Finite element analysis of bolted connection of hydro-generator shaft

Aiming at the problem that the low reliability of the result that the maximum stress of bolted connection without gaskets is 72.0 MPa,which is obtained by the traditional safety factor method applied to design the bolted connection of the hydro-generator shaft,a nonlinear finite element model of the bolted connection of the hydro-generator shaft was built by ANSYS,which composed of the fine structure and the general structure. Both parts were connected with constraint equations. The fine structure was a symmetrical 1/12 bolt coupling structure. The general structure,not including the bolts,only simulated the up/down flange which transmitted the torsional moment of the shaft. Elements of TARGE170/CONTA174 and PREST179 were used to simulate the bolt-flange contact and the bolts preload respectively. The stress distribution of the bolted connection structure of the main shaft under the rated working condition with/ without 14.5 mm gaskets was calculated. The results indicate that the strength requirements of the bolted connection structure with/ without 14.5 mm gaskets of the main shaft can be both satisfied. In terms of the no-gaskets structure,the maximum stress of the bolts is 92.6 MPa which increases by 28.61% compared with the results obtained by the safety factor method. In terms of the structure with gaskets,the maximum stress of each component increases by 4.10%~8.55%. The maximum stress of the bolts is 96.4 MPa,which increases by 4.10% compared with the no-gaskets structure.