Analysis of modal frequency optimization of railway vehicle car body

Abstract

High structural modal frequencies of car body are beneficial as they ensure better vibration control and enhance ride quality of railway vehicles. Modal sensitivity optimization and elastic suspension parameters used in the design of equipment beneath the chassis of the car body are proposed in order to improve the modal frequencies of car bodies under service conditions. Modal sensitivity optimization is based on sensitivity analysis theory which considers the thickness of the body frame at various positions as variables in order to achieve optimization. Equipment suspension design analyzes the influence of suspension parameters on the modal frequencies of the car body through the use of an equipment-car body coupled model. Results indicate that both methods can effectively improve the modal parameters of the car body. Modal sensitivity optimization increases vertical bending frequency from 9.70 to 10.60 Hz, while optimization of elastic suspension parameters increases the vertical bending frequency to 10.51 Hz. The suspension design can be used without alteration to the structure of the car body while ensuring better ride quality.

Numerical study on the influence of suspended equipments on the ride comfort in high speed railway vehicles

“…The weight lightening design of carbody implies using light materials and altering mechanical structures [3], which often leads to a lower carbody structural stiffness and, therefore, a decrease of the eigenfrequencies. The lighter the vehicle carbody, the higher its flexibility that will thus facilitate an easy excitation of the carbody structural vibrations that have a negative effect upon the ride comfort.…”

“…As principle, the results confirm that the frequency of suspended equipment should be sufficiently low and the equipment should have the largest possible mass and be mounted closest to the carbody centre, in order to have a significant reduction in the carbody flexible vibration. At the same time, there are studies suggesting new methods of designing the equipment suspension [3,12] or new solutions for this suspension requiring the use of highdamping elastic support [13].…”

“…[2,7,9,14,16]. A more complex representation of the carbody would use 3D rigid-flexible coupled models built in compliance with the multi body system (MBS) theory and the finite element method (FEM) [3,6,7,8,12,17]. In reality, more suspended pieces of equipment are mounted under the EMU underframe, as shown above.…”

“…For instance, Sun et al [3] built a model 3D with FE software HYPERMESH, in which an electropneumatic brake unit, charger, inverter, and battery system were included. Shi et al [7,18] set up a 3D rigid-flexible coupled vehicle system dynamics model for a passenger coach of EMU by ANSYS and SIMPACK where six equipment were mounted on the underframe, namely traction transformer, traction converter, braking unit, power inverter, waste discharge unit, effluent tank.…”

Modal Strain Based Method for Dynamic Design of Plate-Like Structures

“…However, the thin plate-like structures can be characterized by low flexural rigidity. The dynamic behaviours of these structures are important properties, because the natural frequencies and mode shapes of the thin plates usually need to satisfy the requirements of structural integrity, durability, and sound radiation when subjected to the shock and vibration loadings, which matters in different branches of engineering: automobile [1,2], naval [3], aeronautics and astronautics [4], and so forth.…”