Evaluation Of Train Seated-passenger Comfort Based On Whole-body Vibration Response And Optimization Of Seat Vibration Reduction

Comfort is the common focus of rail transit development in the world,which directly affects passengers’riding experience and travel choice.The general-speed train body vibrates violently and the passengers take a long time,resulting in the deterioration of the vibration comfort of the passengers increasingly prominent,which cannot meet the passengers’growing demand for a comfortable travel environment.Aiming at the above problems,this thesis carried out a study on the whole-body vibration comfort evaluation of the train seated-passengers and the optimization of seat vibration reduction.The main research contents and conclusions are as follows:（1）A series of field trials on the whole-body vibration comfort of the seated-passengers in the general-speed train were carried out,and the subjective and objective data of 18 subjects were obtained.These tests were performed on the China Railways 25K rolling stock with running on the Beijng-Guangzhou railway from Changsha to Shaoguan.The acceleration sampling frequency is 6000Hz,the subjective score is collected every 10 minutes,and the whole trials lasts 240 minutes.（2）The degradation law of passenger vibration comfort and the whole-body vibration response characteristics were analyzed.It is found that the human buttocks and back are in uncomfortable state for the longest time,accounting for 55%of the total time.Among the subjective scores of all local parts of the human body,the subjective scores of buttocks and back could better reflect the deterioration law of overall comfort.In addition,it’s found that the root mean square accelerations（RMS）values on the cushion surface in the z direction is the largest,and the RMS values on the seatback in the x and z direction are equivalent.The faster the train speed,the greater the RMS value,and the RMS values measured in the tunnel environment are higher than the open line.（3）Carried out research on occupant whole-body vibration comfort evaluation.An estimated vibration dose value（EVDV）index for the passengers’vibration comfort evaluation was proposed.The passenger vibration comfort evaluation model was constructed,and the limit value of the EVDV and the maximum endurance time(T_max)were determined.The research on the passengers’vibration comfort evaluation under different working conditions was carried out.The results show that with the increase of v and TR,the a_v value increases,the T_max value gradually shortens,the T_max value gradually shortens,and the time when passengers are overall uncomfortable duration increase,which up to 76.2%of the total time.（4）The optimization research of train seat vibration reduction was carried out.The 4DOF lumped-parameter biodynamic model for passenger-seat was constructed and verified.The input and output data sets required by the multi-objective optimization model are obtained through the"human-seat"Simulink model.The fourth-order polynomial response surface model is established,and the seat stiffness and damping of general train seat was multi-objective optimized based on the elitist strategy of the nondominated genetic algorithm（NSGA-II）.The results showed that the optimized RMS values of the lower trunk,upper trunk and head are reduced by over 28%compared with the values measured at traditional conditions,which proves that the optimized train seat can effectively improve the vibration comfort of the general speed train passengers.