PSI - Issue 75

Marco Bonato et al. / Procedia Structural Integrity 75 (2025) 719–729 Author name / Structural Integrity Procedia (2025)

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recommended, because it is a quick simulation but the base modal analysis must be carried out before performing harmonic MSUP analysis[7]. Analysis of the results focuses in particular on the following elements: natural frequency and associated mode shape, stress, operating deflection shape . Fatigue analysis is also used to calculate damage in weak areas of the design (Figure 6).

Figure 6. PCB bending mode, which affects the flyback

3.1 FEA results for the Fixed Sine Signal For the product qualification, the signal provided by the customer is a fixed sine with a frequency of 150 Hz, an amplitude of 7 g, with a duration of 30 hours per axial orientation. From Figure 7, the cumulative damage observed on the flyback transformer is negligible (the fatigue is much lesser than the expected value to reach failure, i.e. damage = 1). This clearly shows that the fixed sine signal is not at all affecting the product as the input frequency is much lower than that of product resonance frequency.

Figure 7. Vibration Fatigue Damage estimated by FEA simulation on fixed sine input.