Analysis On The Influence Of Skirt Board On Interior And Exterior Noise Of Suburban Train

Noise problem is a key factor in the development of rail transit.Compared with high-speed railway,the population along the suburban railway is more intensive.Moreover,the installation of sound barrier is limited due to the cost and other factors.Compared with the subway train,the suburban trains are mostly running on the elevated railway at higher speeds.Therefore,more attention needs to be paid to the noise impact on residents along the railway.Reasonable installation of skirt is one of the effective methods to reduce the train pass-by noise,but on the other hand,it will also have a negative impact on the train interior noise,reducing the passenger ride comfort.In this thesis,the following aspects of work are mainly carried out for the interior and exterior noise after installing the skirt.(1)Based on the ray tracing method,a simulation model of suburban train exterior noise is established.Considering the location of the sources,the amplitude-frequency characteristics and the sound absorption,sound insulation and diffraction characteristics of the skirt board,the influence of skirt parameters such as skirt location,skirt size and skirt sound absorption treatment on exterior noise is investigated.When the train runs at 140 km/h and the skirt installed at the bogies and auxiliary equipment,the exterior noise can be further reduced by 1.9 d BA from half shielding to full shielding,and the 25 m standard point exterior noise can be reduced by 3.3 d BA.Laying sound-absorbing materials inside of the full shielding bogies skirt can reduce the exterior noise by 4.0 d BA.(2)Based on the boundary element method,a simulation model of the car body acoustic response is established.According to the actual geometry size of the suburban train,the basic parameters of the train and the main noise sources,the excitation characteristics and transmission path of the sources are considered.The acoustic response of the car body surface were analyzed and calculated when the train without skirt,the skirt installed at the bogies,and the skirt installed at the bogies and auxiliary equipment.As the source excitation boundary for subsequent study of train interior noise.(3)Based on statistical energy analysis method,a simulation model of train interior noise is established.The vibration and sound radiation of wheel/rail source and the sound pressure level of auxiliary equipment which obtained from experiments are taken as the excitation input of source.The vibration of the car body plate obtained from experiments is taken as the structural vibration excitation.The validity of the model is verified by experiments.The influence of skirt location and skirt size on interior noise was investigated.According to the optimal results of sound insulation of car body structure and sound absorption of skirt,the interior noise reduction effect is evaluated.When the train runs at 140km/h and the skirt installed at the bogies,the interior noise will increase by 1.5 d BA.In order to eliminate the impact of the skirt on interior noise,the floor and door sound insulation can be increased by 5 d B.Installating skirt at bogies and auxiliary equipment will increase interior noise by about 3.0 d BA.By increasing the sound insulation of the floor and door by 6 d B,and the skirt is fully laid with sound-absorbing materials,the influence of the skirt on interior noise can be eliminated.The relevant research results can provide reference for the formulation of interior and exterior noise control measures of suburban train.