bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of self‐activating temperature influence on cracks initiation in GRP laminates
Authors: Katunin Andrzej , Moczulski Wojciech
Published: March 2010

The paper deals with problems of fatigue processes of GRP laminates under the influence of cyclic loads. An important aspect which takes place in laminate fatigue with polymer matrix is self‐activating temperature generated by friction. As it has been shown in previous authors' research, the phenomenon has significant influence on laminate behavior, also, when self‐activating temperature comes to glass‐transition temperature, which begins transition from elastic to viscoelastic material model. After passing over of this temperature the stiffness decreasing is supervised, that can lead to more quick propagation of faults (especially delaminations) and decreasing of life cycle of composite laminate element. The aim of the presented paper is simulation research of fatigue processes with taking into consideration self‐activating temperature and rheology of material. In the research four cases are analyzed, in which layers rotation, self‐activating temperature increasing and changes of rheological model were taken into consideration. As the research shows, the self‐activating temperature has significant influence on fatigue processes, because it can cause transition of the rheological model of the material. In the future research an experimental verification of the model is planned. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the calculation of crack face opening displacements in fiber reinforced composites under plane loading
Authors: Richter Mike , Bayer Daniela
Published: March 2010

This paper concerns with the calculation of the crack face opening displacement in fiber reinforced composites using analytical, semi‐analytical and numerical approaches. Crack bridging is one of the most characteristic effects of fibers on the material behavior of the composite. Knowing the crack face opening displacement the additional strain due to cracks can be calculated and used in homogenization procedures. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Ghost Forces in 3D Quasicontinuum Model
Authors: Shan Wenzhe , Nackenhorst Udo
Published: March 2010

In this contribution, we propose an intuitive explanation for the artificial effect, named as ghost force, that arises in the coupling region of a multiscale method, known as Quasicontinuum method, and introduce a simple technique that can be used to reduce this ghost force. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanical material models for polymer composites through advanced numerical simulation techniques
Authors: Al Kassem G. , Weichert D.
Published: March 2010

The paper deals with the determination of macroscopic material properties of polymer composites by meso‐mechanical numerical modeling. Focus is laid on the methodology how to build up appropriate representative volume elements (RVE) to describe the microstructure of spherical‐particles and fibers reinforced composites and how to apply appropriate 3D boundary conditions. The work includes the comparison of the effective material parameters calculated through numerical homogenization of our FE‐models with existing analytical formulations as well as with experimental data. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Obtaining Cosserat material parameters by homogenization of a Cauchy continuum
Authors: Branke Dominik , Brummund J. , Haasemann G. , Ulbricht V.
Published: March 2010

An increasing importance of composites with sandwich architecture and fibre‐reinforced components is recognizable especially in aerospace and light weight industry. Due to the inner structure such materials often exhibit a complex behavior. If the ratio of micro‐ and macroscopic length scales, l and L, violates the condition l/L ≪ 1, a higher order continuum should be used to describe the macroscopic material behavior correctly. The numerical simulation requires reliable material constants, for which 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 linear Cosserat theory is followed by an extended homogenization procedure to derive the macroscopic material constants of a linear Cosserat continuum. The parameters obtained with a heterogeneous cell are used to simulate different bending load cases. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bounds for the Elastic Properties of Pyrolytic Carbon
Authors: Böhlke Thomas , Langhoff Tom‐Alexander , Piat R.
Published: March 2010

The elastic properties of heterogeneous materials without defects depend on both the constitutive properties of the constituents and the microstructural characteristics. In this paper the first‐order bounds of aggregates of domains with hexagonal material symmetry are determined in terms of tensorial texture coefficients. The predictive capability of these bounds is compared to higher‐order bounds for pyrolytic carbon. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A numerical homogenisation strategy for micromorphic continua
Authors: Jänicke Ralf , Diebels Stefan
Published: March 2010

In this contribution, we apply a numerical homogenisation scheme for micromorphic continua replacing constitutive equations on the macroscale by a microscopic boundary value problem. The aim of this procedure is to describe the influence of the microtopology on the effective behaviour of microstructured materials such as biological tissues as well as polymer or metal foams. On the one hand, that allows for avoiding the numerically expensive calculation of a fully resolved microstructure. On the other hand there is no need to identify additional material parameters which are in general hard to interpret from the physical point of view. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization of microstructures in dynamics using periodic boundary conditions
Authors: Stadler Michael , Schanz Martin
Published: March 2010

A homogenization method is used to calculate effective material properties of periodic microstructures subjected to small, time‐harmonic strain fields. The method is based on the equivalence of averaged micro‐field quantities in dispersive heterogeneous media and those in effective homogeneous media with frequency dependent elastic constants. Solutions to the elastodynamic boundary value problem (BVP) are obtained from a boundary element method where periodic boundary conditions on the unit‐cell are incorporated using Lagrangian multipliers. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Scaling laws for turbulent boundary layer flows in favorable and adverse pressure gradient
Authors: Vigdorovich Igor
Published: March 2010

An analytical theory is proposed to describe incompressible plane and axisymmetric turbulent boundary layer flows in favorable and adverse pressure gradients for near‐equilibrium conditions. Scaling laws for the mean velocity, the Reynolds stress components, and the skin friction have been established. A universal friction law makes it possible to represent the skin friction distributions corresponding to different Reynolds numbers and pressure gradients in terms of a function of one variable. The theory is based on general physical assumptions and does not involve any special hypotheses on the nature of the turbulent motion. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Towards large eddy simulation on moving grids
Authors: Löbig Stefan , Dörnbrack Andreas , Fröhlich Jochen , Hertel Claudia , Kühnlein Christian , Lang Jens
Published: March 2010

When turbulent flows are modelled by means of Large Eddy Simulation (LES), the characteristic length scale of the turbulent fluctuation needs to be resolved by the grid. In complex geometries this length scale varies substantially over the computational domain. The present paper proposes an approach to adjust the grid size in an LES adaptively such that the resolution capacity of a grid with a given number of points is used at best. This is done with so‐called r‐refinement. The paper presents the work of three groups collaborating on this issue. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Turbulent diffusion: Direct numerical simulation
Authors: Khujadze George , Oberlack Martin
Published: March 2010

Direct numerical simulations (DNS) of a vibrating grid turbulence at two different Reynolds numbers (based on an amplitude and frequency of the grid) Re = 500, 1000 are presented. The evolution of a turbulent/non‐turbulent interface was detected and compared to the theoretical results obtained in the paper [1] using Lie group analysis of the governing equations. Good agreement was found between DNS and theory. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Turbulent Boundary Layer Under the Influence of Adverse Pressure Gradient
Authors: Drobniak S. , Drozdz A. , Elsner W. , Materny M.
Published: March 2010

The paper deals with the experimental analysis of turbulent boundary layer at the flat plate for large value of Reynolds number equal Reθ ≈︁ 3000. The adverse pressure gradient generated by curvature of the upper wall corresponded to the case of pressure variation in axial compressor. The fully developed structure of turbulence was achieved by proper triggering of the boundary layer. The mean and turbulent flow‐fields were investigated with the use of hot‐wire technique while mean and instantaneous pressure fields were examined with piezoelectric transducers. The scaling and turbulence structure of fully developed turbulent boundary layer under the influence of adverse pressure gradient revealed the more pronounced contribution of outer region to the downstream development of turbulent boundary layer. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unstable Thermocapillary Flow at a Gas‐Liquid Phase Boundary
Authors: Schade Klaus‐Peter , Wozniak Günter , Rubes Daniel
Published: March 2010

We present results of thermocapillary experiments in the vicinity of a bubble under a heated wall. Thermocapillary convection is a flow along the interface of two fluids, which is caused by local gradients of the surface tensions σ.

The aim of the present work is to study this flow phenomenon at higher Marangoni‐numbers Mg. At sufficiently high values of Mg the flow exhibits oscillatory fluid motion and eventually becomes turbulent. For the detection of the flow velocity and temperature field, we applied a PIV method and a modified differential interferometer. In order to separate buoyancy effects from thermocapillary convection, we chose an experimental setup, where a bubble is positioned in a liquid matrix under a heated wall.

We could observe various regimes of Marangoni flow, from steady flow over regular oscillating up to highly irregular oscillating flows at Mg up to 63,000. However, we also found unexpected stable flow regions and additional evaporation processes. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Subgrid Scale Modeling of Turbulent Channel Flow with Adverse Pressure Gradient
Authors: Elsner W. , Kuban Ł. , Tyliszczak A.
Published: March 2010

The paper presents the results of LES simulation of turbulent channel flow with one curved wall, in which way the pressure gradient was imposed. The influence of grid density as well as subgrid scale models on the solution has been analysed. For the last purpose two models have been considered i.e. Smagorinsky and WALE. For the simulation the in‐house code SAILOR_WALL, which relies on the projection method for the pressure‐velocity coupling was used. The results were compared to the Direct Numerical Simulations (DNS) of Marquillie et al. [4]. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability of bifurcating solutions of the problem about capillary‐gravity surface waves in spatial layer of floating fluid
Authors: Andronov Artyom N. , Kim‐Tyan Luiza R. , Loginov Boris V.
Published: March 2010

In prolongation of our previous investigations on capillary‐gravity surface waves in spatial fluid layers the stability of the bifurcating families of solutions in the horizontal layers of the floating (and without flotation) incompressible heavy capillary fluid is considered. The assumption about layer depth simplifies the proof of the existence of bifurcating solutions at the high dimensions of the linearized operator degeneracy, computation of their asymptotics and as the main subject of this communication the investigation of their stability, relative to perturbations with the same symmetry as bifurcating solutions. Group analysis methods of differential equations are used. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local Interaction Theory for Laminar Transonic Flows in Slender Channels
Authors: Kluwick Alfred , Kornfeld Matthias
Published: March 2010

Transonic flows through channels so narrow that the classical boundary layer approach fails are considered. As a consequence the properties of the inviscid core and the viscosity dominated boundary layer region can no longer be determined in subsequent steps but have to be calculated simultaneously. The resulting viscous inviscid interaction problem for weakly three dimensional laminar flows is formulated for perfect gases under the requirement that the channel is sufficiently narrow so that the flow outside the viscous wall layers becomes planar in the leading order approximation. Representative solutions for subsonic as well as for supersonic flows disturbed by three dimensional surface mounted obstacles will be presented. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vortex Interaction in a Ducted Flow
Authors: Alexandru Dumitrache , Horia Dumitrescu , Florin Frunzulica
Published: March 2010

The objective of this study is to describe the structure of pipe flow by considering it as a superposition of many axisymmetric vortex rings. In knowing the unsteady gross feature of pipe flow, the investigation on vortex interactions is important. As a first step to the goal, we investigate the nonlinear interaction among vortex rings whose number is three at most. The interaction among vortex rings of equal circulation is here investigated. Momentum and energy conservation of the present vortex ring system are also discussed to know a better understanding of the perturbed pipe flow. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical simulation of the flow in semicircular canals with the method of fundamental solutions
Authors: Boselli Francesco , Obrist Dominik , Kleiser Leonhard
Published: March 2010

We present a numerical model for the simulation of the flow in semicircular canals (SCCs). The governing equations for the flow are solved with the method of fundamental solutions (MFS), a mesh free method for boundary value problems. We describe the flow field in a SCC with utricle, and we find a vortex that had not yet been reported in literature. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental Investigation of thermal convection in an inclined narrow gap II
Authors: Rubes Daniel , Heiland Hans Georg , Wozniak Günter
Published: March 2010

In the past decade the development in micro technology has experienced great progress, what made the knowledge of the flow behavior in small cavities fundamentally interesting. Our experimental contribution describes the measured temperature and velocity fields in a fluid containing inclined cavity with the dimensions 17 × 6 × 24 mm3 (w × d × h). Using PIV/T, we can determine the velocity and temperature distribution in the cavity simultaneously. The chamber is illuminated with a white light sheet of 1 mm. A 20% glycerin‐water mixture is examined. The lower side is heated to 46.2°C, while the upper side has a constant temperature of 26°C. In this work we present the measured velocity and temperature fields of the fluid at different angles of the cavity orientation with respect to the direction of gravity in the stationary state. This is a continuation of last years presentation [1] in the sense that the temperature difference has been substantially increased. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Obtaining of noise map of great city of Cluj‐Napoca. Step by step.
Authors: Solea Geamilia , Arghir Mariana
Published: March 2010

The traffic of autovehicles in pilot zone of great city of Cluj‐Napoca is presented in the work. There are established the noise measuring locations for the fixed station and successive positions of the mobile station in pilot zone. Noise pollution measurements are done on the mentioned locations. The “Sound plan” programme pack is used to fulfill the sound map of the great city of Cluj‐Napoca; its graphic representation is compared to the real measurement results. Present paper represents a part of research activity of T.U.C.N. researchers in studying for fulfilling of E.U. tasks of environment protection. This research is made for the application of the EU legislation on the Romanian cities. First we worked in the great city of Cluj‐Napoca, but the extensions will be to all the urban agglomerations having greater than 100000 people. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Piezoelectric Induced Lamb Waves in Plates
Authors: Vivar‐Perez Juan Miguel , Willberg Christian , Gabbert Ulrich
Published: March 2010

In the paper, piezoelectric induced Lamb wave propagation on homogeneous plates is studied by applying different approaches. Assuming the presence of piezoelectric actuators and sensors the transient wave analysis is made using the classical formulation of the finite element method (FEM) and the novel approach of spectral finite element method (SE). Pure mode excitation and mode conversion are numerically simulated for the fundamental modes S0 and A0. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of fluid transients, for nonlinear fluids, with a lumped parameter model
Authors: Haas Rainer , Manhartsgruber Bernhard
Published: March 2010

This paper deals with the modeling of transients in low pressure transmission lines. Modeling of low pressure lines becomes more and more important for increasing efficiency of fast switching applications and performance of pumps e.g. common rail diesel injection systems and suction pipes of pumps. One simulation method is the lumped parameter model. For example a straight pipe can be modeled as a cascade of inertia, friction and compressibility blocks. In this paper, the idea of cascades is adopted for transient simulation of nonlinear fluids. The model includes a nonlinear fluid law of an oil‐air mixture and the balance equations i.e. the compressibility and the inertia of the fluid. Friction is modeled by the frequency dependent friction model of Kagawa et.al. Comparison of simulation results with measurements from a test rig shows good correlation. Finally the scope of this simulation model is discussed and compared with measurements. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Linear Elastic Wave Propagation in Unsaturated, Unconsolidated Soils
Authors: Albers Bettina
Published: March 2010

By means of a macroscopic linear model for a poroelastic medium with three deformable components the acoustic behavior of four unconsolidated soil types, filled by water and air, is studied. Necessary material parameters are mainly gathered from the German standard DIN 4220. It provides some useful parameters, as for example, van Genuchten parameters, for thirty‐one different soil types including sands, silts and clays. There appear four body waves: three longitudinal waves and one shear wave. The slowest compressional wave does only exist if at least two pore fluids appear and is driven by the capillary pressure between the pore fluids. The wave analysis yields the dependence of velocities and attenuations of these waves on the saturation and on the frequency. This is compared to the so far most frequently studied case of partially saturated sandstones. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Lp – Lq time decay estimate to the solution of the Cauchy problem for the system of equations describing nonlocal model of the thermoviscoelastic body
Authors: Gawinecki Jerzy , Lazuka Jaroslaw , Rafa Jozef
Published: March 2010

The aim of this paper is to present a new system of equations describing nonlocal model of thermoviscoelastic theory. We used the Papkin and Gurtin approach based on the constitutive relations for stress tensor σ(x), internal energy e(x) and heat flux q(x), with integral terms. Using the modified Cagniard‐de Hoop's method we constructed the matrix of fundamental solutions for this system of equations in three‐dimensional space. Basing on this matrix we represent in the explicit formula the solution of the Cauchy problem to this system of equations. Next, applying the method of Sobolev spaces, we proved the Lp–Lq time decay estimate to the solution of the Cauchy problem. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of parametric modulation on the onset of thermomagnetic convection
Authors: Engler H. , Odenbach S.
Published: March 2010

Magnetic fluids – so called ferrofluids – are suspensions of nano‐scaled particles in an appropriate carrier liquid. The flow properties of these fluids can be influenced by applying an external magnetic field. It is possible to introduce a magnetic force in a horizontal ferrofluid layer which is able to drive a convective flow. The magnetic force arises in the presence of an external magnetic field if a temperature gradient exists in the fluid gap. The behaviour of the onset of convection depends on the strength of the external magnetic field and on the temperature gradient. In this paper the onset of convection under the influence of time‐modulated magnetic field has been investigated. The experimental results presented here show a shift in the onset of convection depending on the frequency of the external magnetic field. This behaviour confirms in principle the theoretical predictions which are also presented here. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cross‐calibration of X‐ray µCT and MRX for tissue analysis
Authors: Rahn H. , Eberbeck D. , Richter H. , Gomez‐Morilla I. , Trahms L. , Odenbach S.
Published: March 2010

Ferrofluids are being considered as an aid for local cancer treatments, such as Magnetic Drug Targeting (MDT) and Magnetic Hyperthermia (MHT). Both methods make use of the strong influence of a magnetic field on the nanoparticles, with the aim of treating the cancer locally while reducing, or even eliminating, the side effects that usually occur during conventional cancer treatments. Microcomputed tomography analysis has been performed on tumour tissue after MDT and MHT in order to examine the distribution of the magnetic nanoparticles within the tissue. The majority of the measurements has been performed in a laboratory based on a polychromatic X‐ray source. The strong energy dependence of the attenuation coefficient and the occurrence of the so called beam hardening artefacts make the quantitative evaluation of data acquired with polychromatic tomography equipment very difficult. In this paper we present a cross‐calibration method for magnetorelaxometry and polychromatic X‐ray tomography for biological tissue samples enriched with magnetic nanoparticles. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Green functions for boundary value problems about divergence of elongated plate
Authors: Badokina Tatiana E. , Loginov Boris V. , V. Makeeva Olga
Published: March 2010

Bucking of a thin flexible elongated plate in supersonic gas flow along Ox‐axis, compressed or extended by boundary stresses at the edges x = 0 and x = 1 is governed by a boundary value problem for nonlinear ordinary integro‐differential equation with two bifurcation parameters: external stress and Mach number. On two examples of boundary conditions Bw″(0) = 0, w‴(0) = 0, w(1) = 0, w′(1) = 0 and B′ w(0) = 0, w′(0) = 0, w″(1) = 0, w‴(1) = 0. Green functions for the linearized problems are constructed. Arising technical difficulties are overcoming with the aid of the bifurcation curves representation through the roots of relevant characteristic equations. In the known literature [1] marked, that Green functions for aeroelasticity problems were not constructed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Optimization the shape of finite element in shot peening process
Authors: Szyc Marcin , Kukielka Leon , Bartosik Przemyslaw
Published: March 2010

This paper contains modelling and numerical simulations of shot peening process. The application in Ansys/LS – Dyna programme were elaborated. The phenomena of shot peening process on a typical incremental step were described using a step‐by‐step incremental procedure, with an updated Lagrangian formulation.Finite elements methods (FEM) and the dynamic explicit method (DEM) were used to obtain the solution. The main purpose of this article is to determinate optimal model of shot peening process (convergence resulting for minimal number of finite elements and their optimal shapes). Examples of calculations were presented. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation and Analysis of Thermal Fatigue Based on Imperfection Model of Brake Discs
Authors: Zhang Lele , Yang Qiang , Weichert D. , Tan Nanlin
Published: March 2010

A non‐linear FEM model of brake discs of high‐speed trains with thermal‐mechanical coupling has been established in ANSYS. The simulation and analysis of 3‐D transient temperature field and stress field of brake discs have been carried out for the braking process. According to typical imperfections of brake discs, some imperfection models of brake discs have been developed and the thermal stresses of different models are obtained through simulation and analysis. By comparing results of different models, the influence of imperfection parameters, including the position, depth and size, is resulted for the thermal resistance of brake discs. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On stability of asymptotic energy for a functional of Ginzburg‐Landau type with ε‐dependent weakly‐star convergent 1‐Lipschitz penalizing term
Authors: Raguž Andrija
Published: March 2010

We apply the approach developed in the paper G. Alberti, S. Müller: A new approach to variational problems with multiple scales, Comm. Pure Appl. Math. 54, 761‐825 (2001) to calculate rescaled asymptotic energy associated to certain Ginzburg‐Landau functional in one dimension. We generalize results from the paper A. Raguž: Relaxation of Ginzburg‐Landau functional with 1‐Lipschitz penalizing term in one dimension by Young measures on micropatterns, Asymptotic Anal. 41(3,4), 331‐361 (2005), where original functional was penalized by 1‐Lipschitz function g. In this note we consider the case when such penalizing functions depend on small parameter ε as their derivatives oscillate with period equal to ε to the power of γ for some γ > 0. We show that there are three distinctive cases of γ which lead to different asymptotic energy. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The sensitivity analysis of the drawpiece response on the material model parameters
Authors: Kaldunski Pawel , Kukielka Leon
Published: March 2010

On this paper the numerical analysis of the drawing process with use the Finite Element Method is presented. The sensitivity of stresses field on the edge and the round edge of drawpiece on the tangent modulus and yield stress is defined. The analysis with the explicit method in the ANSYS LS‐Dyna system is passed. The Die and the stamp as not deformable bodies are accepted and with the shell finite elements are discretized. The drawpiece with the solid finite elements are discretized. Sample results of computer simulations are presented. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Reissner‐Mindlin plate is the Γ‐limit of Cosserat elasticity
Authors: Neff Patrizio , Hong Kwon‐Il , Jeong Jena
Published: March 2010

The linear Reissner‐Mindlin membrane‐bending plate model is the rigorous Γ‐limit for zero thickness of a linear isotropic Cosserat bulk model with symmetric curvature. For this result we use the natural nonlinear scaling for the displacements u and the linear scaling for the infinitesimal microrotations Ā ∈ so(3) affecting the in‐plane drill rotations. No boundary conditions on the microrotations are prescribed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fractal analysis of thermally sprayed coatings
Authors: Łabacz‐Kęcik Anna , Hejwowski Tadeusz , Litak Grzegorz
Published: March 2010

Functional performance of thermally sprayed coatings depends to a large degree on their surface topography. Surface topography of coatings was studied by analyzing numerically data sets aquired by contact profilometry. The effect of spraying method and powder composition was explored for a range of coatings. The effect of coating composition was studied for cermet coatings flame sprayed with mixtures of Ni‐5%Al with ZrO2‐30%CaO. To characterize the coating surface topography, multifractal analysis was performed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Navier‐Stokes equations with regularization
Authors: Asanalieva Nazgul , Varnhorn Werner
Published: March 2010

We consider the initial boundary value problem for the nonstationary Navier‐Stokes equations in a bounded three dimensional domain Ω with a sufficiently smooth compact boundary ∂Ω. These equations describe the motion of a viscous incompressible fluid contained in Ω for 0 < t < T and represent a system of nonlinear partial differential equations concerning four unknown functions: the velocity vector v = (v1 (t, x), v2 (t, x), v3 (t, x)) and the kinematic pressure function p = p(t, x) of the fluid at time t ∈ (0, T) in x ∈ Ω. The purpose of this paper is to construct a regularized Navier‐Stokes system, which can be solved globally in time. Our construction is based on a coupling of the Lagrangian and the Eulerian representation of the fluid flow. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kinematical and dynamical analysis of closed kinematic chains using graphs and contour equations
Authors: Drewniak J. , Zawiślak S.
Published: March 2010

The classical method of determination of velocities and accelerations of the closed kinematical chains consists in calculation of derivatives of the position vector in relation to time. In the paper, the methods of kinematical and dynamical analysis of the closed kinematical systems based upon the graph representation are presented. Planetary gears are the exemplary mechanical systems which have been considered. Two types of graphs are assigned to the gears. Both graphs allow for derivation of systems of equations which constitute the kinematical analysis. The results of classical and graph‐based methods were compared. The graph based methods allow for further considerations like e.g. synthesis, enumeration of design solutions and even evolutionary design of mechanisms. Dynamical analysis is shown in graphical form, only. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Probabilistic sensitivity of limit states of structures. The Monte Carlo simulation
Authors: Skowronek M.
Published: March 2010

The main issue of the paper is the probabilistic sensitivity of the limit states of structures with respect to selected input design variables. Attempt to the problem is done by the dedicated Monte Carlo simulation procedure. Basic design variables are random variables of given probability distributions, presented in the form of random numbers. Uni‐parametrical increment of the dominant basic variable (basic variables) is done, finally achieving the structural limit state. The simulation procedure restuls in a set of limit multipliers. Statistical analysis leads to the estimate of the probability density function of the limit state. Thus the numerical image is presented of the probabilistic sensitivity of the structural limit state. Reliability or the probability of failure are to be estimated, as statistical parameters of the histogram. Numerical examples of engineering structures illustrate the method introduced in the paper, conclusions are formulated eventually. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reliability of silo structure with geometric imperfections
Authors: Górski Jarosław , Mikulski Tomasz
Published: March 2010

Reliability of a silo structure with geometric imperfections is estimated. As the silo cylindrical constructions can be loaded with pressure below the atmospheric any geometric discrepancies are very dangerous and can significantly reduce their capacities. A probabilistic approach was applied. Two cases were considered. The imperfections were described by a uniform and a truncated Gaussian distribution. In the first case an uncorrelated random field was considered while in the second a theoretical nonhomogeneous correlation function was formulated. The realizations of the random imperfection fields are generated using a conditional rejection method. A version of a stratified sampling method is applied. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A probabilistic description of footbridges vibration serviceability
Authors: Winkelmann Karol , Górski Jarosław
Published: March 2010

Vibration serviceability of pedestrian bridges is considered. Imperfections in the human walking force are described as changes in walking factors. Probability distributions of walking frequencies, step length, and amplitude of walking force are taken into account. The imperfections can influence the level of footbridge vibration response. The Monte Carlo method is applied. The generated realizations of the loads formulate a set of initial data for numerical calculations. The probability distribution of maximal vertical acceleration is obtained. The results are presented as a probability that the required level of vibration will not be exceeded. A reliability describing the footbridges serviceability is also estimated. The probabilistic based approach can be used for future optimalizations of footbridge design codes due to the dynamic force loads. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Computation of Parametric Induced Roll Motions in Random Seas
Authors: Dostal Leo , Kreuzer Edwin
Published: March 2010

For a vessel in open seas, the sudden appearance of roll motions due to waves from the front or rear leads to dangerous situations up to capsizing. The equations of motion used to analyze the roll motion include the righting lever curve. This curve is set up by means of hydrostatic calculations and approximated by polynomials for further analysis. The irregular waves are modeled in terms of a continuous‐time ARMA process. The resulting model of stochastic differential equations is investigated numerically by Local Statistical Linearization. The necessary stochastic moments and their derivatives are computed using Itô's differential rule and Gaussian closure. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On an one‐step modification of Gauss‐Newton method under generalized Lipschitz conditions for solving the nonlinear least squares problem
Authors: Shakhno Stepan , Iakymchuk Roman
Published: March 2010

We investigate convergence of the one‐step modification of Gauss‐Newton method using the divided differences and the weak generalized Lipschitz condition for the divided differences. Convergence order of the method was examined and the uniqueness ball for the solution of the nonlinear least squares problem was proved. Numerical experiments were also provided. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Local buckling design problem for topology optimized truss girders
Authors: Kutylowski Ryszard , Rasiak Bartosz
Published: March 2010

The paper presents practical applying of structural topology optimization algorithm based on the formulation of optimal design with compliance minimization. Problem was presented and discussed for several 2D examples. Analysis of local buckling problem was made for various results obtained by the algorithm and approximated into the truss structures. Real bridge load was considered for girders. Topology based optimal girders were compared to typical truss structure. Relation between rods thicknesses was considered. Stress level including buckling in compressed members was examined. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Efficient Reliability Sensitivity Estimation for Optimization Under Uncertainty
Authors: Valdebenito M.A. , Schuëller G.I.
Published: March 2010

In this contribution, an efficient framework for performing reliability‐based optimization is presented. Key issues of the proposed approach are the decoupling of optimization and reliability estimation and efficient reliability sensitivity estimation. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Applications of singular value decomposition in structural optimisation
Authors: Gerzen Nikolai , Barthold Franz‐Joseph
Published: March 2010

The usage of the singular value decomposition (SVD) in scope of structural optimisation is motivated. We briefly outline several applications of SVD from different scientific fields to point out their similarities with structural optimisation. Here, our focus is on model reduction, on numerical defects and on their quantitative description using SVD. In this context we address the singular value decomposition of matrices which appear in an optimisation algorithm, i.e. the pseudo load matrix and the sensitivity matrix. In this contribution on the example of topology optimisation we would like to clarify all the properties of SVD. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Model of the Internet mortgage market optimization
Authors: Mieloszyk Eligiusz , Orłowski Aleksander
Published: March 2010

The Internet mortgages are currently a fast growing market, allowing selling mortgages cheaper and faster than in the traditional methods such as in bank departments. Given the specificity of selling mortgages in the Internet, banks try to sell more mortgages by spending more money on advertising and paying higher commission to the brokers selling their products. It is important to optimise the amounts of money in both sectors (the balance of money for advertising and for brokers) and to compare these amounts with the level of mortgages can be sold within this period (which is related to the economic indicators such as the current level of interest rate, unemployment rate etc.)It is suggested to create a knowledge base rule model defining the Internet mortgage market which will include the variables important for the problem (preliminary choice of such indicators the level of commission that is paid to the brokers, the current interest rate in the country), restrictions concentrating optimising the amounts of money that will be spend with the correlation to the current possibilities of selling mortgages (defined by the current situation of the economy). The model will be supported with the data from two banks and two brokers representing the market. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New graph products of specified domains for configuration processing
Authors: Kaveh A. , Alinejad B.
Published: March 2010

In this paper new graph products are defined with specified domains. In these products the logical operations of the graph products are only applicable in specified domains, and therefore these products can produce configurations which do not need to be regular. Compound models can be generated and cut‐outs and other irregularities can be incorporated using these products. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The contributions regarding the conception, designing, modelling and the implementation in a flexible cell of fabrication of a modular serial robot
Authors: Petrişor Silviu Mihai , Ispas Viorel , Arghir Mariana
Published: March 2010

The authors of the presented paper are propose to relief the calculus, modelling and construction of the translation module of an industrial robot which possess in his cinematic chain five degrees of freedom, type TTRTR. It is propose a choosing variant of the direct current driving engine of the translation module, knowing the output momentum and calculating the input momentum. This is realized by equalize of an equation which results from dynamic modeling of the robot with a designing equation which keep in view the component elements of the structure of the module. The robot is composed by: module of translation on horizontal to the base of the robot (MTB‐Sil), module of translation on vertical (MTV‐Sil), module of rotation round the vertical axis from the robot's arm, module of translation from the structure of the robot's arm (MT‐Sil) and module of orientation assembled with clamping device. In the paper, also is presented an economic study regarding the implementation of the analyzed robot in a manufactural cell concerning the manufacturing and assembling of some types of car radiators. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Another derivation of the local double logarithmic reconstruction formula
Authors: Niessner Herbert
Published: March 2010

In [1] Artebrant and Schroll presented a finite volume method for hyperbolic conservation laws of 3rd order accuracy with no limiter and no special shock treatment. The method is based on local reconstruction of a double logarithmic function from cell averages on a 3‐point stencil. Results shown in [1] make it appear very attractive and highly efficient. The derivation of the reconstrucion formula however starts with a relativ complex expression in some way anticipating the final result. In the following a more lucid one is shown proceeding from scratch and permitting symmetries to be clearly seen. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Boundary Integral Formulation for Poroelastic Materials
Authors: Schanz Martin , Steinbach Olaf , Urthaler Peter
Published: March 2010

Wave propagation in porous media is an important topic, e.g. in geomechanics or the oil‐industry. We formulate a linear system of coupled partial differential equations based on Biot's theory with the solid displacements and the pore pressure as the primary unknowns. To solve this system of coupled partial differential equations in a semi‐infinite homogeneous domain the BEM (Boundary element method) is especially suitable. Starting from a representation formula a system of two boundary integral equations is derived. These boundary integral equations are used to solve related boundary value problems via a direct approach. Coercivity of the resulting bilinear form is shown, from which unique solvability of the variational formulation follows from injectivity. Using these results we derive the unique solvability of the related boundary integral equations. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On Optimal Control of a Free Surface Flow
Authors: Repke Sabine , Marheineke Nicole
Published: March 2010

We discuss an optimal control approach for a 2D Stokes flow with a free surface. The aim is to optimize the shape of a polymer film by adjusting the ambient pressure in a casting process. The resulting minimization problem is solved by the method of steepest descent. Numerical results will be presented. Furthermore we state the adjoint system for the Lagrangian formalism. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical solutions for optimal control of monodomain equations
Authors: Nagaiah Chamakuri , Kunisch Karl , Plank Gernot
Published: March 2010

We present the numerical solutions of optimality systems corresponding to optimal control problems governed by the mono‐domain equations which are widely used for describing the electrical activity of the cardiac tissue. This mono‐domain model is based on a parabolic equation and a system of stiff ordinary differential equations. The space discretization of the state variables and dual variables is done using piecewise linear finite elements and the time discretization is based on linearly implicit Runge‐Kutta methods. The main goal of this work is to study the optimal control behavior of the electrical potentials under the influence of extracellular ionic currents as control variables. The numerical results presented are based on first and second order optimization methods. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A priori estimates for optimal Dirichlet boundary control problems
Authors: Deckelnick Klaus , Günther Andreas , Hinze Michael
Published: March 2010

We consider variational discretization of control constrained elliptic Dirichlet boundary control problems on smooth twoand three‐dimensional domains, where we take into account the domain approximation. The state is discretized by linear finite elements, while the control variable is not discretized. We obtain optimal error bounds for the optimal control in two and three space dimensions. Furthermore we prove a superconvergence result in two space dimensions under the assumption that the underlying finite element meshes satisfy certain regularity requirements. We confirm our findings by a numerical experiment. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Novel digitally controlled drive for the vibratory conveyors
Authors: Kucharski Tomasz , Jakubowski Piotr , Zurek Krzysztof
Published: March 2010

The vibratory conveyors are used in the industry for continuous transportation of loose substances over short distances (2–10 m). The presented conveyor is designed for transportation in aseptic conditions. To obtain high efficiency for granulated mass with different size of grain and different physical properties it is necessary to set the appropriate vibration amplitude independently of vibration frequency. This is not possible with the conveyors currently being used. Therefore it was proposed to apply the novel drive made up of rotary exciter with digital controller. Moreover some methods for dynamic stiffening of the panels were developed and their effectiveness was ascertained. A digitally controlled exciter allowed dynamic panel stiffening by using light closed panels in construction of the conveyor. The control system with encoders for measuring the vibration amplitude of the panel was also established. A study of the conveyor's prototype shows the effectiveness of the drive system. The possibility of digitally setting the vibration amplitude of the light panel to obtain the maximum productivity for particular materials was also shown in results of the research. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibration surveillance during milling of flexible details with a use of the optimal control
Authors: Kaliński Krzysztof , Chodnicki Marek
Published: March 2010

The paper concerns vibration surveillance during ball end milling of curved flexible details. Here is explained dynamic analysis of non‐stationary vibrating system, from which are separated subsystems: modal, structural and connective. An assessment of coincidence of the calculation model results with those from investigation on milling machine is performed. Ball end milling of flexible details is observed very frequently in case of modern machining centres. It is obvious that tool‐workpiece relative vibration plays principal role during cutting process. The most important task is to create a FE‐model of machined flexible detail and obtain its good correlation with the results of experimental modal analysis. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)