| The mechanical properties of battery pack structure,especially the fatigue performance,directly affect the stability of energy system,which is related to the safety and reliability of the entire electric vehicle(EV),and somehow affects the development of new energy automotive industry.However,the battery load conditions are relatively complex,conventional analysis methods like fixed frequency vibration analysis,sweep frequency vibration analysis,and random vibration analysis,will not truely reflect the practical performance of battery pack,the load spectrum measuring requires high cost and long time,and typical working conditions which used in traditional automobile may not be suitable for the electric vehicle,virtual test technique is not good enough in simulation precision.In order to obtain accurate load spectrum and predict the fatigue performance of EV’s battery pack,virtual iterative technique combined with mesured road spectrum is used to study the prediction method of load spectrum and fatigue performance of battery pack takes an electric vehicle as the object.The research status of power battery pack is introduced,and the necessity of the research method of fatigue performance of EV’s battery pack is expounded.The finite element model of battery pack is established based on the actual battery pack structure,and the model is verified by experiment.The basic mechanical properties of the battery pack were studied based on the battery pack finite element,in which the static analysis and dynamic analysis are carried out under different working conditions.The road spectrum acquisition scheme of the electric vehicle is developed with reference to the relevant standards,and the battery pack road spectrum acquisition system was built with dynamic signal tester and the accelerometer and other sensors.The road spectrum are collected under the real load environment from urban roads,highways and bad roads,etc.The response to the road excitation is preliminary analysed.The virtual six-channel test bench of the body-battery pack system is built,to reconstruct the load spectrum of the battery pack.the body-battery pack rigid-flexible coupling multi-body dynamics model based on the virtual test bench is used,combined with the collected battery pack road spectrum.The battery pack load spectrum is simulated by virtual iteration,and the convergence of the iteration is verified by signal comparison.Based on the multi-body model of rigid-flexible coupled battery pack system virtual test bench,the battery pack fatigue test is carried out with the load spectrum obtained by virtual iteration.Considering the dynamic effect of battery pack structure,the modal stress superposition method is used to solve the fatigue problem of the battery pack structure,and the improvement scheme is put forward.The research method integrate the road test with virtual simulation to realize the acquisition of the road random excitation spectrum and the prediction of the fatigue performance of the battery pack.The research has practical significance for the improvement of the general battery pack structure and the development of the new product.The method has important reference value for the study of vibration response characteristics related to battery pack structure. |
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