The paper deals with the modelling of balancing machine vibration and the identifícation of the stiffness and damping coefficients of oil-film bearings. The real balancing machine consists of a flexible rotor, oil-film bearings and bearing heads on spring elements. The mathematical model enables to calculate eigenvalues, critical revolutions and unbalance vibrations in dependence on the rotational speed. The identification method of the oil-film bearing stiffness and damping matrices is based on the minimization of differences between measured and calculated rotor critical speeds and bearing head displacements in balancing machines. The rotor is excited by attached known trial masses fixed in chosen balancing planes. and Obsahuje seznam literatury
The paper deals with mathematical modelling of dynamic response of the electric locomotive wheelset drive caused by short-circuit traction motor torque. The individual wheelset drive is composed of five subsystems - rotor of the traction motor with driving gear, driven gear, stator of the traction motor with gear housing, hollow graduated shaft with clutches and wheelset. The couplings between subsystems are linearized in dependence on longitudinal creepage and locomotive forward velocity before sudden short-circuit in the asynchronous traction motor. In comparison with previous models of the wheelset drives, the rotor of the electromotor is characterized by flexible shaft suppported on flexible rolling-element bearings. The sheet metal packjet of cylindrical shape is connected by parallel cooper bars with two short circuit rings. In conseqquence of strong excitation an interruption of gear mesh can be observed. This nonlinear effect and dynamic load of individual wheelset drive with large number of DOF is investigated using the condensed mathematical model created by model synthesis method. and Obsahuje seznam literatury
The paper deals with the mathematical modelling and the computer simulation of forced vibrations of the reactor core barrel excited by pressure pulsations generated by main circulation pumps. The modelling is focused on a possible core barrel flange slip along a pressure vessel flange. The slip in this internal reactor linkage is analysed providing the solid friction and the backlash between slip tongues of the pressure vessel flange and grooves in the core barrel flange. The impact motion can produce an excessive abrasive wear of the tongues and grooves. A guarantee of the fail-safe operation is achieved by calculated pre- stressing of toroidal tubes inserted between the upper flange of the core barrel and the pressure vessel cover. and Obsahuje seznam literatury
The paper deals with the modelling of forced vibrations of reactor components excited by pressure pulsations generated by main circulation pumps. For the vibration analysis a new generalised model of the reactor with spatial localization of the nuclear fuel assemblies and protection tubes, continuously mass distribution of beam type components and more accurate model of the linear stepper drives for actuation of control cassettes was applied. Slightly different pump revolutions are sources of the heating which causes an amplification of vibration and possibility of the contact loss in internal linkages of the core barrel. and Obsahuje seznam literatury
The paper deals with derivation of the dynamical model of the turbochargers with rotor supported on the two floating ring bearings. The model respects the bearing forces acting upon the journals and floating bearing rings by means of inner and outer oil-films. The gyroscopic effects, external and internal damping of the flexible rotor shaft and the rigid turbine and compressor wheels are respected. The modal analysis and the Campbell diagram is used in the turbocharger linearized model to find the critical speeds. and Obsahuje seznam literatury
The paper deals with mathematical modelling and computer simulation of the seismic response of chosen components of hte nuclear WWER 1999 reactor. The seismic response is investigated by numerical integration method in time domain. The seismic excitation is given by two horizontal and one vertical synthetic accelerograms at the level of the pressure vessel seating adjusted for a certain damping vallue 5 %. The main aim of the paper is seismic response assessment for two variants of nuclear fuel assemblies - VVANTAGE 6 and TVSA-T. The maximal values of displacements and linkages or component deformations are compared for both fuel assembly variants. and Obsahuje seznam literatury