Paper Title
Torque Design, Analysis And Characterization Of Critical Fasteners In Diesel Engines

It is well known that in the assembly of diesel engines large numbers of fasteners are used. They are mainly to provide leak proof joints, assembly of various components etc. In and off the working, they are subjected to various loads. Currently, pre-tensioning load of fasteners is an area of interest and concern for design engineers dealing with the assembly of Diesel Engines. Present work details out the analysis of critically loaded fasteners of cylinder head and connecting rod to prevent potential failure modes such as embedding, clamp load loss, bolt yielding and bolt fatigue failure. In this investigation analytical approach is used to estimate external forces to which joints are subjected. Preloading force to be applied is calculated on the basis of percentage yield of bolt. Fatigue analysis is carried out for this preload using Goodman line criterion. Cover factor is calculated taking into account losses due to embedding, relaxation and temperature effects on preloads. This cover factor was compared with permissible values for safe design. On the basis of estimated preloads elongation of bolts and deformations of mating parts were calculated. Elongation of bolts is then obtained computationally using FEA software ANSYS 14 and experimentally. Experiments were conducted with two different tightening techniques; direct torque tightening technique and angular torque tightening technique. The elongation of bolt was measured by using “ultrasonic bolt meter”. The characteristic curves between Angle vs. Elongation were plotted to compare the analytical, FEA and experimental results. It is observed that these results compares well within permissible deviation. The characteristics curves reveals that angular torque tightening technique gives better results to achieve desired preload in fasteners than direct torque tightening technique. The parametric study is also carried out to develop correlation between Angle turned and elongation, for bolts used in different engines.