bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental verification of damage detection methods based on mode shape measurements for beams and plates.
Authors: Radzieński Maciej , Krawczuk Marek 
Published: March 2010

AbstractThis paper presents experimental verification and comparison of damage detection methods based on changes in mode shapes such as: mode shape curvature (MSC), damage index (DI), strain energy (SE), modified Laplacian operator (MLO), generalized fractal dimension (GFD) and Wavelets Transform (WT). The object of the investigation is to determine benefits and drawbacks of the aforementioned methods and to develop data preprocessing algorithms for increasing damage assessment effectiveness by using signal processing techniques such as interpolation and extrapolation of measured points. Noise reduction algorithms are also tested. The experiments were performed on a steel cantilever beam and on an aluminium plate with riveted stiffeners. Damage was introduced in a form of open crack for beam object and damaged rivets and a saw cut in the angle bar for plate structure. Measurements were made using non‐contact Scanning Laser Doppler Vibrometer (SLDV) at 125 points along beam length and 101 points in two rows, distributed on over the plate height and positioned along two reinforcing ribs. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selection of the eddy currents frequency for conductivity measurements in two‐layer structures
Authors: Dziczkowski Leszek 
Published: March 2010

AbstractConductance measurements of conductive parts can serve as a background for conclusion about structure of material and possible defects (e.g. fractures, fissures, delamination, flaking, etc.) that may occur in examined parts. When the need arises to test surfaces of parts that are made of a conductive but non‐ferromagnetic material, the method of eddy currents offers unsurpassed advantages. The problem refers to application of the eddy current method to examination of conductive material coated with conductive films. The major outcome consists in development of a very simple and useful mathematical model that can be used to determine conductivity of the deep layer for the needs of non‐destructive tests. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Energy driven crack propagation at finite strains based on the embedded strong discontinuity approach
Authors: Radulovic Radan , Bruhns Otto Time , Mosler Jörn 
Published: March 2010

AbstractNew advances in three‐dimensional finite element modeling of crack propagation at finite strains are presented. The proposed numerical model is based on the Enhanced Assumed Strain concept. The enhanced part of the deformation gradient is associated with a displacement discontinuity. In contrast to previous works, a new, energy based criterion for crack propagation is presented. The necessity for a tracking algorithm for the crack path is avoided by using more than one discontinuity within each finite element. This leads to a strictly local formulation, i.e., no information about the neighboring elements are required. Further advantages of such a formulation are a symmetric tangent stiffness matrix and the reduction of locking effects. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Phase field simulation of thermomechanical fracture
Authors: Kuhn Charlotte , Müller Ralf 
Published: March 2010

AbstractIn Francfort and Marigo's variational free‐discontinuity formulation of brittle fracture [1] cracking is regarded as an energy minimization process, where the total energy is minimized with respect to any admissible crack set and displacement field. No additional criterion is needed to determine crack paths, branching of cracks and crack initiations. However, a direct discretization of the model is faced with significant technical problems, as it involves minimizations in a set of possibly discontinuous functions. A regularized version of the model has been introduced by Bourdin [2] and based on this, we use the concept of a continuum phase field model to simulate cracking processes. Cracks are indicated by the order parameter of the phase field model and cracking can be regarded as a phase transition problem. Additionally, introducing the heat equation into the model, it is capable to also take account of crack propagation due to thermal stresses. In the numerical implementation, crack parameter as well as temperature are treated as additional degrees of freedom and the coupled field equations are solved using the finite element method together with an implicit time integration scheme. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fracture Mechanical Investigation of Elastomeric Material
Authors: Morgner Christiane , Kaliske Michael 
Published: March 2010

AbstractThe increasing use of elastomeric components in advanced engineering applications requires a thorough understanding of the complex material properties and a reliable assessment of the quality and durability of the products. This contribution concentrates on the computational determination of fracture mechanical parameters for rubber material using the material force method. For dissipative, inelastic material, a distinction between two fracture mechanical parameters is presented. The time‐dependent behaviour of these fracture mechanical parameters is illustrated by an application to the dwell‐effect. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of short crack propagation using a hybrid boundary element technique
Authors: Kübbeler Martin , Fritzen Claus‐Peter , Roth Ingmar , Christ Hans‐Jürgen , Krupp Ulrich 
Published: March 2010

AbstractService life of cyclically loaded components is often determined by the propagation of short fatigue cracks, which is highly influenced by microstructural features such as grain boundaries. A two‐dimensional model to simulate the growth of such stage I‐cracks is presented. The crack is discretised by dislocation discontinuity boundary elements and the direct boundary element method is used to mesh the grain boundaries. A superposition procedure couples these different boundary element methods to employ them in one model. Varying elastic properties of the grains are considered and their influence on short crack propagation is studied. A change in crack tip slide displacement determining short crack propagation is observed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A comparison of ductile damage models with application to LCF
Authors: Kintzel Olaf 
Published: March 2010

AbstractIn the present research work, the modification of the microvoid damage model of Gurson by Leblond et al. is considered using a common framework of multiplicative finite strain elastoplasticity. The formulation for an advanced kinematic hardening model for cyclic plasticity is outlined. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Compressor Blade Health Monitoring with Use of Tip Timing and Modal Analysis Method
Authors: Witos Miroslaw , Wisnioch Marcin 
Published: March 2010

AbstractThe intended aim of this report is to deliver a short review of AFIT experience in the field of the blade health monitoring. A special attention has been put down for diagnostic methods (tip timing, modal analysis, metal magnetic memory) and symptom verification. Knowledge, which is necessary for reliable diagnosis and prognosis, during engine operation, as well as during overhaul and numerical simulation. It has been proven that the resonance characteristic shape analysis gives an ability to determinate if we deal with fatigue or with a blade crack. Early fatigue symptoms, i.e. modal properties of material strengthening and weakening phases have been shown. A new source of diagnostic information to ‘actively’ control blade fatigue (VHCF, HCF & LCF) has been described. The discussed problems have been illustrated with some examples. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Comparison of Alternative Space‐Time Discretizations of Nonlinear Shells
Authors: Sänger Nicolas , Betsch Peter 
Published: March 2010

AbstractGeometrically exact shell models are suitable for modelling shell‐type flexible components in the context of finite‐deformation multibody dynamics. Conserving time‐stepping schemes are known to yield enhanced numerical stability properties. This approach is compared to alternative methods, including a momentum‐symplectic variational integrator. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling issues of a holistic finite element approach in the virtual engineering design process
Authors: Barthel Corinna , Gabbert Ulrich 
Published: March 2010

AbstractIn the paper methods for the coupling of different meshed local domains of a product model, which occur in an adaptivity process are compared. The properties of the applied coupling methods are demonstrated on finite element models from structural mechanics to point out the advantages and disadvantages of the methods in a model adaptivity process in the field of automotive engineering. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear third‐order shear deformation theory and finite element simulation of smart plates with piezoelectric layers
Authors: SCHMIDT Ruediger , VU Thang Duy 
Published: March 2010

AbstractThis paper deals with nonlinear finite element analysis of plates incorporating piezoelectric layers. The finite elements are based on von Kármán‐type first‐ and third‐order transverse shear deformation theory (FOSD and TOSD, respectively). The presented finite element implementation is based on a total Lagrangian approach. As an example we consider shape control of a hinged plate with PZT actuator layers bonded to the top and bottom surfaces. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polygonal finite element formulations for 2d linear‐elastic FE problems
Authors: Kraus Markus , Steinmann Paul 
Published: March 2010

AbstractPolygonal finite elements provide great flexibility meshing complex structures and for the refinement of meshes. The actual task in the development of these elements is to offer adequate and secure numerical results compared with regular finite elements at low computational costs. Particulary, finding an efficient and appropriate interpolation of the arbitrary element domain exhibits strong difficulties. Based on the general interpolant equation three element formulations are shown that use different interpolation strategies. The elements' performances are shown with a numerical example considering 2d linear elasticity. The results of the different element formulations are compared among each other, with analytical as well as with regular elements' results. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modes of transition from imperfection sensitivity to imperfection insensitivity
Authors: Mang Herbert A. , Hoefinger Gerhard , Jia Xin 
Published: March 2010

AbstractIn order to a priori find the mode of conversion of a structure from imperfection sensitivity to insensitivity in the course of sensitivity analysis of the initial postbuckling path (cf. [2]), terms appearing in the consistently linearized eigenvalue problem (cf. [1]) are studied. Two main classes can be identified (cf. [4]). The first one is characterized by the restriction of the prebuckling deformations to axial deformations. For this class, the quality of the aforementioned conversion is better than the one for the other class, for which the above restriction does not hold. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stability of thin walled structures strongly coupled with contact
Authors: Izi Ridvan , Schweizerhof Karl , Konyukhov Alexander 
Published: March 2010

AbstractStability problems strongly coupled with contact are examined using different contact algorithms. Applying the penalty formulation a high dependence of the buckling load on the penalty parameter is found. This observation becomes clear when considering a classical Euler case. Applying kinematical constraint conditions (close to a Lagrange scheme) for contact on the other hand more consistent results regarding the buckling load are obtained. Thus for a Nitsche scheme a better and more flexible solution is expected. The FE implementation of a Nitsche interface element is carried out. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free vibrations of thin annular plates made from functionally graded material
Authors: Wirowski Artur 
Published: March 2010

AbstractSubject of the consideration is thin annular plate made of a two‐phase functionally graded composte. The plate has periodically inhomogeneous microstructure slowly varying in space: the λ‐periodic structure along circular coordinate, but smoothly graded apparent (averaged) properties in the perpendicular, radial direction. The aim of the contribution is to derive and apply a deterministic macroscopic model describing the free vibrations of this plate. Modeling procedure is based on tolerance averaging technique. We received, equations system with smooth coefficients. We made numerical solution of this problem, using finite difference method, and analyze influence of material proportion and microstructure size on first frequency of free vibrations. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduced hybrid model of moving and rotating continua
Authors: Orlikowski Cezary , Hein Rafał 
Published: March 2010

AbstractThe paper introduces the method of the model reduction of systems that experience a Coriolis acceleration or gyroscopic effect component. In such causes that corresponding system equations are non‐self‐adjoined. Modal reduced model is built up for the system without Coriolis or gyroscopic effect terms. These phenomena are next included by application of any lumping technique. Hence, the final reduced model is a hybrid one, obtained by both lumping and modal methods of modeling. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micro‐vibrations of thin cylindrical shells with uniperiodic structure
Authors: Tomczyk Barbara 
Published: March 2010

AbstractMicro‐vibrations of thin linear‐elastic Kirchhoff‐Love cylindrical shells, having a periodic structure along one direction tangent to the shell midsurface, are investigated using the new averaged non‐asymptotic model of such shells proposed by Tomczyk (2008). This model describes the effect of microstructure size on the overall shell behaviour and makes it possible to analyze the shell's micro‐dynamics independently of its macro‐dynamics. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Damped vibrations of the beam systems in rotational transportation
Authors: Żółkiewski S. 
Published: March 2010

AbstractThe major aim of this thesis is dynamical analysis of systems in rotational transportation with taking into consideration in the mathematical models the damping forces. The dissipation of energy in form of damping is inseparable connected with motion of analyzed systems. Up to now modelling of rod and beam systems in transportation was very often based on simplification and reduction of damping effect and on the other side the considerations very rarely apply to systems where the transportation effect was took into consideration. In this thesis the dynamical flexibility of the damped beam systems in transportation was presented. Analyzing systems were assumed as simple homogenous beam systems with symmetrical cross‐section constant on whole length of the system. Most popular technical applications of such systems are put into use in propellers and sails of wind power plant, main, auxiliary rotors of helicopters, turbines, etc. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Disturbance Propagation in the Melt Spinning Process
Authors: McVeigh Anthony 
Published: March 2010

AbstractThis work deals with the propagation of a disturbance acting on a fibre in the melt‐spinning process, where molten polymer is ejected vertically downwards from an orifice before being drawn onto a wind‐up spool. The disturbance may be produced by a sudden horizontal draught of air impinging on a part of the fibre. The flow is modeled as a wave propagating on a moving string under the influence of damping and variable tension. The amplitude of the disturbance is obtained in closed‐form along the characteristics which emanate from the boundaries of the localised initial disturbance; the general solution of the damped disturbance is determined numerically. An important aspect of the model is the ability to predict the magnitude of this disturbance close to the orifice, where the extruded polymer is molten and therefore extremely sensitive to disturbances. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear stability analysis of rotor‐bearing systems
Authors: Boyaci Aydin , Seemann Wolfgang , Proppe Carsten 
Published: March 2010

AbstractHigh‐speed rotors supported by floating ring bearings exhibit beside self‐excited vibrations various nonlinear vibration effects, which may cause the damage of the rotor. After deriving the equations of motion of a perfectly balanced turbocharger rotor supported by floating ring bearings, bifurcation analyses are carried out with both rigid and flexible model by applying numerical continuation methods. Thereby, the main focus of the investigation is on the critical bifurcations emanating destructive limit‐cycle oscillations of higher amplitudes. Finally, the influence of the shaft elasticity on the critical limit‐cycle oscillations is discussed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical modelling and analysis of high frequency dynamic contact in the hybrid transducer type ultrasonic motor
Authors: Weerayuth Nantawatana , Seemann Wolfgang 
Published: March 2010

AbstractThe finite element model for describing the intermittent contact dynamics between the stator and the rotor of a hybrid transducer type piezoelectric ultrasonic motor is presented. The contact simulations are performed using an augmented Lagrangian method to determine the normal contact force, the interface condition between the stator and the rotor as dependency of the other factors such as pre‐load force on the stator, the thickness of friction layer, the electrical driving voltage and the operational frequency of the stator. Effects of friction layer, both for elastic and viscoelastic frictional materials, are numerically investigated. The numerical results provide some aspects to make the impact that may occur between the contact interface pairs effectively softer. Furthermore, the noncontact phase between the stator and the rotor of this kind of piezoelectric ultrasonic motor will also be optimized. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An ultrasonic motor with intermittent contact modeled as a two degree of freedom oscillator in time domain
Authors: Wurpts Wiebold , Twiefel Jens 
Published: March 2010

AbstractThe driving mechanism of standing wave ultrasonic motors is basically caused by changing contact states: as the tip of the motor describes an ellipse a tangential force drives an object during contact. The tip moves back without contact and hence produces a resulting driving force. Although ultrasonic motors are known for several decades, the contact description is still topic of ongoing research. As an extension of previous models the trajectory of the tip is not impressed but part of a dynamic structure. An elementary model is proposed using a two degree of freedom oscillator with one mass and a moving ground representing the driven body. The contact forces are given in differential form for stick, slip and separation. The oscillator is simulated for different frequencies, normal contact forces and ground velocities in time domain. The results show a nonlinear frequency behavior and in some configurations stable sub harmonic solutions. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Free vibrations and stability of hydraulic cylinder fixed elastically on both ends
Authors: Uzny Sebastian 
Published: March 2010

AbstractThe boundary value problem of the stability and free vibration of a hydraulic cylinder has been formulated and solved in this paper. The considered hydraulic cylinder has been elastically fixed at both ends and loaded by Euler force. An elastical fixation has been modelled by rotational springs. The mentioned above hydraulic cylinder consists of a piston rod and cylinder replaced by rods. There are conditions of continuity between the rods. The boundary value problem has been formulated on the basis of minimum potential energy (static problem) and on the basis of Hamilton's principle (free vibration problem). In this paper example results of numerical calculations of the stability and free vibration have been presented. Experimental research has been performed in order to verify the correctness of the assumed mathematical model. Professional measuring apparatus and special stand for research into the slender systems have been used in experiment. Natural frequencies have been measured in dependence on the values of an external load. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the role of dislocation conservation in higher‐order crystal plasticity
Authors: Hirschberger C. B. , Peerlings R. H. J. , Brekelmans W. A. M. , Geers M. G. D. 
Published: March 2010

AbstractThe interactions between individual dislocations contribute significantly to size effects as observed at the plastic deformation of miniaturized structures. When employing a crystal plasticity framework, these interactions are usually captured by an additional balance relation. In this paper we study two approaches to capture dislocation interactions in crystal plasticity that differ by the conservation of dislocations. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Strength Analyses of Laminated Composite Structures Based on Different Theories
Authors: Wilde R. , Ostwald M. 
Published: March 2010

AbstractModern materials, such as composite ones, slowly replace conventional materials in structures of different kind and their growing popularity is caused by their multiple advantages. Through selection of parameters, such as number of layers, thickness of layers, direction of arranging fibers, or material from which internal and outside layers are made, it is possible to control properties of a structure. In the result, structures made of composite materials have high ratio of flexural stiffness to weight. The goal of this paper is to compare three theories of laminated composite plates and shells with the help of the multilayered rectangular plate model subjected to crosswise pressure perpendicular to the surface of a plate. Comparison was made for the classical laminated theory (CLT), first‐order laminated theory and third‐order laminated theory (TSDT). In all these theories, the number of parameters describing the displacement doesn't depend on the number of layers. For each of these theories strains and displacements were determined. Additionally, the computations time for every method were compared. Obtained results are presented in the form of tables. The analysis of the obtained solutions will be used as the base in choosing the best theory in multicriteria optimization process of composite thin‐walled structures. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constitutive Modeling of Rubber Behavior with an Application to Dynamics of Rolling Tires
Authors: Suwannachit Anuwat , Nackenhorst Udo 
Published: March 2010

AbstractMechanical response of technical rubbers is described by nonlinear elastic deformation, damage and hysteretic behavior under quasi‐static cyclic loading conditions, while dynamic stiffening and viscous effects are predominant for high frequency analysis. For the computation of the vibration of rolling tires, a material description incorporating all of these effects is needed. A constitutive model for filled rubbers under low frequency excitation is presented. A good agreement between the computational results and experimental data is also presented here. Furthermore, an idea to extend the constitutive model into a broad frequency domain is suggested through the uncoupled kinematic response in linear and nonlinear part. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)