PSI - Issue 75

Said Allouch et al. / Procedia Structural Integrity 75 (2025) 299–310 S. Allouch/ Structural Integrity Procedia (2025)

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The design spectrum is superposed by several partial-spectrum (different driving maneuvers) and described by their distribution, the number of cycles (run time) and the maximum stress. Besides, the maximum local stresses, which are the unknown figure/quantity, all other parameters are defined by the LBF design spectra. Therefore, for the complete definition of the LBF design spectra, these maximum stresses (spectra maximum values) must be determined. The maximum values of the spectra are caused by two different scenarios:

• Dynamic wheel forces that occur during straight driving • Quasi-static wheel forces that arise during cornering

The design forces, which are the maximum forces of the wheels, are derived based on existing measurement data or existing LBF load assumptions. 3. Load File Development To transfer the design spectrum to the test environment a load file needs to be developed in the next step. The load file development process is critical for ensuring that the design spectrum accurately reflects the real-world loading conditions that wheels experience throughout their operational life. This process is inherently iterative. Initially, measurements are taken on our LBF flat base roll rig, where a strain-gauge equipped wheel is used to record the local strains over one revolution. These strain measurements are then converted into required fatigue strength (RFS) values, which define the LBF design spectra (Sonsino et al., 2020), (Sonsino C. M., et al., 2021).

Fig. 2. BiAx/ZWARP load file development