VIBRATIONAL CHARACTERISTICS OF A ROTATING SHAFT CONTAINING A TRANSVERSE CRACK

ABSTRACT:The influence of a transverse crack upon the dynamic behavior of a rotatingshaft is studied. Introduction of such a crack results in lower transverse naturalfrequencies due to the added local flexibility. The strain energy release function isrelated to the compliance of the cracked shaft that is to the local flexibility due tointroduction of crack. This function is related to the stress intensity factor, which fortransverse of a shaft with a crack has a known expression. As a result, the localflexibility of the shaft due to the presence of the crack has been computed. This result,can be further utilized to yield the dynamic response of a shaft with complex geometry.Starting from the equation of motion for the shaft under bending to derive theexpression of calculating the natural frequency of the shaft.Two cases of fixing the shaft are suggested in this study to investigate andanalyze the vibration characteristics of the shaft with and without cracks. Thefundamental natural frequency showed strong dependence on the crack depth, Thisdependence is smaller as the order of the frequency increase. Experimental results are inclose agreement with those practical from the theoretical analysis. Finally, the resultsshowed that the change in dynamic response due to the crack is high enough to allowthe detection of the crack and estimation of its magnitud