PSI - Issue 18

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000–000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 18 (2019) 443–448

25th International Conference on Fracture and Structural Integrity Discovery of the Source of the Vehicle Brake Discharging Resistor Box Failures Jan Chvojan*, Jiří Német, Jaroslav Václavík Research and Testing Institute Plze ň Ltd., Dynamic Testing Laboratory, Tylova 1581/46, 30100 Plze ň , Czech Republic 25th International Conference on Fracture and Structural Integrity Discovery of the Source of the Vehicle Brake Discharging Resistor Box Failures Jan Chvojan*, Jiří Német, Jaroslav Václavík Research and Testing Institute Plze ň Ltd., Dynamic Testing Laboratory, Tylova 1581/46, 30100 Plze ň , Czech Republic

Abstract Abstract

The comprehensive testing program is described to determine the reason of early damage of insulators of brake discharging resistor box including laboratory tests, measurement during the trolleybus operation in Bologna and tests on vibration tables to find the best improvements for decreasing the insulator stress. The comprehensive testing program is described to determine the reason of early damage of insulators of brake discharging resistor box including laboratory tests, measurement during the trolleybus operation in Bologna and tests on vibration tables to find the best improvements for decreasing the insulator stress.

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.

Keywords: Trolleybus; brake discharging resistor box; insulator; strain gauge test; laboratory vibration test; Bologna Keywords: Trolleybus; brake discharging resistor box; insulator; strain gauge test; laboratory vibration test; Bologna

1. Introduction The brake discharging resistor box is a part of traction vehicles. It serves for energy dissipation during vehicle electrodynamic braking. The internal design of the box is very easy; it includes blocks of resistors (Fig. 1a, pos. 8), fixed on several internal insulators (pos. 12). Here presented discharging box is assembled on the roof of the ŠKODA trolleybuses (Fig. 1b) using another set of insulators (pos. 12), operating in the town passenger fleet in Bologna, Italy. Trolleybuses are also incorporated to traction vehicles and use the same principle of energy dissipation. The fracture of the box internal insulators appears after a relatively short period of trolleybus performance. It should be mentioned here, that the same discharging boxes were used for another trolleybuses in other towns without problems. The box producer has successfully performed the vibration test of the box according the standard EN 61373 where the long life test is simulated with the tree-axes vibration signal, derived from several different measurements. Hence the opinion 1. Introduction The brake discharging resistor box is a part of traction vehicles. It serves for energy dissipation during vehicle electrodynamic braking. The internal design of the box is very easy; it includes blocks of resistors (Fig. 1a, pos. 8), fixed on several internal insulators (pos. 12). Here presented discharging box is assembled on the roof of the ŠKODA trolleybuses (Fig. 1b) using another set of insulators (pos. 12), operating in the town passenger fleet in Bologna, Italy. Trolleybuses are also incorporated to traction vehicles and use the same principle of energy dissipation. The fracture of the box internal insulators appears after a relatively short period of trolleybus performance. It should be mentioned here, that the same discharging boxes were used for another trolleybuses in other towns without problems. The box producer has successfully performed the vibration test of the box according the standard EN 61373 where the long life test is simulated with the tree-axes vibration signal, derived from several different measurements. Hence the opinion

* Corresponding author. Tel.: +420-371-430-710. E-mail address: chvojan@vzuplzen.cz * Correspon ing auth r. Tel.: +420-371-430-710. E-mail address: chvojan@vzuplzen.cz

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo.

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Gruppo Italiano Frattura (IGF) ExCo. 10.1016/j.prostr.2019.08.186