چكيده به لاتين
In the recent years, there have been advances in railway industry and increasing train speeds. Thus, the studies of design railway track and vehicles have been considered.
One of the defect is lack of suitable support sleepers or unsupported sleeper, because of improper maintenance, area weather situation and so on. In this regard, Conditions of track operation would disturb because of such defect in ballasted railway track, and would have negative effects on the dynamic behavior of the rail vehicle.
By investigating recent studies, it can be received that most of these studies have been in field of the unsupported sleepers effect on operation of track component and train-track interaction, and less attention has been paid on the rail vehicle dynamic behavior. Thus, in the present study, rail vehicle dynamic behavior is investigated by using 3D model of train and track.
Numerical modeling results are validated by using field test on the ballasted track and rail vehicle. The numerical model is done by using the finite element program (ANSYS) and the multibody dynamics program (SIMPACK). To use these programs, it is possible to design the unsupported sleepers on the railway flexible track.
Furthermore, by investigating rail vehicle behavior under effect of the unsupported sleepers, studies like ride comfort index, rail irregularities in accordance with the Federal Railroad Administrator and rail corrugation have been attended. Results present that rail displacement has different behavior when the number of unsupported sleeper and vehicle speed are changed. Although the effect of speed is insignificant on the rail displacement when the number of unsupported sleepers are less than 4, the rail displacement is increased, when the number of unsupported sleepers are increased. In this situation, when the vehicle has 30 and 110 km/h, and passes on the track having six unsupported sleepers, wheel-rail contact increases in comparison with track having one unsupported sleeper 8% and 67%, respectively. Moreover, driver cab acceleration increases 8% and 67%, respectively. While the ride comfort index is in the level of less than “uncomfortable”, the vehicle speed should be less than 70 km/h in track having one unsupported sleeper.
To investigate of the wheel-rail contact force, it can be concluding that the effect of class 1 irregularity is more than the effect of unsupported sleeper on the increase of wheel-rail contact force, in track having class 1 irregularity and the unsupported sleeper. It means that, varieties of the wheel-rail contact have dominant effects in competition with track having unsupported sleepers in track having class 1 irregularity. Moreover, tracks having unsupported sleeper and rail corrugation simultaneously, changes of wheel-rail contact force are different in various speed ranges. For instance, when track having rail corrugation with a wavelength 80 mm and an amplitude 0.05 mm, a wavelength 120 mm and amplitudes 0.05 and 0.1 mm, the increase of wheel-rail contact force in speed of 90 km/h is 41%, 30% and 28%, respectively, in track having six unsupported sleepers in comparison with track having one unsupported sleeper.
