In this work, the authors have developed a Matlab‘ tool called “TTBS01”, which implements the method for the calculation of braking performances described in (2]. The tool has been validated on experimental results con- cerning AnsaldoBreda EMU V250. The results, which will be detailed through this paper, showed an acceptable agreement with experimental tests, and then confirmed the reliability of the proposed tool and its applicability to the prediction of stopping distance of different types of trains in various operative conditions, including degraded con- ditions and failure of some subsystems. The proposed tool can thus be adopted in the design phase to choose proper dimensions of the braking system components and to pre- liminarily evaluate their performance.

Since the detailed description of the calculation method is directly available on the reference regulation (2], in this work, the authors will give a more general description of the

Fig. 1 EMU V250 vehicle composition and braking plant layout

L. Pugi et aJ.

algorithm, focusing mainly on the considered test case, the numerical results, and the matters that have proven to be critical during the validation activities. A particular attention has been paid to some features that are originally not pre- scribed by the regulations in force, but could be considered to further increase result accuracy and reliability. In particular, some parameters, such as friction factor of braking pads, which should be slightly variable according to different operating conditions, were identified and tabulated.

2 The test case: the EMU V250 train

The simulation tool described in this paper, named “TTBS01”, was tested and validated using the data obtained on an Ansaldo EMU V250 train: a high-speed electrical multiple unit for passenger transport with a maximum operating speed of 250 km/h (maximum test speed 275 kin/h), composed of two train sets of eight coaches. The traction is distributed with alternating motor and trailer vehicles in the sequence “MTMTTMTM”, where M indicates motorized coaches and T the trailer ones. The arrangement of each motorized wheelset is B0-- B0. Train composition is shown in Fig. l: the motorized coach traction motors can be used for electro-dynamic braking types, both regenerative and dissipative. The 2nd and the 7th coaches are equipped with an electro-magnetic track brake that should be adopted in emergency condition. The mandatory pneumatic braking system is implemented with the support of both direct and indirect electro-pneu- matic (IEP) operating modes: the braking command can be directly transmitted by wire to the BCU (braking control unit) on each coach, or indirectly, by controlling the pressure of the pneumatic pipe, as seen in the simplified scheme shown in Fig. 2.

BAG

EP assist valve Ep assist valve

Brake Pipe

BAG

Driver Valve

Distributo nd braking unit

First Caach M1

Fig. 2  Braking plant in the IEP  mode

ringer

Distributor and Distributor and Distributor d (braking units , braking units braking units

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Intermediate  coaches ustCoach   M8

J. Mod. Transport. (2013)  21(4):247-257

Design and preliminary validation of a tool

2.1 Further controls: double pressure stage and load

sensing