bluuebunny/crossref_metadata_2025_split huggingface dataset:
A revised taxonomy for the competence oriented description of learning outcomes for study programs in engineering sciences
Authors: Mittermeier Franziska , Ullmann Rupert , Müller Gerhard 
Published: December 2018

AbstractThe modularisation of study programs due to the Bologna Process leads to a growing number of selection choices and an increasing flexibility in the individual curriculum design. Therefore an appropriate description of the learning outcomes of the individual modules is crucial for ensuring consistent personal curricula and the continuous acquisition of competences. At the Technische Universität München, learning outcomes are currently described in continuous texts using Bloom's taxonomy. Although this taxonomy is commonly accepted, in practical applications there are problems regarding a clear description of the acquired competences in engineering sciences. Thus, we extended Anderson's and Krathwohl's revision of Bloom's taxonomy for the explicit application to engineering studies. In the reformulation we expressed the stage of qualification via a breakdown into quantified levels of knowledge (know what), skills (know how), and competences (know why). Furthermore, we introduced a tabular description instead of a continuous text. This allows for a systematic storage and analysis in a database. Therefore besides an appropriate and clear description of learning outcomes, the new system delivers access to various possibilities: First, the new taxonomy facilitates the detection of conflicts between learning outcomes of different modules using a web‐based tool for the analysis of module interfaces. Furthermore, the level system eases competence orientated examination via adapting questions to the respective qualification level addressed in the module description. Finally, the new system simplifies the recognition of credits, which becomes more important due to the increasing mobility of students.
Nitsche's method for form‐finding of multipatch isogeometric membrane analysis
Authors: Apostolatos Andreas , Bletzinger Kai‐Uwe , Wüchner Roland 
Published: December 2018

AbstractMembranes constitute an important category of thin‐walled and in particular tensile structures [1], for which in contrast to shells their structural rigidity is obtained by means of prestress rather than relying on bending stiffness. In particular, the structures considered in this study act in pure membrane state and have no bending stiffness. A big challenge of such structures is finding the shape of static equilibrium. This is not a trivial task since not every shape under any prestress distribution or loading condition renders a static equilibrium configuration. This is even more prominent when prestressed cables are attached to the structure. To overcome this problem for general tensile structures, various types of form‐finding methods were developed [2, 3]. In this study, the Updated Reference Strategy (URS) [4, 5] is presented in combination with multipatch isogeometric analysis [6] as discretization method. The enforcement of the continuity constraints along the common patch interfaces [7] is realized using a Nitsche‐type method [8] while the results are evaluated and compared with the Penalty‐based approach [9].
The Particle Finite Element Method for the modelling and simulation of solid body interactions
Authors: Schewe Markus , Menzel Andreas 
Published: December 2018

AbstractBoth simulation and, in particular, the underlying algorithmic treatment of effects such as fracture or abrasive wear are generally very complex in nature and thus computationally expensive. The Particle Finite Element Method (PFEM) according to [1] constitutes a promising compromise between physical accuracy and computational efficiency. The PFEM allows the separation of material within a repeated remeshing and shape detection step. Such applications of the PFEM may be incorporated in simulations of fracture and cutting. The methods used in PFEM can be adapted to the task of identifying contact areas and meshing the contact zone between solid bodies. Therefore, PFEM offers a good framework to combine both, the contact between solid bodies and the separation of material, in order to develop a simulation framework for abrasive wear.
Modeling of Electromechanically Induced Phase Transitions in Lead Zirconate Titanate (PZT) Based on the Condensed Method
Authors: Uckermann Philip , Lange Stephan , Ricoeur Andreas 
Published: December 2018

AbstractThis research is about determining the effects of phase transitions in lead zirconate titanate. Transformations between tetragonal and rhombohedral phases have been implemented using an adapted evolution law. Predictions concering polycrystalline material behavior are made by the condensed method. Stresses and strains under electric loads are considered to investigate upcoming effects near the morphotropic phase boundary. An interpretation concerning actuator applications will be provided.
New thoughts on the anti plane shear problem
Authors: Voss Jendrik , Neff Patrizio , Baaser Herbert 
Published: December 2018

AbstractWe reconsider anti‐plane shear deformations of the form ϕ(x) = (x1, x2, x3 + u(x1, x2)) based on prior work of Knowles and relate the existence of anti‐plane shear deformations to fundamental constitutive concepts of elasticity theory like polyconvexity, rank‐one convexity and tension‐compression symmetry. In addition, we provide finite‐element simulations to visualize our theoretical findings.
Sensitivity analysis of a non‐local, gradient enhanced damage model
Authors: Guhr Fabian , Barthold Franz‐Joseph , Menzel Andreas , Sprave Leon , Liedmann Jan 
Published: December 2018

AbstractThe sensitivities for a non‐local, gradient enhanced damage model are analysed. To model the damage accumulation, a non‐local, gradient enhanced damage model is proposed. Contrary to other approaches, where a local variable is coupled to a non‐local one, see e.g. [1–3], solely a non‐local variable is introduced which is calculated simultaneously with the displacements for each node point. By means of a variational approach, the stiffness matrix as well as the sensitivities, see [4], can be calculated for implementation into the finite element method (FEM) and the minimisation, using sequential quadratic programming (SQP). The framework allows to optimise given geometries with respect to the damage evolution either directly with the damage as the objective function, or indirectly by choosing the damage as a constraint at every finite element node.
Viscoelasticity of cross‐linked actin network embedded in cytosol
Authors: Wiegold Tillmann , Klinge Sandra , Aygün Serhat , Gilbert Robert P. , Holzapfel Gerhard A. 
Published: December 2018

AbstractAn eukaryotic cell is a complex system including various components with different structures and roles. The current contribution deals with the microscopic and macroscopic simulations of a cell if two of its components are considered: cytosol and actin network. At the microscopic level, the actin is modeled by the Holzapfel‐Ogden model, including an extension for viscous effects. The model provides a relationship between the stretch of a single polymer chain and the applied tension force. This relationship includes the influence of the physical length of a single chain, its end‐to‐end distance and the stretch modulus. The viscous effects occurring due to deviatoric changes are modeled corresponding to a spring and a dashpot of the generalized Maxwell model. The cytosol is modeled by a large strain viscous model from the FEAP program. Finally, the effective behavior of the cell cytoplasm is simulated by using the multiscale finite element method. This method has been chosen since it is suitable for simulating nonlinear heterogeneous materials with a zero‐ratio of the characteristic lengths of scales. The selected numerical example deals with the effective material behavior for a tension test with two holding phases.
Modeling and simulation of curing processes using time‐adaptive, high‐order time integration
Authors: Leistner Chris , Abliz Dilmurat , Ziegmann Gerhard , Hartmann Stefan 
Published: December 2018

AbstractNowadays, epoxy resins are extensive applied as a matrix in fiber‐reinforced materials. However, its production process is very sensitive to temperature control. High process temperatures substantially accelerate the exothermic production process, which can lead to combustion. Therefore, a constitutive model of the matrix material must be provided first. Second, initial boundary value problems need to be treated by time‐adaptive, high‐order time integration schemes within finite elements in order to obtain precise and reliable results within an appropriate calculation time.
A new insight into the J‐, M‐, and L‐integrals of dislocations
Authors: Agiasofitou Eleni , Lazar Markus 
Published: December 2018

AbstractThe explicit formulas of the J‐, M‐, and L‐integrals of straight (screw and edge) dislocations in isotropic materials are presented. The obtained results reveal the physical interpretation and significance of the M‐, and L‐integrals for straight dislocations. The M‐integral between two straight dislocations (per unit length) is equal to half the interaction energy of the two dislocations (per unit length) depending on the distance and on the angle, plus twice the corresponding pre‐logarithmic energy factor. The L3‐integral between two straight dislocations is the z‐component of the configurational vector moment or the rotational moment (torque) about the z‐axis caused by the interaction between the two dislocations.
Multi‐Disciplinary Design Optimization of Missile Fin Configuration
Authors: Rašuo Boško , Vidanović Nenad , Kastratović Gordana 
Published: December 2018

AbstractThe aim of the paper is to establish and demonstrate the significant capacity and performances of a well predictive numerical environment, developed for multidisciplinary design optimization purposes, which presents one more contribution in cases of fluid‐structure interaction numerical modelling. Numerical modelling of fluid‐structure interaction was conducted through closely coupled aerodynamic and structural computational domains, with very good overall computational reliability and accuracy. The developed algorithm enabled an increased number of feasible optimal geometries of fin, while its special feature was the overall improvement of the missile initial geometry.
Numerical approximation for dynamic analysis based on NURBS and the Scaled Boundary Finite Element Method
Authors: Méndez Salas Arturo , Chasapi Margarita , Klinkel Sven 
Published: December 2018

AbstractThis contribution deals with a numerical modelling approach for time domain analysis. A parametrization method, established on NURBS as basis functions, is adopted in combination with the principles of the scaled boundary finite element method. This fusion allows a strong domain discretization minimizing the number of degrees of freedom since fewer points are necessary to represent a domain due to the nature of NURBS basis functions and the adopted boundary representation. In this proposal, the differential equation of motion for an idealized linear elastic, homogeneous and isotropic material is solved by applying the weak form along a boundary and scaling direction, and based on an implicit integration scheme. The adopted formulation is carried up to represent an open and a closed boundary. Both cases are under plane strain motion and their performance is studied, compared and validated with help of the conventional FEM. For the close domain, the analytical solution is also used and a damped system.
Reducing structure‐borne noise in thin‐walled structures by local thickness variations
Authors: Miksch Matthias , Aumann Quirin , Müller Gerhard 
Published: December 2018

AbstractThickness variations can modulate the propagation of bending waves in thin‐walled structures. A smooth reduction of the thickness results in a decreasing propagation speed and an increasing amplitude of the bending wave. Acoustic black holes (ABH) make use of this modulation to enhance the energy dissipation in the vicinity of this thickness diminution. Using the concept of ABH, no additional mass is needed to reduce structure‐borne noise. Therefore, this concept is suitable for reducing the vibrational energy in lightweight structures, which is vital in aerospace and automotive applications, among others. Locally modifying the thickness of a structure can significantly influence the global energy distribution in the structure. This contribution investigates the influence of different local thickness profiles on the global energy distribution. The results deliver insights for the design of such thickness variations in thin‐walled structures to improve their vibrational behavior. Several numerical models are evaluated to assess the dependency between the geometric design parameters of the thickness variation and the energy distribution in the structure.
A macroscopic model on the dynamic behaviour of open cell foams
Authors: Kirchhof Stephan , Ams Alfons 
Published: December 2018

AbstractOpen cell foams are widely used in engineering which includes an application in areas, where vibration excitations can act on the structures. Therefore dynamical properties as eigenfrequencies and natural modes are of great interest. Here a modelling approach of the dynamic behaviour of open cell foams by macroscopic stochastic models will be discussed. Based on a 3D computed tomography scan of the foam, statistic and spectral analysis has been carried out to determine the parameters of the stochastic model. Additionally a vibration measurement has been done to provide eigenfrequencies, frequency transfer functions and natural modes of the real foam, which can be compared with the simulation results of the macroscopic model.
A multi‐physics approach to investigate the influence of hydrogen on short fatigue crack propagation
Authors: Schippl Volker , Brück Sven , Christ Hans‐Jürgen , Fritzen Claus‐Peter 
Published: December 2018

AbstractHydrogen can substantially increase the material degradation under cyclic loading. During short fatigue crack growth, which is often the dominating stage during crack propagation, the crack growth rate is highly influenced by microstructural characteristics such as grain boundaries, the formation of slip bands and the local concentration of hydrogen at the crack tip. To address the problem of prediciting the short crack growth behavior, a multi‐physics approach is presented accounting for these interacting influences.
Towards tensor generalizations of TLS & core problem theory
Authors: Hnětynková Iveta , Plešinger Martin , Žáková Jana 
Published: December 2018

AbstractDespite the wide attention, there are still several not well understood parts in the theory of total least squares (TLS) formulation of linear algebraic approximation problems. In particular, in the problems with multiple (matrix) right‐hand sides one can ask about the meaning of the nongeneric solution in the context of the original data, the nonexistence of the TLS solution for the so‐called irreducible core problems, etc. In the single (vector) right‐hand side TLS, these problems can be easily explained through the core problem theory or simply do not appear. Here we summarize, how the existing TLS and core problem theory can be generalized to problems with tensor right‐hand sides. Such generalization also gives a natural and wider context for further analysis of the above mentioned questions.
Modelling Thermo‐Viscoplasticity of Case‐Hardening Steels Over Wide Temperature Ranges
Authors: Oppermann Philip , Denzer Ralf , Menzel Andreas 
Published: December 2018

AbstractThe aim of this work is the development of a thermodynamically consistent fully coupled thermo‐viscoplastic material model for metals. The model is based on a split of the free energy into a thermo‐elastic, a thermo‐plastic and a purely thermal part and covers nonlinear cold‐work hardening and thermal softening. Nonlinear temperature dependent effects are accounted for the elastic moduli, the plastic hardening moduli, the thermal expansion, the heat capacity and the heat conductivity. Furthermore, strain rate‐dependency of the current yield stress is realized using a temperature dependent nonlinear Perzyna‐type viscoplastic model based on an associative flow rule. The model and its parameters are fitted against experimental data for case hardening steel 16MnCr5 (1.7131).
Implementation of a Phase Mixture Model for Rate‐Dependent Inelasticity
Authors: Eisenträger Johanna , Naumenko Konstantin , Altenbach Holm 
Published: December 2018

AbstractPower plant components have to withstand complex thermo‐mechanical loads, i.e. frequent start‐ups and shut‐downs in combination with long holding times at high temperatures induce creep‐fatigue loads. Tempered martensitic steels with high chromium content feature high creep strength and corrosion resistance among other properties such that these alloys are often used for power plant components.This contribution focuses on the simulation of the complex mechanical behavior of the alloy X20CrMoV12‐1 based on a multi‐axial phase mixture model. Within this model, we distinguish two phases: a hard and a soft phase. Both phases are connected via an iso‐strain approach, and nonlinear kinematic hardening as well as microstructural softening effects are taken into account by introducing a backstress and a softening variable as internal variables. The model is implemented into the commercial finite element code ABAQUS with a user material subroutine. For this purpose, the stress update algorithm and the consistent tangent operator are implemented based on the backward EULER method in combination with NEWTON‐RAPHSON iteration. Next, a wide range of benchmarks for uni‐axial as well as multi‐axial stress states is taken into account in order to verify the numerical implementation. Furthermore, a thermo‐mechanical fatigue test based on a typical sequence of start‐ups and shut‐downs of power plants is simulated.
Efficient Quantification of Free and Forced Convection
Authors: Glänzel Janine , Stoll Martin , Unger Roman 
Published: December 2018

AbstractThermo‐elastic deformations represent one of the main reasons for positioning errors in machine tools. Investigations of the thermo‐mechanical behaviour of machine tools often rely on accurate simulations involving large‐scale CFD simulations, where the heat transfer coefficient is computed. It has been shown that radial basis functions (RBFs) are a valid tool to reduce the number of CFD simulations by interpolation. We here present an efficient approach for the case of a three‐axis milling machine.
Modelling of nonlinear damage accumulation for the lifetime prediction of adhesively bonded joints
Authors: Kroll Ulrich , Matzenmiller Anton 
Published: December 2018

AbstractTwo enhancements of a continuum damage mechanics model with a creep and fatigue part are presented in order to capture nonlinear damage accumulation of structural adhesive joints subjected to service loading. The enhancements are applied to the fatigue part and have an effect on its lifetime prediction due to variable amplitude loading, while its prediction for constant amplitude loading is not affected. Both approaches are validated by means of the comparison of test data with numerical lifetime predictions for shear loading with variable amplitudes.
Towards a unified Lagrangian multi‐scale model for interacting particles
Authors: Bender Jens , Klar Axel , Kuhnert Jörg 
Published: December 2018

AbstractThe simulation of interacting particle systems by individual tracking in a Lagrangian framework can become virtually impossible in feasible time frames and for large problem sizes. This is why there are many approaches to describe the resulting behavior by continuous equations which are usually much more efficiently solved using an Eulerian grid on a larger scale. Motivated by the development of a Lagrangian generalized finite difference solver using moving point clouds, we work towards a method that can blend between the different scales in a unified framework. To this end, we derive a macroscopic model which still contains microscopic information in the form of an integral term. Different approximations of this term based on the point cloud configuration shall allow for a scaling between the representation of microscopic particles and the solution of a purely macroscopic model by the point cloud. Here we will present an extension of the model to interacting particle systems that involve damping and focus on the macroscopic model performance.
Model reduction of gyroscopic systems in ALE formulation with and without non‐linearities
Authors: Weidauer Tim , Willner Kai 
Published: December 2018

AbstractRotating systems are subject to gyroscopic influences which alter their dynamic behaviour. The Arbitrary Lagrangian Eulerian (ALE) formulation is a popular approach for related models, e.g. for the simulation of tire rolling contact. It allows for decoupling the rotational guiding motion from the relative deformation of the rotating structure. At the same time it complicates contact computations as the relative displacement between two material particles is not tracked naturally by the ALE observer. Model reduction techniques for (non‐linear) systems face additional challenges in this context, of which a variety is discussed here for common approaches such as the Second order modal truncation, the Krylov subspace method or the Craig‐Bampton method.
A geometric view on the kinematics of finite‐dimensional mechanical systems
Authors: Winandy Tom , Capobianco Giuseppe , Eugster Simon R. 
Published: December 2018

AbstractFinite‐dimensional mechanical systems can be described in terms of a set of generalized coordinates and their time‐derivatives. In this case, the Lagrange equations of the second kind provide the equations of motion of these systems. The Volterra–Hamel–Boltzmann equations generalize the Lagrange equations of the second kind in the sense that they allow for more general velocity parametrizations. In this work, we show in the context of scleronomous finite‐dimensional mechanical systems that both sets of equations can be interpreted as being different chart representations of the intrinsic Euler–Lagrange equations on the tangent bundle over the configuration manifold of the mechanical system.
Investigation of Tenocyte Migration Behaviour by Application of the Mechanobiological Concepts
Authors: Dursun Gözde , Ürek‐Yavas Dilmin , Tohidnezhad Mersedeh , Markert Bernd , Stoffel Marcus 
Published: December 2018

AbstractCell migration plays a key role in tendon wound healing. The migration characteristics of tenocytes can be motivated by external signals. Our study aims to examine and enhance the migration activities of tenocytes by the appliance of uniaxial mechanical stretch using a custom‐made tensile bioreactor. Uniaxial mechanical stretching is applied to tenocyte‐seeded silicone as well as collagen membranes, which possess different material characteristics. The collagen membranes are considered a promising candidate for tendon tissue engineering due to its biological properties.