EXPERIMENTAL INVESTIGATION OF THE EFFECTS OF TORSIONAL EXCITATION OF VARIABLE INERTIA EFFECTS IN A MULTI-CYLINDER RECIPROCATING ENGINE

The failures of crank shaft assemblies because of excessive torsional stresses have long been reported in the literature. Many different factors were attributed these failures. One of the important attributes in case of few marine engines as reported by authors was variable inertia effect. All reciprocating engines have periodically fluctuating inertia function which leads to variation in natural frequencies. This would further lead to a non linear frequency coupling between the torsional natural frequencies of the system and the rotational speed and their harmonics. This is generally referred to as Secondary Resonance. This theory of variable inertia effects and secondary resonance in case of reciprocating engines has been explored, analyzed and confirmed by many earlier researchers, but theoretically. Experimental investigations were not attempted by earlier researchers, to verify the above phenomenon.