PSI - Issue 75

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

729 11

of the manufacturing process that helps minimize the stress during vibration loads etc. FEA (Finite Element Analysis) was used to optimize the flyback design for manufacturability by simulating its performance under stress, particularly vibration, during pre-production. The simulations identified two main failure points: the application of glue to a critical component (the flyback) and the torque and angle of the screws securing the PCB. By iteratively adjusting parameters in the FEA model, such as glue placement, screw position, and torque values, engineers were able to improve the flyback's resistance to vibration-induced failures and optimize the assembly process for greater reliability and reduced risk of variability (see Figure 9), so that the vibration fatigue damage is lowered to an infinite fatigue life level. This "design for manufacturing" approach using FEA allowed for improvements to be implemented before physical prototyping and testing, saving time and resources. 6. Conclusions The paper investigates the consequences of preliminary design validation phases for an automotive component (an electrical driven compressor) where the vibration validation specification considered for the FEA simulations and accelerated shaker test is not representative of the in-service vibration stress. The use of such non-correlated signals results in the initial validation of the design of the eDC and its sub components, including those that are more exposed to vibration stress, such as the PCB flyback. In the following final vehicle tests, performed by the carmaker on the proving ground, the flyback fails due to the cumulative vibration damage induced on the eDC. The investigation focuses on the difference in predicting the vibration fatigue life when comparing a more representative vibration test (in this case, an internal standards) from both the severity (the fatigue content) and the nature of the signal (a random PSD vs a fixed sine requested by the carmaker). The authors advocate the utilization of FEA simulation to replace as possible long and expensive physical tests, on the condition that the input specification be correlated with the in-service stress. In this paper, the FEA calculations show how the simulation performed on a more representative vibration signal would have highlighted the risk of vibration failure concerning the flyback. The internal specification is used as reference to optimize the flyback reliability by ameliorating its design-for-manufacturing, thanks to FEA based optimization techniques. References 1. M. Bonato and D. Delaux, "Synthesis and validation of accelerated vibration durability tests," 2015 Annual Reliability and Maintainability Symposium (RAMS), Palm Harbor, FL, USA, 2015, pp. 1-6, doi: 10.1109/RAMS.2015.7105195. 2. Duraipandi, A., Raja, A., Leon, R., Ribot, H. et al., 2023. Electrical Driven Compressor – Vibration Correlation for PCB & Electronic Components, SAE Technical Paper 2023-01-0535, https://doi.org/10.4271/2023-01-0535. 3. M. Bonato and P. Goge, "Test tailoring approach for reliability assessment of automotive heat exchangers," 2017 Annual Reliability and Maintainability Symposium (RAMS), Orlando, FL, USA, 2017, pp. 1-7, doi: 10.1109/RAM.2017.7889731 4. M. Bonato and E. Czerlunczakiewicz, "Pitfalls of Accelerated Validation Test on Automotive Components," 2021 Annual Reliability and Maintainability Symposium (RAMS), Orlando, FL, USA, 2021, pp. 1-7, doi: 10.1109/RAMS48097.2021.9605763. 5. Lalanne, C. (2014a), Mechanical Vibration and Shock Analysis, Fatigue Damage, Wiley. 6. Lalanne, C. (2014b), Mechanical Vibration and Shock Analysis, Specification Development, Wiley. 7. Introduction to Mode Superposition- https://innovationspace.ansys.com/courses/wp-content/uploads/sites/5/2021/01/4.3.1_Introduction-to-Mode-Superposition_New_Template.pdf