Casing is an imporant part of Vertical Pelton Turbine unit, which acts as a housing for runner and the suppport for Generator. The design of casing requires consideration of hydraulic as well as mechanical aspects. The size and shape of the casing should be designed to give proper guidance to water flow. Casing should have enough strength to meet the mechanical/structural requirements such as to withstand the dead weight of the generator, forces developed in the manifold/branch pipes, load due to the four jets in different combinations and load due to various actuation mechanisms. After satisfying above aspects, the casing should be checked for vibration behavior by modal analysis. The design of casing for four jet vertical Pelton turbine is carried out considering all above mentioned criterion. Ansys Mechanical software is used to study the structural behavior of casing and also for weight optimization by reducing the thickness of casing and changing arrangement of ribs. and Obsahuje seznam literatury
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
Frequency response analysis of hybrid aluminium beam with piezoelectric actuators was performed using finite element method The finite element model was implemented in Matlab software. The one-dimensional beam element is based on Euler-Bernoulli theory and it assumes bilinear distribution of electric field potential. The piezoelectric actuators were driven by harnonic signal around the first eigenfrequency and the beam oscillations were investigated. Results were compared to experiment. and Obsahuje seznam literatury
The aim of the paper is modal condensation of a system which represents bladed disk. These kinds of systems are mainly used in steam turbines what is the topic of the article. The model of the bladed disk is based on decomposition into a disk subsystem and a blading subsystem. The finite element method is used for modeling of the both subsystems. All influences of steady-state rotation are respected as centrifugal forces, gyroscopic effects, centrifugal stiffening of blades and dynamic softening. Blades are modeled by using ID elements and the disk is modeled by using 3D hexahedral elements. Modal condensation is applied to a disk subsystem. Different levels of the condensation are presented and compared on a testing bladed disk. 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 paper deals with the modelling of a real gearbox used in cement mill applications and with the sensitivity analysis of its eigenfrequencies with respect to design parameters. The torsional model (including a motor and couplings) based on th finite element method implemented in an in-house MATLAB application is described. The sensitivity analysis of gearbox eigenfrequencies is performed in order to avoid possible dangerous resonance states of the gearbox. The parameters chosen with respect to the sensitivity analysis are used for tuning the gearbox eigenfrequencies outside resonance areas. Two approaches (analytical and numerical) to the sensitivity calculation are discussed. and Obsahuje seznam literatury
The paper deals with possibilities of using high-speed correlation system Q-450 produced by Dantec Dynamics for determination of modal parameters of tested object. In the paper there is described a new methodology for experimental measurement of eigenshapes and eigenfrequencies and explained a design of software developed for evaluation of such measurements. and Článok sa zaoberá možnosťami využitia vysokorýchlostného korelačného systému Q-450 od firmy Dantec Dynamics pri určovaní modálnych parametrov testovaného objektu. V článku je popísaná nová metodika postupu experimentálneho merania vlastných tvarov a frekvencií, ktorej súčasťou je aj návrh softvérového nástroja pre vyhodnotenie takéhoto merania.