bluuebunny/crossref_metadata_2025_split huggingface dataset:
Implementation of a cohesive zone model for crack closure analysis of rotors
Authors: Liong Rugerri Toni , Proppe Carsten 
Published: March 2010

AbstractThe presence of a crack in a rotor introduces a local flexibility which affects its dynamic response. Moreover, the crack may open and close during the vibration period. The crack status is a function of time and also depends on the rotational speed and the vibration amplitude of the rotor. This nonlinear case is still a challenging research topic especially in the field of closing crack in the rotating shaft. A cohesive zone model is developed in order to analyze the stiffness of a crack in a rotating shaft. The proposed expression will be compared to three different crack models, namely, a breathing crack model, a switching crack model and an open crack model. Moreover, a cohesive law to predict and to analyse the stress at the crack tip is presented. The numerical model is implemented using a finite element formulation. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of experimental and numerical results on metallic plates subjected to explosions
Authors: Pyrzowski Łukasz , Kłosowski Paweł , Woznica Krzysztof , Pennetier Olivier 
Published: March 2010

AbstractA comparative study of dynamic response including damage and rupture processes of thin metallic plates subjected to shock‐wave impulses – explosions is presented. The results of the finite element numerical analysis are related to experiments. Due to high strain rate during explosions the elasto‐viscoplastic Chaboche's constitutive law including damage effects has been applied. For the assumed model proper material parameters identification has been done. In the dynamic, geometrically non‐linear analysis the MSC.Marc system has been used. A good correlation between numerical and experimental results has been observed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of domain structures in cracked ferroelectric materials
Authors: Xu Bai‐Xiang , Müller Ralf , Schrade David , Gross Dietmar 
Published: March 2010

AbstractThe domain structure around a crack tip plays a significant role in the fracture behavior of ferroelectrics. A continuum phase field model is used to investigate the microstructure at the crack front. The concept of the Eshelby momentum tensor and configurational forces is then generalized to account for the contributions of the polarization term. Implementation of the generalized configurational force in the Finite Element code enables us to numerically obtain the driving force at the crack tip, which corresponds to the crack‐tip energy release rate. Calculations show that additional positive electric fields tend to prohibit crack growth, whereas additional negative electric fields tend to promote crack growth. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Formulation and Application of the Initially Rigid Cohesive Finite Element Method
Authors: Geißler Gordon , Kaliske Michael 
Published: March 2010

AbstractThe presented procedure for cohesive crack propagation is based on an adaptive finite element (FE) implementation, which enables the introduction of cohesive surfaces in dependence on the current crack state. In contrast to already existing formulations, the focus of the present model lies on failure processes that can be described at quasi‐static conditions within an implicit framework. Furthermore, an extension for mesh independent crack propagation in terms of an additional mesh adaptive formulation is presented. By the evaluation of the failure criterion considering the preferred crack direction, a new crack tip coordinate is computed and the discretization is accordingly adjusted. The remaining mesh is modified for the new boundary representation. The application of the proposed method is shown by the numerical investigation of a concrete fracture specimen from an experimental research project. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A variational coupled damage‐plasticity model via gradient enhancement of the free energy function
Authors: Dimitrijevic Bojan J. , Hackl Klaus 
Published: March 2010

AbstractWe present a coupled damage‐plasticity model, whose regularization is achieved through gradient enhancement of the free energy function by introducing new variables. They serve to transport the values of the inelastic variables across the element boundaries, and their gradients play regularisation role in the model. Variational formulation results in a pure minimisation problem, leading to model non‐local in nature and preserving C0 interpolation order of the variables. Numerical examples illustrating the performance of the proposed model are presented. It is shown that the pathological mesh dependence is efficiently removed, together with the difficulties of numerical calculations in the softening range. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Variational–Based Formulation of Regularized Brittle Fracture
Authors: Hofacker Martina , Welschinger Fabian , Miehe Christian 
Published: March 2010

AbstractThe paper performs a comparative study of variational‐based brittle fracture with its gradient‐type regularization, and outlines aspects of the numerical implementations of both approaches. The latter smoothes out sharp displacement discontinuities of cracks. On the side of discrete crack modeling, we propose a variational framework of configurational‐force‐driven crack propagation. The latter provides the basis for the computation of material nodal forces and drives the crack propagation in our proposed finite element framework with adaptive nodal doubling. Such a formulation is of limited applicability for the modeling of crack inititation in homogeneous bodies without defects and in situations with complex crack branching. This can be overcome by a regularized crack modeling. Here, an elliptic approximation of the crack surface term yields a regularized two field functional, where an additional scalar field approximates the set of discontinuities. We provide a simple interpretation of such a transition from the sharp crack to the regularized setting. It results in a smooth continuum‐damage‐type theory with a specific gradient‐damage and hardening terms, depending on a length scale that represents the width of a zone that surrounds the crack. Such a variational framework is implemented by a coupled two‐field finite element framework in a staightforward manner. We compare representative numerical results obtained by both methods for selected crack patterns and highlight the pro and contra of both meshes. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Simulation Model for Shield Tunnelling and its Interactions with Partially Saturated Soil
Authors: Nagel Felix , Stascheit Janosch , Meschke Günther 
Published: March 2010

AbstractThe design of shield supported tunnel construction in urban areas requires the reliable determination of the expected time‐variant ground response and the prognosis of possible critical conditions endangering the soil stability. In partially saturated soil the response of the surrounding underground depends strongly on the interactions between the construction process and the surrounding underground and its constituents. The paper gives an overview on a Finite Element model for the simulation of shield supported tunnel advance in partially saturated soil that is capable of accounting for these interactions. Special emphasis is laid on the description of the surrounding underground, modelled as a three phase continuum within the Theory of Porous Media (TPM). Applicability of the simulation model is discussed by results obtained from the simulation of compressed air application for the heading face support. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of a Flexible Cantilever Beam Equipped in Piezoelements for Vibration Control System
Authors: Koszewnik Andrzej 
Published: March 2010

AbstractThe identification of an active vibration damping system with the use of piezoelements glued to the structure is presented in the paper. Lab stand was completed with smart beam, power amplifier and charge amplifier. First, the open‐loop system was identified in the frequency domain in using experimental setup The piezo‐stripes to have worked in the mode of actuators and sensors, respectively. For the frequency range from 1 Hz to 400 Hz we obtained Bode plots with help of the Dynamic Signal Analyzer. Frequency characteristics are a base for further calculations. Second, the mathematical model was obtained by finite elements methods and was adjusted to the experimental results by least square sum approach. Third, observable canonical‐form in state space model was derived by using of the LMFD method (Left Matrix Fraction Description). Finally, a minimal realization of the transfer function was reached by Balance method. The transfer function describes the first three resonances and first three anti‐resonances in considered frequency range. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time‐dependent reliability assessment of structures using uncertain fractional rheological models
Authors: Freitag Steffen , Kaliske Michael , Graf Wolfgang 
Published: March 2010

AbstractIn this paper, a concept for time‐dependent reliability assessment of civil engineering structures is presented. This concept bases on the uncertainty model fuzzy randomness. The time‐dependent behaviour of materials with fading memory is captured by means of rheological models using uncertain fractional time derivatives. The presented method can be applied to the reliability assessment of engineering constructions. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mechanical model of a mistuned 2DOF‐structure coupled by viscous damping
Authors: Laborenz Jacob , Siewert Christian , Panning Lars , Wallaschek Jörg , Gerber Christoph 
Published: March 2010

AbstractIn this paper the vibration amplitude reduction of a mechanical system is investigated when applying a damper between different DOF of that structure. Thereby, an elementary mechanical model consisting of two mass‐spring elements with slightly differing eigenfrequencies and which are connected via a viscous dashpot damper is regarded. To investigate the systems behavior, an analysis of the transfer function and its poles and zeros in the L APLACE domain is performed when varying the damping constant. This reveals that the achievable amplitude reduction depends on the mistuning of the system and that even ideal viscous damping leads to a coupling which results in a shift of eigenfrequencies. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Shaking table experimental study on the effectiveness of polymer bearings for seismic isolation of structures
Authors: Banaś A. , Jankowski R. 
Published: March 2010

AbstractSeismic isolation has been recognised to be a very effective way of protecting structures from damage during earthquakes. It allows us to extend the natural period of the structure and therefore avoid resonance with the ground motion. Moreover, by increasing damping in the isolation devices, more energy can be dissipated and thus the structural response can be further reduced. The aim of this paper is to show the results of the study focused on verification of the applicability of the innovative method of seismic isolation by installing bearings made of a polymer mass, which is an especially designed flexible elastoplastic two‐component grout based on polyurethane resin. In the study, a model structure was tested experimentally on a shaking table under earthquake excitation. First, the structure was fixed directly to the table and its response was recorded. Then, the response of the structure with polymer bearings installed at its base was observed and both responses were compared. The results of the study show that equipping the structure with the polymer bearings can considerably reduce the structural response under earthquake excitation. The innovative method considered in the study has been verified to be an effective seismic isolation technique. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Imperfection Sensitivity or Insensitivity of Zero‐stiffness Postbuckling … that is the Question
Authors: Jia Xin , Hoefinger Gerhard , Mang Herbert A. 
Published: March 2010

AbstractZero‐stiffness postbuckling of a structure is characterized by a secondary load‐displacement path along which the load remains constant. In sensitivity analysis of the (initial) postbuckling path it is usually considered as a borderline case between imperfection sensitivity and imperfection insensitivity. However, it is unclear whether zero‐stiffness postbuckling as such is imperfection sensitive or insensitive. In this paper, Koiter's initial postbuckling analysis is used as a tool for sensitivity analysis. Distinction between two kinds of imperfections is made on the basis of the behavior of the equilibrium path of the imperfect structure. New definitions of imperfection insensitivity of the postbuckling behavior are provided according to the classification of imperfections. A structure with two degrees of freedom with a zero‐stiffness postbuckling path is studied, considering four different imperfections. The results from this example show that zero‐stiffness postbuckling is a case of transition from imperfection sensitivity to imperfection insensitivity for imperfections of the first kind and that it is imperfection insensitive for imperfections of the second kind. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Comparison of classical Winter's bracing requirements of compressed truss chord with stability analysis of 3D truss‐model
Authors: Iwicki P. 
Published: March 2010

AbstractMost code requirements concerning bracing are based on principles developed by Winter. The present research is devoted to study a lateral buckling of truss with linear elastic side supports. The classical Winter's model of truss chord in the case of out of the truss plane buckling is compared with nonlinear analysis of 3D truss model. Full bracing condition, that permits the truss chord to support load level corresponding to an unbraced length equal to the distance between braces is calculated. Then an approximate buckling load with less than full bracing is developed and the model is modified to account for unequal normal force distribution in compressed chord. The coefficient of buckling length related to side support distance in function of bracing stiffness is also calculated. The results are compared to design code requirements. It is shown that buckling length of truss chord with side supports considered as elastic elements is larger than assumed in design codes. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Is hilltop buckling imperfection sensitive or insensitive?
Authors: Hoefinger Gerhard , Jia Xin , Mang Herbert A. 
Published: March 2010

AbstractHilltop buckling is the coincidence of a snap‐through point with a bifurcation point on the primary equilibrium path. An originally imperfection sensitive structure cannot be modified such that it shows both hilltop buckling and imperfection insensitivity. This is a rule for designing structures for imperfection insensitivity and guarantees validity of Koiter's postbuckling analysis, which would fail for imperfection insensitive hilltop buckling. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical analysis of laminated shells under in‐plane axial compression
Authors: Sabik A. , Kreja I. 
Published: March 2010

AbstractThe authors of the paper present numerical stability analysis of axially compressed laminated shells. The analysis is carried out by using the commercial code NX‐Nastran and authors' own program. In both cases the Equivalent Single Layer approach is adopted, in which the laminated shell is treated as an orthotropic single layer panel with the resultant stiffness calculated for the multilayered cross‐section. Since the distribution of displacement in the thickness direction is assumed to be linear (First Order Shear Deformation), the shell kinematics is consistent with the Reissner‐Mindlin type theory. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling problems of steeply inclined cableway subjected to moving load
Authors: Knawa Marta , Bryja Danuta 
Published: March 2010

AbstractProblems of structural modeling of multi‐span bicable ropeway systems due to significant inclination of a track are discussed in this paper with reference to the vibration analysis. The analytical continuous model of a cableway is formulated in a form which enables to describe in‐plane vibrations of steeply inclined carrying cable subjected to traveling passenger carriers modeled by moving pendulums. The nonlinear interaction between carrying cable and moving carriers is taken into account in the moving load definition. Effects of a steep track slope are discussed on the basis of equations of motion of the system. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Methods of Analysis of Discrete ‐ Continuous Systems Vibrations and Their Application to Railway Transport Problems
Authors: Kumaniecka A. 
Published: March 2010

AbstractIn the paper some aspects of the interaction between the current collector and the overhead equipment have been presented. A model of the system that consists of a discrete subsystem modelling the pantograph and a continuous subsystem modelling the contact wire has been introduced. The dynamic interaction between the discrete oscillator of two degrees of freedom and a continuous string has been studied. At the contact point of the pantograph and the wire a varying component of force appears. It is the source of waves that propagate along the contact wire. There are also two standing sources of wave generation, i.e. varying forces at the points of catenary supports. General results have been illustrated by numerical examples in which the effect of wave propagation is confirmed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the influence of contact mechanics on friction induced flutter instability
Authors: Hetzler Hartmut 
Published: March 2010

AbstractWithin this contribution, the general form of perturbation equations for systems of moving elastic bodies is derived and examined with respect to symmetry and definiteness properties. The contact is enforced by a penalty formulation, which is motivated by a constitutive contact model relying on statistical data of the surface. Evaluating Hamilton's Principle and carrying out a linearization about a stationary transport motion, the general perturbation equations are derived. The resulting differential operators are stated and discussed. The findings are exemplified for a rotating cicular Timoshenko beam with frictional contacts. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the modelling of vehicle‐road interaction
Authors: Vogt Heike , Seemann Wolfgang 
Published: March 2010

AbstractDuring the last years axle loads and demand for transport have been increasing steadily. Although a lot of experimental data exists on the corrugation of roads by heavy vehicles, basic investigations concerning vehicle‐road interaction are still necessary to improve the understanding of the process. Therefore, a simple model is built which will allow for some analytical reflections. The road exhibits viscoelastic and plastic characteristics whereas the vehicle is approximated as a simple quarter car model. Results of long term simulations are presented. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bifurcation analysis of a stochastic non‐smooth friction model
Authors: Gaus Nicole , Proppe Carsten 
Published: March 2010

AbstractNon‐smooth friction systems such as systems with dry friction show several bifurcation phenomena. The discontinuity of these so called slip‐stick vibrations makes these systems interesting and there has been a lot of research in this field, see for example Hinrichs [1]. Due to the non‐smooth friction force even the deterministic system shows a rich bifurcation behavior. Measurements indicate that the friction coefficient which plays a large role in the system behavior is not deterministic but can be described as a friction characteristic with added white noise. Therefore, the stochastic characteristic is introduced into the non‐smooth system and the change of the bifurcation behavior is studied. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of natural modes of linear mass‐spring vibration systems by Laguerre polynomials
Authors: C. Müller Peter 
Published: March 2010

AbstractChain structured vibration systems with N degrees of freedom with massesmjand stiffnesseskjhave been discussed in detail [1]. Some of them can be solved explicitly, others only numerically. Here, an inverse problem is considered: Howmj,kj,j= 1, …, N, should be chosen such that the related eigenvalue/eigenvector‐problem can be solved by Laguerre polynomials? (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of lateral oscillations in the interface of brake systems
Authors: Dombek Dominika , Ostermeyer Georg‐Peter 
Published: March 2010

AbstractThe research of the dynamics in the boundary layer of brake pads can afford revealing technical expertise concerning different phenomena occurring in brake systems (e.g. squealing, judder, Hot Spots). For manufacturers of brake systems, the phenomenon “squealing” is of particular interest due to the desired driving comfort. The mentioned phenomena have been researched by numerous scientists. Different models have been developed and approved by experimental results. The authors agree upon the fact that the main excitation mechanism of the mentioned effects in brake systems is caused by the variation of the lateral (in‐plane) friction force and friction torque respectively [1]. A model describing the dynamical interaction of friction and wear in the contact zone of brake systems has been introduced in [2]. Based on this theory, the brake pad's boundary layer consists of characteristic hard and smooth structures on the mesoscopic length scale. A new concept of the initiation of the squealing mechanism is based on the synchronisation mechanism of these so‐called patches emerging from the dynamical interaction of the friction partners. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Model Order Reduction of a Drill‐String‐Model with Self‐Excited Stick‐Slip Vibrations
Authors: Kreuzer Edwin , Steidl Michael 
Published: March 2010

AbstractThe dynamical behavior of a drill‐string is defined by its small diameter‐to‐length ratio, which makes the string vulnerable to torsional vibrations. In combination with the nonlinear friction characteristic at the drill bit, this can lead to self‐excited stick‐slip vibrations which are detrimental to the drilling process. The string can be modeled by the Finite Element Method or as a Multi‐Body system to represent the distributed character of the system. The analysis of the resulting high‐dimensional model is, however, elaborate and time‐consuming. We show that through Galerkin Projection onto the first two Characteristic Functions gained from Karhunen‐Loève‐Transformation, a reduced system can be obtained which reproduces the essential dynamical properties of the original system, e.g. the stick‐slip motion. With the reduced system, the linear stability of the drill‐string can be analyzed. We show that by reducing the inertia of the rotary table the system can be stabilized. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Identification of chaos in a regenerative cutting process by the 0‐1 test
Authors: Litak Grzegorz , Radons Günter , Schubert Sven 
Published: March 2010

AbstractWe examine the regenerative cutting process by using a single degree of freedom non‐smooth model with a friction component and a time delay term. Instead of the standard Lyapunov exponent calculations, we propose a statistical 0‐1 test for chaos. This approach reveals the nature of the cutting process signaling regular or chaotic dynamics. We are able to show that regular or chaotic motion occur in the investigated model depending on the delay time. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)