As high-speed trains operate at a higher speed, the problem of rail wear is more serious. In this paper, a new Gaussian function correction (GFC) method is proposed to design the new rail profile, two parameters are introduced to control the removal area. Then a high-speed train vehicle dynamic model is established, the Kriging surrogate model (KSM) is used to reduce the number of simulations and the Non dominated sorting genetic algorithm-II (NSGA-II) algorithm is used to optimize the rail profile. Finally, the dynamic characteristics and wheel/rail wear evolution of the optimized profile are analyzed. The results show that the dynamic performance of the optimized rail profile has been improved. The maximum wear depth of the optimized rail profile is reduced by 15.63% when passing a total weight of 16 Mt. The wheel wear depth of S1002CN profile contact with CHN60OPT is reduced by 4.8%. The proposed GFC method can quickly generate a new rail profile and has good engineering significance for rail grinding. The GFC-KSM-NSGA- II method can be used to optimize the rail profiles for high-speed lines, and it can further guide the operation and maintenance.
In order to comprehensively consider the dynamic behavior of vehicle system and the contact forces between wheel and rail, the vehicle-track coupling model is established considering the flexible wheelset and rail modal characteristics. Guyan reduction theory is introduced to reduce the degrees of freedom of wheelset and rail and to improve the calculation speed. Due to small axle load variation of freight wagon operating on the special line for the coal transportation, the vehicles with different speeds and wheel flat lengths, whether in empty or loaded conditions, are simulated and then the mapping relations between the flat lengths and wheel/rail impact force are obtained. Subsequently, the fitting functions for the empty and loaded vehicles are fitted to quantitatively detect the wheel flat by trackside equipment. The results indicate that the fitting function of empty vehicle has a better effect on predicting the flat length within 6% error since wheel/rail contact force of empty vehicle induced by wheel flat increases with the increase of flat length, while that of loaded vehicle presents a parabola variation trend at low speed and increasing trend at higher speed.
The polygonal wear around the wheel circumference could pose highly adverse influences on the wheel/rail interactions and thereby the performance of the vehicle system. In this study, the effects of wheel polygonalisation on the dynamic responses of a freight wagon are investigated through development and simulations of a comprehensive coupled vehicle-track dynamic model. The model integrates flexible ballasted track and wheelsets subsystem models so as to account for elastic deformations caused by impact loads induced by the wheel polygonalisation. Subsequently, the vehicles with low-order polygonal wear, whether in empty or loaded conditions, are simulated at different speeds considering different amplitudes and harmonic orders of the wheel polygonalisation and thus the mapping relation between wheel/rail impact force and wheel polygonalisation is obtained. The results reveal that the low-order wheel polygonalisation except 1st order and 3rd order can give rise to high-frequency impact loads at the wheel/rail interface and excite 1st-bend modes of the wheelset and “P2 resonance” leading to high-magnitude wheel/rail contact force at the corresponding speed.
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