Modelling and analysis of passenger rail vehicle for the improvement of critical speed using MR damper based semi-active suspension

Developing economies focus to enhance train speed by introducing high speed corridors and upgrading existing rail infrastructure. Higher speed has adverse impact on vehicle stability and ride comfort. Therefore, in order to improve critical speed and ride comfort magneto-rheological (MR) based dampers are used. Here, the lateral dynamics of an Indian passenger rail vehicle is expressed with 17 degrees of freedom model and after validation, it is used to examine the effect of suspension parameters such as damping and stiffness on critical speed. Moreover, a sensitivity analysis is performed and it is found that critical speed is the most sensitive to secondary lateral damping coefficient. Therefore, these dampers are replaced with MR fluid dampers to evaluate improvement in stability and critical speed. The modified Bouc-Wen model is formulated to characterise the behaviour of the MR damper. Herein, two distinct controllers: disturbance refusal and damper force tracking control algorithms are employed to govern the entire system. Measured random track irregularities are applied as an input to simulate the system. The results reveal that the semi-active suspension improves the critical speed by 19.38 km/h (9.89%) when compared to the existing passive suspension, and significantly reduces the vibration responses of the carbody in a wide frequency spectrum at higher speeds of the train.