FG Systemdynamik und Reibungsphysik

93 Items

Recent Submissions
Influence of Chemical Heterogeneity and Third Body on Adhesive Strength: Experiment and Simulation

Lyashenko, Iakov A. ; Li, Qiang ; Popov, Valentin L. (2021-03-24)

We investigate experimentally and numerically the influence of chemical heterogeneity and of third-body particles on adhesive contact. Chemical heterogeneity is generated by chemical treatment of the contacting bodies changing locally the surface energy. For studying the influence of the third body, two types of particles are used: sand particles with various geometrical shapes and sizes, and s...

Editorial: Contact Mechanics Perspective of Tribology

Goryacheva, Irina G. ; Paggi, Marco ; Popov, Valentin L. (2021-03-19)

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Artificial neural network modeling of sliding wear

Argatov, Ivan I. ; Chai, Young S. (2021-04-01)

A widely used type of artificial neural networks, called multilayer perceptron, is applied for data-driven modeling of the wear coefficient in sliding wear under constant testing conditions. The integral and differential forms of wear equation are utilized for designing an artificial neural network-based model for the wear rate. The developed artificial neural network modeling framework can be ...

Synovial Joints. Tribology, Regeneration, Regenerative Rehabilitation and Arthroplasty

Popov, Valentin L. ; Poliakov, Aleksandr M. ; Pakhaliuk, Vladimir I. (2021-02-02)

Synovial joints are unique biological tribosystems that allow a person to perform a wide range of movements with minimal energy consumption. In recent years, they have been increasingly called “smart friction units” due to their ability to self-repair and adapt to changing operating conditions. However, in reality, the elements of the internal structure of the joints under the influence of many...

Calculation for High Pressure Behaviour of Potential Solar Cell Materials Cu2FeSnS4 and Cu2MnSnS4

Küllmey, Tim ; González, Miguel ; Heppke, Eva M. ; Paulus, Beate (2021-02-02)

Exploring alternatives to the Cu2ZnSnS4 kesterite solar cell absorber, we have calculated first principle enthalpies of different plausible structural models (kesterite, stannite, P4¯ and GeSb type) for Cu2FeSnS4 and Cu2MnSnS4 to identify low and high pressure phases. Due to the magnetic nature of Fe and Mn atoms we included a ferromagnetic (FM) and anti-ferromagnetic (AM) phase for each struct...

Adhesion and friction in hard and soft contacts: theory and experiment

Popov, Valentin L. ; Li, Qiang ; Lyashenko, Iakov A. ; Pohrt, Roman (2021-01-29)

This paper is devoted to an analytical, numerical, and experimental analysis of adhesive contacts subjected to tangential motion. In particular, it addresses the phenomenon of instable, jerky movement of the boundary of the adhesive contact zone and its dependence on the surface roughness. We argue that the “adhesion instabilities” with instable movements of the contact boundary cause energy di...

Dynamic stiction without static friction: The role of friction vector rotation

Nakano, Ken ; Popov, Valentin L. (2020-12-10)

In the textbook formulation of dry friction laws, static and dynamic friction (stick and slip) are qualitatively different and sharply separated phenomena. However, accurate measurements of stick-slip motion generally show that static friction is not truly static but characterized by a slow creep that, upon increasing tangential load, smoothly accelerates into bulk sliding. Microscopic, contact...

Principios y aplicaciones de la mecánica de contacto en tribología, fricción y adherencia

Popov, Valentin L. (2020)

Este libro actualizado hasta 2019 sobre la mecánica del contacto es multidisciplinar y constituye una herramienta muy útil para los ingenieros, los físicos, geólogos y los investigadores en el campo de los materiales y los adhesivos. La existencia de una obra en castellano sobre esta temática constituye una novedad que abre el campo de trabajo de los hispano-hablantes a una disciplina raramente...

Ludwig Föppl and Gerhard Schubert: Unknown classics of contact mechanics

Popova, Elena ; Popov, Valentin L. (2020-09-07)

At the beginning of 1941, Professor Ludwig Föppl published an eight‐page paper “Elastische Beanspruchung des Erdbodens unter Fundamenten” (Elastic stress in the ground under foundations). It was further developed by his doctoral student Gerhard Schubert and led to a publication by Schubert in 1942, which contains many results obtained by researchers in contact mechanics in the subsequent decade...

Non-adhesive Contacts With Different Surface Tension Inside and Outside the Contact Area

Li, Qiang ; Popov, Valentin L. (2020-09-02)

In the past decade, the influence of surface tension on contact properties has attracted much attention, especially in the context of contact of very soft materials (such as gels) or contacts at the nanoscale. However, in the most current studies it is assumed that the tension of the surface inside and outside the contact area is the same. In practical terms, this means that the object consider...

The Influence of Vibration on Friction: A Contact-Mechanical Perspective

Popov, Mikhail (2020-08-20)

A unified model for active control of static and sliding friction by normal, tangential, and transverse oscillations is discussed, building on a series of past publications. The model in question is quasi-static, uses Amontons friction and takes into account contact stiffness in both normal and tangential directions. This makes the model fully macroscopic, which stands in contrast to Prandtl-To...

Adhesion Between Rigid Indenter and Soft Rubber Layer: Influence of Roughness

Lyashenko, Iakov A. ; Pohrt, Roman (2020-07-29)

We report a series of experiments on the indentation of steel indenters into a soft layer of transparent rubber with relatively high adhesion. The roughness properties of the steel indenters are varied by undergoing preparation using sandpaper with different grain sizes. Starting from a smooth surface, additional roughness increases the adhesive strength up to a critical roughness value, after ...

Boundary Element Calculations for Normal Contact of Soft Materials With Tensed Surface Membrane

Yuan, Weike ; Wang, Gangfeng (2020-07-29)

This work considers the non-adhesive frictionless contact problem of soft materials with surface being tensed by equi-biaxial tension. The boundary element method (BEM) based on Fast Fourier Transform and conjugate gradient algorithm is extended to deal with this problem. By comparing with existing analytical solutions for the axisymmetric contact between a rigid parabolic indenter and an elast...

Contact Geometry Adaptation in Fretting Wear: A Constructive Review

Argatov, Ivan ; Chai, Young Suck (2020-07-03)

Fretting is a special type of wear, which appears at the contact interface between two solids subjected to constant normal load and periodic tangential forces. Although most studies on fretting have been executed experimentally, some approaches for simulating fretting wear have also been introduced during the last decades. In particular, fretting wear analysis is concerned with the evolution of...

Multiscale biomechanics and tribology of inorganic and organic systems

(2021)

This open access book gathers authoritative contributions concerning multiscale problems in biomechanics, geomechanics, materials science and tribology. It is written in memory of Sergey Grigorievich Psakhie to feature various aspects of his multifaceted research interests, ranging from theoretical physics, computer modeling of materials and material characterization at the atomic scale, to app...

Simulation of Adhesive Contact of Soft Microfibrils

He, Xin ; Li, Qiang ; Popov, Valentin L. (2020-10-16)

Adhesive contact between a flat brush structure with deformable microfibrils and an elastic half space is numerically simulated. The stiffness of pillars is modeled by linear springs. The fast Fourier transform-assisted boundary element method for the contact of rigid indenters is modified to include the microfibril stiffness so that the deflection of pillars and elastic interaction to elastic ...

Energy loss and wear in spherical oblique elastic impacts

Willert, Emanuel (2019)

Percussive and erosive wear by repetitive impacting of solid particles damages surfaces even at low impact velocities. As the impact wear is often directly related to the energy loss during the collision and therefore to the coefficients of normal and tangential restitution, in the present study the oblique low-velocity impact of a rigid sphere onto an elastic half-space is analyzed based on th...

Dugdale-Maugis adhesive normal contact of axisymmetric power-law graded elastic bodies

Willert, Emanuel (2018)

A closed-form general analytic solution is presented for the adhesive normal contact of convex axisymmetric power-law graded elastic bodies using a Dugdale-Maugis model for the adhesive stress. The case of spherical contacting bodies is studied in detail. The known JKR- and DMT-limits can be derived from the general solution, whereas the transition between both can be captured introducing a gen...

Boundary element method for nonadhesive and adhesive contacts of a coated elastic half-space

Li, Qiang ; Pohrt, Roman ; Lyashenko, Iakov A. ; Popov, Valentin L. (2020-01)

We present a new formulation of the boundary element method for simulating the nonadhesive and adhesive contact between an indenter of arbitrary shape and an elastic half-space coated with an elastic layer of different material. We use the Fast Fourier Transform-based formulation of boundary element method, while the fundamental solution is determined directly in the Fourier space. Numerical te...

Stress tensor and gradient of hydrostatic pressure in the contact plane of axisymmetric bodies under normal and tangential loading

Willert, Emanuel ; Forsbach, Fabian ; Popov, Valentin L. (2020-05-14)

The Hertzian contact theory, as well as most of the other classical theories of normal and tangential contact, provides displacements and the distribution of normal and tangential stress components directly in the contact surface. However, other components of the full stress tensor in the material may essentially influence the material behaviour in contact. Of particular interest are principal ...