The Dynamics Simulation Of Engine Crank And Connectuing Rod Mechanism And The Fatigue Life Prediction Of Connectuing Rod

With the improvement of automotive engine performance parameters,crank and connecting rod mechanism operating conditions are becoming bad.As one of the important component parts of engine,connecting rod endures complex and alternate cyclic loading,so its reliability has the direct bearing on performance and use value about complete machine,then fatigue analysis attracts much attention.This paper applies UG to establish three-dimensional solid models of crank and connecting rod mechanism,imports assembly parts into multi-body dynamics simulation software ADAMS to carry out dynamic simulation that is conducted with characteristic of kinematics and dynamics about components obtained.Using the maximum compressive loading and maximum tensile loading as the finite element analysis input data about small-end of connecting rod,this data makes measurements closer to the true value than calculated value.It makes a finite element analysis of connecting rod by finite element software ABAQUS,considers the influence of small-end of connecting rod and the preload in the process of assembly.Analysis result obtains stress distribution of connecting rod with maximum compressive and tensile operating condition.Through static strength checking,connecting rod is reliable.On this basis,fatigue analysis of connecting rod is necessary because it will have fatigue failure with the action of alternate cyclic loading.In the paper,Miner-Haibach model is used to modify the S-N curve of material,and obtain the fatigue property curve of component.Asymmetric cyclic stress is converted into symmetrical cyclic stress according to the fatigue strength theory about mean stress sensitivity coefficients.At last,fatigue life of connecting rod is estimated by nominal stress approach.The research result shows that the failure part of connecting rod is consistent with the actual one.The predicted fatigue life of connecting rod meets the requirement that should have a long life than equivalent service life.So it has better fatigue reliability.This research method has instruction and reference value to estimate reliability about other components of crank and connecting rod mechanism.