PAMM
A porous ceramic preform, the pore structure of which is created via a freeze‐casting technique, is infiltrated with a metal melt via sqeeze‐casting. The microstructure of the obtained metal/ceramic composites has lamellar domains with geometrical characteristics which are dependent on the manufacturing parameters. The aim of our study is to predict the coefficients of thermal expansion of single...
Marker based motion capture methods are well known techniques for the acquisition of human motion. For the kinematic and dynamic analysis the recorded data is usually used to drive a rigid body model of the human body. Skin artifacts, which are caused by skin deformation and displacement of markers with respect to the underlying bone, are regarded as the most critical source of error in the inverse...
Passivity‐based control has exclusively been pursued for dynamical systems possessing energetic state functions that are quadratic in the generalized velocities. This assumption does not apply to many dynamical systems, for instance in electromechanics, thus passivity‐based control has not been established for these classes of systems. This contribution presents an augmented PD control scheme for...
We consider nonlinear implicit control systems and discuss the construction of a system parametrization in the context of flatness. To this end, quasilinear systems will play a prominent role since they are affine in the derivative variables which alleviates the proposed reduction and elimination strategy. (© 2010 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Oscillation control of container handling is dominated by open‐loop or closed‐loop control of the crane trolley, which highly effects the crane operator's well‐being. An alternative actuating approach is presented using the hoists of the crane system. Simulation and test stand results prove the effect of modal coupling control of container handling and its capability to assure improved work environment...
The optimal control methodology called concentration‐of‐measure optimal control (COMOC), seeks to minimise a concen‐ tration‐of‐measure upper bound on the probability of failure of an uncertain system. This bound is computed for a system characterised by a single performance measure depending on random inputs.
This work considers controlled multibody dynamics taking place in an uncertain environment...
In this contribution, an approach on the mechanically stimulated osseointegration of hip joint endoprostheses considering load cases of daily movements is presented. The mechanical behavior of the bone‐implant interface is modeled with a material model adopted from computational plasticity. Under consideration of a detailed analysis of the interface conditions, limiting factors for the osseointegration...
Trajectory planning of human motion is done unconsciously by the central nervous system (CNS). To get a better understanding about how the human CNS controls movements in a particular example, we investigate the trajectory of the index finger during grasping. Varying forefinger movements are formulated as optimal control problems for constrained motion. For the solution of the optimal control problem,...
In recent years, increasing interest in so‐called smart materials such as ferroelectric polymers and ceramics has been shown. Those materials are used in various actuators, sensors, and also in medical devices. In this paper, we outline a micro‐macro approach to the modeling of macroscopic hystereses which directly takes into account the microstructural evolution of electrically poled domains. To...
The flow‐field in the wake of Ahmed body was studied experimentally. The study is oriented on unsteady behavior of the lateral vortex pair arising in the wake as well as on the wake itself. The time‐mean characteristics of the wake flow are presented. The dynamical behavior of the longitudinal vortex pair is studied in details. The Stereo Time‐Resolved PIV method was applied in the wake plane perpendicular...
We present results of the experimental investigation of the impact of particles on a rough wall. The particle‐wall impact influences considerably the behavior of particle laden gas flows. The aim of the present work is to study the influence of the wall roughness on the particle trajectory and the particle rotation after impact. The measurements were carried out in a special test facility, which allows...
For one‐dimensional simulation of flow in ramified pipe systems loss prediction in junctions is essential. In the standard literature (e.g. [1]) total pressure loss coefficients serve this purpose. Elementary formulas follow from the principle of momentum and some simple assumptions [2]. They yield rather crude estimates, often twice as large as experimental values. Modifications described by Idelchik...
To study the nonlinear phenomena of rotors in the sense of bifurcation theory, the mechanical model of a symmetric flexible rotor is investigated which is supported by two identical journal bearings. Two types of journal bearings are considered. While the oil whirl and oil whip oscillations of rotors in plain journal bearings are widely examined, the floating ring bearings cause a quite different...
This work focuses on the calculation of shakedown load‐factors of structures by using the lower‐bound theorem of shakedown analysis. The resultant optimization problem is solved by an interior‐point algorithm.
In general, the application of shakedown analysis to practical problems leads to large‐scale problems with large numbers of unknowns and constraints. Thus the solution turns out to be computationally...
We employ the theory of elastic materials with voids to describe the mechanical behavior of porous rods. In this purpose, we consider the direct approach to the theory of rods, in which the thin body is modeled as a deformable curve with a triad of rigidly rotating orthonormal vectors attached to every material point. For orthotropic and homogeneous rods, we determine the constitutive coefficients...
The objective of this study is to present an implicit method to predict the dynamics of granular particles. In the proposed methodology, the dynamics equation of colliding particles are solved implicitly which means the positions of particles at the next time step are also used to compute the next state of the particles. This is in contrast with the explicit approach where only known i.e. past information...
The present works deals with the incorporation of both flexible beam and shell structures into the realm of flexible multibody dynamics. Geometrically exact beam formulations based on classical Simo‐Reissner kinematics are suitable for modelling beam‐type flexible components in the context of finite‐deformation multibody dynamics. So geometrically exact shell formulations are based on Reissner‐Mindlin...
This work considers the optimal control of multibody systems being actuated with control forces which impact the system's motion directly. The goal is to find a dynamically feasible trajectory of states and control leading from an initial to a desired final state, while minimising an objective function. The optimal control problem is solved using a direct transcription method, i.e. boundary conditions...
Due to higher requirements in productivity and cost efficiency of production lines, robots and other manipulators have to move faster. One possibility to fulfill the mentioned goals is to build lightweight constructions having elastic deformations in joints and links. The elastic components tend to vibrations and static deflections. Methods that compensate or minimize these drawbacks are the focus...
The present work aims to present a different set of parameters for Euclidean motions which have a definite physical interpretation. The orientation here is obtained via vector‐parameters which are elements of a Lie group with a nice and clear composition law. The method is quite convenient for describing of rigid body and manipulators motions such as scene and image processing and recognition. (©...