Novel Service Lifetime Estimation for an Oil-Damper Rubber Bush for a Railway Vehicle
A railroad bogie's components experience repeated loading during service. Especially, the oil-damper rubber bush becomes fatigue fractured on the plane between the rubber and the steel stem during service, and this results in inferior performance of the bogie. In this study, in order to offer a proper maintenance method for the bush, a novel service lifetime estimation for an oil-damper rubber bush operating under different repeated loads was proposed by normalizing the degrading rate of its spring constant. When 13,720 N, 11,760 N, and 9,800 N of repeated loads were applied to the rubber bush, final damage fraction was shown to be 63.7%, 50% and 40%, respectively. The normalizing lifetime (N/Nf) can be predicted as a function of damage fraction (D/Df), regardless of the load amplitude, as follows: N/Nf = 0.043 + 0.376(D/Df) + 0.489(D/Df)2.