Perpustakaan Digital ITB

Indonesia’s intercity railway network is predominantly built on 1,067 mm narrow-gauge track. Increasing the operating speed toward 160 km/h intensifies the competing demands on the passive bogie suspension: settings that improve curving safety and lateral ride comfort may reduce hunting stability. This study optimizes four suspension parameters of a medium-speed passenger vehicle, namely primary longitudinal bushing stiffness (kx), secondary yaw damper (cyaw), secondary lateral air-spring stiffness (ks), and secondary lateral damper (clat). A three-level full-factorial Design of Experiments (DOE) of 81 configurations was evaluated in the multibody software Universal Mechanism (UM). Response Surface Methodology (RSM) was used to fit six second order models: four optimization objectives, the wheel-unloading constraint, and the sum of guiding forces. A controlled elitist genetic algorithm based on the Non-dominated Sorting Genetic Algorithm II (NSGA-II) generated the non-dominated set, from which one compromise design was selected by the Minimum Manhattan Distance (MMD) criterion and verified by direct UM simulation. The selected configuration is kx= 4.430 MN/m, cyaw = 98.61 kNs/m, ks = 76.15 kN/m, and clat = 10.29 kNs/m. Relative to the baseline it lowers the derailment quotient by 24.84%, the lateral Sperling index by 4.29%, and the frame force by 5.41%, while its nonlinear critical speed falls by 14.74% to 81.79 m/s (294.44 km/h), still 67.3% above the adopted requirement. Direct simulation differs from the RSM predictions by at most 2.02%. Threshold, window, and local parameter variation analyses confirm that all adopted criteria remain satisfied within the DOE range. The study delivers a recommended configuration and a repeatable optimization procedure.