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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The latest version of nCode provides specific glyphs that perform the generation of time series for sine-on-random signals. The FDS is calculated by numerical integration and scaled to the total duration of the customer specification. Then, the equivalent sine sweep is obtained by inversion of the FDS as explained in Section 1.3.

Figure 6. Sensitivity of b & Q factor for a equivalent sine sweep spectrum (from SSoR signal)

1.

Methods and Tools for FEA vibration fatigue

1.1.

Simulation methodology

The HVCH and alternator is modeled using solid 187 tetrahedron elements. This meshing enables us to model the stiffness and mass distribution of the product equivalent to the real part. The different components of the product are connected together through contact elements and material properties (density, Poisson ’s ratio and Young's modulus) are assigned to each component. Boundary conditions representative of the mounting conditions of the overall product are also modeled. As a first step, a modal analysis of the overall product is done to evaluate the natural frequencies. Then a 1g Frequency Response Function (FRF) is calculated.Adding to this FRF on one hand the mechanicalloading (equivalent random signal described in section 1.5 for the HVCH product and equivalent sinus signal described in section 1.6 for the alternator product), on the other hand the fatigue material properties (Wohler curves), the nCode vibration fatigue solver is then in position to calculate a damage on the overall product. 1.1.1. Relative Damage For HVCH, the analysis of the stress and fatigue damage results clearly shows that the hot spots are to be found on the component brackets (Figure 7a). During vibration fatigue, the higher stress loads are therefore concentrated on the mechanicalpart of the HVCH, leaving the electronic sub-component (the coils and the PCB) with a negligent level of vibration stress. For the alternator, the FE damage results performed on the alternator clearly shows that the hot spots