Analysis Of Deformation And Failure Behavior Of CID In Prismatic Power Batteries

Currently,with the more and more serious environmental pollution,electric vehicles are developing rapidly.Power battery is an important component of electric vehicles and the CID is an important safety component to prevent thermal runaway and pressure runaway during battery use.Considering the serious consequences of thermal battery runaway and pressure runaway,it is significant for us to carry out the research on the safety structure of the power battery to improve the safety of the power battery and the whole vehicle.Firstly,in order to explore the elastic-plastic properties of MFX2 aluminum alloy,the elastic-plastic tensile test was designed at different temperatures.The isotropic hardening multilinear elastic-plastic constitution of MFX2 aluminum alloy is established based on the experimental data,and the notched tensile test is carried out to verify the constitution of MFX2 aluminum alloy at 80℃.The verification results are reasonable,which proves the validity of the elastoplastic constitutive model.The overturning pressure and the overturning displacement of the CID are discussed separately,and the instantaneous pressure simulation analysis is designed for the overturning pressure,and the simulation analysis is designed for the solution of the overturning displacement.Overturning pressure is 0.7MPa and the overturning displacement is1.34 mm at room temperature.Then,the creep test of MFX2 at various temperatures is designed based on a lot of test data,The creep constitution,the time hardening Norton constitution can describe the first and second stages of material creep,is established based on the experimental data.After the simulation verification of the creep test of the notched test piece of the aluminum alloy creep constitutive at80°C,the simulation curve is consistent with the test curve,which proves the validity of the creep constitutive model.The finite element model of the CID is established by a lot of experimental date and object.In order to study the influence of temperature and load on the creep deformation behavior independently,the simulation test in the constant temperature and constant load of CID is designed.The test temperatures are 60,80,100 ℃,the test load levels are 0.1,0.2,0.3,0.4MPa,the test temperature is 150 ℃,the test load level are 0.02,0.05,0.1MPa,the simulation test lasts for 88000 h.The conclusions are as follows:(1)The increase of temperature and load will lead to the increase of the displacement rate of the CID,the advance of overturning time,the reduction of service life of power battery.(2)The creep of materials will affect the deformation and failure of the CID seriously,and the degree of influence will increase with the increase of temperature and load.In the end,the simulation test of the CID with the constant temperature and variable load is designed.The test temperature is 60,80,100 ℃,and the test load is 0 ～ 0.7MPa.The conclusions are as follows:(1)When the temperature is 60℃ or above,the CID will flip ahead of time,leading to the failure of the power battery.(2)The overturning pressure of the CID also decreases with the increase of temperature.(3)Because of the early overturning of the CID caused by creep deformation,the effective service life of the power battery is greatly reduced with the increase of temperature.