Dynamic Stress Calculation Of Engine Connecting Rod Based On Multi-body Dynamics

As one of the most important parts of an engine, the connecting rod is under tremendous stress from the reciprocating load represented by the piston, actually stretching and being compressed with every rotation, and the load increases as the square of the engine speed increase.Failure of a connecting rod is one of the most common causes of catastrophic engine failure in cars, frequently rendering the engine irreparable. Therefore,the dynamic characteristics study of the connecting rod are of great significance to the reliability analysis of the connecting rod.The development of Multi-body System Dynamic makes precise analysis of the connecting rod possible.In this thesis, the Multi-body System Dynamics as well as the Finite Element Method are taken as main technologies and the Multi-body System Dynamics software ADAMS, FEM preprocess software HYPERMESH as well as the Finite Element Analysis software ABAQUS are taken as main applications, besides, the engine connecting rod mechanism of engine is taken as the the target of research.After analyzing the movement condition of connecting rod mechanics through setting up the geometrical model, the relative motion parameters can be determined by the operating data and the geometric dimensioning. Multi-body dynamics model of the engine connecting rod is built and simulated by ADAMS, and the analysis of mode is carried out by HYPERMESH after that. The dynamic characteristic is studied by the FEM modal analysis, the Modal Neutral File is got at the same time. Finally, the model of the connecting rod is gained by using the flexible-body dynamics simulation model.Due to this method, the virtual prototype models are set up by considering many factors. The internal dynamic stress distribution in 2 cycles is study in order to validate the rationality of the results. The load spectrum of connecting rod is calculated as boundary condition of load in the finite element dynamic analysis based on ABAQUS. The stress calculations under different rotational speeds are determined and compared.By comparing the calculations of two analysis methods, the validity and accuracy of the flexible multi-body dynamics analysis method of the connecting rod are proved. The research provides a theoretical basis for optimization of structure design of the connecting rod.