FG Systemdynamik und Reibungsphysik

25 Items

Recent Submissions
Contacts With Negative Work of “Adhesion” and Superlubricity

Popov, Valentin L. (2020-01-22)

Van der Waals forces between solids in vacuum are always attractive and are considered as the main source of adhesion. However, in the presence of an intermediate medium, they can also be repelling (Dzyaloshinskii et al., 1961) which means that the “work of adhesion” becomes negative. Similarly to the case of adhesion, the interaction range of these forces can be either comparable (or larger) t...

Grundlagen und interdisziplinäre Anwendung von mechanischen Stoßproblemen

Willert, Emanuel (2020)

Die vorliegende Dissertation konzentriert sich auf die Grundlagen von Stoßproblemen und deren Anwendungen in Physik, Technik und Medizin – von der Dynamik granularer Systeme über Sport bis hin zur Schädigung und Prüfung von technologischen oder biologischen Materialien. Stoßprobleme treten in technologischen oder biologischen Prozessen und Systemen häufiger auf als normalerweise angenommen. Es ...

Voltage-Induced Friction with Application to Electrovibration

Heß, Markus ; Popov, Valentin L. (2019-11-20)

Due to the growing interest in robotic and haptic applications, voltage-induced friction has rapidly gained in importance in recent years. However, despite extensive experimental investigations, the underlying principles are still not sufficiently understood, which complicates reliable modeling. We present a macroscopic model for solving electroadhesive frictional contacts which exploits the cl...

Stoßprobleme in Physik, Technik und Medizin

Willert, Emanuel (2020-01)

Dieses Open Access Buch widmet sich dem Problem der Mechanik des Zusammenstoßes zweier makroskopischer Körper. Falls die Dynamik der Körper als Ganzes dies erlaubt, ohne in unüberschaubare Komplexität zu verfallen (in der Regel ist das nur für das reine Normalstoßproblem der Fall), werden allgemeine axialsymmetrische Stoßpartner betrachtet. Für das allgemeine räumliche Stoßproblem wird sich auf...

Wear Analysis of a Heterogeneous Annular Cylinder

Li, Qiang ; Forsbach, Fabian ; Schuster, Maximilian ; Pielsticker, Daniel ; Popov, Valentin L. (2018-03-18)

Wear of a cylindrical punch composed by two different materials alternatively distributed in annular forms is studied with the method of dimensionality reduction (MDR). The changes in surface topography and pressure distribution during the wear process is obtained and validated by the boundary element method (BEM). The pressure in each annular ring approaches a constant in a stationary state wh...

Is Tribology Approaching Its Golden Age? Grand Challenges in Engineering Education and Tribological Research

Popov, Valentin L. (2018-11-19)

In spite of its obvious importance, the subject of tribology has relatively low visibility in the engineering community and among the general public. The author's hypothesis is that this problem is at least partly due to the poor “availability” of tribology. In other words, there are practically no simple methods or concepts having high predictive power for tribological problem-solving. That si...

Investigation on Dynamic Response of Rubber in Frictional Contact

Nakano, Ken ; Kawaguchi, Kai ; Takeshima, Kazuho ; Shiraishi, Yu ; Forsbach, Fabian ; Benad, Justus ; Popov, Mikhail ; Popov, Valentin L. (2019-03-26)

In the present work, we analyze a device for measuring the dynamic response of rubber in sliding contact. The principle of the device is to measure excited oscillations of a mechanical system with a sliding contact between a rubber roller and a rigid surface. Depending on the contact properties, varying oscillation amplitudes are measured. The goal is to determine dynamic response properties of...

Editorial: Friction and Wear: From Elementary Mechanisms to Macroscopic Behavior

Pohrt, Roman ; Popov, Valentin L. (2019-08-02)

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Artificial Neural Networks (ANNs) as a Novel Modeling Technique in Tribology

Argatov, Ivan (2019-05-29)

In the present paper, artificial neural networks (ANNs) are considered from a mathematical modeling point of view. A short introduction to feedforward neural networks is outlined, including multilayer perceptrons (MLPs) and radial basis function (RBF) networks. Examples of their applications in tribological studies are given, and important features of the data-driven modeling paradigm are discu...

Effect of elastic grading on fretting wear

Willert, Emanuel ; Dmitriev, Andrey I. ; Psakhie, Sergey G. ; Popov, Valentin L. (2019-05-24)

We consider fretting wear in elastic frictional contact under influence of oscillations of small amplitude and investigate the question, how wear damage can be influenced by the introduction of material gradients. To achieve a general understanding we restrict our consideration to media with a power-law dependency of the elastic modulus on depth. In this case, a complete analytical solution can...

Handbook of contact mechanics

Popov, Valentin L. ; Heß, Markus ; Willert, Emanuel (2019-04)

This open access book contains a structured collection of complete solutions of all significant axially symmetric contact problems. It provides solutions for classical profiles such as the sphere, cone or flat cylindrical punch as well as a multitude of other technically relevant shapes, e.g. the truncated cone, the worn sphere, rough profiles, hollow cylinders, etc. Normal, tangential and tors...

Adhesive Strength of Contacts of Rough Spheres

Li, Qiang ; Pohrt, Roman ; Popov, Valentin L. (2019-03-26)

The adhesive contact between a parabolic indenter with superimposed roughness and an elastic half space is studied in the JKR-limit (infinitely small range of action of adhesive forces) using the boundary element method with mesh-dependent detachment criterion suggested in 2015. Three types of superimposed roughness are considered: one- and two-dimensional waviness and randomly rough roughness....

Heterogeneity of material structure determines the stationary surface topography and friction

Li, Qiang ; Voll, Lars ; Starcevic, Jasminka ; Popov, Valentin L. (2018-09-21)

The character of surface roughness and the force of friction in the stationary state after a sufficiently long run-in process are of key importance for numerous applications, e.g. for friction between road and tire. In the present paper, we study theoretically and experimentally the asymptotic worn state of a bi-phasic material that is arbitrarily heterogeneous in the contact plane, but homogen...

General procedure for solution of contact problems under dynamic normal and tangential loading based on the known solution of normal contact problem

Popov, Valentin L. ; Pohrt, Roman ; Heß, Markus (2016)

In this article, we show that the normal contact problem between two elastic bodies in the half-space approximation can always be transformed to an equivalent problem of the indentation of a profile into an elastic Winkler foundation. Once determined, the equivalent profile can also be used for tangential contact problems and arbitrary superimposed normal and tangential loading histories as wel...

Limiting shape of profile due to dual-mode fretting wear in contact with an elastomer

Mao, Xinyu ; Liu, Wei ; Ni, Yuanzhi ; Popov, Valentin L. (2016)

We consider fretting wear due to superimposed normal and tangential oscillations of two contacting bodies, one of which is an elastomer with a linear rheology. Similarly to the contact of elastic bodies, at small oscillation amplitudes, the wear occurs only in a circular slip zone at the border of the contact area and the wear profile tends to a limiting form, in which no further wear occurs. I...

Reduction of friction by normal oscillations. II. In-plane system dynamics

Mao, Xinyu ; Popov, Valentin L. ; Starcevic, Jasminka ; Popov, Mikhail (2017)

The influence of out-of-plane oscillations on friction is a well-known phenomenon that has been studied extensively with various experimental methods, e.g., pin-on-disk tribometers. However, existing theoretical models have yet achieved only qualitative correspondence with experiment. Here we argue that this may be due to the system dynamics (mass and tangential stiffness) of the pin or other s...

Reduction of friction by normal oscillations. I. Influence of contact stiffness

Popov, Mikhail ; Popov, Valentin L. ; Popov, Nikita (2017)

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Adhesive normal contact between flat punch and a visco-elastic half-space in Dugdale approximation

Rengshausen, Julia (2017)

This work shows an analytical approach to solving problems of normal adhesive contact where visco-elastic material behavior is present. The geometry is limited to a flat punch in contact with a half-space, but the approach presented here can also be adapted to different geometries. The adhesion is modelled as a Dugdale potential which has a constant pressure value over the area of adhesion. Usi...

Simulation von Kontaktproblemen bei linearem viskoelastischem Materialverhalten

Kusche, Stephan (2016)

Auf dem Gebiet der Kontaktmechanik von Körpern mit elastischen Eigenschaften sind bereits viele analytische Lösungen bekannt. Im Gegensatz dazu konnten für viskoelastische Materialien bisher nur einfachste Problemstellungen analytisch gelöst werden. Der Grund dafür ist das zeitabhängige Verhalten viskoelastischer Materialien, das bei Simulationen eine Betrachtung der Deformationsgeschichte erfo...

Analyse und Verbesserung der Simulationsmethode des Bremsenquietschens

Gräbner, Nils (2016)

Bremsenquietschen ist ein Phänomen, bei dem das gesamte Bremssystem innerhalb des hörbaren Frequenzbereichs von 1 kHz – 16 kHz schwingt. Aus Sicht von Kunden stellt das Quietschen von Kfz-Bremsen einen erheblichen Qualitätsmangel dar und berechtigt unter bestimmten Voraussetzungen sogar zur Rückgabe des Fahrzeuges. Die Entwicklung geräuscharmer Bremsen ist im Allgemeinen keine triviale Aufgabe....