Study On The Design Of Acoustic Vibration Characteristics Of Lightweight Stiffened Plate Structure Of Virtual Track Train

With the continuous improvement of the living quality of city residents,people’s demand for the comfort of transportation vehicles is increasing,and the impact of vibration and noise on the vehicle is particularly significant in studying the riding comfort.The virtual track train has high requirements for the lightweight design of the train body due to using rubber wheel.However,lightweight design also brings challenges to the vibration and noise control of trains.At the beginning of the lightweight design,considering the interior noise of the virtual track train and its acoustic and vibration performance is the key problem which needs to be solved and has very important practical application value.Aiming at the design of sound insulation and acoustic radiation characteristics of the lightweight rib-plate structure in the virtual rail train based on the hybrid FE-SEA method and the periodic structure theory,considering the mid-frequency vibration problem of the lightweight rib-plate structure in the car body structure,it is proposed to design the acoustic and vibration performance of the car body at the initial stage of the structure design.In view of the rib-plate structure type studied in this thesis,based on the multi-objective optimization principle,the most suitable optimization algorithm is selected for several optimization design methods for common structures,which can effectively improve the sound insulation performance and acoustic radiation performance of the rib-plate structures of car bodies during realizing the lightweight of the car body.Aiming at the key problems of the design of the acoustic and vibration characteristics of the lightweight stiffened-plate structure in the virtual track train,the following research work is carried out.First,based on the test method,the interior noise spectrum and sound source distribution characteristics of the virtual rail trains in normal operation are investigated.The main sources and transmission paths of in-vehicle noise are determined,and the goal of structural optimization design is clarified.In the main source area of interior noise of vehicles,the sound transmission loss and vibro-acoustic radiation characteristics of the lightweight stiffened-plate structure are calculated based on the hybrid FE-SEA method,determining the vibro-acoustic characteristics to provide the subsequent design parameter indexes for multi-objective optimization.In the structural areas with significant acoustic properties,the influence of geometric parameters on the acoustic and vibration characteristics were analyzed based on the hybrid FE-SEA method and the periodic structure method,and the input parameters of the optimization design are clarified.The results show that the significant frequency bands of the interior noise of the virtual rail train are all at315～1000 Hz in the 1/3 octave band.The interior noise is mainly from the external noise through the floor structure,followed by the sidewall area and the roof area.For the floor structure and the sidewall structure,the selected parameters have an impact on the acoustic and vibration characteristics of the structure.Secondly,based on the hybrid FE-SEA method and the periodic structure method,combined with multi-objective optimization algorithm,three classical global optimization algorithms used in structural optimization design are selected to optimize the acoustic and vibration characteristics of the lightweight stiffened-plate structure in the virtual rail trains.According to the principle of optimization algorithm,the results of optimization design and computing costs of the periodic cell,a comprehensive analysis is carried out.Based on the parameters of the optimized periodic unit,the stiffened-plate structure model is re-established,and the optimization results are analyzed,the adaptability of these optimization algorithms is checked for the study of stiffened-plate structure.The results show that for the targeted parameters of the sidewall structure and the periodic cell,except for the slightly different optimization effect of the total radiated sound power level,the optimization effect of the quality and weighted sound insulation is same,which verifies the effectiveness and reliability of the optimization of the periodic structure method.For the computational cost of structural optimization,the MIGA takes much less time,which is44.3% lower than the ASA.Due to the large periodic structural elements of the lightweight rib-plate structure studied,the MIGA is more suitable considering the optimization effect and the calculating cost of the structure.Thirdly,according to the optimized optimization algorithm,the floor and sidewall structures of the lightweight rib-plate structure in the virtual track train body are optimized in the sound insulation and vibration-acoustic radiation characteristics.At the same time,the weight of the rib-plate structure is reduced,and the sound-insulation performance and vibration-acoustic radiation performance of the structure are improved.The results show that:based on the hybrid FE-SEA method and the periodic structure method,the optimal MIGA method is used to optimize the design of the acoustic and vibration characteristics of the lightweight rib-plate structure of the virtual rail train to meet the limit requirements for the multi-objective parameter optimization.The sound insulation performance is improved,the radiated sound power level is reduced,and the optimization goal is achieved.The thesis filtrates the optimization algorithms of acoustic and vibration characteristics suitable for lightweight stiffened-plate structure,which can realize the lightweight of the stiffened-plate structure of the virtual track train and improve the acoustic and vibration performance of the structure,providing a reference for the optimization design of acoustic and vibration characteristics of lightweight stiffened-plate structures.