bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electromechanical modelling of skeletal muscle contractions
Authors: Sturmat Maike , Böl Markus 
Published: December 2011

AbstractIn the present paper, the aim was to develop a numerical method for optimisation an existing mechanical material model [1] including muscle activation concerning the excitation of skeletal muscles. The modelling idea was a weak and non‐monolithic coupling of an electric current expressed by Ohm's law with a hyperelastic muscle model with transversal isotropic characteristics, see [2]. We confirmed the ability of the proposed model by applying on real reconstructed complex muscle geometry. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of a biomechanical model to study the horizontal vibration transmitted from shoulder to head
Authors: Truţa Aurica , Pop Aurora‐Felicia , Bălcău Monica , Arghir Mariana 
Published: December 2011

AbstractOn daily activity a human operator is exposed to vibration in working environment. So, the human body will react in different way. The problem is how much from the initial signal will be sent to the other parts of the body and how much that motion will be damped along the studied parts. The vibrations in horizontal plane are some unexpected, so the human operator will not take any position to prevent them. In this condition the horizontal vibrations will have the higher effect possible. In this paper, the shoulder, neck and the head are modeled together like a mechanical system with four degree of freedom. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new description of cracks in the XFEM
Authors: Fries Thomas‐Peter 
Published: December 2011

AbstractThis work outlines an approach that combines the advantages of explicit and implicit descriptions of the crack geometry in the context of the extended finite element method (XFEM). The XFEM is typically combined with an implicit description of the crack which is realized by the level‐set method. This facilitates the definition of the enrichments in the XFEM. However, the update of the crack geometry during the propagation of a crack is simpler by means of explicit crack descriptions where the crack surface is meshed. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crack tip fields in rubber‐toughened polymers
Authors: Helbig Martin , Seelig Thomas 
Published: December 2011

AbstractNumerical simulations of the formation and the characteristic shape of plastic zones at crack tips in rubber‐toughened polymers are performed in order to get a better understanding of the underlying micromechanisms. Complementing previous work, the present study focuses on the contribution of distributed crazing. A macroscopic constitutive model therefore has been developed that describes the overall effect of distributed crazing as an anisotropic flow process. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Phase Field Model for Three‐Dimensional Dynamic Fracture and its Efficient Numerical Implementation
Authors: Hofacker Martina , Miehe Christian 
Published: December 2011

AbstractThe numerical modeling of dynamic failure mechanisms in solids due to fracture based on sharp crack discontinuities suffers in situations with complex crack topologies and demands the formulation of additional branching criteria. This drawback can be overcome by a diffusive crack modeling, which is based on the introduction of a crack phase field. We focus on the extension of a recently developed phase field model for fracture from the quasi‐static setting towards the dynamic setting. It is obtained by taking into account inertial terms and associated dynamic integrators. The introduction of a history field, containing a maximum fracture‐driving energy, provides a very transparent representation of the balance equation that governs the diffusive crack topology. In particular, it allows for the construction of an extremely robust operator split technique. In a subsequent step, the proposed model is extended to three dimensional problems. The dynamic treatment opens the door to the analysis of complex fracture phenomena like multiple crack branching and crack arrest. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cohesive zone model for a transverse breathing crack in a rotor
Authors: Liong Rugerri Toni , Proppe Carsten 
Published: December 2011

AbstractThe breathing mechanism of a transversely cracked rotor and its influence on a rotor system that appears due to the shaft weight is studied. This breathing mechanism is based on experimental and simulation result for the crack shape reported in the literature. If the crack depth is small, the crack closure line is a straight line while for larger crack depths the crack closure becomes more curved. For both cases, a method is proposed for the evaluation of the stiffness losses in the cross section that contains the crack. This method is based on a cohesive zone model (CZM) instead of linear elastic fracture mechanics (LEFM) approach, because LEFM is valid only for the fully open crack and cannot be extended to other intermediate situations. As the crack is closed, the stress intensity factor (SIF) will not appear at the boundary between the closed cracked areas and the open cracked areas. The CZM is developed for mode‐I plane strain conditions and accounts explicitly for triaxiality of the stress state by using constitutive relations. The proposed model gives more realistic results than models based on LEFM for the stiffness losses of the crack rotor system for a wide range of the crack depth. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A strong discontinuity based adaptive refinement approach for the modeling of crack branching
Authors: Raina Arun , Linder Christian 
Published: December 2011

AbstractIn the current work, the physical phenomena of dynamic fracture of brittle materials involving crack growth, acceleration and consequent branching is simulated. The numerical modeling is based on the approach where the failure in the form of cracks or shear bands is modeled by a jump in the displacement field, the so called ‘strong discontinuity’. The finite element method is employed with this strong discontinuity approach where each finite element is capable of developing a strong discontinuity locally embedded into it. The focus in this work is on branching phenomena which is modeled by an adaptive refinement method by solving a new sub‐boundary value problem represented by a finite element at the growing crack tip. The sub‐boundary value problem is subjected to a certain kinematic constraint on the boundary in the form of a linear deformation constraint. An accurate resolution of the state of material at the branching crack tip is achieved which results in realistic dynamic fracture simulations. A comparison of resulting numerical simulations is provided with the experiment of dynamic fracture from the literature. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of interface cracks in layered piezoelectric composites by a SGBEM
Authors: Wünsche Michael , Zhang Chuanzeng , Sladek Jan , Sladek Vladimir 
Published: December 2011

AbstractPiezoelectric materials offer many possibilities in advanced engineering structures due to their inherent coupling effects between mechanical and electrical fields and are widely applied in smart devices and structures like transducers, actuators and sensors [2]. An important application of piezoelectric materials is related to layered or laminated composites because they can be optimized to satisfy the high‐performance requirements according to different in‐service conditions. Beside cracks inside homogeneous domains, one of the most dominant failure mechanisms in layered or laminated composites is the interface failure. Interface cracks and interface debonding may be induced by the mismatch of the mechanical, electrical and thermal properties of the material constituents during the manufacturing process and the in‐service loading conditions. This paper presents a hypersingular symmetric Galerkin boundary element method (SGBEM) for crack analysis in two‐dimensional (2D), layered and linear piezoelectric solids. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reduction of vibrations using mechanical and electrical elements
Authors: Białas Katarzyna 
Published: December 2011

AbstractThe main aim of this work is the introduction of analysis and synthesis of mechatronical systems including mechanical and electrical elements reducing vibrations. In results of synthesis were received structures and parameters of a discrete model meeting the defined requirements concerning the dynamic features of the system, in particular, the frequency spectrum. The approach adopted makes it possible to take actions aiming at the reduction of phenomena resulting in the unwanted operation of machinery or generation of hazardous situations in the machinery environment. Thank to the approach, the above mentioned preventive activities can be conducted as early as during the designing of future functions of the system as well as during the construction of the system in question. In this work is also comparison of these two kind of elements, mechanical and electrical, of reduction of vibrations. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Monitoring fatigue cracks and SIFs in plate structures solving inverse boundary value problems
Authors: Boukellif Ramdane , Ricoeur Andreas 
Published: December 2011

AbstractIn this work we present methods for the detection of cracks in plate and shell structures. In contrast to most of the common monitoring methods taking advantage of the reflection of surface waves at crack faces, the presented approach is based on the strain measured at different locations on the surface of the structure. This allows both the identification of crack position parameters, such as length, location and angles with respect to a reference coordinate system and the calculation of stress intensity factors (SIF). The solution of the direct problem is performed on the basis of the BFM (body force method) and the method of assembled point dislocations. The inverse problem is solved applying the PSO (particle swarm optimization) algorithm. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Extension of the scaled boundary finite element method to plate bending problems
Authors: Dieringer Rolf , Hebel Jochen , Becker Wilfried 
Published: December 2011

AbstractThe scaled boundary finite element method (SBFEM) is extended to the static analysis of thin plates in the framework of Kirchhoff's plate theory. The governing equations are transformed into scaled boundary coordinates. Applying a discrete form of the Kantorovich reduction method results in a set of ordinary differential equations, which can be solved in a closed‐form analytical manner. The element stiffness matrices for bounded and unbounded media can be computed, using appropriate subsets of the analytical solution. Examples show the efficiency of the method, applied to plate bending problems. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Boundary Conditions and Multi‐Patch Connections in Isogeometric Analysis
Authors: Dornisch Wolfgang , Klinkel Sven 
Published: December 2011

AbstractIsogeometric analysis is a high‐continuity alternative to the standard finite element method. However, for practical application several issues remain to be addressed. This contribution discusses the imposition of Dirichlet boundary conditions as well as the connection between multiple patches. In particular necessary manipulations of the geometrical input data are provided. Dirichlet boundary conditions can be imposed in weak or in strong form. Due to the non‐interpolatory characteristics of NURBS surfaces weak imposition of Dirichlet conditions is a viable option which avoids local transformations. The connection of multiple patches can be realized in a weak manner by adding additional terms to the variational equations, for example by the Lagrange multiplier method or the perturbed Lagrangian method. Both base on the idea of multiplying the mutual deformations with an additional unknown to force the deformations on shared edges to be equal. The numerical treatment leads to different sets of equations. In contrast to strong inter‐patch connections, where coinciding control points share the same degrees of freedom, weak imposition allows for hanging nodes and therefore local refinement. The theoretical background and issues of implementation are given. Some numerical examples compare error norms for all mentioned methods and demonstrate that in particular cases a reduction of continuity leads to more accurate results. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New solid‐shell and solid‐beam finite elements with applications to medical technology
Authors: Frischkorn Jan , Reese Stefanie 
Published: December 2011

AbstractIn this paper, new solid‐shell and solid‐beam finite element formulations for finite deformation problems are introduced. One application of interest, concerning these types of elements, can be found in the simulation of stent implementation in the treatment of stenosis. The beam‐like structure of the stent and the shell‐like structure of the blood vessel can be modelled easily by using these types of elements. Moreover, the modelling of the interaction of the different structural types between each other and with the surounding tissue becomes more simple. A high rate of convergence, by using only one element in thickness direction that is comparable to classical structural elements, can be named as a major requirement for the element formulations. In this regard, different locking effects are cured by a special combination of the assumed natural strain method (ANS) and the enhanced assumed strain method (EAS). In addition a variable number of quadrature points can be used in thickness direction in order to capture nonlinearites. This is combined with the concept of reduced integration for the sake of computational efficiency. An adaptive hourglass stabilization that also accounts for material nonlinearities is a crucial issue in this regard. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Reverse task as a designing of mechatronic vibrating branched systems
Authors: Buchacz Andrzej , Galeziowski Damian 
Published: December 2011

AbstractIn this paper a new approach for designing mechatronic vibrating branched structures has been presented. Mechatronic structures have been built from mechanical discrete systems connected to piezoelectric actuator and externalLxRxCx network, with different configurations. Modeling simplification has been performed by use of non dimensional transformations and retransformations. In each case reverse task has been solved by distribution into partial fraction method in respect to required dynamic properties in form of frequency spectrum: resonant and anti resonant frequencies. Furthermore, different configurations of final LxRxCx network have been presented. These considerations have been supported by calculation examples, and all results have been presented in the graphical form. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerische und Experimentelle Modalanalyse eines Statorblechpaketes
Authors: Mair Mathias , Rainer Siegfried , Weilharter Bernhard , Ellermann Katrin , Bíró Oszkár 
Published: December 2011

AbstractDas Übertragungsverhalten sowie die Eigenfrequenzen und Eigenformen zweier Statorblechpakete wurden experimentell und numerisch, mittels einer Modalanalyse eines homogenen Finite‐Elemente Modells, ermittelt. Durch geeignete Abstimmung der Materialparameter des Simulationsmodells wurde die Strukturantwort an die der Messung angepasst. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Mathematical modelling of heat conduction in certain functionally graded composites
Authors: Nagórko Wiesław , Woźniak Czesław 
Published: December 2011

AbstractThe aim of contribution is to formulate a certain extended version of the tolerance modelling technique for functionally graded composites. For the sake of simplicity, the considerations are restricted to the bidirectionally graded heat conductors. It is shown that the proposed approach enables to determine an entire class of mathematical models for which applications can be found in various specific problems. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On dynamic finite element analysis of viscoplastic thin‐walled structures with non‐local damage
Authors: Nguyen A.D. , Stoffel M. , Weichert D. 
Published: December 2011

AbstractIn this article we propose a non‐local damage model for dynamic finite element computation of viscoplastic thin‐shell structures. To take void nucleation and growth into account, the free energy function is enhanced phenomenologically in terms of a non‐local damage variable and its gradient on the mid‐surface of shell structures. The dynamic thin‐shell elastic theory including large rotations proposed by Simo and Tarnow (1994) is used to capture finite deformation. Local constitutive laws considering viscoplastic behaviour, isotropic hardening and isotropic ductile damage leading to softening in Velde et al. (2009) are employed. The performance of the proposed approach is demonstrated through the preliminary numerical simulations of shock‐wave loaded structures, which are validated by comparision with the experimental results. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The orders of singular stresses at plane bi‐ and trimaterial junctions ‐ Closed‐form analytical solutions
Authors: Sator Christian , Becker Wilfried 
Published: December 2011

AbstractThe plane problem of a bi‐ or trimaterial‐junction, consisting of dissimilar, homogeneous, isotropic and linear elastic sectors is considered. The asymptotic behaviour of the stresses of this composite situation is analyzed by the complex variable method, based on an appropriate choice of the Kolosov‐potentials which are applicable in the vicinity of the vertex. In the analyses, the identification of the singularity exponent is emphasized. With the help of a novel approach it is demonstrated how to derive some solutions for the orders of the stress singularities at bi‐ and trimaterial combinations in a closed‐form analytical manner. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the magnitude of surface stresses of buckled plates
Authors: Schagerl Martin 
Published: December 2011

AbstractConsidering a simply supported plate under uni‐axial compression it is well‐known that after buckling the stress concentrates at the unloaded boundaries as the out‐of‐plane displacement at the buckle causes an in‐plane relaxation, i.e. a decrease of the mid‐plane stress. This stress distortion is described by the so‐called effective width. The knowledge of the effective width allows the calculation of the stress at the unloaded boundaries, which is usually considered as the highest stress in the plate. However, the out‐of‐plane displacement also bends the plate, which produces additional stresses. This article analysis the fundamental question, if the total stress at the surface of the buckle is higher than the stress at the unloaded boundaries. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A consistent second‐order plate theory for monotropic material
Authors: Schneider Patrick , Kienzler Reinhold 
Published: December 2011

AbstractMathematical homogenization (or averaging) of composite materials, such as fibre laminates, often leads to non‐isotropic homogenized (averaged) materials. Especially the upcoming importance of these materials increases the need for accurate mechanical models of non‐isotropic shell‐like structures. We present a second‐order (or: Reissner‐type) theory for the elastic deformation of a plate with constant thickness for a homogeneous monotropic material. It is equivalent to Kirchhoff's plate theory as a first‐order theory for the special case of isotropy and, furthermore, shear‐deformable and equivalent to R. Kienzler's theory as a second‐order theory for isotropy, which implies further equivalences to established shear‐deformable theories, especially the Reissner‐Mindlin theory and Zhilin's plate theory. Details of the derivation of the theory will be published in a forthcoming paper [3]. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of structural hypotheses on the elastic‐viscoplastic response of shock wave‐loaded plates
Authors: Stoffel Marcus , Vu Thang Duy , Nguyen An Danh , Schmidt Rüdiger , Weichert Dieter 
Published: December 2011

AbstractIf circular metal plates are subjected repeatedly to impulsive loadings, damage and failure of the structures can occur. In order to predict the damage evolution in finite element simulations, a structural theory combined with viscoplastic constitutive equations acounting for damage is used. However, different structural hypotheses, used in the theoretical model, can lead to variations in the numerical result. Therefore, first‐ and third‐order shear deformations theories are applied in a finite element code. Moreover, local and non‐local damage approaches are used. The aim is to determine the numerical model, which leads to the most accurate results compared to experiments. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear transient FE analysis of piezolaminated smart structures
Authors: Vu Thang Duy , Schmidt Ruediger 
Published: December 2011

AbstractThe presented paper focuses on the modeling and finite element simulation of thin composite structures with integrated piezoelectric layers. Geometrically nonlinear piezolaminated finite elements are based on the Reissner‐Mindlin or third‐order transverse shear deformation hypotheses and the assumptions of small strains but moderate rotations. The numerical results are compared to results in literature. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The piezoelectric phenomena analysis of the material internal damping
Authors: Wrobel Andrzej 
Published: December 2011

AbstractIn the manufacturing of technical systems piezoelectric materials are used. These materials have one or more variables. Under the influence of applied voltage they change shape or generate on the linings the potencial under the influence of deformation. In the foregoing analysis, for both simple and complex systems, the ideal model was used, not taking into account the damping value. Assuming, that the bodies deformation under the influence of vibration is a partially irreversible process, which is due to damping of the internal part of the dissipated energy, the piezoelectric system was analyzed. The level of damping value is mainly affected by the structure of the material. This article presents an analysis of piezoelectric phenomena, taking into account internal damping. A description of the rheological properties of materials using a Kelvin ‐ Voigt model was used. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the parametric excitation of rotors with rolling element bearings
Authors: Fritz Felix , Seemann Wolfgang , Krousgrill Charles M. 
Published: December 2011

AbstractIn this approach a 1‐DOF‐model for a rotor in rolling element bearings is derived. The nonlinear equation of motion with a cubic restitution force and harmonic time dependent variation is solved by Multiple Time Scales Approach. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)