1,721,148 research outputs found
Modello fisico predittivo del comportamento in deriva di un pneumatico in condizioni di moto a regime e transitorio
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Flexible-carbody multibody simulation for the analysis of ride comfort in rail vehicles
No full textThis paper illustrates the numerical procedure set up to simulate the dynamic response of a rail vehicle running on an irregular track. The proposed methodology, which involves finite element modelling of the carbody and vehicle multibody simulation, allows predicting the comfort performance of a new rail vehicle from the very beginning of the design process. An example of application is illustrated, showing the influence of the heavy undercarbody electrical equipment on the comfort levels of modern distributed traction units
Train-track-bridge interaction: influence of track typology on structure dynamic performances
No full textExperimental determination of out of plane elastic shear modulus by three point bending test with varying span: application to composite laminates and particle wood panels
No full textEquivalent Models of an Infinite Track for Frequency and Time Domain Analyses
No full textPurpose: Railway track models for the study of train-track interaction are generally based on beam structures on viscoelastic foundations and infinite-length track models are typically used when the track is supposed to be unbounded. However, when non-linear dynamic features or discontinuities of track properties should be considered, it is necessary to perform time domain numerical integration using a finite-length one. This work proposes an approach to develop finite-length models so that the computed results of the frequency and time domain train-track interaction analyses have negligible differences compared to those computed by an infinite-length model, by assigning proper values to the crucial model parameters. Particular attention is paid to obtain equivalent rail responses to stationary and moving point loads. Methods: The track model consists of an Euler–Bernoulli beam supported by a viscoelastic foundation. The beam is formulated by both analytical and Finite Element models. The solution techniques adopted include the exact solution of differential equation, the numerical computation based on the Finite Element model, and the modal superposition approach. Proper values of the beam parameters are firstly determined through frequency domain analysis. Then the parameter values of the beam formulation techniques and solution techniques are determined with time domain analysis. Results and Conclusions: Frequency responses and responses to moving load excitations are computed. The developed finite-length models lead to negligible difference in terms of frequency responses and responses to low-frequency moving loads. For high-frequency moving loads the responses are highly similar. Consequently, the developed finite-length track models are regarded as equivalent to the infinite-length one for both frequency and time domain analyses
A numerical model to analyse the dynamic behaviour of modern tramcars
No full textIn this paper, a numerical model specifically developed for tramcar vehicles is presented. The proposed numerical model allows to reproduce the most common tramcar configurations and to analyse the vehicle performance in terms of combined longitudinal, lateral and vertical dynamics. A particularly detailed procedure for the calculation of wheel-rail contact forces is implemented, thus allowing to deeply investigate sharp curve negotiation behaviour and its effect on vehicle safety, comfort and wheel/rail wear and fatigue. The main features of the model are summarised and some numerical results are reported, in comparison with the corresponding experimental data
Numerical investigation on load transfer effects in bogies of urban rail vehicles
No full textUrban rail vehicles can present many types of architecture, definitely different from those of traditional rail vehicles. When dealing with long articulated tramcars, complex coupling effects between the vertical and lateral dynamics may arise. Making reference to a modern tramcar, the coupling phenomena are investigated in detail by means of numerical simulation, considering the dynamic behaviour during the negotiation of curves with or without superelevation
Numerical model of the admittance function for the evaluation of the aerodynamic loads on vehicles due to cross wind
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