD for the micelle solutions had the similar behavior, otherwise, the value of NAF for the micelle solution with surfactant DiF8-PO4-Na+ had the minimum relative to other surfactant micelle solutions, suggesting that Cu particles would be more easily removed in micelle solution with DiF8-PO4-Na+ surfactant.

Sign in / Sign up

Export Citation Format

Share Document