Analysis of diesel engine crankshaft torsional vibrations

The development and application of a technique for the transient analyses of diesel engine crankshaft torsional vibrations is presented in this paper. Crankshafts in emergency diesel generators undergo torsional vibrations due to the effect of cylinder firing pressure and the inertia of the reciprocating parts. Computer program STAMS (Shaft Transient Analysis by Modal Superpostion) has been developed at Failure Analysis Associates (FaAA) for the dynamic transient torsional analyses of crankshafts. This program is based upon a modal superpostion approach, also known as the normal mode method, and provides an efficient means for the solution of forced vibration problems. STAMS predicts the free-end amplitude of vibration and the stress amplitudes at each shaft section in a crankshaft. The modal superposition method is briefly discussed, followed by a detailed description of STAMS. Comparisons of the analytical results obtained using STAMS with test data obtained during testing of diesel generator engines is included. A brief description of the use of the results from STAMS is then presented. (orig./GL)