Fatigue Test and Calculation Methods for Battery Package Based on Load Spectrum

As one of the core components of electric vehicles, battery package has a critical impact on the overall performance of the electric vehicle. During the operation of electric vehicles, the battery package is constantly subjected to continuous impact from the road, causing fatigue damage to the battery package, which affects the safety of drivers and passengers as well as the performance of the whole vehicle. Taking battery package of electric vehicles as research object, this study established random vibration test method and calculation method for fatigue life of battery package. Firstly, it carried out frequency sweep analysis on Shaker table, fixture and battery package, and obtained the values of the acceleration sensors at shaker table surface, fixture unloaded end plate, and the connection end plate between battery package and fixture, which were consistent with the input frequency sweep acceleration values, verifying the effective transmission of the vibration signal and ensuring that the input vibration signal can be accurately transmitted to the battery package. After that, random vibration test of battery package was carried out. Cell performance testing, air tightness inspection, insulation resistance inspection, and resonance frequency inspection on the battery package were conducted and the damaged parts of battery package were obtained. The calculation method of battery pack fatigue damage was studied, and the battery box, battery module and battery pack were finely modeled. Based on the fine modeling, frequency response of battery package was analyzed. Based on the results of frequency response analysis and the random vibration load spectrum curve of the battery package obtained from the vehicle road spectrum acquisition test, and combined with the S-N curve of the battery pack material, random vibration fatigue life of battery package was analyzed under load spectrum by using Goodman fatigue life estimation method and Miner linear cumulative damage rule. The damage positions of battery package obtained from the test are in good agreement with the failure positions obtained from the analysis, which confirms the accuracy of the fatigue life calculation method proposed in this paper.