bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of freeze‐thaw‐cycles in liquid‐ and gas saturated porous media
Authors: Bluhm Joachim , Ricken Tim , Bloßfeld Wolfgang Moritz 
Published: November 2010

AbstractIn this contribution, a quadruple macroscopic model for the simulation of freeze‐thaw cycles in liquid‐ and gas filled porous media is presented. In effect, this model describes the following aspects: expansion of ice during freezing, liquid and gas pressure on the surrounding surfaces, capillary effecs, temperature distribution, and the influence of filter velocities. The main focus lies in the description of capillary effects before and during the phase transition. The illustrated results of the numerical example show that the simplified model is capable of predicting physical and experimental observations. Besides the influence of the heat of fusion, especially, the capillary suction in liquid‐ and gas filled porous media will be presented. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transformated Hypergraphs in Synthesis of Vibrating Beam‐Systems
Authors: Buchacz Andrzej 
Published: November 2010

AbstractIn this paper the characteristics of subsystems obtained by the approximate and exact method were compared, because purpose is to answer to the question ­ if the method can be used to nominate the characteristics of mechatronic systems. In this paper frequency‐modal analysis have been presented for the mechanical system, that means flexibly vibrating free beam. The model of the beam was presented in the five‐vertex hypergraph, which in case of approximate frequency‐modal analysis we can imitate in three‐vertex hypergraph. Such formulation maybe the introduction to synthesis of flexibly vibration complex beam systems with constant cross‐section. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mathematical and physical aspect of the solution to the Lamb's problem for nonlocal visco‐thermo‐elastic medium
Authors: Gawinecki Jerzy August , Rafa Józef , Łazuka Jarosław 
Published: November 2010

AbstractIn our paper we constructed the solution of the initial‐boundary value problem so‐called Lamb's problem for the half space occupied with visco‐thermo‐elastic medium. The visco‐elastic medium was described by Biot model, where the thermal influencely by Gurtin and Pipkin model. Using the Cagniard de Hoop method we obtained the solution of the Lamb's problem to the considered system of integro‐differential equations. Based on the constructed solution of the above mentioned problem, we described the type of waves which propagate in the visco‐thermo‐elastic medium and the domain of their influence. The propagation of the Rayleigh's wave were investigated. We discovered the new Rayleigh's wave in visco‐thermo‐elastic medium (second Rayleigh's wave) and named it GRL‐wave (Gawinecki‐Rafa‐Łazuka ‐ wave). Finally, we determined the exact geometric description of new kind of waves in visco‐thermo‐elastic medium: • cone waves (Schmidt's type) • surface waves of the Rayleigh's type (among theim new one) and the character of their origin. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Pseudoelasticity of Shape Memory Alloys ‐ a 1D Material Model and Finite Element Implementation
Authors: Kohlhaas Benedikt , Klinkel Sven 
Published: November 2010

AbstractThis contribution is concerned with the formulation of a 1D‐constitutive model accounting for the pseudoelastic behavior of shape memory alloys. The stress‐strain‐relationship is idealized by a hysteresis both in the compression as in the tension loading range. It is characterized by an upper loading path, which is to be ascribed to the transformation of the lattice to a martensitic structure. Unloading the material, a lower path is described, because of the reverse transformation into austenitic lattice. The constitutive model is based on a switching criterion which serves as a potential function for the evolution of the internal state variables. The model distinguishes between local and global variables to describe the hysteresis effects for the compression and tension range. A strain driven algorithm which captures the complete nonlinear material behavior is presented. The boundary value problem is solved for a truss element applying the finite element method. A consistent linearization of the nonlinear equations is derived. Simple examples will demonstrate the applicability of the proposed model. For future developments the usage of shape memory alloys within civil engineering structures is aimed. The advantage of the material is the very good damping behavior and the potential to overcome great strains. Both properties are distinguished to be of engineering interest. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zero Leakage Sealings for Reciprocating Compressors
Authors: Kotesovec Bernhard , Steinrück Herbert 
Published: November 2010

AbstractThe piston rod of a reciprocating compressor is sealed with elastic cylindrical sealing elements. Across the sealings the pressure drops from the operating pressure to the ambient pressure. The lubrication gap between the elastic sealing and reciprocating piston rod is studied with the aim to find conditions of a leakage free sealing. The flow in the lubrication gap and the elastic deformation of the sealing are determined simultaneously. The netflow during one cycle of the reciprocating piston rod is calculated. It turns out that maintaining zero leakage is very sensible. Indeed the outbound flow during out‐stroke has to be equal the inbound flow during the instroke. By prescribing a special shape of the undeformed sealing zero leakage can be attained — at least theoretically for certain operating conditions. It turns out that temperature dependent material data and a model for cavitation is necessary. The model, its numerical implementation and results will be discussed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The exact and approximate method in mechanical system's analysis
Authors: Buchacz Andrzej , Płaczek Marek 
Published: November 2010

AbstractThe main aim of this work is to present results of the mechanical system's analysis based on the exact and approximate Galerkin's methods. The considered system is the flexural vibrating one‐dimension bending beam. The exact and approximate method were used to assign the dynamic flexibility of the considered system and results of this work were juxtaposed to verify the approximate method's accuracy. The correction coefficients were introduced into the approximate method to unify results of both methods. The aim of this work was to check accuracy of the approximate method and to verify if this method may be used to mechatronic system's analysis, where it is impossible to use the exact method. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective computational methods for the solution of ferroelectroelastic problems under complex loading
Authors: Semenov Artem S. , Liskowsky Albrecht C. , Neumeister Peter , Balke Herbert 
Published: November 2010

AbstractEnhanced numerical methods for the solution of three‐dimensional nonlinear electromechanically coupled boundary value problems are considered. A vector potential finite element formulation with return mapping algorithm and consistent tangent operator is developed. The accuracy and robustness of the algorithms are assessed with the help of numerical examples concerning a ferroelectroelastic analysis of structures under complex multiaxial non‐proportional loading. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the General Solution of Coupled Problems: Comparison of Monolithic and Partitioning Approaches
Authors: Zinatbakhsh Seyedmohammad , Markert Bernd , Ehlers Wolfgang 
Published: November 2010

AbstractCoupled systems arise whenever there is a dynamic interaction between two or more functionally distinct components. The mathematical model for such a phenomenon consists of a system of coupled partial differential equations (PDE) in space and time, that has to be solved, either analytically or numerically, in order to describe or predict the response of the system under specific conditions. In spite of the natural accuracy of the analytical methods, they are less favourable due to their disability to treat more complex problems. Instead, different numerical schemes have been developed during the last decades, which are specialised to solve various coupled problems. These methods can be divided into two main categories, namely,monolithicandpartitionedapproaches. The main goal of this work is to study the general ideas behind monolithic and partitioned solution schemes for the pure differentially coupled systems. In the next step, the coupled problem of linear thermoelasticity is considered as benchmark example and theisothermalandisentropicoperator‐splitting schemes as two typical decoupling methods for this problem are presented. A canonical initial boundary‐value problem has also been solved monolithically as well as by using the a.m. operator‐splitting schemes and using the acquired results, the efficiency and stability of the methods are compared. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Zur Homogenisierung mechanischer Materialparameter in heterogenen Lotwerkstoffen
Authors: Müller Wolfgang H. , Brandmair Andreas 
Published: November 2010

AbstractIn der Mikroelektronik spielen die Gruppe der Lotwerkstoffe eine wichtige Rolle. Sie stellen zwischen einzelnen Komponenten, wie beispielsweise Chip und Platine, nicht nur die elektronische, sondern auch die mechanische Verbindung her. Ihre Stabilität ist deshalb zur Lebensdauervorhersage mikroelektronischer Bauteile von besonderer Bedeutung. Die unterschiedlichen verwendeten Legierungen weisen dabei eine gemeinsame Charakteristik in ihrem Alterungsprozess auf. Die Mikrostruktur ändert sich aufgrund von Entmischung und nachfolgender Vergröberung. Da die eingesetzten Materialmengen meist sehr gering sind, ist eine Änderung der Mikrostruktur bei der Zuverlässigkeitsvorhersage nicht zu vernachlässigen. Von besonderem Interesse ist deshalb, die unterschiedlichen Größenskalen zu berücksichtigen, insbesondere wie sich die mikrostrukturelle Änderung auf die makroskopischen Materialparameter auswirkt. Da eine exakte Simulation der sich zeitlich ändernden Strukturen zu großen Problemen bei Netzerstellung und Modellierung führt, wird eine Homogenisierung der benötigten Materialeigenschaften durchgeführt. Die so erhaltenen effektiven Materialparameter sollen das reale Werkstoffverhalten möglichst genau wiedergeben und so einfache Simulationen zur Festigkeitsanalyse ermöglichen. Zunächst wird eine Methode vorgestellt, aufgrund äquivalenter Formänderungsenergie die elastischen Konstanten eines komplett anisotropen Lotwerkstoffes zu bestimmen. Dabei kommen finite Elemente, gekoppelt mit einem Generator unterschiedlich entmischter Strukturen zum Einsatz. Von besonderem Interesse ist dabei die zeitliche Entwicklung der homogenen Materialparameter. Weiterhin wird ein Ausblick gegeben, wie die Homogenisierung plastischer und viskoser Materialparameter durchgeführt werden kann. Insbesondere wird darauf eingegangen, welche Parameter zur Zuverlässigkeitsanalyse heterogener Lotwerkstoffe besonders relevant sind. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of Cosserat material parameters obtained by homogenization of a Cauchy continuum
Authors: Branke Dominik , Brummund J. , Haasemann G. , Ulbricht V. 
Published: November 2010

AbstractIf a higher order continuum theory is used in a numerical simulation, the material parameters have to be derived. The experimental determination is laborious and sometimes impossible. Alternatively homogenization methods can be used for the numerical identification of overall material parameters. A short introduction to the micropolar continuum and the homogenization approach is followed by the discussion of the identified properties. Therefore some parameter studies are presented. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A non‐conforming finite element for limit analysis of periodic composites
Authors: Chen M. , Hachemi A. , Weichert D. 
Published: November 2010

AbstractIn this work, a non‐conforming three‐dimensional finite element coupled with direct methods and homogenization technique is presented for the limit analysis of periodic metal‐matrix composites. Using this element, which is constructed from bilinear shape functions and enriched by internal second‐order polynomials, limit analysis of composite material can be efficiently carried out. Accuracy and overall performance are illustrated through comparison with different structural solid elements in the context of direct as well as incremental methods. It is shown that the limit domain of periodic composites for different fiber distributions and volume fractions provides a foundation for the structural design. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanical modelling and two‐scale simulation of epoxy/glass composites with interphases and interfaces
Authors: Fleischhauer Robert , Dal Hüsnü , Kaliske Michael 
Published: November 2010

AbstractComposite systems consisting of glass fibres and epoxy matrix with interphases and interfaces will be considered in the modelling approach. The interphase forms the transition zone between the epoxy matrix and the glass fibre. The interface is the layer between the glass fibre and the surrounding interphase. The macroscopic strength of the composite material is intrinsically related to the bond strength of the polymeric/solid interface and the micromechanical characteristics of the three phases (epoxy, glass and interphase). Homogenization is an appropriate methodology to link these two scales to predict the overall physical behaviour of the composite. The nonlinear behaviour of amorphous polymers, cohesive interface elements and the elastic behaviour of glass fibres as part of the considered composite material are presented, as well as a representative example to show the necessity of taking interface influences into account. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Computational Homogenization of Piezoelectric Materials using FE2
Authors: Khalaquzzaman Md. , Ricker Sarah , Müller Ralf 
Published: November 2010

AbstractDue to the growing interest in determining the macroscopic material response of inhomogeneous materials, computational methods are becoming increasingly concerned with the application of homogenization techniques. In this work, two‐scale classical (first‐order) homogenization of electro‐mechanically coupled problems using a FE2‐approach is discussed. We explicitly formulated the homogenized coefficients of the elastic, piezoelectric and dielectric tensors for small strain as well as the homogenized remanent strain and remanent polarization. The homogenization of the coupled problem is done using different representative volume elements (RVEs), which capture the microstructure of the inhomogeneous material, to represent the macro material response. Later this technique is used to determine the macroscopic and microscopic configurational forces on certain defects. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Acoustic Band Structures and Homogenization of Periodic Elastic Media
Authors: Stadler Michael , Schanz Martin 
Published: November 2010

AbstractDispersion curves and frequency dependent velocity surfaces of periodic heterogeneous elastic media are determined from unit‐cell problems using quasi periodic boundary conditions. Effective material parameters are obtained using a least square optimization of the phase velocities in the heterogeneous and the effective, generally anisotropic, homogeneous medium. For efficiency, a preconditioned iterative eigenvalue solver and a model order reduction scheme are used. This “dynamic” homogenization procedure is validated for frequencies below the first stop band employing FEM calculations on a finite structure consisting of an array of unit‐cells and the effective homogeneous material. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of homogenized diffusion properties in micro‐cracked porous materials
Authors: Timothy Jithender Jaswant , Kruschwitz Jens , Meschke Günther 
Published: November 2010

AbstractMethods of micromechanics [2, 3] are used to obtain homogenized diffusion properties for intact and micro‐cracked porous materials. A two scale homogenization technique is proposed. A REVuc that represents the porous microstructure is modelled as a spherical pore‐space inclusion in a matrix, whose diffusion coefficient does not depend on the microstructure geometry but only on the porosity. For cracked porous materials, a REVc is modelled with the diffusion coefficient for intact porous materials as the matrix phase with ellipsoidal inclusions representing micro‐cracks. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spreading of Gas from a Line Source in the Flow over Two‐dimensional Hill
Authors: Antos Pavel , Mazur Oton , Uruba Vaclav 
Published: November 2010

AbstractFlow around the two‐dimensional hill is of great interest in engineering application, namely in transport and dispersion of pollutants in atmosphere. A case of polynomial shaped 2D hill with the line source of tracer gas has been studied in detail. Experimental study of both, the time‐averaged velocity field and the binary‐mixture concentration field has been done. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Parallel Simulation of a Compressible Jet Including Nozzle Modelling
Authors: Bühler S. , Luginsland T. , Obrist D. , Kleiser L. 
Published: November 2010

AbstractCircular jet flows play an important role for many technical applications. Realistic simulations of such flows require modelling of the nozzle geometry to represent the turbulent state of the boundary layer at the nozzle exit. An available high‐order finite‐difference code for solving the compressible Navier‐Stokes equations on a cylindrical grid was adapted to account for the nozzle geometry within the simulation domain. The code was parallelized using the message‐passing interface MPI to be able to complete the simulations within acceptable turn‐around times. Validation of the implementation was performed by checking the convergence behaviour of the spatial discretization schemes. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of shear and normal forces in standard and shear flow sequencing batch reactor (SF‐SBR)
Authors: Mansour Hussam , Kowalczyk Wojciech 
Published: November 2010

AbstractThe purpose of this contribution is to compare the shear and the normal stresses in two different types of bioreactors. In the first one (SBR), the granules are generated by liquid and bubbles flow, whereas in the second one (SF‐SBR), the shear rate is achieved by installing a rotating cylinder inside the reactor. Such shear flow can be applied for anaerobic process in the wastewater treatment. The results demonstrate the effective role of the process parameters and the reactor geometry on the shear and normal stresses and consequently on the granulation process. Hereby, the different tendencies of the velocity fields, the particle sedimentation as well as Taylor vortices in (SF‐SBR), are observed. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Significance of Truckenbrodt's Energy and Momentum Coefficients for Loss Calculation in Ramified Pipe Systems
Authors: Niessner Herbert , Codan Ennio 
Published: November 2010

AbstractFor one‐dimensional simulation of flow in ramified pipe systems loss prediction in junctions is essential. In the standard literature (e.g. [1]) total pressure loss coefficients serve this purpose. Elementary formulas follow from the principle of momentum and some simple assumptions [2]. They yield rather crude estimates, often twice as large as experimental values. Modifications described by Idelchik [3] look nice, but after all turn out to be not more accurate. We explain deviations and propose improved loss formula based on Truckenbrodt's energy and momentum coefficients [4], thus paying regard to velocity distributions over pipe cross‐sections. We further discuss extraction of the coefficient's values from experiments. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental investigation of the particle‐wall‐impact under particular consideration of the wall surface influence on the particle trajectory and the transition between sliding and adhering impact
Authors: Schade Klaus‐Peter , Wozniak Günter 
Published: November 2010

AbstractWe present results of the experimental investigation of the impact of particles on a rough wall. The particle‐wall impact influences considerably the behavior of particle laden gas flows. The aim of the present work is to study the influence of the wall roughness on the particle trajectory and the particle rotation after impact. The measurements were carried out in a special test facility, which allows the investigation of single particle‐wall impacts. Particle velocities and trajectories were recorded by a video system and evaluated by using a particle tracking technique. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lateral Vortex Dynamics behind Ahmed body
Authors: Uruba Vaclav 
Published: November 2010

AbstractThe flow‐field in the wake of Ahmed body was studied experimentally. The study is oriented on unsteady behavior of the lateral vortex pair arising in the wake as well as on the wake itself. The time‐mean characteristics of the wake flow are presented. The dynamical behavior of the longitudinal vortex pair is studied in details. The Stereo Time‐Resolved PIV method was applied in the wake plane perpendicular to the mean flow. Two variants of Ahmed Body with slat angle 25 and 35 degrees are investigated respectively. Comparison shows considerable differences in the vortex pair topology and dynamics of the cases in question. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Meshless Boundary Method for Computation of Stokes Flow with Particles in the Semicircular Canals of the Inner Ear
Authors: Boselli Francesco , Obrist Dominik , Kleiser Leonhard 
Published: November 2010

AbstractBenign paroxismal positional vertigo (BPPV) is modeled by introducing free‐floating particles (canaliths) which settle inside the semicircular canals (SCC). The Stokes flow induced by a canalith is evaluated by coupling the force coupling method (FCM) to the method of fundamental solutions (MFS). The proposed methodology results in a straightforward meshless boundary method for the simulation of bounded Stokes flow with finite‐size particles. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Active Control of Separating Boundary Layer
Authors: Florin Frunzulica , Alexandru Dumitrache , Horia Dumitrescu , Octavian Preotu 
Published: November 2010

AbstractFlow control refers to the ability to alter flows with the aim of achieving a desired effect: examples include drag reduction, noise attenuation, improved mixing or increased combustion efficiency among many other industrial applications. The reduction and control of the viscous drag force exerted on bodies moving in a fluid is of great technical interest. Several active and passive methods to achieve a delay of separation in the boundary layer have been developed and are being developed. In this paper we present a new concept for boundary layer separation control that is based on the synthetic jet concept which converts acoustic oscillations into mean fluid motions. We use synthetic jets as methods for Coanda effect's amplification. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Simulation and analysis of molten flow in the shot sleeve of die casting process
Authors: Laouar Roudouane , Wünsch Olaf 
Published: November 2010

AbstractThis work presents a numerical study of the flow of molten metal in the shot sleeve of horizontal high‐pressure die casting machine during the injection process. The analysis of the wave of the molten metal created by plunger motion can be of help in reducing porosity in manufactured parts caused by air entrapment. The used numerical model, which considers the problem as two‐dimensional, is based on the conservation equations of mass and momentum. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)