1,721,175 research outputs found
Modelling the viscoelastic behaviour of elastomeric components: An application to the simulation of train-track interaction
No full textThe paper deals with the experimental characterisation of the frequency dependent behaviour of elastomeric track components and with the definition of appropriate models in time domain for these elements.
It is shown in particular that the dynamic stiffness of elastomeric components depends on both amplitude and frequency of deformation. Moreover, the dissipative behaviour is closer to the hysteretic hypothesis than to the viscous one.
Some simple models allowing to reproduce the measured behaviour of these elements are defined and a procedure for the identification of their parameters is set-up.
It is shown that rather simple models can provide better results than the classical ones composed by a spring in parallel to a viscous damper. It is also shown that the introduction of these models into a finite element description of the track provides a significant improvement in the calculation of track inertance and on the results of the simulation of train-track interaction
ELECTROMECHANICAL INTERACTION BETWEEN CARBON BASED PANTOGRAPH STRIP AND COPPER CONTACT WIRE: A HEURISTIC WEAR MODEL
Full text linkMain contributions to the wear in the sliding contact between pantograph's strip and catenary's wire can be classified as: i) mechanical contribution, due to friction, ii) electrical contribution, due to current flow at the contact and iii) electrical arcs contribution related to power dissipated during arc generation. In this work, a heuristic wear model for the contact wire, which accounts for the mentioned three main contributions to the wear, is presented. After a tuning phase with results obtained by an experimental campaign aimed at evaluating the wear for the couple “pure copper contact wire – Kasperovski contact strip”, the wear model is used in combination with a dynamical electromechanical model able to reproduce the electromechanical pantograph-catenary interaction
A procedure for the wear prediction of collector strip and contact wire in pantograph-catenary system
No full textThe effects of friction and electrical phenomena like arcing and sparking govern the wear rate in the sliding contact between the contactwire and the collectorstrip, these two effects are mutually interconnected in a complex manner. A means of investigating the wear of the collectorstrip and the contactwire is to carry out laboratory tests that allow to perform comparative tests between different material combinations and to establish the dependence on the main parameters such as sliding speed, contact force and current intensity. A problem to be considered in the application of the laboratory test results is their extrapolation to the real operating conditions, in order to assess the effective benefit among different solutions. In this paper, aprocedure that combines awear model for the contact between collectorstrip and contactwire with the simulation of the dynamic interaction between pantograph and catenary is proposed. The adopted wear model is based on the wear map concept, including the effect of electrical current flow, and it is tuned by means of the results obtained on laboratory test rig.
The dependence of the electrical contact resistance on the contact force between each contactstrip of the pantograph and the contactwire of the overhead line is considered and the corresponding electrical current on each of the two collectors of the pantograph is evaluated. Instantaneous values of contact forces and electrical current are then fed into the wear model and the amount of the wear of the collectorstrips and of the contactwire along the overhead line is calculated, generating an irregular profile of the contactwire.
The proposed procedure is applied to two cases: in the first one the wear of the contactwire using copper collectorstrips and graphite collectorstrips for dc line are compared. In the second one, the consequence of the variation of the mechanical tension of the contactwire on the wear levels is predicted
Effect of contact strip-contact wire interaction on current transfer at high sliding speed in the mid-high frequency range
No full textPARMA, ITAL
Application of a modal updating technique to the FEM schematization of piping-pump assembly: two case studies
No full text
A power recirculating test rig for ball screw endurance tests
No full textA conceptual design of an innovative test rig for endurance tests of ball screws is presented in this paper. The test rig layout is based on the power recirculating principle and it also allows to overtake the main critical issues of the ball screw endurance tests. Among these there are the high power required to make the test, the lengthy duration of the same and the high loads between the screw and the frame that holds it. The article describes the test rig designed scheme, the kinematic expedients to be adopted in order to obtain the required performance and functionality and the sizing procedure to choose the actuation system
Interazione dinamica pantografo catenaria in presenza di più pantografi
No full textL’interazione pantografo catenaria riveste un ruolo di fondamentale importanza nell’esercizio dei sistemi ferroviari, in particolare se si considerano le applicazioni riguardanti l’alta velocità. Infatti un comportamento non adeguato dei due sistemi interagenti, pregiudicando la qualità di captazione di potenza elettrica, limita di fatto le massime velocità esercibili.
Il presente lavoro si propone di analizzare attraverso la simulazione numerica differenti aspetti riguardanti l’interazione dinamica tra pantografo e catenaria ed in particolare il comportamento in presenza di più pantografi e gli effetti legati alle perturbazioni che si propagano dal singolo pantografo lungo il filo di contatto
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