PSI - Issue 18

Jan Chvojan et al. / Procedia Structural Integrity 18 (2019) 443–448 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The box was also tested for original variant in transversal direction under conditions from standard EN 61373 for functional test for class 1B. The strain amplitudes were very small, say one order lower, than strain peaks or amplitudes measured during operational test in Bologna. The random signal of standard condition and small acceleration were not able to excite the bending mode of the box. The final goal was to reduce these resonance oscillations. Several modifications of the clamping the box as well the internal box stiffness were tested; the resulting easiest but most effective is presented in Fig. 8b. Here the transversal movement of the resistor blocks is reduced with the plate, connecting both blocks in both front and rear sides. Making this arrangement the stress amplitudes drop to 20% of the values, measured during operational tests in Bologna. 3. Conclusion According the laboratory tensile tests, the strain level causing the insulator damage was estimated. During the operational tests in Bologna the transversal damage loading mode was determined as the dominant and the representative acceleration profile was derived for laboratory vibration tables excitation for all three directions. The vibration tests confirm also that the reason of insulator damage is bending of the insulators. Several modifications were tested to lower this insulator bending. The best solution was found using the plate, connecting both internal resistor blocks. It is easy to implement on the trolleybus. Using this modification, the insulator strain is lowered more than five times, which prevents the insulators damage. Thus the trolleybuses producer have solved out the bad design of the discharging box supplier. Acknowledgements The article has originated in the framework of the institutional support for the long-term conceptual development of the research organization. References

ČSN EN 61 373: Railway applications - Rolling stock equipment - Shock and vibration tests, September 1, 2010.