Finite Element Analysis of the fatigue strength of a big-end bolt

This thesis investigates, with the use of finite element method, the stress formation in a big-end bolt during the power stroke in an IC piston engine. The method used is quasi-static analysis of the lower part of the connection rod (big-end) assembly for different time intervals during the stroke. Two big end configurations is analyzed with the aim of finding regions in the bolt with stress concentrating feature that could induce fatigue. The simulation is, performed with Abaqus FEA software. The results is, compared with previous performed studies, industrial reports and hand calculations. Supported by literature, the results shows that the combination of reduced area due to thread curvature, and forces through bolt from power stroke creates high stresses. The weakest part of the bolt is the first thread, as this carries most of the load. Future work will include improving the FE model and performing FE analysis on other configurations. This could include investigating different bolt configurations and more complex and realistic bolt geometry