Analisa Kegagalan Pegas Ulir Pada Bogie Tipe Nt 11 (K5) Untuk Gerbong Kereta Ekonomi (K3)

Abstract

Abstract : Fracture on thecoil spring of bogie NT 11 (K5) of the economic passenger car(K3) is one of the causes railway accidents. The purpose of this study is to determine the cause of the failures and alternative solutions that can be done to reduce accidents. Material of thecoil spring is spring steel SUP 9. Physical characteristics were analyzed by the chemical composition investigation, macro-micro structur, SEM investigation, while the mechanical characteristics were analized bytensile shear stress test, compression shear stress test, impact test, and hardness test. Finite Element Method was used to determine the stress distributions at thecoil springs. Test results showed that cause of the failure in the coil springswere as follows: 1) the chemical composition such as 2.010 % Si, 1.090 % Cr, 0.073 % P were higher than the standard spring steels JIS SUP 9 so that to increase the hardness, while 0.035 % Cu was lower than standard spring steels JIS SUP 9 that causes corrosion. 2) gap of 10 mm made the spring was active so that the highest stress is in this area andthat causes the cracks. The solution is 1) Si, Cr, Cu and P elements were to be adapted the standard JIS SUP 9. 2) make the gap of the coil springs with a die gap of 1 mm.

Keywords : Failure analysis, Coil spring, Finite Element Method