Thermal Elastic-plastic Analysis On The Loosening Mechanism Of A Bush Press-fitted In The Small End Of A Connecting Rod

With the continuous strengthening of the diesel engine, the small end of a connecting rod suffers from poorer working conditions. During the process of load bearing, the bush interference fitted in the small end of a connecting rod may run out with loosening, wearing down and erosion failure forms, etc. On account of that, a thermal elastic-plastic analysis on the loosening of a bush press-fitted in the small end of a connecting rod will be done in this paper, studying the mechanisms and key factors of loosening through theories, software simulation and experiments. The main contents are as follows:(1) Taking an interference fitted double thick walled cylinder as a model, theoretically analyze its stress states from the process of “assembling-heating-cooling” based on thermal elastic-plasticity mechanism, separately using elastic material, linear strengthening material and power exponent strengthening material.(2) The axisymmetric finite element model of the interference fitted double thick walled cylinder was established, and the analytical results based on different materials and conditions correspond with the analytical solutions. Then we got the results that the contact pressure between the two cylinders would decrease because of the temperature rise.(3) Three-dimensional finite element model of the connecting rod and its bush were established, and its plastic strain, contact pressure, stress and strain distribution caused by different temperature rise is analyzed in detail.(4) Carry out an experiment of the effect of temperature on the connecting rod and its bush with several specimens, and the case of the loosening situation of different bush material and different forms of bushing at different temperature is compared. The experiment proved the analysis through finite element software right.