The Simulation And Analysis Of Interference Fit Of The Engine Connecting Rod Bush

As a power source, engine is one of the largest amount and the most widely used machines. With the development of economic and technology, the technology of engine also develop rapidly. Connecting rod is one of the core power transmission components of engine, when in the course of the work, it bears cyclical changing combustion pressure and inertia force of alternating load, the mechanical load is serious, working condition is poor. Therefore, the reliability of connecting rod in the engine has been studied hot in order to improve it.The sliding bearing-bush is pressed into the small end of the connecting rod, in order to avoid the the stress concentration in the connecting rod small end, which belong to the interference fit of thick cylinder and thin cylinder. The traditional interference theory are based on the model of thick cylinder, which is not suitable for the interference fit of bush and the small end of connecting rod. In long time, the installation of bush is basced on experiences and lacked of a good theoretical support system. This paper make an analysis for a certain engine, received a reasonable amount of interference, and extended to such model. The research contents are as follows.1) Simplify the model of the small end of connecting rod and bush, which belong to thick cylinder and thin cylinder respectively.2) Based on the existing theory of thick cylinders, make a reasonable assumption for the forces on thin-walled cylinder. Deducing the formula of the stress and strain of the thin-walled cylinder which under external pressure and the formula of the amount of interference fit of thick cylinder and thin cylinder base on the Lame formula.3) Aanalysis the force of a certain type of engine in the work process, calculating the minimum pressure in the small end of connecting rod and bush when they bear the maximum loads and the maximum pressure which ensure the connecting rod and bush won't take place plastic deformation, which the amount of interference range will be obtained;4) Using the ANSYS software to Make a simulate analysis, which obtains the maximum stress and contact stress in the different amount of interference. Then compare with the theoretical values to verify the correctness of theoretical calculations, and the practicality of ANSYS software;5) Design ANSYS program, achieving to the parametric design in order to fit the rest of the models.The results of research show that, the formula for the amount of interference of thick cylinder and thin cylinder is suitable for the small end of connecting rod and bush, and using the ANSYS software can achieve to the parametric design of such issues.