Applied Mechanics and Materials Vol. 821

Abstract: In this paper, an approximate method for determining the complex eigen-values of non-classically damped linear system is presented. Only the systems consisting of a linear classically damped system to which one viscous damper is attached are assumed. The proposed method reflects the difference in the eigen-values of classically and non-classically damped systems using the first-order perturbation technique. The procedure is easy to code and avoids using a numerically demanding state-space approach. It operates in the original dimension of the physical problem and requires only the knowledge of eigen-modes and eigen-values of the classically damped and undamped systems. Numerical example is given to demonstrate application and accuracy of the method.

Abstract: The turbocharger is a unique example of the rotating machinery. Not only for its very high speed, but also because of its compact design and difficult operating conditions (i.e. high temperature, harsh vibrations, etc.). Moreover, measuring of most parameters characterizing the rotor dynamics is a very difficult task. Thus, it is advantageous to replace the real turbocharger by computational model and determine the turbocharger rotor dynamics using simulation tool. The development of such tool will be presented in this paper.

Abstract: This contribution reviews utilization of parallel computers in various engineering problems. First, parallel computers are classified and a very short review of the most powerful computers is presented. Then, engineering problems are sorted with respect to possible parallelization.Finally, two examples of different utilization of parallel computers are described. Domaindecomposition method based on the Schur complement method is the first example and a multi-scale analysis of masonry structure is the second one.

Abstract: The paper deals with the description of a computational model of an ATV vehicle in Simulink software. This computational model is created using the basic elements of own library and represents the main driveline parts for the simulation of longitudinal and lateral vehicle dynamics. The article describes the design and function of the computational model and demonstrates the usage of an ATV model in the NI VeriStand software. It can be simulated on the hardware for real-time testing. A simulation of drive is then done to verify the functionality of the assembled model.

Abstract: The paper deals with the response analysis of interaction of a gaseous shock wave and a glass plate structure with particular reference to the character of excitation wave and material characteristics of structure. The goal of this analysis is the determination of a hypothesis of failure of window glass plate on the basis of the actual plate rotation during extreme plate displacement. Pressures greater than the ultimate stress or plate rotation bring to the collapse of the glass plate structure. The assumptions and results of theoretical - numerical solution are compared with experiments in situ and in laboratory conditions.

Abstract: The aim of the paper is to inform about main features of Non-linear Normal Modes (NNM) as a powerful tool for investigation of multi-degree of freedom (MDOF) dynamic systems. In particular, it is shown how this concept can be used to investigate forced resonances of non-linear symmetric systems including non-linear localization of vibrational energy. NNMs can provide a valuable tool for understanding essentially non-linear dynamic phenomena having no counterparts in linear theory and which do not enable analysis using linearized procedures. Discrete MDOF systems are considered in this study. A couple of possible approaches are outlined together with some demonstrations of numerical results.

Abstract: The Triple Hybrid Hydrogen Bus project comprises research and development, implementation and a test operation of a city bus with hybrid electric propulsion using hydrogen fuel cells. The mass distribution and the total bus mass are rather different from common buses. This is, among others, the reason for investigating the bus driving stability. In order to obtain a tool for dynamic analysis, multibody models of the bus were created. Verification of multibody models was performed based on the comparison of simulation results and experimental measurements focused on handling behaviour of the bus. To perform the simulations two approaches were used. The first (original) one, at which the initial position of the bus multibody model at the beginning of the simulation of the manoeuvre depends on the bus motion trajectory, and the second (new) one, at which the initial position of the bus multibody model at the beginning of the simulation of the manoeuvre is set an equilibrium position.

Abstract: The influence of flexible pins of planet gears on the dynamic properties of planetary gearing box is investigated by means of a general analysis with some alternative values of parameters. For discovering of basic dynamic behaviour of planetary gear system the simplest planetary gear set with neglected compliance of teeth contacts, fixed axes of central sun wheel and fixed planetary carrier, etc is used One mode of free vibration with eigenfrequency Ω proportional to and zero frequency mode Ω→0 corresponding to the rotation with constant angular velocity were analysed. Forced vibrations, analysed by means of response curves, were oriented on ascertaining of influence of driving aggregate characteristic on frequency spectrum of the whole set.

Abstract: Submitted paper is focused on dynamic analysis of the footbridge structure, which is represented by the simply supported beam. The continuous beam model was discretized by the FEM to MDOF system and loaded by pedestrians, walking across the structure. Three states of loading are considered in this paper. Firstly, it is the mathematical description of pedestrian's ordinary traffic, where each pedestrian is randomly generated by the Monte Carlo method. Secondly, the movement of single pedestrian, simplified by viscoelastic models, is introduced. Thirdly, the DLF model of stochastic vandals is investigated as well.

Abstract: A novel approach to vibration attenuation, based on the eddy current principle, is described. The combined effects of all magnetic forces acting in the oscillatory system attenuate frame vibrations and, concurrently, decrease the damped natural frequency. A mathematical model of the forces balance in the oscillatory system was derived before. Some experimental results from a mock-up machine frame excited by an asynchronous motor are presented.