PSI - Issue 57

Marco Bonato et al. / Procedia Structural Integrity 57 (2024) 799–809 / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 8. Comparison of the HVCH bracket damage for equivalent PSDs obtained with combinations of Q and b.

The effect of the parameters and the resulting useful life at the hot spots of the alternator are shown in Figure 20. Compared to the HVCH, the difference in cumulative damage between the three equivalent PSDs is less dramatic (Figure 20). The fatigue damage calculated at the same node of the bracket has been normalized to the reference PSD, i.e. the one obtained with b=10 and Q=17. In the case of different combinations of the FDS settings, the results over estimate the cumulative vibration damage by a factor of 2.5.

Figure 9. Comparison of the alternator casing damage for equivalent PSDs obtained with combinations of Q and b.

4. Conclusions & Further Works OEMs can provide complex vibration signals for Valeo product validation, such as random sinusoids, more random shocks, multiple SPDs. Finite element analysis is used to evaluate the strain and stress tensor over the entire product. Specific post-processing is then performed on the high-level stress/strain region of the structure. Unfortunately, due to the size of our finite element models, it is not possible to run this simulation in a time domain using a transient methodology. The frequency approach is therefore preferable. Special care and methodology must be taken to synthesize an appropriate equivalent vibration signal in the frequency domain, as discussed in this paper. Depending on the failure mode (mechanicalpart failure or electronic part failure), the dampingratio Q and the Basquin fatigue coefficient b must be correctly selected as described in the two use cases HVCH and alternator. Correlation activities between physical validation tests and simulation models should be carried out to strengthen numerical validation, which is a key factor in reducing development time.

Acknowledgements

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