PSI - Issue 77

Miloslav Kepka et al. / Procedia Structural Integrity 77 (2026) 272–278

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more detailed research purposes, signals were selected from those gauges positioned on the most heavily stressed welded joints—specifically, the joints of vertical window and door posts with the horizontal roof-supporting profiles. The vehicles were tested under real operating conditions, on the same route both when empty and when fully loaded (the latter simulated by artificial loading equivalent to passenger weight). For the processing of measurement signals and for the generation of rainflow histograms, the HBM nCode software was employed. In fatigue analyses, it is common practice to pre-filter small amplitudes from the measured signals. In this case, a gate value of 2 MPa was applied in nCode. The partial recordings were not concatenated into a single continuous signal to avoid discontinuities between individual signals and thereby prevent potentially erroneous results in the load analysis. For each recording, a uniparametric load histogram was generated using the rainflow method. An example of the evaluation of a load spectrum with nCode is presented in Fig. 5.

Fig. 5. Workflow of the evaluation of a load spectrum.

A complete evaluation of the cumulative stress spectra for two selected strain gauges, T14 and T35, on the bodywork of the SKODA 27Tr trolleybus is shown in Fig. 6.

Škoda 27Tr

T14 – empty (Pilsen )

T14 – empty (Bratislava)

T14 – full (Bratislava)

T14 – empty (Pilsen)

1 100 100001000000 5 65 125 H

1 100 100001000000 5 65 125 H

5 45 85 125

5 65 125

Δ Smax

Δ Smax

Δ Smax

Δ Smax

1

1000

1

1000

H

H

T35 – full (Pilsen )

T35 – empty (Bratislava )

T35 – full (Bratislava)

T35 – empty (Pilsen)

5 45 85 125

1 100 100001000000 5 65 125 H

5 45 85 125

5 65 125

Δ Smax

Δ Smax

Δ Smax

Δ Smax

1 100 10000

1

100 10000

1

100 10000

H

H

H

Pilsen city

Bratislava city

ν = 1,00

ν = 0,99

T14

Empty bus T14

Empty bus

ν = 0,95

ν = 1,08

Full bus

T14

Full bus

T14

ν = 0,97

ν = 0,99

T35

Empty bus T35

Empty bus

ν = 0,89

ν = 0,92

Full bus

T35

Full bus

T35

Fig. 6. Evaluation of the cumulative stress spectra – SKODA 27Tr.