bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamics and control of underactuated mechanical systems: analysis and simple experimental verification
Authors: Blajer Wojciech , Dziewiecki Krzysztof , Kołodziejczyk Krzysztof , Mazur Zenon 
Published: March 2010

AbstractUnderactuated mechanical systems are systems with fewer control inputs than the degrees of freedom, m < n, the relevant technical examples being e.g. cranes, aircrafts and flexible manipulators. The determination of an input control strategy that forces an underactuated system to complete a set of m specified motion tasks (servo‐constraints) is a demanding problem. The solution is conditioned to differential flatness of the problem, denoted that all 2n state variables and m control inputs can algebraically be expressed, at least theoretically, in terms of the desired m outputs and their time derivatives up to a certain order. A more practical formulation, motivated hereafter, is to pose the problem as a set of differential‐algebraic equations, and then obtain the solution numerically. The theoretical considerations are illustrated by a simple two‐degree‐of‐freedom underactuated system composed of two rotating discs connected by a flexible rod (torsional spring), in which the pre‐specified motion of the first disc is actuated by the torque applied to the second disc, n = 2 and m = 1. The determined control strategy is then verified experimentally on a laboratory stand representing the two‐disc system. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamical behavior of washing machines
Authors: Gödecker Holger , von Wagner Utz , Heubner Axel 
Published: March 2010

AbstractDue to the maximum rotational speed of modern washing machines (1600 rpm) and the resulting high excitation forces, an appropriate modeling of the dynamical behavior is of interest. As an example, different models of a front‐end loader fabricated by Bosch Siemens Hausgeräte GmbH (BSH) are discussed. Using AUTOLEV, a symbol manipulation tool, the nonlinear and linearized differential equations are derived. Based on those, the dynamical behavior is examined with particular interest in the stability of the solutions. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of model reduction techniques on the impact force calculation of two flexible bodies
Authors: Eberhard Peter , Fehr Jörg , Mathuni Stefan 
Published: March 2010

AbstractOne important issue for the simulation of flexible multibody systems is the reduction of the flexible body's degrees of freedom. For the reduction process finite element data and user inputs are necessary. The model reduction program for elastic multibody systems MOREMBS, which is developed at the ITM, has an easy‐to‐use interface and the data can be gained from the programs ABAQUS or ANSYS. In this work, the simulation of a fuel injection process is investigated with MOREMBS. We focus on the interaction between valve and armature. These two bodies impact in every injection circle. The impacting bodies are modeled as flexible and the contact force is calculated by a penalty approach. One essential part of this work is the investigation of the influence of different model reduction techniques on the impact force calculation of the flexible multibody system. The main reduction techniques modal reduction, Krylov‐subspace based and Gramian matrix based techniques are compared. The results achieved with modal reduction, the state of the art reduction method, are not acceptable here. Krylov‐subspace based techniques are especially well‐suited for large sparse systems but are not error controlled. However, by choosing appropriate moment‐matching properties the impact force calculation is nearly as good as with a full finite element model. The Gramian matrix based reduction techniques can be fully automated and are error controlled but require high computational effort. Hence, appropriate approximation schemes have to be used for them. With Gramian matrix based methods we can even further reduce the size of the subsystems compared to Krylov‐subspace based methods and still have an impact force calculation nearly as good as with finite element results, but we gain a simulation speedup by the factor 4000. In addition, a parameter study of the parameters involved in the model reduction process is presented. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
3D domain decomposition problems, consistent in time and space
Authors: Hesch Christian , Betsch Peter 
Published: March 2010

AbstractDuring the past years tremendous developments have been achieved in the field of domain decomposition problems as well as in the field of time integration schemes. In the present work actual developments in both fields are merged; the result of this is an extremely stable numerical method in space and in time. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An energy‐momentum conserving method for the optimal control of multibody dynamics
Authors: Siebert Ralf , Betsch Peter 
Published: March 2010

AbstractThe present work deals with inverse multibody dynamics problems, more precisely with optimal control problems for dynamical systems governed by differential‐algebraic equations. The used numerical integration method relies on the Hamilton formulation of the equations of motion. We will apply an energy and momentum conserving time discretization which typically exhibits superior numerical stability properties. The rigid body equations of motion are basically formulated using the director formulation, which requires the implementation of internal constraints. To eliminate the constraints the system will be reduced to its minimal dimension by applying the discrete nullspace method [3]. For the derivation of the necessary conditions of optimality the calculus of variation is used [4]. This approach leads to an indirect transcription method. The arising algorithm yields a sequence of discrete configurations together with a sequence of actuating forces. We test the formulation with the help of representative numerical example problems. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Evaluation of Different Methods to Compute Excitation Signals Based on Measured Targets in Agricultural Machines
Authors: Reichl Stefan , Steiner Wolfgang , Steinbatz Michael , Hofer Manfred 
Published: March 2010

AbstractBasis for a strength calculation of a mechanical system is the knowledge of the outer excitation. In the case of agricultural machines it is either not possible or financially not affordable to measure such variables directly at the wheels. Therefore, measureable output parameters are defined as targets and they are used to calculate the input variables in an inverse process. Trailed agricultural machines are characterized by nonlinearities like complex tires, bearing slackness or elasticity of hydraulic components. All these phenomena have to be included in a MBS (multi‐body simulation) in order to describe the behaviour of the real system. As shown in this paper, the results of a test track can be reproduced with a model consisting of rigid and flexible bodies. The excitation signals can be calculated in different ways. A well known method and a new approach are evaluated. By using mathematical methods in combination with a virtual test rig, time and costs can be reduced compared to a real test rig. Another advantage is that inner variables can be calculated, which cannot be taken out from the physical system. Key words: virtual test rig, virtual iteration, multi‐body simulation, inverse problem (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modelling Elasto‐plastic Material Behaviour within the Multi‐Body Frame
Authors: Fischer Katrin , Ostermeyer Georg‐Peter 
Published: March 2010

AbstractHighly dynamic problems can be well described using multi‐body systems. Nevertheless this method is limited to systems whithout large elasto‐plastic deformations that can e.g. be found during an extrusion process. To model such a system, multi‐body systems can be adequately combined with special particle approaches like the mesoscopic particle method [1], [2]. These mesoscopic particles have internal variables describing hidden degrees of freedom. Interaction forces between particles similar to those on the atomic scale have to be taken into account to describe phase transitions. So materials' properties concerning temperature and pressure can successfully be reproduced. This paper therefore deals with the description of an extrusion process in the multi‐body frame using mesoscopic particles. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Contribution to Jerk Detection
Authors: Schiefer Frank , Ostermeyer Georg‐Peter 
Published: March 2010

AbstractIn technical applications the jerk information will be used for i.a. motion control, comfort evaluation or prediction of acceleration. In the majority of cases the jerk will be determined indirectly by differentiation of measured acceleration signals and depends consequently on the acceleration signals' quality and the differentiation's algorithms. An accurate jerk determination can only be realized by using an appropriate filter with respect to the relevant frequency range. In order to avoid such limitation a method of direct jerk detection will be required. Based on a 2 DOF mass system with viscous coupling a possible method was presented in [1] to detect directly the jerk. Thereby, in certain conditions the jerk is proportional to the displacement of one mass. Another method of direct jerk detection is given implicitly in [2]. With this method the jerk information will be generated by an additional inner variable of a damped single mass system based on the fundamental idea of the Mesoscopic Particle Method [3]. Both presented methods will be investigated and evaluated regarding its limits of applicability as a result of arbitrary periodical and impact‐like excitations. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effect of wing deformation on highlift systems of transport aircraft
Authors: Winter Evelyn , Woernle Christoph , Heyden Thomas 
Published: March 2010

AbstractAn elastic multibody model is developed that combines highlift system models consisting of flap and slat mechanisms with an elastic wing model. It describes the motions and deformations of the highlift systems with airloads applied and, in particular, the effect of wing deformations on the highlift systems. In addition the model contains a flexible wing with the engine and the middle section of the fuselage that is fixed at the symmetry plane of the aircraft. While previously wing deformation was taken into account in static FE simulations only the developed multibody model provides the investigation of the motions and inner loads of the highlift mechanisms with consideration of the wing deformations with dynamical effects. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A fast method for computing time‐dependent normal pressure distributions with cellular automaton
Authors: Graf Matthias , Ostermeyer G.‐P. 
Published: March 2010

AbstractWhen two bodies slide against each other, one part of the dissipated energy causes a topography change. Tribological research on brake bads shows a rich dynamic of the boundary layer: plateau‐like structures of a typical length scale grow with time due to agglomerating wear particles and collapse spontaneously at a stability limit [4], [1]. This time‐dependent behaviour can be modeled with cellular automata, which consider local resolution of temperature, wear particle density and frictional power [4]. Beside this the instationary normal pressure distribution and the distinction between areas with and without contact is expected to have a significant influence [3]. This paper derives a fast scheme to estimate the time‐variant pressure distribution of a deterministic and dynamic topography by a cellular automaton. The approach is discussed in the light of computational performance and the solution's characteristics. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Co‐Simulation Approach for the 3D Dynamic Simulation of Vehicles Considering Sloshing in Cargo and Fuel Tanks
Authors: Fleissner Florian , Eberhard Peter 
Published: March 2010

AbstractThe sloshing of liquids in cargo and fuel tanks mounted on vehicles can have a significant influence on the vehicle's driving dynamics and stability. To evaluate and optimize the quality of tank designs, we propose a co‐simulation approach that consists of a coupled multibody system simulation for the vehicle and a Discrete Element Method and Smoothed Particle Hydrodynamics simulation for the sloshing cargo. This approach is beneficial especially for the simulation of fluid cargos, as Smoothed Particle Hydrodynamics does not require additional models to track and reconstruct free fluid surfaces. By means of dynamic 3D simulations of a double lane change maneuvers we compare the two different cargo models and demonstrate the viability of the co‐simulation approach. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kinematics of Drawbar Combinations with Many Trailers
Authors: Beitelschmidt M. 
Published: March 2010

AbstractModern articulated busses as well as road trains can be modeled as a chain of simple drawbar trailers. If the cross slip of the wheels is neglected, the system can be simplified to a planar single track model. The motion of the chain is governed by the geometrical constraints of the pivot joint in each coupling point and the nonholonomic kinematical constraints at each wheel contact point. With these simplifications a system of first order non‐linear differential equations for the angular velocities of all trailers is obtained that can be calculated recursively along the chain beginning at the forced movement of the first drawbar. The geometry and the kinematics of the trailer chain depend on two parameter sets: The drawbars' lengths of each trailer and the distances between the successors' coupling points and the axles on the predecessor's trailers. Especially the trailers' path‐following depends strongly on the ratio of these lengths. Systems of up to 50 identical trailers are examined. If special values for the ratio of the lengths are chosen, very strange behavior of the trailer chain can be observed. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
New cases of integrability in dynamics of a rigid body with the cone form of its shape interacting with a medium
Authors: Shamolin Maxim V. 
Published: March 2010

AbstractThe purpose of the activity is to elaborate the qualitative methods for studying the dynamics of rigid bodies interacting with a resisting medium under quasistationarity conditions. This material refers equally to the qualitative theory of ordinary differential equations and the dynamics of rigid bodies. We use the properties of body's motion in a medium under conditions of the jet flow past this body. We study the plane model problems of the motion of a body with the cone form of its shape in a resisting medium. The new families of phase portraits of variable dissipation systems are obtained, their absolute or relative roughness is demonstrated. The integrable cases of equations of motion of rigid bodies are found. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A viscoelastic‐diffusion model for cartilage replacement material
Authors: Stoffel Marcus , Weichert Dieter , Müller‐Rath Ralf 
Published: March 2010

AbstractIn order to predict deformations and internal stresses of articular cartilage replacement material, two viscoelastic diffusion models are proposed in the present study. Also, the remodeling effect of the material seeded with human cells is verified experimentally. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Absorbed power as a method to evaluate the health risk of seated occupants exposed to vertical vibration
Authors: Rodean S. , Arghir M. 
Published: March 2010

AbstractThe biodynamic responses of seated occupants exposed to whole‐body vibration have been mostly investigated in terms of apparent mass characteristics, which show negligible contributions due to exposure level. Considering that the severity of vibration exposure is related to the level and duration of exposure, the apparent mass responses cannot be used for assessment of the associated risks. Alternatively, the absorbed power characteristics of the seated vibration exposed occupants show strong dependence on the level of exposure. The measured data, expressed in terms of the vertical absorbed power, are analyzed to study the effects of sitting posture on the biodynamic response under whole‐body vertical vibration. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of the Physiological Contact Pressure Distribution in the Human Hip Joint
Authors: Lutz André , Fietz Kristin , Nackenhorst Udo 
Published: March 2010

AbstractIn this contribution a finite element analysis of the proximal femur and the acetabulum regarding the physiological contact pressure distribution is presented. Using a detailed 3D finite element model obtained from CT data, the contact pressure in the human hip will be analysed and a summary with respect to different movement situations will be shown. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A micro‐sphere‐based remodelling formulation for anisotropic biological tissues
Authors: Waffenschmidt Tobias , Menzel Andreas 
Published: March 2010

AbstractSoft biological tissues possess a pronounced composite‐type multi‐scale structure together with strongly anisotropic mechanical properties. A fibre‐like network structure is characteristic for this kind of materials. If the tissue is exposed to mechanical loading, the initially possibly unstructured collagen fibre network tends to reorient with the local dominant stretch direction – it adapts according to the particular loading conditions. In general, biological tissues exhibit changes in mass, also denoted as growth, and internal structure, which is commonly referred to as remodelling. In this regard, an anisotropic micromechanically motivated model that incorporates such time‐dependent remodelling effects will be discussed in this contribution. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Damage Hysteresis in Soft Biological Tissues
Authors: Brinkhues Sarah , Balzani Daniel , Holzapfel Gerhard A. 
Published: March 2010

AbstractArterial lumen reductions result in hypertension and possibly rupture of plaque deposits as a consequence of atherosclerotic degeneration which can finally cause a heart attack or a stroke. Hence, therapeutical treatments such as balloon angioplasty and stenting are required. The aim of this work is to propose a new model for the softening hysteresis observed in overstretched arterial tissues and related computer simulations. The physiological loading domain is described by a purely elastic polyconvex anisotropic strain‐energy function, which is decoupled into an isotropic part related to the non‐collagenous matrix material, and into a transversely isotropic part related to the embedded (collagen) fibers. A scalar‐valued damage variable is taken into account for the fibers to cover a saturation function converging to a maximal damage value at a fixed maximum load level. In addition, the model captures remnant strains in the fiber direction after unloading. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A three‐dimensional multiscale finite element model describing the adhesion of a gecko seta
Authors: Sauer Roger A. 
Published: March 2010

AbstractA three‐dimensional multiscale model is presented which describes the adhesion and deformation of a gecko seta. The setae are micrometer fine hairs, covering the surface of the gecko toes, which enable the gecko to adhere to inclined and overhanging surfaces. The seta modeling is approached on three different length scales: At the top level, on the order of several micrometers, a finite element rod model is chosen to capture the branched microstructure of the gecko seta. At the intermediate level, on the order of several nanometers, a second finite element model is used to capture the detailed behavior of the seta tips, the so‐called spatulae. At the third level, on the order of Ångstroms, the adhesion forces between spatulae and substrate are modeled on the molecular level. The model allows for a detailed, yet efficient simulation of the mechanical seta behavior. A numerical relaxation technique is introduced to handle the jump‐off‐contact instability that can occur in pull‐off computations. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An Enriched Biphasic Model for Solute Driven Degradation
Authors: Ricken T. , Bluhm J. , Epple M. , Wehmöller M. , Annen T. 
Published: March 2010

AbstractTransport of solutes in porous materials plays an important role in many kinds of materials such as biological tissues, porous implants or even soils. In most of the cases the liquid phase in the pores acts as a solvent for one or more solutions. The motion of the solutions is driven by both, the advective and convective transport. The former is related to the fluid phase velocity whereas the letter follows the concentration gradient. The interactions between the solutes and the solid and liquid phase may influence the overall material behavior. Although the solutes often carry electrical charges this paper is focused on neutrally charged solutions. In this contribution the model to describe the solute transport in a fluid saturated porous material is based on the well founded Theory of Porous Media. We will present the basic framework and the governing equations. Finally, we will show a three dimensional numerical example of the solute driven degradation of a skull implant. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Modeling and numerical simulation of fluid flow induced by the sutureless 3F‐Enable aortic valve
Authors: Hou Guojun , Wendt Daniel , Stühle Sebastian , Tsagakis Konstantinos , Jakob Heinz , Kowalczyk Wojciech 
Published: March 2010

AbstractDiseases of the aortic valve belong to the most common health problems. The aortic valve maintains the blood flow in one direction and serves to prevent retrograde flow from aorta to the left ventricle. To date, new bio‐prosthetic, suturless heart valves have been designed. The purpose of the present study is therefore to evaluate their influence on hemodynamics in the cardiovascular system. Especially the blood flow in the vicinity of the aortic valve, in the sinus of Valsalva and the ascending aorta becomes on importance from the fluid dynamical point of view. The three‐dimensional geometrical model is generated after segmentation of CT data of the 3F‐Enable aortic valve prosthesis. A set of simulations with different initial velocity profiles and pulse frequencies has been created to examine the transient behavior of the fluid flow and the heart valve prosthesis. The function of heart valve system, however, involves an analysis of fluid‐structure interaction to predict the motion of leaflets. Hence, the separation of the soft tissue and the hard nitinol‐based frame is carried out. The results reveal pressure and velocity distributions as well as normal and shear stresses acting on the wall of the prosthesis and aorta. (© 2009 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)