Study On Virtual Fatigue Test Method Of Electric Vehicle Reducer Based On Actual Load Spectrum

At present,the main form to drive electric vehicle is the scheme of "motor +reducer".The reducer will be replacing the transmission of the traditional vehicle and become an important part of the transmission system.Its fatigue reliability is related to the driving safety of the vehicles.In recent years,with the rapid development of cutting-edge computational technology such as CAE,the utilisation of virtual testing technology has been greatly promoted.In the stage of product development,the use of virtual testing technology can effectively improve the product development,save development costs and shorten the period of research and development.However,the current virtual testing on the reducers is meeting issues that the loading signal is simple where it is difficult to reflect the real load condition of the reducer in the process of actual driving,which leads to the poor reliability of the results.Therefore,provided is a thesis illustrating the virtual fatigue test method of reducer based on the load spectrum collected by real vehicle,which contains great theoretical significance and engineering application value in which the accuracy of virtual test can be vitally improved and the duration of design and development of reducer will be decreased.The overall methodologies can be demonstrated below.Firstly,combining the laser speed sensor,the six-component force sensor and the CAN bus,etc.,a real-vehicle load spectrum acquisition scheme for electric vehicle reducers was established,and the actual vehicle load spectrum acquisition was carried out.Combining information such as vehicle speed and logic switches,the load spectrum of each typical road was identified and intercepted,and time-frequency domain analysis was carried out.The harder and more energy-consuming enhanced road surface and rapid acceleration and emergency control in dynamic conditions were selected to be the input load for the virtual test of the reducer.Secondly,a virtual fatigue test system was proposed for a certain two-stage fixed speed ratio reducer.The three-dimensional model and finite element model of the transmission components of the reducer were established,and the statics analysis was carried out.A virtual fatigue test system model of the reducer with multiple rigid bodies was established by adding boundary constraints such as driving and load.On this basis,the flexible body file of the gear was extracted,and the rigid-flexible coupling virtual fatigue test system model of the reducer was established,and its kinematics and dynamics were verified.Thirdly,the rigid-flexible coupling virtual fatigue test of the reducer was debugged based on the fixed-value signal and the measured load spectrum.And the dynamic simulation was performed respectively by using the driving load on the road surface was strengthened and the rapid acceleration and braking in the dynamic conditions as input forces.Through analysis,the gear meshing force load spectrum was extracted,and the meshing force load spectrum of each working condition was connected.Finally,according to the extracted meshing force load spectrum,the finite element result file and the modified S-N curve of the material,the fatigue life of the reducer gear was analyzed and evaluated based on the Design Life application of the nominal stress method.On this basis,a virtual fatigue test method of electric vehicle reducer based on actual load spectrum is established.