bluuebunny/crossref_metadata_2025_split huggingface dataset:
A multivariate stochastic material model with correlated material parameters
Authors: Penner Eduard , Caylak Ismail , Mahnken Rolf 
Published: March 2018

AbstractThis paper concentrates on the aleatoric uncertainty of hyperelastic material models caused by material parameters which are characterized by random variables. To this end, the Polynomial Chaos Expansion (PCE) is applied to represent the random variables by a series of deterministic coefficients and random polynomials. To determine the corresponding PC coefficients and the polynomials of correlated stochastic material parameters we use the Cholesky decomposition and the Gram‐Schmidt algorithm. Based on experimental results and artificial data parameter identification of an Ogden material model for rubber is applied. As a numerical example we consider a static problem for uniaxial tension of the rectangular plate. This structure is investigated in order to represent the conditions for the experimental setup. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A primal discontinuous Petrov‐Galerkin Finite Element Method for linear elasticity
Authors: Steiner Tobias , Wriggers Peter 
Published: March 2018

AbstractVolume‐locking is a significant problem when using the standard Finite Element Method (FEM) since this phenomenon can lead to failure of a numerical method. To circumvent constraints as related in (nearly) incompressible materials the novel discontinuous Petrov‐Galerkin (dPG) FEM is introduced for linear elasticity. A first result of the implemented primal dPG FEM is shown for a patch test. Further tests on the performance of the proposed method are work in progress and are not part of this contribution. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of a locking‐free hybrid discontinuous Galerkin element that is very easy to implement into FE‐codes
Authors: Wulfinghoff Stephan , Bayat Hamid Reza , Alipour Atefeh , Reese Stefanie 
Published: March 2018

AbstractIn this work, a hybrid discontinuous Galerkin (dG) quadrilateral element formulation is investigated. In hybrid formulations, the elements' interior is treated independently from the skeleton (the element boundaries). The global degrees of freedom (dofs) are located on the element corners. This makes the implementation into existing finite element codes simple. The dofs in the element interior are condensed out. The deformation gradient is taken homogeneous within the element instead of using bilinear shape funcitons. The result is a very simple formulation and numerical implementation. The element has been shown to be free of volumetric locking and shear locking. Moreover, the mesh convergence is close to well‐known formulations like the Q1E4‐, Q1P0‐ or Q1SP‐element. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling of hydraulic fracturing and fluid flow change in saturated porous domains
Authors: Heider Yousef , Markert Bernd 
Published: March 2018

AbstractThe underlying research work aims to develop a numerical model of pressure‐driven fracturing of saturated porous media. This is based on the combination of the phase‐field modelling (PFM) scheme together with a continuum‐mechanical approach of multi‐phase materials. The proposed modelling framework accounts for the crack nucleation and propagation in the solid matrix of the porous material, as well as the fluid flow change in the cracked region. The macroscopic description of the saturated porous material is based on the theory of porous media (TPM), where the proposed scheme assumes a steady‐state behaviour (quasi‐static) and neglects all thermal and chemical effects. Additionally, it assumes an open system with possible fluid mass production from external source. Special focus is laid on the description of the interface and change of the volume fractions and the permeability parameter between the porous domain and the crack. Finally, a numerical example using the finite element method is presented and compared with experimental data to show the ability of the proposed modelling strategy in capturing the basic features of hydraulic fracturing. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Heated vertical duct flow of liquid metal with and without expansion
Authors: Niemann Martin , Saini Vishal , Fröhlich Jochen 
Published: March 2018

AbstractThe effects of buoyancy on vertical duct flows with one heated side wall are investigated by means of Direct Numerical Simulations. In particular, the flow through square ducts and behind the expansion of a backward‐facing step with side walls are presented for the forced and mixed convection regime. These configurations allow studying the interaction of buoyancy forces with secondary flow of second kind in the square duct and with the shear layer and recirculation zone in case of the expansion. In both configurations, buoyancy substantially alters the mean flow field, the turbulent stresses, and the heat transfer compared to the corresponding forced convection cases. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Rotorcraft Aeromechanics Simulation — When applied mathematics hits real engineering
Authors: Keßler Manuel 
Published: March 2018

AbstractAerodynamic simulation has reached a level of sufficient maturity, that not only benchmark problems are solved easily, but real application data can be delivered even for such complex configurations like rotorcraft. Leaving behind generic cases like driven cavity or isotropic turbulence and moving on to actual engineering, several fields more or less remotely related to aerodynamics have to be taken into account to provide accurate and reliable value. This is less a matter of ingenious invention, but much more so a careful selection of usable procedures for problems identified to matter, and mostly hard work, putting the pieces together and shaking all the wrinkles out. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Higher‐Order Index‐1 Co‐Simulation Approach: Solver Coupling for Multibody Systems
Authors: Meyer Tobias , Li Pu , Lu Daixing , Schweizer Bernhard 
Published: March 2018

AbstractThis paper attends to a co‐simulation approach for solver coupling in time domain. A general multibody system is divided into several subsystems, which are coupled by algebraic constraints. The coupling technique analyzed here is a linear‐implicit predictor/corrector approach, i.e. coupling variables for the corrector step are calculated by one step of a Newton‐iteration. Within the presented approach, the coupling conditions together with its first and second derivatives are enforced simultaneously at the communication‐time points. This index‐1 approach uses cubic polynomials to approximate the coupling variables. The space of polynomials of degree ≤ 3 is a four‐dimensional vector space. One of the four degrees of freedom is used for a continuous approximation of the coupling variables at the communication‐time points. The three remaining degrees of freedom are used in order to enforce the coupling conditions on position, velocity, and acceleration level. Due to the higher order approximation, the numerical errors are very small and a good convergence behavior is achieved. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The long History of Impact Mechanics, Rolling Contact and Multibody System Dynamics
Authors: Schiehlen Werner 
Published: March 2018

AbstractContact mechanics is a branch of solid mechanics where two or more bodies are involved. The contacting points are characterized by a common tangential plane and a common normal vector given by the surface curvature of the bodies. Additional parameters of contact problems are the material of the bodies, the forces and torques acting on the bodies as well as their time history, location of the centers of mass and the roughness of the surface around the contact point. The classical contact problem is based on spherical bodies surfaces, linear‐elastic material, constant static loading in normal direction and smooth surfaces. The rigorous solution [1] is often used for benchmarking. More details can be found in the monographs [2, 3]. The bodies of mechanical systems in engineering applications get in contact to each other mainly by impacts, rolling or sliding, or by joints. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical realisation of freezing processes in frost‐resistant plant tissues
Authors: Eurich Lukas , Wagner Arndt , Ehlers Wolfgang 
Published: March 2018

AbstractUnderstanding functional principles of frost‐resistant plant tissues under frost conditions is considered as an important milestone with regard to frost damage prevention in construction materials, as plant tissues are capable to withstand many freezing and thawing cycles without any damage. This contribution introduces a modelling approach for the biological role model based on the Theory of Porous Media (TPM) with an emphasis on structural properties and the phase transition of extracellular water. The presented numerical examples show the ice formation, represented by a frost front, where also structural effects of the plant's microstructure, such as inhomogeneity, can be considered in a numerical investigation. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical modeling of active response of arteries
Authors: Gilbert Rose Rogin , Hartmann Stefan , Kudela László , Rank Ernst , Yossef Ofry , Yosibash Zohar 
Published: March 2018

AbstractEven though many studies have been conducted to understand and model the passive response of arteries, very few studies have been performed to develop constitutive equation for the active response of arteries and to perform numerical simulations. In this paper, the diffusion of the neurotransmitter, for example noradrenaline, is combined with the anisotropic constitutive model to describe the temporal contraction of the smooth muscle cells in the artery wall. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Adaptive Algorithms for Optimal Hip Implant Positioning
Authors: Moldenhauer Marian , Weiser Martin , Zachow Stefan 
Published: March 2018

AbstractIn an aging society where the number of joint replacements rises, it is important to also increase the longevity of implants. In particular hip implants have a lifetime of at most 15 years. This derives primarily from pain due to implant migration, wear, inflammation, and dislocation, which is affected by the positioning of the implant during the surgery. Current joint replacement practice uses 2D software tools and relies on the experience of surgeons. Especially the 2D tools fail to take the patients' natural range of motion as well as stress distribution in the 3D joint induced by different daily motions into account. Optimizing the hip joint implant position for all possible parametrized motions under the constraint of a contact problem is prohibitively expensive as there are too many motions and every position change demands a recalculation of the contact problem. For the reduction of the computational effort, we use adaptive refinement on the parameter domain coupled with the interpolation method of Kriging. A coarse initial grid is to be locally refined using goal‐oriented error estimation, reducing locally high variances. This approach will be combined with multi‐grid optimization such that numerical errors are reduced. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Development of patient‐specific computational models of the human aortic valve under healthy and diseased conditions
Authors: Morales Ortuno Sergio , Röehrle Oliver 
Published: March 2018

AbstractA 3‐D finite element modelling (FEM) approach of the human aortic valve (AV) is developed to study its extra‐cellular matrix (ECM) destructive remodelling caused presumably by ventricular diseases, assuming that the function, deformation and performance of the valve is strongly dependent on its geometry. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of Vibrissa Morphology on Artificial Tactile Sensors for Surface Texture Detection
Authors: Scharff Moritz , Steigenberger Joachim , Behn Carsten , Alencastre Jorge 
Published: March 2018

AbstractAnimals, e.g. rats and cats, have different types of tactile hairs. One type are the mystacial vibrissae. They are located around the snout and in combination with the follicle‐sinus complex they are powerful tactile sensors. With them, animals are able to detect the distance to an object, recognize the object shape and determine the surface texture. Adapting the natural example, the goal is to design an artificial tactile sensor with a similar functionality. In the course of this, a model for surface texture detection is developed. The vibrissa is modeled as an Euler‐Bernoulli bending beam, incorporating large deflections. The contact, between vibrissa and surface, is modeled using Coulomb's law of friction. The mechanical modeling results in a nonlinear, system of first order differential equations. Solving the boundary‐value problem by applying a shooting method, a quasi‐static simulation is performed. Some first relations between the vibrissa morphology and the surface contact are analyzed. With view to an artificial sensor, the change of the reaction forces and moments at the base of the vibrissa due to the surface contact is the point of focus. Out of the reaction forces, the coefficient of static friction between vibrissa and surface is determined. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Vibration of the Basilar Membrane and Fluid Pressure Distribution in the Human Cochlea
Authors: Ziegler Pascal , Wahl Philipp , Eberhard Peter 
Published: March 2018

AbstractThe human inner ear or cochlea is a bone structure of spiral shape and is composed of mainly two conical chambers which are filled with fluid and separated by a soft membrane, referred to as the basilar membrane. At the apical end, both chambers are connected through a small opening, the helicotrema. At the base, the chambers are closed by the stapes footplate and the round window membrane. In case of a normal ear, sound is received by the eardrum, transmitted through the middle ear ossicles and finally excites the inner ear fluid through the vibration of the stapes footplate. According to present hearing theory, this leads to pressure waves in the cochlear fluid which in turn results in characteristic vibration behavior of the basilar membrane. Related to the sound frequency, hair cells in certain areas of the basilar membrane are stimulated and cause hearing nerve stimulation. In order to predict the effect of inner ear diseases on hearing impression as well as to develop new hearing implants, a deeper understanding of the cochlear dynamics is needed. However, since the cochlea represents a closed hydraulic system with a complex geometry, the motion of the basilar membrane as well as the fluid pressure can hardly be measured. Therefore, a numerical model of the uncoiled cochlea is developed representing the fundamental physical effects occurring in the cochlea. Taking the fluid‐structure interactions into account, the transfer behavior of the cochlear system is investigated for different excitation frequencies within the auditory frequency range of humans. The simulations show the passive vibration of the basilar membrane resulting in the characteristic traveling wave. These results allow to study the mapping of the excitation frequency to its characteristic pattern along the basilar membrane, called tonotopy. Further, the spatial fluid pressure distribution along the cochlear chambers is evaluated and allows new insights into the cochlear physics. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Determination of the diameter of columnar jointed volcanics using bifurcation analysis
Authors: Anderssohn Robert , Hofmann Martin 
Published: March 2018

AbstractThe development of the typical hexagonal pattern of solidifying volcanic material can be described by fracture mechanics. While following the moving inhomogeneous temperature field, these columns reach a steady growth with a certain diameter. This spacing increases sometimes instantaneously. Using a bifurcation analysis based on the free Helmholtz energy this phenomenon is investigated and presented with this contribution. In order to handle the complex three‐dimensional geometry, regularity in the pattern and a Fourier series expansion of the crack contour are used. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Experimental investigation and numerical simulation of fatigue crack formation in polycrystalline materials
Authors: Hohe Jörg , Beckmann Carla , Kennerknecht Tobias , Preußner Johannes , Farajian Majid , Luke Michael 
Published: March 2018

AbstractThe present contribution is concerned with an experimental investigation of fatigue crack initiation in polycrystalline metals using a micro scale specimen testing technique. Based on the results of the experimental investigation and a fractographic investigation, a probabilistic microscale simulation procedure for prediction of the fatigue crack formation phase is proposed. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crack path predictions in anisotropic structures considering residual stresses
Authors: Judt Paul , Ricoeur Andreas 
Published: March 2018

AbstractDifferent mechanical processes induce a directional microstructure (texture) during the production of a material, e.g. during the hot rolling of aluminum plates or the injection molding process of natural fiber reinforced bio‐polymers. In such materials the anisotropic mechanical features are related to the texture and have a decisive impact on the fracture process. Rolling or shot peening processes, on the other hand, induce an irreversible plastic deformation and residual compressive stresses for the purpose of a surface toughening. Similarly, residual stresses are induced if a circular core with interference fit is inserted into a drilled hole. The measurement of crack paths in specimens with residual stresses due to a core reveals an influence of the core's interference with respect to the crack deflection and the resulting paths [1,2]. Numerical investigations of fatigue crack growth show that conventional crack deflection criteria are not valid in such specimens, as the deflection angle depends on the magnitude of the external loading, going along with a rotation of the principal stress axes and thus the Jk‐vector [2]. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Calibration of a gradient‐enhanced damage model for viscoplastic shell structures subjected to shock‐wave loadings
Authors: Nguyen An Danh , Stoffel Marcus 
Published: March 2018

AbstractIn this study, we proposed both a numerical and experimental methodology for material parameter identification to validate the gradient‐damage model in [1]. A nonlocal anisotropic damage model for viscoplastic thin‐walled shells was proposed by introducing a gradient‐enhanced free energy function. For the experimental methodology, cyclic micro‐bending and ‐tensile tests were conducted to identify the damage size effects to calibrate the proposed FE model. Numerical results were obtained and compared with displacement‐force curves from shock‐tube tests. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new approach in material modeling towards shear cutting of CFRP
Authors: Poggenpohl Lukas , Wulfinghoff Stephan 
Published: March 2018

AbstractIn this project, the punching process of carbon fiber reinforced plastics (CFRP) is investigated numerically and experimentally. Punching presents a low cost and potentially high quality manufacturing technology for piercing, but has not been investigated sufficiently so far for CFRP. The project aims on the key mechanical processes from a damaging point of view. The goal of the project is to identify the principle influence parameters on the quality of the cutting face from a simulational and an experimental point of view. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Application and parameter identification of cohesive zone elements for intergranular fracture in thin layer
Authors: Rezaei Shahed , Wulfinghoff Stephan , Reese Stefanie 
Published: March 2018

AbstractCoating layers are usually applied on different manufacturing tools to improve their wear resistance and surface properties of the final parts. In this work, fracture and damage behavior of hard coatings such as (Cr,Al)N is studied. The coatings are produced by means of direct current magnetron sputtering (dcMS) and high power pulsed magnetron sputtering (HPPMS) method. The fracture properties of the coating are measured by investigating the force‐displacement curve obtained from a bending test [1]. The cohesive zone element parameters are then fitted to the experimental results to simulate the same behavior. The intergranular fracture within the coating system can then be modeled by employing the cohesive zone (CZ) regions at grain boundaries [2]. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bending of Viscoplastic Cables
Authors: Dörlich Vanessa , Linn Joachim , Diebels Stefan 
Published: March 2018

AbstractThis contribution deals with the experimental investigation of cables showing inelastic behavior under bending deformation. A new experimental device, which enables the direct measurement of the quantities entering the constitutive law for bending, i.e. the bending moment and bending curvature, is introduced. Results from advanced cyclic experiments executed on this new pure bending device show inelastic effects. It is remarkable, that this procedure allows for the distinction of intrinsic inelastic effects, e.g. due to friction between the constituents, from global inelastic effects such as damage of the specimen. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The finite cell method: Polygonal and tetrahedral cells
Authors: Duczek Sascha , Duvigneau Fabian , Würkner Mathias , Gabbert Ulrich 
Published: March 2018

AbstractPartial differential equations arising in many physical problems are most commonly solved by using the finite element method (FEM). Despite being very versatile, the FEM has one crucial drawback when heterogeneous material systems are considered, i.e. it relies on geometry‐conforming discretization. This meshing process often constitutes a bottleneck in the simulation pipeline and therefore needs to be alleviated. One idea is to exploit the benefits of the fictitious domain concept. Here, Cartesian grids can be deployed to straightforwardly discretize an extended domain. In conjunction with higher order shape functions the recently introduced method is referred to as the finite cell method (FCM).The main objective of the contribution at hand is to extend the FCM to arbitrary unstructured meshes. In two‐dimensional application polygonal finite elements based on generalized barycentric coordinates are deployed, while the three‐dimensional implementation is based on tetrahedral finite elements. A further extension to pyramidal and pentahedral (wedge) elements is, however, straightforward.There are two distinct advantages of using unstructured meshes: (i) a local mesh refinement can easily be conducted and (ii) existing computational models can be re‐used for parametric studies. The latter point is important if virtual defects need to be introduced in the ideal model to study their effect on the material behaviour. These possibilities make the unstructured FCM a powerful numerical tool for the investigation of complex highly heterogeneous materials. (© 2017 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)