PSI - Issue 18

5

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

447

Fig. 7 Time histories of accelerations, used for laboratory tests

b

a

Fig. 8 (a) Discharging box during tests on vibration table; (b) effective modification of the box

During the laboratory test, following observations were found. The strain responses during vibration tests in transversal direction was of more than one order higher than for both other directions and the measured strains levels were comparable with operational once only at excitation in this direction. During the test the resonance movement of resistor boxes was visible with own eyes. The out of phase strain time history of opposite strain gauges in transversal direction was also the same, as measured on the trolleybus. This is in conformity with the results obtained and formulated during operational tests in Bologna that the insulators are stressed from bending in transversal direction.