This paper deals with the basic dynamical model of electromotor whose creation motivated by problems of electromotor vibrations and its subsequent fatigue. The model is chaacrterized by a flexible shaft with mounted padket of sheet metals that are equipped with parallel copper bars connected by end shortcircuit rings. Finite element analysis is used for the disretization of the shaft, while the sheet metal packet of cylindrical shape is modelled as a set of rigid bodies joined using chosen viscoelastic forces and torques. The shortcircuit rings are supposed to be rigid in this basic dynamical model and the pieces of copper bars are substituted by massless springs of calculated properties. Problematic model parameters are identified by means of performed experimental modal analysis. and Obsahuje seznam literatury
This paper focuses on the modelling of harmonic vibration of two rotating blades affected by friction in contact of a rigid body placed in between the blade shroud. Harmonic blade excitation uniformly distributed in blade nodes in circumferential and axial direction is supposed. Flexible blades are discretized by FEM using 1D Rayleigh beam elements. The nonlinear friction forces in contact surfaces between the blade shroud and the friction element are taken into account using the harmonic balance method. Orbits of central contact points and dissipation energy are investigated in dependence on the excitation frequency. Dissipation energy amount in contact surfaces is confronted with blade tips vibration. and Obsahuje seznam literatury
The article provides a method of mathematical modelling of the dynamic properties of the electric locomotive wheelset drive. The linkage of the traction motor by means of the rotor pinion gear with the gear of wheelset drive is considered. The impact of couplings and operation conditions on the dynamic properties is studied. The method of decompositon into subsystems is applied for derivation of mathematical model of an interconnected system. This model is used for the calculation of modal values and also for investigating the forced vibration excited by pulsation moments of the asynchronous traction motor. The method is applied to a particular drive of the locomotive SKODA 109E. and Obsahuje seznam literatury
The methodology of modelling and of qualitative analysis of large rotating systems with gear and bearing couplings is presented. The emphasis is laid on the modelling of nonlinear gear and bearing couplings and on their influence on the dynamic system response to the internal kinematic excitation in gearing and to parametric excitation caused by the time-varying meshing stiffness. The aim is to introduce a method of investigation the beahviour of the rotating system influenced by the mentioned excitation and to examine the influence of chosen operational parameters. The methodology of modelling and of qualitative dynamic behaviour analysis is tested on a two-stage gearbox. and Obsahuje seznam literatury
The aim of the paper is to show the influence of design parameters on the suppression of rotating blade vibration. The derivation of nonlinear mathematical model of a blade couple mutually connected by a friction element is summarized. After that, the linearization of the mathematical model is performed by harmonic balance method. The linearized model is used for sensitivity analysis of real and imaginary parts of eigenvalues in the course of rotation and sensitivity analysis of stead-state response with respect to the design parameters of internal friction coupling. and Obsahuje seznam literatury