Article
Engineering, Mechanical
Martin Kraus, Matthias Lenzen, Marion Merklein
Summary: This study utilizes a sheet metal compression test to describe the relationship between friction values and strain, confirming that friction values change during the forming process.
Article
Engineering, Chemical
Brodie K. Hoyer, Rong Long, Mark E. Rentschler
Summary: Rolling contact experimentation is a useful method for studying adhesive contact between surfaces. The researchers have designed a tribometric device to capture forces between a rolling indenter and substrate, and validated its effectiveness through experiments. This device can facilitate investigations of rolling contact mechanics in medical robotics.
Review
Engineering, Mechanical
Biao Li, Peidong Li, Runhua Zhou, Xi-Qiao Feng, Kun Zhou
Summary: This paper provides a comprehensive review of the recent progress in contact mechanics for tribological and contact damage-related problems. It briefly introduces contact mechanics, elaborates on its applications in various problems, and concludes with future perspectives and major challenges to be addressed.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Multidisciplinary Sciences
Reinhard Hentschke, Jan Plagge
Summary: Current theoretical descriptions of rubber or elastomer friction are complex due to detailed mathematical models, but experimental coefficients of sliding friction show little structure, suggesting a simpler approach is possible. Through scaling and dimensional analysis, a relatively simple expression for the coefficient of friction is obtained, providing an intuitive understanding of the underlying physics and fitting experimental data for various conditions.
SCIENTIFIC REPORTS
(2021)
Article
Engineering, Chemical
Felix Harden, Birgit Schaedel, Marlon Siegel, Roland Kral, Rainer Adelung, Olaf Jacobs
Summary: Accurate assessment of wear behavior is crucial for optimization of tribological systems. This work proposes a novel approach to implement in-situ wear measurement of both wearing counterparts and demonstrates its feasibility on a ball-on-prism tribometer. Challenges such as radial runout, testing in media, and debris accumulation remain, but this advancement offers new possibilities for wear evaluation and optimization.
Article
Engineering, Mechanical
Anahita Emami, Seyedmeysam Khaleghian, Saied Taheri
Summary: Modeling the real contact area is crucial in various tribological processes, and the accuracy of predicting friction, adhesion, and wear depends on it. Consideration of physical parameters such as surface roughness characteristics, material properties, sliding velocity, and normal load can lead to a more precise estimation of the friction coefficient.
Article
Engineering, Mechanical
Eliot Chaize, Emilie Vieville, Frederique Valiorgue, Cedric Courbon
Summary: This paper presents a method for in-operando contact monitoring of a sliding contact using an ultrasonic array. The method assesses the contact area and wear between two metallic materials by studying the propagation of ultrasonic waves and their interaction with the contact interface. The experimental set-up integrates an ultrasonic array on an open tribometer and uses a multi-channel pulser receiver and dedicated software for real-time monitoring.
Article
Engineering, Mechanical
Murong Li, Yong Lei, Yingda Hu, Shilun Du, Dedong Gao, Zhen Wang, Tian Xu
Summary: A novel friction coefficient model based on modified classical elastic friction theory was proposed in this study to establish the relationship between the friction coefficient and parameters such as normal pressure and velocity. The model was validated using computational inverse technique, showing varying friction coefficients between needle and PVA tissue phantom with different normal pressures and insertion velocities. The results can aid in understanding needle-tissue interactions and optimizing needle actuation strategies.
JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME
(2022)
Article
Chemistry, Physical
Andreas Hausberger, Marina Pecora, Damien Favier, Elisabeth Rossegger, Martin Tockner, Thomas Ules, Matthias Haselmann, Sandra Schloegl, Christian Gauthier
Summary: Structured surfaces have potential to serve as functionalized surfaces by specifically influencing friction and deformation behaviors. This study investigated the influence of different structures on surface friction behavior and its relation to real area of contact.
Article
Chemistry, Multidisciplinary
Christopher A. Mizzi, Laurence D. Marks
Summary: This article presents a new flexoelectric model for triboelectricity, where contact deformation at the nanoscale drives charge transfer through band bending. The authors use first-principles and finite element calculations to investigate the implications of charge transfer for different contact geometry and materials combinations. They demonstrate that their ab initio based formulation is compatible with existing empirical models and experimental observations.
Article
Materials Science, Multidisciplinary
Joseph M. Monti, Lars Pastewka, Mark O. Robbins
Summary: Surface roughness affects the contact area and geometry of solids. Small contact patches have simple geometries and low pressure, while larger contact patches have higher pressure and can be ramified with regions out of contact. Bubbles also affect the area and perimeter of contact patches.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2022)
Article
Engineering, Mechanical
Arata Ishizako, Masaki Tomosada, Kazuo Hokkirigawa, Takeshi Yamaguchi
Summary: The friction coefficients between a glass plate and rubber blocks with different end-face corner radii were investigated. It was found that rubber blocks with a larger end-face corner radius exhibited higher friction coefficients under dry conditions, while rubber blocks with a smaller end-face corner radius had higher friction coefficients under lubrication conditions. Additionally, the friction coefficients for rubber blocks with a smaller end-face corner radius increased with the sliding velocity and lubricant viscosity due to the formation of a fluid-free gap at the contact interface.
TRIBOLOGY INTERNATIONAL
(2022)
Article
Engineering, Mechanical
S. Runge, P. A. Ignatyev, M. Wangenheim, C. Bederna, B. Wies, J. Wallaschek
Summary: Abrasive processes, specifically local slip, play a significant role in the friction and wear of vehicle tires. Understanding the dynamic contact between rubber blocks and abrasive surfaces is crucial for analyzing tire tread friction and wear mechanisms. Detailed consideration of realistic transient dynamics is essential for accurate characterization beyond typical abrasion testers.
Article
Mechanics
Jagoba Lekue, Florian Doerner, Christian Schindler
Summary: This article discusses the deviation in measuring the size and shape of the wheel-rail contact area using Prescale pressure measurement film, highlighting the importance of correcting the systematic measurement error for accurate assessments.
Article
Chemistry, Analytical
Iakov A. Lyashenko, Valentin L. Popov, Roman Pohrt, Vadym Borysiuk
Summary: In this study, we present the design of a high-precision tribometer laboratory setup. The entire design process is described, starting from concept development to the creation of an accurate 3D model and final assembly of functional parts. The setup is based on a previously designed device, with modifications made to address its limitations. An example is provided to demonstrate data processing and correction for backlash and signal drift errors. The flexibility of the equipment is highlighted, as peripheral parts can be modified without changing the main frame.
Article
Physics, Multidisciplinary
Martin H. Mueser, Bo N. J. Persson
Summary: This article presents simulations on the sticking contact between a rigid cylinder and a viscoelastic half space, revealing a maximum in the work of separation at intermediate pull-off velocities. The maximum tensile forces increase monotonically with the pull-off speed and the crack tip speed, consistent with the Persson-Brener approach. Additionally, the fracture mode transitions from interfacial crack propagation to quasi-uniform bond breaking with an increasing range of adhesion.
Article
Nanoscience & Nanotechnology
Tomas F. Babuska, John F. Curry, Michael T. Dugger, Ping Lu, Yan Xin, Sam Klueter, Alexander C. Kozen, Tomas Grejtak, Brandon A. Krick
Summary: This study investigates the effects of water and oxygen on the structural modifications of MoS2 coatings in space applications and their impact on friction due to aging. The results show that basally oriented surfaces have lower initial friction, while oxidation increases initial friction and prolongs the transition from high to low friction after aging. Patches formed in air show improved resistance to oxidation after aging.
ACS APPLIED MATERIALS & INTERFACES
(2022)
Article
Cell Biology
Duy T. Nguyen, Jack E. Famiglietti, Ryan A. Smolchek, Zadia Dupee, Nickolas Diodati, Diego Pedro, Juan M. Uruena, Matthew A. Schaller, W. Gregory Sawyer
Summary: A new cell culture platform has been developed, which utilizes a pump-free suction device for controlled perfusion of cell culture media, leading to more physiologically relevant cell culture models. This platform has demonstrated versatile applications, including the culture of cellular spheroids and the maintenance of tissue microexplants with high viability and prolonged contractility.
Review
Cell Biology
Duy T. Nguyen, Elizabeth Ogando-Rivas, Ruixuan Liu, Theodore Wang, Jacob Rubin, Linchun Jin, Haipeng Tao, William W. Sawyer, Hector R. Mendez-Gomez, Matthew Cascio, Duane A. Mitchell, Jianping Huang, W. Gregory Sawyer, Elias J. Sayour, Paul Castillo
Summary: This article discusses the important role of the tumor microenvironment in CAR-T cell therapy and explains the advantages and limitations of preclinical models.
Article
Polymer Science
Rebecca A. Olson, Megan E. Lott, John B. Garrison, Cullen L. G. Davidson, Lucca Trachsel, Diego I. Pedro, W. Gregory Sawyer, Brent S. Sumerlin
Summary: This paper describes the synthesis of ultrahigh molecular weight water-soluble polymers via photoiniferter polymerization under inverse miniemulsion conditions. The process utilizes low-intensity UV irradiation and offers rapid polymerization rates, excellent molecular weight control, and viscosity control. By optimizing the polymerization conditions, acrylamido homopolymers and block copolymers with molecular weights exceeding 1,000,000 Da have been successfully synthesized at ambient temperature.
Article
Engineering, Biomedical
Tyler C. Hunt, Tomas Grejtak, Deeksha Kodangal, Soumya Varma, Caroline E. Rinaldi, Siddhartha Pathak, Brandon A. Krick, Gregory M. Erickson
Summary: Beavers have the unique ability to use their continuously growing incisors to fell trees. Despite being blunted, their incisors maintain a sharp cutting edge. The microstructure of the enamel in their incisors plays a crucial role in maintaining their sharpness.
ACTA BIOMATERIALIA
(2023)
Article
Engineering, Chemical
Kylie E. Van Meter, Tomas F. Babuska, Christopher P. Junk, Kasey L. Campbell, Mark A. Sidebottom, Tomas Grejtak, Andrew B. Kustas, Brandon A. Krick
Summary: This study demonstrates that PTFE filled with iron-cobalt microparticles is an ultralow wear, magnetic, multifunctional tribological material. Compared to PTFE filled separately with iron or cobalt microparticles, PTFE filled with FeCo microparticles shows significantly improved steady-state wear behavior.
Article
Engineering, Mechanical
Toshi Tada, Satoshi Kawasaki, Ryouske Shimizu, Bo N. J. Persson
Summary: We investigate the friction between a rectangular tire tread rubber block and an ice surface under different temperatures (-38 to -2 degrees C) and sliding speeds (3 mu m/s to 1 cm/s). At low temperatures and low sliding speeds, slip between the ice surface and ice fragments attached to the rubber surface plays a significant role in the friction force. When the temperature is above -10 degrees C or the sliding speed is high enough, a thin premelted water film forms on the ice surface, reducing the contribution of shearing the area of real contact to the friction force. Instead, the viscoelastic deformations of the rubber caused by the ice asperities become the dominant contribution to the friction force. We also discuss the impact of waxing on the friction between skis and snow (ice particles).
Article
Nanoscience & Nanotechnology
Tomas F. Babuska, John F. Curry, Ryan Thorpe, Md. Istiaque Chowdhury, Nicholas C. Strandwitz, Brandon A. Krick
Summary: The density of sputter-deposited nanocrystalline MoS2 coatings affects their oxidation resistance and wear resistance. Low-density coatings with voids and columnar microstructure result in severe surface and subsurface oxidation. Shear-induced reorientation of the surface microstructure and elimination of oxygen pathways can significantly improve the oxidation resistance of low-density MoS2 coatings.
ACS APPLIED NANO MATERIALS
(2023)
Article
Biophysics
D. T. Nguyen, D. I. Pedro, A. Pepe, J. G. Rosa, J. I. Bowman, L. Trachsel, G. R. Golde, I. Suzuki, J. M. Lavrador, N. T. Y. Nguyen, M. A. Kis, R. A. Smolchek, N. Diodati, R. Liu, S. R. Phillpot, A. R. Webber, P. Castillo, E. J. Sayour, B. S. Sumerlin, W. G. Sawyer
Summary: Tumor invasion is driven by intrinsic and extrinsic stresses, reduced intercellular adhesion, and interactions with the extracellular matrix. This study investigates nonenzymatic mechanisms of invasion using a bioconjugated liquid-like solid (LLS) medium to mimic a loose capillary-like network. The LLS is made of soft granular microgels and allows for the exploration of 3D tumor invasion using confocal microscopy. The study reveals that tumor invasion is guided by the interstitial space and geometrical cues, independent of proteolytic ability.
Article
Engineering, Mechanical
Kylie E. Van Meter, Md Istiaque Chowdhury, Mark J. Sowa, Alexander C. Kozen, Tomas Grejtak, Tomas F. Babuska, Nicholas C. Strandwitz, Brandon A. Krick
Summary: This study investigates the influence of deposition temperature on the wear behavior and material properties of plasma enhanced atomic layer deposited (PEALD) TiVN films. The wear rates of the TiVN films varied with deposition temperature, with the 250°C sample achieving ultralow wear. The PEALD TiVN films exhibited low wear and friction properties, low electrical resistivity, and high density and crystallinity.
Article
Engineering, Mechanical
Kylie E. Van Meter, Angela A. Pitenis, Kathryn L. Harris, W. Gregory Sawyer, Brandon A. Krick
Summary: The wear of PTFE can be significantly reduced by compositing it with 1-5 wt% alumina particles. This composite achieves ultra-low wear rates and exhibits specific friction behavior within a range of contact pressures. The formation of tribofilms at the sliding interface plays a crucial role in the wear and friction behavior of these materials.
Article
Engineering, Mechanical
T. F. Babuska, B. A. Krick, N. Argibay, M. T. Dugger, M. Chandross, J. F. Curry
Summary: Solid lubricants such as molybdenum disulfide (MoS2) are commonly used in space applications and often experience changes in friction behavior after prolonged periods of dormancy. This phenomenon, known as the dwell or stop-time effect, has been studied for over 50 years but the driving mechanism is still not fully understood. In this study, experiments were conducted to investigate the dwell effect in MoS2 coatings under varying dwell times and vacuum pressures. Results suggest that the change in friction behavior is driven by interactions between water and the sliding interface. The role of microstructure on the dwell effect was also explored, revealing that coatings with a shear-modified surface have a smaller dwell effect compared to spray-deposited coatings.
Meeting Abstract
Oncology
W. Gregory Sawyer, Duy Nguyen, Ryan Smolchek, Jack Famiglietti, Stephanie Warrington
JOURNAL FOR IMMUNOTHERAPY OF CANCER
(2022)
Article
Materials Science, Multidisciplinary
Jianjun Wang, Avinash Tiwari, Jie Gao, Yang Huang, Yu Jia, Bo N. J. Persson
Summary: In this study, we investigate the role of electronegativity in sliding friction of two-dimensional monolayer systems. Our results show that the friction force strongly depends on the electronegativity difference between the atoms involved. When sliding along a nonpolar path, the friction force is almost the same for all studied systems, regardless of the material and surface structures. However, for sliding along a polar path, the friction force follows a universal linear scaling law, where the force is proportional to the electronegativity difference between constituent atoms. We further demonstrate that the electronegativity-induced atomic dipoles enhance the corrugation of charge distribution, leading to increased sliding barriers.
