Inst. Mechanik

105 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...

Numerical and experimental investigation of the assessment of rail damper parameters with a new lab-scaled model

Jahan Tigh Kuchak, Alireza (2020)

One of the major problem in the development of railway network is track noise. Control of the noise pollution is an important environmental concern in urban areas. Rolling noise is one of the major sources of noise, and rail dampers as an extra installed-mass on the rail are a common method to reduce the rail vibration and consequently rail noise. In most cases, the experimental results from fi...

On the discretization of a bistable cantilever beam with application to energy harvesting

Noll, Max-Uwe ; Lentz, Lukas ; Wagner, Utz von (2019)

A typical setup for energy harvesting is that of a cantilever beam with piezoceramics excited by ambient base vibrations. In order to get higher energy output for a wide range of excitation frequencies, often a nonlinearity is introduced by intention in that way, that two magnets are fixed close to the free tip of the beam. Depending on strength and position of the magnets, this can either resu...

Coupling and computation of electromagnetism and mechanics

Abali, Bilen Emek (2019-09-04)

Accurate coupling of electromagnetism and mechanics is of interest in computations of transducers such as piezoelectric, pyroelectric, electromagnetic sensors and actuators. Balance equations in mechanics as well as the MAXWELL equations for electromagnetism have been established in science. However, if the coupling between these governing equations are necessary, several difficulties arise. He...

Thin‐layer inertial effects in plasticity and dynamics in the Prandtl problem

Georgievskii, Dmitri V. ; Müller, Wolfgang H. ; Abali, Bilen Emek (2019-10-23)

Especially in metal forming, large plastic deformation occurs in thin plates. The problem of compressing dies is analyzed to evaluate the spreading of a thin layer in between. The velocity of dies is a given function in time so that the kinematics of the process is known. This problem can be considered as a generalization of the classical Prandtl problem by taking inertial effects into account ...

A note on couette flow of nematic crystals according to the Ericksen–Leslie theory

Rickert, Wilhelm ; Vilchevskaya, Elena N. ; Müller, Wolfgang H. (2019-12-12)

In order to model the flow of nematic crystals, the theoretical framework according to Ericksen and Leslie is applied. The essentials of the theory are compiled and then specialized to Couette flow. The profiles for linear velocity and orientation angle will be computed and, in particular, we shall also study the rise in temperature due to viscous dissipation, which is frequently ignored by mec...

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...

Analysis and development of a monolithic computational approach for fluid–structure interaction by means of the finite element method

Piekny, Florian (2019)

The phenomenon of fluid–structure interaction (FSI) appears in many engineering applications. Its computation allows to quantify the mechanical behaviour of both fluid and structure interacting with each other. For that purpose, appropriate field equations are specified for an incompressible, viscous fluid and a linear elastic solid. The domain movement is considered by utilizing the arbitrary ...

Mechanotherapy of bone fracture: Adapted fixation conditions

Heyland, Mark (2019-10)

While mechanical overloading caused a fracture, well-controlled mechanical loading can be an integral part of a coordinated fracture healing process. The relative movement of fracture segments affects tissue strain close to the fracture and thus controls the healing pathway. More specifically, moderate hydrostatic or volumetric strain improves osteogenic development while high distortional or d...

A System for Retrieval and Incubation of Benthic Sediment Cores at In Situ Ambient Pressure and under Controlled or Manipulated Environmental Conditions

Jackson, Keith ; Witte, Ursula ; Chalmers, Stewart ; Anders, Erik ; Parkes, John (2017)

The investigation of benthic biodiversity and biogeochemical processes in the deep sea is complicated by the need to conduct experiments at in situ pressures. Recovery of sediment samples to the surface without maintaining full-depth ambient pressure may damage the organisms that are of interest or cause physiological changes that could influence the processes being studied. It is possible to c...

Ein hocheffizientes finites Dreieckselement zur Berechnung dünnwandiger piezoelektrischer Strukturen

Rama, Gil (2019)

Verbundlaminate aus lasttragenden und multifunktionalen Schichten stellen leistungsfähige moderne Materialsysteme dar. Die dabei verwendeten passiven lasttragenden Schichten bestehen in der Regel aus Faserverbundwerkstoffen oder aus isotropen Materialien. Piezoelektrische Materialien eignen sich aufgrund ihrer sehr gut nutzbaren elektromechanischen Kopplungseigenschaften zur Ausführung multifun...

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...

Thermodynamik der deformierbaren Festkörper unter Einfluss des Elektromagnetismus und die numerische Berechnung multiphysikalischer Prozesse

Abali, Bilen Emek (2019)

Die mathematische Beschreibung und zugehörige Simulation deformierbarer Festkörper unter mechanischer, thermischer und elektromagnetischer Belastung werden dargestellt. Ein solches multiphysikalisches System wird durch Bilanzgleichungen im Verbund mit konstitutiven Gleichungen berechenbar. Die Bilanzgleichungen inklusive Elektromagnetismus werden diskutiert und motiviert. Die konstitutiven Glei...

In Silico Optimization of Femoral Fixator Position and Configuration by Parametric CAD Model

Korunovic, Nikola ; Marinković, Dragan ; Trajanovic, Miroslav ; Zehn, Manfred ; Mitkovic, Milorad ; Affatato, Saverio (2019-07-22)

Structural analysis, based on the finite element method, and structural optimization, can help surgery planning or decrease the probability of fixator failure during bone healing. Structural optimization implies the creation of many finite element model instances, usually built using a computer-aided design (CAD) model of the bone-fixator assembly. The three most important features of such CAD ...

Dealing with Nap-Core Sandwich Composites: How to Predict the Effect of Symmetry

Ha, Giap ; Zehn, Manfred ; Marinković, Dragan ; Fragassa, Cristiano (2019-03-15)

The behavior of nap-core sandwiches was investigated with a special focus on the effect of symmetry in nap cores. A nap-core is, in general terms, a 3D-formed hollow structure made of knitted textile impregnated by a thermosetting resin. The molding process determines if the nap-core is double-sided (symmetric) or single-sided. The sandwich with nap-core owns various remarkable properties of a ...

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...

An Accurate Finite Element Method for the Numerical Solution of Isothermal and Incompressible Flow of Viscous Fluid

Abali, Bilen Emek (2019-01-08)

Despite its numerical challenges, finite element method is used to compute viscous fluid flow. A consensus on the cause of numerical problems has been reached; however, general algorithms—allowing a robust and accurate simulation for any process—are still missing. Either a very high computational cost is necessary for a direct numerical solution (DNS) or some limiting procedure is used by addin...

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...