Virtual Fatigue Test Research Of A Type Of Internal Combustion Engine Crankshaft Based On Multi-body Dynamics

As internal combustion engine crankshaft is the most important part,its main form of failure is fatigue failure,how to carry out the anti-fatigue design in crankshaft structure design phase,estimate fatigue strength and full cycle fatigue life,and complete different structural design optimization,they are the important content to enhance the reliability of internal combustion engine structure.The paper applies widely recognized virtual fatigue test technology that based on multi-body dynamics theory,fatigue damage theory and finite element theory to crankshaft fatigue research by numeral simulation software.Firstly,dynamics simulation analysis is carried out on the crankshaft system in ADAMS.take full load case as the research condition,and then establish the coupled dynamic simulation model of crankshaft system that includes flexible crankshaft to get the modal coordinates time load history;secondly,use ANSYS to carried out finite element modal analysis of crankshaft to determine its each order natural frequency and vibration mode,then calculate the working frequency of the crankshaft,because its natural frequency and working frequency is relatively close,thus to determine the application of modal stress recovery theory to the full cycle of crankshaft fatigue life calculation.At the same time,extract dynamic boundary conditions in dynamic simulation to conduct transient intensity calculation for stress information;at last analyze and evaluate fatigue strength and full cycle fatigue life,forecast S-N curve of crankshaft materials by theory,according to the structure characteristics of crankshaft to calculate fatigue comprehensive influence coefficient,hence fatigue strength evaluation is completed.And then the results of different types are brought into nCode DesignLife,use modal stress recovery theory to calculate the full cycle fatigue life of crankshaft.The virtual fatigue test results show that fatigue strength and full cycle fatigue life can satisfy design requirements.In conclusion,this paper uses virtual fatigue test technology to carry out the internal combustion engine crankshaft fatigue research that completes on crankshaft fatigue strength assessment and full cycle fatigue life calculation completely with the aid of computer platforms.In internal combustion engines and other product design phase,this technology can be used for the structure fatigue life evaluation,selection of design plan and providing reference for the fatigue test of physical prototype in order to save time and economic cost.