Sairam Sundaram

A Method to Predict Fretting in Diesel Engine Connecting Rod Bearing Bores

The highly dynamic nature of the loads imposed by the rotating and reciprocating components of diesel engines makes this machine highly susceptible to fretting fatigue problems. The authors have developed a method to predict the potential for fretting damage between the connecting rod and its big-end bearing shells. This method uses the ABAQUS finite element software package to conduct detailed contact analysis at the interface between the bearing shells and the connecting rod under the applied loads of the engine operating cycle. This analysis can be performed at the design stage, given the geometry of the connecting rod assembly and the data necessary to calculate the loads. Experimental measurements of the coefficient of friction between the bearing shell and the connecting road are presented, since this is an important factor in the contact analysis. Correlations of the predicted fretting damage to observed fretting locations from engine operation are presented for two variants of connecting rod design. As with any design analysis method, caution must be exercised in the application of the technique to new cases and in the interpretation of the results.Copyright

Fretting Fatigue Modeling and Repair Evaluation for Generator Rotors

Generator Rotor Tooth Cracks have been recently observed on some long service generator rotors. The purpose of this paper is to document the root cause analysis as well as a repair methodology that was developed in support of one of these cracked units. The paper discusses the development of a finite element model to understand the operating modes and failure mechanisms that caused the initiation of these cracks. The results of the analysis agreed very well with field observations on cracked units and with some limited repair options that have been successfully used in the past. An experimental fretting fatigue testing program is currently underway to substantiate and extend the results reported in this paper.Copyright