Desarrollo de una metodología experimental para el ensayo a escala reducida de suspensiones ferroviarias activas y convencionales

Abstract

This thesis is framed within a research project aimed to design and build a servo-controlled suspension system for railway vehicles and can be regarded as forming part of this project. This report summarizes the work done to define and to develop a test bench to test new secondary suspension systems to be adopted in a future prototype.

The first chapter lists and describes the test benches for rail vehicles available today, including some that use scale models. Then outlines the objectives of the thesis describing briefly the principle of active suspension systems and defines the tests for which the bench was designed: vertical dynamic tests, lateral and tilting. It also justifies the use of a scale model.

Later the developed methodology is discussed that, being general and applicable to other problems, as it simplifies the problem of experimental simulation of wheel-track interaction. This methodology is applied to reproduce the vertical, lateral and tilting excitations on the bench.

A scale model of the vehicle was used in the test bench; therefore the model theory was applied. Within the text the different scaling relations between physical parameters of the model and prototype is explained. A detailed description of the necessary instrumentation on the bench follows: control equipment, actuators and sensors. Control equipment was based on a compatible computer hardware that provides digital signal processor stops (DSP) and card A / D and D / A.

In the chapter devoted to the actuators a distinction is made between excitation actuators –those responsible for introducing predetermined forces in the bogie that simulate that the vehicle is in the track- and control actuators, which are the elements that introduce forces between the bogie and vehicle body. Actuators being key elements a theoretical and experimental study of three types of actuators: pneumatic, electromechanical and hydraulic systems are included in the text. This study was based on tests performed on the actuators designed and constructed for the test bench. These tests where contrasted with theoretical models, to assess the main characteristics and application fields of these three types of actuators.

The method used to simulate the track excitation is the next chapter. It details the solution chosen, in view of the possibilities and limitations of equipment used. In order to verify that the test bench can faithfully reproduce a rail vehicle circulating on the track a series of checks have been done. Specifically, we compared the experimental results obtained in the test bench with results of previous theoretical models contrasted with measurements made on track, yielding a good correlation between them. This comparison has been made for different models and different model parameters.

The last chapter is devoted to the establishment of conclusions, which also include new lines of investigation remain open after this work.