Recent advancements in electric buses and the increasing use of lithium-ion batteries have introduced new challenges in the design and analysis of battery packs. These challenges primarily stem from the need to optimize performance, enhance safety, and extend battery life. The design and production of battery packs for electric buses must consider random vibrations and varying environmental conditions, as these factors can significantly impact battery fatigue life and overall performance. The main objective of this thesis is to investigate the fatigue life of electric bus battery pack under conditions of random vibrations and to propose design improvements to enhance their durability and safety. Random vibrations may be caused by factors such as uneven roads, temperature changes, and varying driving conditions, which can lead to fatigue and ultimately damage the battery pack. In this study, the focus was on simulating the ISO 6469 standard under conditions of random vibrations. To achieve this goal, various stages were undertaken in this research. Initially, a precise three-dimensional modeling of the battery pack was performed using SolidWorks software. Subsequently, several types of analysis were conducted in Abaqus software, including the determining natural frequencies, dynamic steady-state analysis, and random vibration analysis. The analysis of natural frequencies helped identify the frequencies that might be prone to amplification, while the dynamic steady-state analysis examined the battery pack's response to periodic loads. The battery pack designed in this thesis had three natural frequencies within the frequency range of the ISO 6469 standard loading, which led to amplifying vibration in the battery pack structure. In this research, random vibration analysis was conducted to assess the resilience of the battery pack against irregular random loads. The analyses performed in this section were crucial for eva‎luating the impact of random vibrations on the battery pack structure and determining its resistance to this type of loading. After an initial eva‎luation of the battery pack's resistance, fatigue life analysis was conducted using FE-Safe software. By employing the Dirlik method, this analysis showed that the fatigue life of the battery pack under random vibration loading according to ISO 6469 standard was 1037 hours. Given the 12-hour loading interval of random vibrations as per the ISO 6469 standard, these results indicate that the battery pack has successfully met this standard.

محسن اصفهانيان

سعيد ضيائي راد

مهران مرادي غريبوند , محمد مشايخي