PSI - Issue 75

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

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The possible failure modes for a compressor can vary depending on the type of compressor and its application. A common issue regarding the validation of the compressor design concerns the mechanical root cause of electrical failures: failures in the motor, starter, or other electrical components can cause the compressor to stop working. For the specific case of an electrically driven compressor in an automotive application, as discussed in the provided paper, the validation process focuses heavily on vibration testing and the potential failure modes related to the electronic components and their mounting on the PCB. 1.1. Vibration Tests for Automotive components During driving conditions, automotive products are subject to different types of vibration loadings. The most common are divided into shocks (highly transient events, such as potholes, bumps, sidewalks, and in general all the unpredictable irregularities o f the road) and stationary (those signals originated from “normal” driving situations, e.g. highways driving). In order to assess the durability of automotive products, car component manufacturers are required to validate the mechanical endurance of the components according to qualification tests that are supplied by each car constructor. Vibration specifications are commonly performed on a mono-axial dynamic tests bench, therefore the samples to be tested are loaded separately for vibration in the vertical direction (Z axis), longitudinal direction (Y axis) and latitudinal direction (X axis). The most commonly used types of vibration signals can be divided into four groups [1]: 1) Fixed sine: a number of sinusoidal cycle loadings are conducted at a given frequency and at a certain level of acceleration (Figure 1a). 2) Swept sine: as opposed to a fixed sine, the sinusoidal cycles are swept in frequency and/or amplitude (Figure 1b). 3) Shocks: excitation type half-sine (also called pulsed signals): the component under validation normally undergoes a shock input in both directions (e.g. +Z ; -Z) (Figure 1c). 4) Random (PSD): vibration tests used to simulate the random vibration environment encountered during driving conditions (Figure 1d). A random signal is the most realistic signal for the design validation of components mounted on the body (chassis) or in the cabin.

Figure 1. Example of classical vibration signals used for validation of automotive components. a) fixed sine; b) swept sine; c) half sine shock; d) random noise (PSD).