bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Uncertainty in Friction Measurements
Authors: Ostermeyer G.‐P. , Mueller M. , Srisupattarawanit T. , Voelpel A. 
Published: March 2018

AbstractIn the fields of mechanical engineering, friction is ubiquitous. It is a fundamental cause of energy loss and wear. Another concern is the occurrence of comfort‐relevant friction induced vibrations. Prominent examples of this are NVH phenomena such as brake squeal, which is being investigated at great expense by the German automotive industry and academia, to determine its causes and potential influencing factors. For this purpose, numerous specialized measurements are performed, and models of varying complexity are used. All of these measurements and models have the common trait that the coefficient of friction (COF), defined as the ratio of the tangential force and normal force, has a decisive influence on the systems' stability. To parameterize the friction coefficient in macroscopic models, measurements must be performed. In this case, often an average value over time and over various loading procedures is used. As the measurements reveal, the coefficient of friction is in reality not constant, but is subject to a high degree of dynamics on various time scales, caused by complex processes in the boundary layer. A treatment of the coefficient of friction as a steady‐state parameter, or even as a constant, is thus a major reduction. The large variability of the coefficient of friction causes a corresponding variance in the stability limits of the models considered. This phenomenon is observed in the real world, where squealing seems to have a non‐deterministic behavior. This suggests uncertainties in the modeling of the friction coefficient. Due to the various types of uncertainty (variability, incompleteness and inaccuracy), the entire problem is a matter of polymorphic uncertainty. This paper focuses on the modeling of the friction coefficient, taking into account the various causes of uncertainty. Selections of raw data obtained at the authors institute throughout many years of research on friction phenomena in brake systems will be evaluated and classified with respect to its uncertainty properties. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational formulation with error estimates for uncertainty quantification via collocation, regression, and sprectral projection
Authors: Rang Joachim , Matthies Hermann G. 
Published: March 2018

AbstractMany real world problems need simplifications in such a way that computing is reduced for answering specific questions, for example, to quantify uncertainties. Therefore so‐called metamodels or surrogate models are developed which are based on interpolation or approximation methods. In this paper we transform the usual approximation or interpolation problem into a variational form such as it is known from the Finite Element method (FEM). With this variational framework it is possible to derive error estimators, which can be used later on for adaptivity. To compute the coefficients of the metamodel one needs some quadrature rules, which should be related to the given data. A numerical example shows the advantages of our proposed methods. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A mechanism‐based homogenization strategy for the determination of flow stress and strain hardening
Authors: Schulz Katrin , Sudmanns Markus 
Published: March 2018

AbstractThe high demand for physically‐based continuum models of plasticity has induced renewed efforts to formulate continuum theories of dislocation kinematics and dynamics. Considering a dislocation density based model incorporating a set of evolution equations for arbitrary curved dislocation lines, the kinetic formulation of a velocity law of dislocation motion including dislocation interaction between different slip systems is investigated. Two short‐range interaction terms accounting for forest interactions are comparatively discussed and differences are pointed out. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Turbulent and transitional sidewall jets in magnetohydrodynamic channels with a homogeneous magnetic field
Authors: Krasnov Dmitry , Boeck Thomas , Bühler Leo 
Published: March 2018

AbstractLiquid metal flows in the presence of a uniform magnetic field experience electromagnetic induction. The eddy currents and associated Lorentz force density modify the flow and give rise to thin electromagnetic boundary layers on the walls of the channel or duct. Hartmann layers develop on the walls perpendicular to the magnetic field whereas side layers develop on the parallel walls. The structure of the laminar flow depends on the conductivity of the walls. The side layers play a critical role in the transition to turbulence and are also strongly affected by the anisotropic character of the Lorentz force. We focus on duct flows with conducting Hartmann walls that give rise side‐layers jets and report numerical studies of the transitional and turbulent regimes. We also examine one‐point statistics and describe specific transitional patterns. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Moreau‐type integrators based on the time finite element discretization of the virtual action
Authors: Capobianco Giuseppe , Eugster Simon R. , Leine Remco I. 
Published: March 2018

AbstractIn this paper, we derive and compare three integrators for nonsmooth mechanical systems by discretizing the principle of virtual action with finite elements in time. The weak as well as the strong variational form of the principle are discretized using a piecewise linear shape function and different quadrature rules. After introducing a suitable constitutive law for the contact forces arising in the discretized system, this approach leads to the well established time‐stepping scheme of Moreau [1], the variational Moreau‐type scheme derived in [3] and another related scheme, which we call the symmetric Moreau‐type scheme. It is shown using a benchmark system that the symmetric and the variatonal Moreau‐type schemes, in contrast to Moreau's scheme, show an excellent longterm energy behavior. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamical Analysis of a Tip Balancing Cube
Authors: Gattringer Hubert , Reiter Alexander , Stöger Christoph , Jörgl Matthias , Müller Andreas 
Published: March 2018

AbstractThis paper discusses some dynamical aspects of a self‐balancing Inertia Wheel Cube (IWC). The acceleration and deceleration of actuated flywheels is used to stabilize the IWC when balancing on one of its corners, which is an unstable equilibrium position. The orientation as well as the rotational velocity of the device are measured by an inertial measurement unit (IMU). The equations of motions are derived with the Projection Equation. Using the rotational velocity of the IWC as part of the generalized velocities leads to well‐structured and interpretable dynamical equations. These equations are the basis for simulation, parameter identification, control synthesis, and stability analysis. The stability of the unstable equilibrium is investigated by means of the linearized motion equations. It can be shown that there are always uncontrollable states by invoking the conservation of momentum. Simulations as well as experimental results are presented. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel approach to Lie group structured configuration spaces of rigid bodies
Authors: Hante Stefan , Arnold Martin 
Published: March 2018

AbstractIn rigid body mechanics, a body's configuration consisting of orientation and position have to be described, as well as angular velocity and velocity. There are several different ways to do this, leading to different configuration spaces. Popular choices include SO(3) × ℝ3, SE(3) or unit dual quaternions. All these configuration spaces possess a Lie group structure. We present the novel approach 𝕊 ⋉ ℝ3, which is a configuration space similar to SE(3), but describes the orientation in terms of unit quaternions instead of rotation matrices. Furthermore we show its relation to and advantages over other configuration spaces. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A homogenisation method for the multiscale modelling of transversely isotropic skeletal muscle tissue
Authors: Bleiler Christian , Ponte Castañeda Pedro , Röhrle Oliver 
Published: March 2018

AbstractSkeletal muscle tissue shows a wide variation in its mechanical response for different persons or different muscle types of one single person. These distinct mechanical properties are due to variations in the microstructure of the material. For skeletal muscles, especially the arrangement and the stiffness of collagen fibres in the connective tissue define the macroscopic passive stiffness, while the sarcomeres (contractile units) enable an active contractility of the muscles. Phenomenological models lack the ability to take into account such microstructural variations in a natural way and need to be fitted to experimental data, which is, however, not available for every desired muscle type. Thus, this work presents a homogenisation‐based multiscale model for skeletal muscle tissue which enables to include microstructural properties in a continuum‐mechanical framework. The underlying homogenisation is done by means of the tangent‐second‐order (TSO) method, which is appropriately extended in order to account for the transversely isotropic behaviour of the muscle material. Moreover, an angular‐integration model is embedded for a comprehensive description of the connective tissue. Concluding, the presented model allows to directly include microstructural‐based material properties on the continuum‐mechanical macroscale and yet avoids the expensiveness of computational homogenisation methods, like FE2, by using well‐founded analytical homogenisation techniques. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Emergence of aortic aneurysms due to failure of adhesive bonds between proteoglycans
Authors: Hillgärtner Markus , Linka Kevin , Itskov Mikhail 
Published: March 2018

AbstractAortic aneurysms are a common disease among older patients. Aneurysm ruptures cause more than 150 000 deaths annually [2]. One of the main risk factors which lead to the abnormal enlargements of vessels (>150% of original size) is arterial hypertension.This contribution presents a modeling approach, where the cyclic loading of the artery caused by the blood pressure leads to fatigue inside the arterial wall. The arterial wall is considered as a composite material, where a matrix (ground substance) is reinforced by collagen fibers consisting of fibrils connected by proteoglycan (PG) bridges. These PG bridges support interfibrillar sliding leading to lower fibril stretch [6]. Molecular adhesive bonds rupture under any pulling force if the force is held sufficiently long enough [1]. This rupturing over time leads to a decrease in the density of PG bridges, higher stretches in the fibrils, more damage inside the fibrils and finally to fatigue of the soft tissue which causes the abnormal enlargement.Finally the model is compared against experimental data of uniaxial tension tests and used in a FEM simulation to study the emergence of aortic aneurysms under arterial hypertension. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Three‐dimensional finite element modeling of dental restorative procedures using various digitization methods
Authors: Joedecke Paul , Guentsch Arndt , Naumenko Konstantin , Weber Christian‐Toralf 
Published: March 2018

AbstractThe objective of the presented paper is to compare the usage of different digitization methods to generate finite element models of dental structures and restorations. Four different virtual models were generated by using intraoral‐, CBCT‐, CT‐ and micro‐CT datasets. Subsequently there were compared due to their field of view (FOV), accuracy and radiation exposure for the patients. Depending on the specific application all four virtual models showed a qualitative and quantitative correlation associated with in‐vitro and in‐vivo studies. Further the influence of artifacts and application limits were classified with weight functions for the use in a database. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling the contraction properties of smooth muscle cells in bladder tissue
Authors: Seydewitz Robert , Morales‐Orcajo Enrique , Böl Markus 
Published: March 2018

AbstractThe major function of the urinary bladder is the storage and release of urine. Undergoing large deformations while keeping the chemically aggressive urine and maintaining a relatively constant pressure during filling, the bladder shows remarkable mechanical properties. Those properties are based on the highly complex structure of the bladder wall. However, irregularities within the bladder wall may have negative implications on the correct functioning. In order to improve the understanding of different physiological processes taking place within the bladder wall during bladder filling and contraction, a computation tool is presented based on a continuum mechanics approach. In that sense the model is applied to complex boundary value problems. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Large time increment approach for fatigue damage computations
Authors: Alameddin Shadi , Bhattacharyya Mainak , Fau Amelie , Nackenhorst Udo , Néron David , Ladevèze Pierre 
Published: March 2018

AbstractThis contribution focuses on the use of a new method to reduce the computational demands of fatigue damage computations using continuum damage mechanics. The LArge Time INcrement (LATIN) method incorporates a model order reduction approach namely the proper generalised decomposition (PGD). LATIN has been extended to tackle damage problems. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Variational framework for phase field modeling of ductile fracture in porous solids at finite strains
Authors: Teichtmeister Stephan , Kienle Daniel , Aldakheel Fadi , Miehe Christian 
Published: March 2018

AbstractThis work outlines a rigorous variational‐based framework for the phase field modeling of fracture in isotropic and anisotropic porous solids undergoing small elastic but large plastic deformations. It extends the recent work [1] to a formulation of porous plasticity with particulate microstructures characterized by spherical pores or by ellipsoidal voids, which additionally undergo a change in size and orientation. A gradient plasticity model for isotropic and anisotropic porous plasticity is developed, and linked to a failure criterion in terms of the local elastic‐plastic work density that drives the fracture phase field [2]. It is shown that this approach is able to model phenomena of ductile failure such as cup‐cone failure surfaces. The proposed model is governed by a rate‐type minimization principle, which describes the coupled multifield evolution problem of plasticity‐damage. Another aspect is the regularization towards a micromorphic gradient plasticity‐damage setting which enhances the robustness of the finite element formulation. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Time‐harmonic analysis of cracks in functionally graded piezoelectric materials
Authors: Wünsche Michael , Sladek Jan , Sladek Vladimir , Zhang Chuanzeng 
Published: March 2018

AbstractModern piezoelectric structures offer certain performance advantages over conventional ones due to their capability of converting electrical energy into mechanical energy and vice versa. In recent years composites with a continuously change of the material properties are getting increasing attention in advanced engineering applications. An important advantage over conventional laminates is that interfaces and stress discontinuities are avoided. Piezoelectric composites are very brittle and have a low fracture toughness. The analysis of functionally graded materials (FGMs) is mathematically complex and analytical solutions are possible only for very simple geometry and loading conditions. Therefore, efficient numerical methods are needed to solve more general problems. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nonlinear analysis of solids in boundary representation – a NURBS based Galerkin method
Authors: Chasapi Margarita , Klinkel Sven , Simeon Bernd 
Published: March 2018

AbstractThe contribution presents a new numerical method to solve nonlinear problems of solids in boundary representation. A formulation for material nonlinearities is derived. The proposed method introduces an approach where the geometrical description of the boundary is sufficient to define the complete solid. While the interior of the domain is described by a radial scaling parameter, the scaling of the boundary with respect to the specified scaling center leads to the complete solid. This idea fits perfectly to the boundary representation modeling technique commonly employed in CAD. The approach exploits the tensor‐product structure of the solid to parameterize the physical domain, i.e., two‐dimensional surfaces are represented by NURBS objects, which parameterize the boundary surfaces. Following the isogeometric paradigm, the NURBS functions that describe the boundary of the geometry form also the basis for the approximation of the displacement at the boundary. The displacement response in the circumferential and radial scaling direction is approximated by one‐dimensional NURBS. The present formulation accounts for material nonlinearity with elasto‐plastic behavior, where small strain theory is assumed. Similar to the Scaled Boundary Finite Element Method (SB‐FEM), the structure is parameterized by a radial scaling parameter that emanates from a scaling center and a parameter in circumferential direction along the boundary. The Galerkin projection of the weak form yields a system of equilibrium equations whose solution gives rise to the displacement response. Due to the nonlinear relation between the stress and the strain, the linear equilibrium equation is not applicable anymore. Applying the weak form in the circumferential and radial direction leads to a nonlinear equation with respect to the unknown displacement response, which is solved with a linearization and the Newton‐Raphson scheme. The applicability of the proposed formulation is shown by means of numerical examples. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Dual Craig‐Bampton State‐Space Approach for Model Reduction of Damped Systems
Authors: Gruber Fabian M. , Rixen Daniel J. 
Published: March 2018

AbstractThe dual Craig‐Bampton method for the reduction of undamped systems is modified for the case of general viscous damping. The final reduction is based on the use of complex free interface normal modes, (residual) flexibility modes and state‐space rigid body modes. For the coupling of the substructures in state‐space representation, a dual coupling procedure based on the interface forces between adjacent substructures is used that is novel compared to other methods that commonly apply primal coupling procedures. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of air spring textile reinforcement by means of resolving the cord structure in FE analyses
Authors: Heinrich Nina , Donner Hendrik , Ihlemann Jörn 
Published: March 2018

AbstractTextile reinforcement is, among many other applications, widely used in rubber bellows of air springs. The objective of this study is to compare the effect of two different cord set‐ups on local rubber matrix strains and stresses by means of FE analyses. For that purpose, a methodology for taking both the geometry of the cord and the filament structure of its yarns into account is employed. With this, a global FE model comprising a cyclic symmetric section of the bellows, and a submodel are analyzed. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prevention of solidification cracking during pulsed laser beam welding
Authors: Bergmann Jean Pierre , Bielenin Martin , Herzog Roland A. , Hildebrand Jörg , Riedel Ilka , Schricker Klaus , Trunk Carsten , Worthmann Karl 
Published: March 2018

AbstractWe present a mathematical model to describe laser beam welding based on the heat equation. Since the material coefficients depend on the temperature, this leads to a quasi‐linear parabolic partial differential equation. It is our goal to prevent solidification cracking. We address this problem by means of optimal control. It is the intensity profile of the laser beam which acts as the control function. The main challenge is the formulation of a suitable objective function. In particular, high velocities of the solidification interface need to be properly penalized in order to deal with and avoid cracking phenomena. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wave dispersion and propagation in a linear peridynamic solid
Authors: Butt Sahir N. , Meschke Günther 
Published: March 2018

AbstractPeridynamics is a nonlocal continuum model which offers benefits over classical continuum models when there are discontinuities, such as cracks, present in the deformation field. However, the nonlocal characteristics of peridynamics leads to a dispersive dynamic response of the medium. In this study, we focus on the dispersion properties of a one‐dimensional state‐based linearized peridynamics model and investigate the effect of different peridynamic parameters on the dispersion relation. Furthermore, a physical interpretation of the peridynamic horizon is discussed and its relation to the experimental dispersion data is presented. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Laser shock peening process modelling and experimental validation of AA2198‐T3 and AA2198‐T8
Authors: Keller Sören , Kashaev Nikolai , Klusemann Benjamin 
Published: March 2018

AbstractLaser shock peening (LSP) is a surface treatment which improves the fatigue life of metallic structures by laser‐induced compressive residual stresses. The purpose of this work is the prediction of the measured residual stresses after LSP in sheets consisting of AA2198. Therefore, a finite element model is set‐up. The Johnson‐Cook material model is used to model the strain rate depend material behaviour during plastic deformations. Stress averaging enables the comparison between measured and predicted residual stresses. Residual stress measurements are performed using the incremental hole drilling method. The initially unknown pressure pulse is identified for AA2198‐T3 and validated with AA2198‐T8. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Basic Ideas for the Quantification of Uncertainty Associated with the Material's Microstructure Morphology using Statistically Similar RVEs
Authors: Miska Niklas , Prüger Stefan , Balzani Daniel 
Published: March 2018

AbstractA method to quantify macroscopic uncertainty caused by variation of the microstructure morphology is proposed by expanding the idea of SSRVEs to variations of microstructures within certain bounds of statistical descriptors. Subsequent homogenization of the RVEs leads to statistical information regarding the variation of macroscopic material properties for further uncertainty analysis. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the Modeling of Textile Membranes with Nonlinear Anisotropic Material Behavior
Authors: Motevalli Mehran , Balzani Daniel , Uhlemann Jörg , Stranghöner Natalie 
Published: March 2018

AbstractCoated fabric membranes have been widely used in construction of light‐weight structures. The material behavior of textile membranes is highly nonlinear and anisotropic which may not be sufficiently represented by commonly used linear elastic orthotropic models. This contribution presents a formulation of a suitable nonlinear anisotropic polyconvex energy function for textile membranes in the geometrically nonlinear framework. Representation of total in‐plane material behavior is the main goal of this paper, however, the induced thickness change is also considered in the continuum model. The material parameters of the energy function are adjusted by introducing and minimizing an objective function enforcing the model response to be as similar as possible to the experimental data. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)